Guidelines for Interpretation and Application of API 1104

Catalog No.L52306 Guidelines for Interpretation and Application of API 1104 PR-82681361-6 Prepared for the Pipeline Research Council International, Inc. Prepared by: DNV Columbus, Inc. Asset Risk Management 5777 Frantz Road Dublin, OH 43017-1386 Publication Date: April 2010 ACKNOWLEDGEMENTS This report is furnished to Pipeline Research Council International, Inc. (PRCI) under the terms of PRCI Contract No. PR-82681361-6 between PRCI and Det Norske Veritas (DNV). The contents of this report are published as received from DNV. The opinions, findings, and conclusions expressed in the report are those of the authors and not necessarily those of PRCI, its member companies, or their representatives. Publication and dissemination of this report by PRCI should not be considered an endorsement by PRCI or DNV, or the accuracy or validity of any opinions, findings, or conclusions expressed herein. In publishing this report, PRCI makes no warranty or representation, expressed or implied, with respect to the accuracy, completeness, usefulness, or fitness for purpose of the information contained herein, or that the use of any information, method, process, or apparatus disclosed in this report may not infringe on privately owned rights. PRCI assumes no liability with respect to the use of, or for damages resulting from the use of, any information, method, process, or apparatus disclosed in this report. The text of this publication, or any part thereof, may not be reproduced or transmitted in any form by any means, electronic or mechanical, including photocopying, recording, storage in an information retrieval system, or otherwise, without the prior, written approval of PRCI. Pipeline Research Council International Catalog No. L52306 Copyright 2010 All Rights Reserved by Pipeline Research Council International, Inc. PRCI Reports are published by Technical Toolboxes, Inc. 3801 Kirby Drive, Suite 520 Houston, Texas 77098 Tel: 713-630-0505 Fax: 713-630-0560 Email: [email protected] ii Final Report for Pipeline Research Council International, Inc. Guidelines for Interpretation and Application of API 1104 This report is furnished to Pipeline Research Council International, Inc. (PRCI) under the terms of PRCI Contract No. API-1-2 between PRCI and DNV Columbus, Inc. (DNV). The contents of this report are published as received from DNV. The opinions, findings, and conclusions expressed in the report are those of the authors and not necessarily those of PRCI, its member companies, or their representatives. Publication and dissemination of this report by PRCI should not be considered an endorsement by PRCI or DNV, or the accuracy or validity of any opinions, findings, or conclusions expressed herein. In publishing this report, PRCI makes no warranty or representation, expressed or implied, with respect to the accuracy, completeness, usefulness, or fitness for purpose of the information contained herein, or that the use of any information, method, process, or apparatus disclosed in this report may not infringe on privately owned rights. PRCI assumes no liability with respect to the use of, or for damages resulting from the use of, any information, method, process, or apparatus disclosed in this report. The text of this publication, or any part thereof, may not be reproduced or transmitted in any form by any means, electronic or mechanical, including photocopying, recording, storage in an information retrieval system, or otherwise, without the prior, written approval of PRCI. Revision No.: 1 Date: April 30, 2010 Page ii Final Report for Pipeline Research Council International, Inc. Guidelines for Interpretation and Application of API 1104 Table of Contents 1. 2. 3. 4. 5. INTRODUCTION ................................................................................................................. 1 BACKGROUND ................................................................................................................... 1 REVIEW OF INDUSTRY NEEDS AND PRACTICES....................................................... 2 FORMAT DEVELOPMENT ................................................................................................ 2 DEVELOPMENT OF GUIDANCE MATERIAL ................................................................ 3 5.1 5.2 6. 7. 8. 9. 10. Example 1 – Wall Thickness Groupings For Specification Information...................... 4 Example 2 – Essential Variable for Joint Design ......................................................... 4 INDUSTRY REVIEW........................................................................................................... 5 RESULTING GUIDANCE DOCUMENT............................................................................ 5 SUMMARY AND CONCLUSIONS .................................................................................... 6 ACKNOWLEGEMENTS...................................................................................................... 6 REFERENCES ...................................................................................................................... 8 Appendix A. Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities Revision No.: 1 Date: April 30, 2010 Page iii Some industry codes and standards contain guidance in the form of commentary sections or companion documents. For example. whereas the Revision No. and the rationale pertaining to how some of the requirements in API 1104 came about. Guidelines for Interpretation and Application of API 1104 1. lies with individuals who have been or were members of the committee for many years. There are often differences in the way requirements are interpreted because of unclear rationale behind the requirements or novel or non-traditional applications. and the applicability of the requirements to both conventional and modern high-strength pipelines.: 1 Date: April 30. This is not the case for API Standard 1104 – Welding of Pipelines and Related Facilities. many of the suggested ranges for procedure and welder qualification are nearly always taken literally. is the Twentieth Edition. Significant changes include the development of higher strength line pipe materials and the development of high-productivity mechanized welding equipment. Many new long-distance transmission pipelines are constructed today using high-strength line pipe materials and highproductivity mechanized welding equipment.Final Report for Pipeline Research Council International. BACKGROUND API Standard 1104 – Welding of Pipelines and Related Facilities. although many of the construction practices that were used then are still used today. Since API 1104 is written in the form of a specification. Many changes in the pipeline industry have occurred since the First Edition of API 1104 was introduced in 1953. In spite of these revisions. where requests for interpretation are common because of unclear requirements or an absence of information pertaining to rationale. Inc. For the majority of cross country pipelines constructed in the United States. which was issued in November 2005. many pipelines are still constructed using lower-strength material and conventional “stove-pipe” welding practices and the completed girth welds are inspected using radiographic testing (RT). The use of this guidance material will allow users and regulators to better understand the intent regarding interpretation of some requirements in API 1104. there are many requirements in API 1104 that are subject to interpretation. it cannot present background information or discuss the intent of the API 1104 committee. and the completed girth welds are inspected using automated ultrasonic testing (AUT) equipment. API 1104 is revised regularly to adapt to changing pipeline construction practices. An addenda/errata to the Twentieth Edition was issued in July 2007. INTRODUCTION The application of requirements contained in many industry codes and standards requires some interpretation by the user and by the regulator who is called upon to enforce their use. The objective of this project was to develop guidance material for API 1104.(1) is the most widely-used industry standard in the world for pipeline construction. The current version. In spite of these developments. The intent of the API 1104 committee. Unfortunately. the use of certain sections of API 1104 is mandated by Federal regulations. 2. the rationale behind the requirements. many of these individuals are no longer with us. 2010 Page 1 . REVIEW OF INDUSTRY NEEDS AND PRACTICES The needs of the industry with respect to what sections of API 1104 require clarification or supplementary guidance were reviewed. AWS B2.Oil and Gas Pipeline Systems(3) also contains a commentary document for this purpose. a very useful document that is part of the American Welding Society Certified Welding Inspector program was identified and used (with permission from AWS).(5) is a universal document that contains requirements for the qualification of welding procedures and for the performance qualification of welders and welding operators. Guidelines for Interpretation and Application of API 1104 intent is to allow flexibility.: 1 Date: April 30. etc. For example. and applicability of the code. There is also a database of previous requests for interpretations (technical inquiries). 4. AWS API-M:2006. A literature search was also performed to identify published journal articles. This on-line document includes inquiries that have been submitted from 1996 to the present. This can result in procedures that are less than completely sound when ranges that are too wide are specified or difficult to execute in the field when ranges that are too narrow are specified. Study Guide for API Standard 1104. 3. Other industry standards that contain guidance pertaining to topics of concern were also reviewed. There is a formal procedure for handling requests for interpretations within the API 1104 committee structure. Representatives from PRCI member companies were also informally surveyed to better define areas of concern.(2) would alleviate some of the concerns raised above.1. This document. conference papers.. The development of a guidance document for API 1104. In addition.1 is the most widely used reference for structural steel welding. it is anticipated that the format would follow the format of the API 1104 document itself. Structural Welding Code – Steel. 2010 Page 2 . no guidance is given as to what constitutes an acceptable range or grouping. This included a review of the API 1104 database for technical inquiries(4) to determine what topics or sections require the most frequent need for interpretation. Where additional guidance and/or a description of the rationale behind the requirement was determined Revision No. The lack of guidance gives regulators little support in terms of enforcement. but these can take weeks and sometimes take up to a full year to resolve. FORMAT DEVELOPMENT The required format for the guidance document was developed. similar to the commentary section contained in AWS D1.(6-8) that contain guidance that could be included in the document. Standard for Welding Procedure and Performance Qualification.1-84.Final Report for Pipeline Research Council International. rationale. The commentary section of this code provides users with valuable information pertaining to interpretation. AWS D1. The Canadian standard CSA Z662. Where the user does elect to specify another range or grouping. From the onset of this project.(9) contains section-by-section guidance pertaining to understanding and learning how to apply API 1104. but this only contains relatively recent inquiries (from 1996) and the existence of this database may not be apparent to the typical user. Inc. For example. Guidelines for Interpretation and Application of API 1104 to be necessary. it will be used as a look-up document) This repetition is intentional and is intended to provide the required guidance in each of the places where it is needed. The outline of the guidance document follows the outline in the API 1104 document itself. 5. API eventually declined a request to allow the use of the API 1104 text in the guidance document. 2010 Page 3 . one contained the text of API 1104 and the other contained the corresponding guidance material. The benefit of this format is that it allowed side-by-side comparison of the text in API 1104 with the guidance material. Discussions were held with personnel at API regarding the use of the API 1104 text in the guidance document. The resulting guidance document therefore contains only the guidance material. Some of the guidance material is repeated in several places in the guidance document. they were reluctant to allow the text of API 1104 to be reproduced in the guidance document. which will require that both documents be available to the user for effective use of the guidance document. but that certain sections will be referred to on as needed basis (i. For example. DEVELOPMENT OF GUIDANCE MATERIAL The majority of the effort for this project focused on the development of material for the guidance document. someone who is qualifying procedures for mechanized welding (Section 12) may not think to look in Section 5 (procedure qualification for manual welding) for essential variable guidance pertaining to preheating and inter-pass temperature..3.2.2. Tables and figures in the guidance document are also preceded with the letter “G” to differentiate between these and the tables and figures in API 1104 itself. Since API 1104 is a top-selling document for API.e. Inc. Where necessary.11. The draft of the guidance document included two parallel columns. guidance material for this section can be found in G5. These resources included: • • • • AWS API-M:2006 – Study Guide for API Standard 1104 API 1104 Technical Inquiries Database CSA Z662 – Oil and Gas Pipeline Systems – code and commentary ASME Section IX – Welding and Brazing Qualifications(10) Revision No. Sections of the guidance document are preceded with the letter “G” for “guidance”.3. items that were determined to be in need of guidance were researched to identify the source of the requirement and the rationale behind the requirement. It is anticipated that this document will not be read cover-to-cover. it was developed and included in a draft of the guidance document. so the guidance material is provided in both places. The guidance material was developed from this and using a variety of resources.: 1 Date: April 30.11 in API 1104 is titled “Type and Removal of Lineup Clamp”. Where the requirement is self-explanatory. In the guidance document. 5.Final Report for Pipeline Research Council International. either outright or through a revenue sharing agreement. this was indicated in the draft document. the thickness range qualified according to ASME Section IX is 3⁄16 inch (5 mm) to 2t. Guidance pertaining to Appendix B of API 1104 (in-service welding) was also developed. Inc. indicates: The suggested groupings shown in 6.1 Example 1 – Wall Thickness Groupings for Specification Information When developing a welding procedure.2.2. are provided below: 5.4. both of which pertain to qualification of welding procedures (Section 5 in API 1104).1:2000.4.Final Report for Pipeline Research Council International.1-84 – Standard for Welding Procedure and Performance Qualification AWS D1. 5. Other groupings can be used provided that there is technical justification for doing so based on sound engineering judgment. where t is the wall thickness used for procedure qualification.2. items d and e. Two examples that describe the development of the guidance material.3.3 of API 1104 (essential variable requirements for joint design) indicates: Revision No. For example.1).3.2. LLC. 2010 Page 4 . Guidance can be found in a variety of other codes and standards. Guidelines for Interpretation and Application of API 1104 • • • • • AWS B2. AWS B2.2 was taken from ASME Section IX (QW-451).1-84 includes this same provision (Paragraph 2. Guidance pertaining to Appendix A of API 1104 (alternative acceptance standards based on fitness-forpurpose criteria) was developed by Yong-Yi Wang at Center for Reliable Energy Systems. some codes limit wall thickness to which the procedure is applicable from some minimum thickness to 2t.3 of API 1104 (specification information for diameters and wall thicknesses) indicates: The ranges of outside diameters and wall thicknesses over which the procedure is applicable shall be identified. the guidance that was developed pertains to both conventional pipelines constructed using conventional stove-pipe welding practices and modern high-strength pipelines constructed using high-productivity mechanized welding equipment.2.2 Example 2 – Essential Variable for Joint Design When determining the applicability of a qualified welding procedure. 5. For procedures qualified on material that is over 3⁄8 inch (10 mm) thick but less than 3⁄4 inch (19 mm) thick.2.: 1 Date: April 30. items d and e are just that – suggested groupings. Examples of suggested groupings are shown in 6.2. 5. The suggestion that some minimum thickness to 2t might be a reasonable alternative to the wall thickness groupings shown in 6. Structural Welding Code – Steel Proposed revisions to API 1104 (from committee member correspondence) Project team member experience Inquiries to PRCI member company representatives To the extent that it was possible.2. in part. The guidance material for 5.3. These included current members of the API 1104 committee. Comments and suggestions from these individuals were incorporated into the draft sections. former (retired) committee members. The final version of the guidance document is provided in the appendix of this report. However.: 1 Date: April 30. thus requiring that a new procedure be qualified. The suggested ranges given in the guidance material were taken from CSA Z662 (Clause 7.4. a branch connection can consist of a groove weld and a fillet weld. 7. in part. as appropriate. Minor changes in the angle of bevel or the land of the welding groove are not essential variables. these were sent to various industry representatives for review. The guidance material for 5.Final Report for Pipeline Research Council International. and 1104-I-0608-04). and other interested individuals. thus requiring that a new procedure be qualified. Inc.5) for manual or semi-automatic welding. Periodic Revision No. The primary focus of this task was the development of an easy to read.50% of the nominal value without the need for requalification. It would seem reasonable to allow changes to the bevel angle of up to + 20%/-5% of the nominal value and changes to the root opening or land of up to +/. a welding procedure qualified by welding a full encirclement sleeve (fillet weld only) is not sufficient for welding a branch connection that includes a groove weld. However. A change from a fillet weld to a groove weld of a branch connection is also a major change in joint design.6.3. 1104-I-0810-96. a welding procedure qualified for a branch connection (groove and fillet weld) is sufficient. indicates: API 1104 does not define what constitutes a minor change in joint design.3 also indicates A change from a butt weld to a fillet weld is a major change in joint design. The guidance material for 5. each the draft sections was used to develop a final version of the guidance document. INDUSTRY REVIEW As draft sections of the guidance document were developed. Therefore. RESULTING GUIDANCE DOCUMENT Following review and revision. for welding fullencirclement sleeves that involve only fillet welds. The guidance material that was developed pertains to the Twentieth Edition of API 1104 (November 2005) as amended by the addenda/errata that was issued in July 2007.2. This guidance material was derived from a combination of responses listed in the API 1104 Technical Inquiries Database (Inquiry Nos. representatives from PRCI member companies. federal regulators in the US. 2010 Page 5 . cohesive document that will be useful to both users and regulators. Guidelines for Interpretation and Application of API 1104 A major change in joint design (for example.2. 1104-I-1122-96. from V groove to U groove) constitutes an essential variable. 6.4. now with US Revision No. the rationale behind the requirements. The guidance document contains a disclaimer in the Forward section that reads as follows: The guidance material contained in this document is not part of the API 1104 standard and it has not been reviewed or approved by the committee responsible for API 1104 (API-AGA Joint Committee on Oil and Gas Pipeline Field Welding Practices). Ken Lee (Lincoln Electric Company. While the authors believe that guidance document provided in the appendix of this report will indeed be useful to both users and regulators. 9. this guidance material does not provide formal interpretations of the standard. Alan Beckett (Alyeska Pipeline Service Company). For example. The use of this document will also increase the safety and reliability of newly constructed pipeline by avoiding misinterpretation of requirements. Inc. SUMMARY AND CONCLUSIONS The use of the resulting guidance document will allow both users and regulators to better understand the intent regarding the interpretation of some requirements. ACKNOWLEGEMENTS The authors would like to thank those individuals who contributed to the development of the guidance material. 8. To request formal interpretations by the committee. The Forward section goes on to say the following: The guidance material contained in this document includes the opinions of the authors and contributors and not necessarily those of API or PRCI. In addition to periodic updates. James Barber (Marathon Pipe Line LLC). Geoff Rogers (Spectra Energy).Final Report for Pipeline Research Council International. These individuals include. further revisions of the guidance document can incorporate expanded guidance for these less-comprehensive sections. either through direct contributions of material or by reviewing drafts of the guidance material. the procedure outlined in the Forward section of API 1104 should be followed.: 1 Date: April 30. the guidance material for some sections is more comprehensive than for others. Guidelines for Interpretation and Application of API 1104 updates to the guidance document will be required as subsequent editions of API 1104 are published. Jan van der Ent (Applus RTD). 2010 Page 6 . but are not limited to. Accordingly. This may in turn reduce the cost of pipeline construction and maintenance activities. It will also allow users to confidently tailor welding procedures to better fit the requirements for their specific needs without fear of violating arbitrarily established ranges and groupings. a planned update and refinement of this document will be beneficial. and the applicability of API 1104 to both conventional and modern high-strength pipelines. there are certainly improvements that are possible. While the authors believe that the guidance document provided in the appendix of this report will indeed be useful to both users and regulators. Gery Bauman (US Department of Transportation). who conceived the idea of this project and acted as the project leader for PRCI. Revision No. 2010 Page 7 . The authors would also like to thank Steve Rapp (Spectra Energy). Inc.: 1 Date: April 30. Permission from American Welding Society for the use of the existing guidance material in AWS API-M:2006 (Study Guide for API Standard 1104) is also greatly appreciated. Guidelines for Interpretation and Application of API 1104 Department of Transportation). Jim McHaney (Microalloying International).Final Report for Pipeline Research Council International. the PRCI project team members. and Bob Wright (retired API 1104 committee member). and Tara Podnar and Libby Brannon at DNV for their contributions in the early stage of this project. Joe Kiefer (ConocoPhillips). 5. International Pipeline Conference – IPC 2006 (Calgary). Canadian Standards Association.. W. Ontario. 2010 Page 8 . Inc. Welding of Pipelines and Related Facilities. Underwood. 1. Bruce.. Liu. 2006. 3. American Petroleum Institute. Canada. New York. M. 8. 9. Study Guide for API Standard 1104. American Welding Society. REFERENCES API Standard 1104. 10. American Welding Society.1-84. “A Tiered Approach to Girth Weld Defect Acceptance Criteria for Stress-Based Design of Pipelines”. 7. Florida. Miami.-Y. Florida. Horsley. API 1104 Technical Inquiries Database – http://committees. July 2007. New York.org/standards/tech/ pplnti.api. and Bauman. Washington. 2005. Florida.Final Report for Pipeline Research Council International. C. 6. 4. CSA Z662-03. 2006. Miami. Revision No. Mississauga. AWS API-M:2006. February 1979.” International Pipeline Conference – IPC 2000 (Calgary). A.. 2.. American Welding Society. Standard for Welding Procedure and Performance Qualification. 1984. D. Miami.” Welding Design & Fabrication. 2003. ASME Boiler and Pressure Vessel Code. Wang Y..C. A. “It Pays to Understand Pipeline Standards. American Society of Mechanical Engineers. Structural Welding Code – Steel.. “Recent Changes in Code Requirements for Repair of In-Service Pipelines by Welding. G. 2000.1:2000.: 1 Date: April 30. D.html AWS B2. Guidelines for Interpretation and Application of API 1104 10. 2000. Section IX: Welding and Brazing Qualifications. Oil and Gas Pipeline Systems. AWS D1. Appendix A Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities . E.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities PRCI Project No. Inc.1 William A. Bruce. API 1-2 – Interpretation and Guidelines for Application of API 1104 DNV Columbus. P. P.. 1 2 Except Appendix A Appendix A only Revision 1 – April 30.D. Center for Reliable Energy Systems. 2010 . Ph. IWE William E. LLC2 Yong-Yi Wang. Amend.E. As indicated in the Forward section above. Both have similar requirements for making a test weld and then subjecting that weld to a variety of tests. While similar. However. 2. It was not possible to include the text of API 1104 in this document because of copyright restrictions. the outline of this document follows that in API 1104. Another common source of error is misunderstanding essential variable requirements. and vice versa. General Comments 1. The guidance material contained in this document is not part of the API 1104 standard and it has not been reviewed or approved by the committee responsible for API 1104 (API-AGA Joint Committee on Oil and Gas Pipeline Field Welding Practices). The guidance material contained in this document includes the opinions of the authors and contributors and not necessarily those of API or Pipeline Research Council International (PRCI). Therefore. the procedure outlined in the Forward section of API 1104 should be followed. It makes little sense to read the guidance material only. A common source of error when using API 1104 is confusing requirements for welding procedure qualification (Section 5) and those for welder qualification (Section 6). Revision 1 – April 30.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities i Forward The objective of this document is to provide guidance material for American Petroleum Institute (API) Standard 1104 – Welding of Pipelines and Related Facilities that will allow users and regulators to better understand the intent regarding interpretation of some requirements in API 1104. and the applicability of the requirements to both conventional and modern high-strength pipelines. the rationale behind the requirements. it was not possible to include the text of API 1104 in this document. it is necessary to have a copy of API 1104 open in front of you for the guidance material to make much sense. The guidance material contained in this document pertains to the Twentieth Edition of API 1104 (November 2005) as amended by the Errata/Addenda issued in July 2007. Updates to this guidance material will be required as subsequent editions of API 1104 are released. this guidance material does not provide formal interpretations of the standard. It is strongly suggested that you read the paragraph in API 1104 and then read the guidance material that corresponds to that paragraph. To request formal interpretations by the committee. Accordingly. It is therefore necessary to use this document in conjunction with a copy of the API 1104 standard itself. 2010 . The essential variables for welding procedure qualification are different than those for welder qualification. there are subtle differences between these two sections. Special attention should be given to assure that the requirements in Section 5 are applied to welding procedure qualification and the requirements in Section 6 are applied to welder qualification. ...............................................................................................7 Retesting................................................ 21 G7.....8 Records...................................2 Record ................................ 4 G5 Qualification of Welding Procedures for Welds Containing Filler-metal Additives......................................................................................5 Destructive Testing ................................2 Alignment................................................................................................................. 20 G7....................................................................... 14 G5............................................. 15 G6..............................10 Identification of Welds.....................................................................................................................................................7 Welding of Test Joints-Fillet Welds ................... 2 G4 Specifications ..................................................... 4 G4.......................................................................................................................................... 21 G7................................................................................................................................... 5 G5.................................................................................................................................................................... 18 G6........................................................6 Clearance............................................................................ 11 G5....................................................................................9 Roll Welding ...... 14 G6 Qualification of Welders...............................................and Post-Heat Treatment ............ 20 G7............................................................................... 19 G7................................................11 Pre.......................................................................................................................... 17 G6.8 Testing of Welded Joints-Fillet Welds.................................................................................... 21 Revision 1 – April 30........................................................................ 2 G3........................1 Equipment ........................................................................................................................................................................................................................................... 16 G6...................2 Single Qualification .........................................................1 General ........ 5 G5............................. 2010 .........................................................1 Procedure Qualification ................................................................................................................................................................................... 19 G7 Design and Preparation of a Joint for Production Welding .... 15 G6..4 Visual Examination............................................................. 19 G7.................................. 15 G6............................................1 General ................................................ 20 G7............... 1 G2 Referenced Publications..... 9 G5.............................2 Definitions........................ 17 G6................................................................................. 5 G5..........Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities ii Contents G1 General ............................................... 1 G1.....................................................5 Welding of Test Joints-Butt Welds...............................4 Essential Variables................... 20 G7........................................................................ 21 G7....................................................................................................................................................... 1 G3 Definition of Terms. 4 G4........................ 5 G5..........................1 General ...........................................................................................4 Bevel ......................6 Testing of Welded Joints-Butt Welds ................................................................................ 18 G6......................... 11 G5.................................................6 Radiography-Butt Welds Only.............................................................3 Multiple Qualification.3 Procedure Specification ...........................................................2 Materials........3 Use of Lineup Clamp for Butt Welds ................... 2 G3............................5 Weather Conditions.....................................................................1 Scope............................... 19 G7.......................................................................................................................................7 Cleaning Between Beads .................................................................. 20 G7........................................................................8 Position Welding.... .....5 Welder..................................... 23 G9...... 24 G9...............................................5 Essential Variables................................1 Acceptable Processes ..................................... 34 G10............. 47 G13................................................................. 46 G12.......................... 37 G12 Mechanized Welding with Filler Metal Additions ...............................11 Radiographic Testing ........ 33 G10............... 22 G8.................1 Rights of Inspection .................................................................................................................................4 Magnetic Particle Testing .... 33 G10............................................................. 26 G9............................................................................................. 40 G12.................. 40 G12......4 Ultrasonic Test Methods .................................7 Records OF Qualified Operators..................................................1 Radiographic Test Methods ..................................................................................................... 34 G11...... 2010 ... 33 G10..... 40 G12......................7 Visual Acceptance Standards for Undercutting ............................................................................2 Procedure Qualification ...................................... 47 G13............ 22 G8.........3 Record ...2 Rights of Rejection..............................................................2 Methods of Inspection.............. 23 G8..........................................................5 Liquid Penetrant Testing........................................................................ 23 G9 Acceptance Standards for Nondestructive Testing ............................................................................................... 34 G10........................................................................Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities iii Contents (continued) G8 Inspection and Testing of Production Welds ............................. 34 G11....................... 47 Revision 1 – April 30.............................................................................metal Additions ................................ 40 G12....................................................... 47 G12........................................................ 27 G9......10 Repair and Removal of Defects .......................................................................4 Supervision........ 24 G9........................ 45 G12................................................................................3 Liquid Penetrant Test Method................................................................... 47 G13 Automatic Welding Without Filler........................................................ 27 G9...................................................................................... 37 G11.................................................................................................. 44 G12...3 Radiographic Testing ..................................................................................................................................................................................................................... 46 G12....................2 Procedure Qualification ..........................................................................................2 Magnetic Particle Test Method ................................................................. 33 G10 Repair and Removal of Defects ................................ 23 G9...........8 Inspection and Testing of Production Welds ..........................................1 General ................. 22 G8.......................................................................................... 46 G12......................6 Qualification of Welding Equipment And Operators .............................................................................................................................4 Procedure Specification ...........................................................................................................3 Acceptance Criteria.................................................................4 Certification of Nondestructive Testing Personnel........................ 36 G11............. 34 G11 Procedures for Nondestructive Testing................................................................ 40 G12.................3 Qualification of Inspection Personnel.................................6 Ultrasonic Testing ........2 Repair Procedure....................................................................................................................................................................................1 Authorization for Repair ....................................9 Acceptance Standards for Nondestructive Testing ..............................................1 Acceptable Processes ................................................................................................................ .....1 General ............................................................................. 51 GA......11 Radiographic Procedure.............................. 48 G13. 49 Appendix A................................................................................................................. 53 GA.2 Mechanical Property Testing ...................................... 57 GA........ 49 G13................. 58 GA............................................................7 Repairs...............................5............................10 Repair and Removal of Defects .......3........................ 52 GA..............1 Planar Imperfections .....................................6 Qualification of Equipment and Operators ....1 Axial Design Stress .........3 Welding Procedure.............................................................5 Inspection and Acceptable Limits.................................................................................................................2 Cyclic Stress................................................... 58 GA........... 57 GA........................ 56 GA.. 55 GA..................................3 Arc Burns .................................................................................................................................2..................................................................... 49 G13......................................... Alternative Acceptance Standards for Girth Welds GA.............................................................................................. 49 G13..............................Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities iv Contents (continued) G13...................................................................................................................5....................... 53 GA........................................................................................................................................... 52 GA......................................................4 Imperfection Interaction.................. 2010 .................. 58 GA.................................................................................. 49 G13................................................ 52 GA...............8 Quality Assurance of Production Welds.......................................................................... 48 G13......5 Residual Stress ................3..............5............................... 58 GA..........................................8 Nomenclature ..............................................................................................................................................................................1 General ...........................2................................... 48 G13.......................................................................................................................9 Acceptance Standards for Nondestructive Testing .....4 Procedure Specification .........................3 Sustained-Load Cracking .......... 58 Revision 1 – April 30........... 50 GA....................................... 51 GA....................5 Essential Variables...................................................................................2.............................................................................................................. 58 Ga...5..........................................................................................2 Acceptable Limits of Volumetric Imperfections...........4 Qualification of Welders ......................... 48 G13.......2...........................................................7 Records of Qualified Operators .............................4 Dynamic Loading............. 53 GA......................................................2 Stress Analysis ....6 Record .....................2.......3 Record . 4...... 60 Gb..................... 62 GB..........................................................................3 In-Service Welder Qualification .......................................................1 Welding of Test Joint ................................................. 59 GB.......................................3...................................................... 2010 ........3................... 67 GB...................2.........6 Standards of Acceptability: Nondestructive Testing (Including Visual) ...3.....................Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities v Contents (continued) Appendix B.......................................................................................................................2............................................................................................................... 68 GB...........7 Repair and Removal of Defects.............................. 60 GB.................................................................................................... 69 Revision 1 – April 30........................................5 Inspection and Testing of In-service Welds .........................................................................................................................................................................4 Testing of Welded Joints........... 66 GB..................3 Records..................... 63 GB............................ 67 GB.................1 General ......................................1 Alignment.......................................................2 Qualification of In-service Welding Procedures ....4.................................3 Welding of Test Joints............2.... In-Service Welding GB..................... 62 GB. 69 GB.................. 67 GB.......................................... 67 GB..............................2............................................ 68 GB....................4 Suggested In-service Welding Practices .................. 69 GB.......2 Essential Variables .......2 Testing of Welded Joints.............................................1 Procedure Specification ..............................2 Welding Sequence....................... • Gas tungsten arc welding (GTAW). The use of nonstandard names for welding processes and NDT techniques should be avoided. • Flux-cored arc welding (FCAW). • Self-shielded flux-cored arc welding (FCAWS). 2010 . Common industry abbreviations and nonstandard names for the nondestructive testing (NDT) techniques covered in API 1104 are: • Radiographic testing (RT). In addition. Non-typical applications requiring additional equipment. • Oxyacetylene welding (OAW) or oxy-fuel welding (OFW). mechanized. • Gas-shielded flux-cored arc welding (FCAWG). also called stick welding. it may not address all issues that may arise during work included in this scope. • Submerged arc welding (SAW). Methods of application that are covered in API 1104 include manual. • Flash butt welding (FW). or automatic. such as: • Pulsed gas metal arc welding (GMAW-P). Established industry practice and other industry standards may provide useful reference to establish sound engineering practice. 2. • Liquid penetrant testing (PT). also called metal inert gas (MIG) or metal-active gas (MAG) welding. Definitions of these are provided in Section 3 of API 1104. The absence of guidance or requirements should not be considered to prohibit a particular activity or approach that is based upon sound engineering judgment. also called subarc welding. • Plasma arc welding (PAW). also called gas welding. The welding processes for which each method of application is generally applicable are shown in Table G1. also called Magnaflux® or MPI. • Ultrasonic testing (UT). Table G1 – Welding Processes and Generally Applicable Methods of Application Process Manual Semiautomatic Mechanized Automatic SMAW 1 SAW 2 1 GTAW 1 2 GMAW 1 1 FCAW 1 2 PAW 1 2 OAW 1 FW 1. also called Sonaray testing. also called tungsten inert gas (TIG) and heliarc welding. also called x-ray or gamma radiation testing.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 1 G1 General G1. semiautomatic. • Automated Ultrasonic testing (AUT) • Magnetic particle testing (MT). Common applications used in industry. 2 1 Revision 1 – April 30. While API 1104 is comprehensive. • Gas metal arc welding (GMAW). • Visual testing (VT). G2 Referenced Publications The footnotes provide full names and contact information for the organizations identified by acronyms in this section.1 SCOPE Common industry abbreviations and nonstandard names for the welding processes covered in API 1104 are: • Shielded metal arc welding (SMAW). several of the welding processes listed above have process variations. also called dye testing or dye penetrant testing. 2. fisheye: An imperfection attributed to the presence of hydrogen in the weld. soldered. faying surface: The mating surfaces of two parts that are to be welded together. filler metal: The metal or alloy to be added in making a brazed. The plunger is forced toward the die. and promotes the union of the metals being joined. post-weld heat treatment: Heat treatment carried out at high temperature (1100 to 1250°F [600 to 675°C]) after completion of welding to relieve residual welding stresses and/or to temper hard weld microstructures.13 and G7.0. Standard Welding Terms and Definitions.ER70S-6.2 G3. See Section 9 for a list of types of imperfections and the criteria that may allow them in a weld. 2010 . lineup clamp: An external or internal device used to bring two pipe segments into acceptable alignment for pre-weld tacking or for welding. Definitions for additional key terms that appear in API 1104 that are not included in 3. fillet weld: A weld of approximately triangular cross section joining two surfaces approximately at right angles. raised above the surface of the parent metal in excess of what is required to fill a groove joint on the side of the base metal from which welding was done. flux: A substance that hinders or prevents oxide formation.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 2 G3 Definition of Terms G3. See Figure G1 in Section G5. destructive testing: Testing that renders the material or weld useless for service.11. nick-break test: A destructive test that judges the soundness of a weld by fracturing the specimen through the weld so the fractured surfaces can be examined for the presence of imperfections. image quality indicator (IQI): Previously referred to as a penetrameter in API 1104. butt weld: A nonstandard term for a weld in a butt joint. Examples of AWS classifications include for SMAW .E7018.2 are shown below: bend test: A soundness and ductility test in which a specimen is placed across the shoulders of a die. A device used to measure the quality of radiographic images. which is a joint between two members aligned approximately in the same plane. and for GTAW . with additions and modifications as shown in 3. discontinuity: An interruption or irregularity in an otherwise uniform structure. face reinforcement: A weld metal build-up.3. Revision 1 – April 30. Not all discontinuities. or indications are rejectable. classification number: A number/letter designation in an American Welding Society (AWS) or other numbering system that identifies electrodes and filler metals according to their chemistry and operating characteristics. It is placed on the weld prior to radiography and must be visible when viewing the resulting film. imperfections.2. post-heat: The heat applied after completion of welding. preheat: The heat applied to a base metal immediately before welding. API 1104 does not use the word discontinuity but rather calls them indications or imperfections. Also used to describe the temperature of the base metal immediately before welding. observed on the fracture surface of a weld in steel that consists of a small pore or inclusion surrounded by a round bright area. procedure qualification record (PQR): A document containing the actual values recorded during welding of a test weld and the test results necessary to comply with a given code or standard. performed to obtain information on material properties and soundness. or welded joint. Also referred to as maintenance of preheat temperature. See guidance in G5. A plunger is positioned such that the area of interest is opposite the plunger.1 GENERAL Welding terms used in API 1104 are based on definitions in AWS A3.2 DEFINITIONS Definitions for key terms that appear in API 1104 are provided in 3. for GMAW . causing the specimen to bend into a U shape. essential variable: A component of a welding procedure specification that requires requalification if changed beyond certain limits specified in the applicable code.EWTH-2. 4 contractor: No guidance material required. Quenched and Tempered Alloy Steel Plate. Examples include AWS A5. Trepanning is generally not permitted for production piping applications. tensile-strength test (also called tension test): A test in which the specimen is subjected to a pulling load until failure occurs. A branch weld can consist of a groove and/or fillet weld. expressed in pounds per square inch (psi) or megapascals (MPa).2. for examination of the weld. stripper beads: Weld passes deposited primarily on the sides of pipeline girth welds in the fixed position to even out the weld cross-sectional thickness prior to depositing the cap pass. G3.. welding procedure: An activity undertaken according to a set of specific instructions provided in a welding procedure specification.2. G3. trepanning: A process for removing a specimen from a welded seam. Standard Specification for High Yield Strength.2.1. underfill: Weld metal that is insufficient in meeting the full thickness of the parent metal due to inadequate filling of a groove joint from the side of the base metal from which welding was done. which seems to imply that a branch weld is a fillet weld. welding bug: A mechanized device that provides movement of the welding torch around the pipe.6 imperfection: required.2. welding procedure specification (WPS): A document that provides the welding variables required for a specific application to assure repeatability by properly trained welders and welding operators to the requirements of a given code or standard. set on the pipe) or it can be set into the pipe wall.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities relevant indication: An indication produced by nondestructive testing that is caused by an imperfection (as opposed to a geometric feature. yield strength: The amount of stress necessary to make a material exhibit a specified permanent deformation under load. G3. Test results are expressed in pounds per square inch (psi) or megapascals (MPa). Specification for Welded Joints in Machinery and Equipment. welder qualification test report (WQTR): A document that identifies the variables and the test results necessary to verify a welder’s ability to perform a procedure to the requirements of a given code or standard. soundness: Freedom from defects. speed of travel: The rate of welding progression along the weld joint. G3. for example).e.2. Also an abbreviated form of welding procedure specification. see Table G1-1 in Section G1. specification number: The number assigned to a document that describes the attributes of some item or operation.1 automatic welding: For methods of applications that are applicable for various welding processes. ASTM A 514. and AWS D14. socket weld: A fillet weld joining two pipes or pipe fittings. shielding atmosphere: A protective gas or vacuum envelope surrounding the welding arc to prevent or reduce contamination of the weld by the ambient atmosphere. Revision 1 – April 30. The hole is cut so the inspector can look inside the pipe to verify the degree of penetration or so the portion of the weld that is removed can be destructively examined. No guidance material G3.5 defect: No guidance material required. using a hole saw for example.2. Specification for Covered Carbon Steel Arc Welding Electrodes. one of which is inserted into the other.4. G3.3 company: No guidance material required. G3.2. The branch can be welded to the outside of the pipe wall (i.2 branch weld: This revised definition of ‘branch weld’ appeared in the July 2007 errata/addendum to API 1104 and was intended to alleviate the confusion caused by Figure 10.7 indication: No guidance material required. The branch can consist of a pipe or a fitting. 3 wagon tracks: Parallel elongated slag inclusions in the root region that are separated by approximately the width of the root bead. 2010 . sound metal: The metal that remains after a defect has been removed. Low-hydrogen electrodes that have exceeded their atmospheric exposure limit must be discarded or reconditioned (re-dried).12 qualified welding procedure: No guidance material required. G3.2..1 Type and Size Filler metals must conform to one of the AWS filler metal specifications listed. Welding while the pipe is stationary.16 root bead: No guidance material required. G3. G3. rolling the pipe. New AWS filler metal specifications are occasionally introduced. As with storage and handling. Revision 1 – April 30.2.2. G3.2.2.2. and excessive changes in moisture. tees.17 semiautomatic welding: For methods of applications that are applicable for various welding processes.1.g. where “XX” represents the ultimate tensile strength level in ksi) should not be allowed to pick up (absorb) an excessive amount of moisture from atmospheric exposure prior to use. Until these are included in 4.2.15 roll welding: Roll welding refers to rolling the pipe while the weld metal is being deposited. Low-hydrogen electrodes (predominantly AWS EXX18-type.2.20 welder: Refers to a person. G3.). G4. their use requires a separate qualification in accordance with the requirements of Section 5. reducers. deterioration.14 repair: Repair refers to repair of welds.2.13 radiographer: No guidance material required. vented ovens at prescribed temperatures.2. G3. G4.1 Pipe and Fittings 4 Pipe and fitting materials must conform to API Spec 5L.10 position welding: No guidance material required. Excessive moisture can lead to elevated weld hydrogen levels and can contribute to heat-affected zone (HAZ) and weld metal hydrogen cracking. after opening their container.1.8 internal concavity: Also called suck-back.2. G3. but to flanges and valves as well. or must be separately qualified for use in accordance with the requirements of Section 5 of API 1104.2. Since different low-hydrogen electrodes behave differently with respect to moisture absorption.2. an applicable ASTM specification. elbows. or have chemical and mechanical properties that comply with one of these specifications.2. 2010 . it is important to follow the specific electrode manufacturer’s recommendations for storage and handling. Low-hydrogen electrodes from some manufacturers may require conditioning (drying) prior to use. see Table G1-1 in guidance material for 1. see Table G1. G3. Manufacturers recommend that.2. Not to be confused with a welding machine.9 mechanized welding: For methods of applications that are applicable for various welding processes. G4.1 EQUIPMENT Appropriate equipment should be used to ensure that all of the variables specified in the welding procedure can be achieved in safe manner.18 shall: No guidance material required.2 MATERIALS G4.2. It is common for companies to consider this standard applicable not only to pipe and fittings (e.2 Storage and Handling of Filler Metals and Fluxes API 1104 requires protection of filler metals and fluxes from damage. G3. G3. Weldor is a nonstandard term.2 Filler Metal G4.2.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities G3.2. G3.11 qualified welder: No guidance material required. G4.2. and then welding again (sometimes referred to as quarter welding) is position welding (not roll welding). etc.2. G3.2.19 weld: No guidance material required. Not to be confused with pipeline repair using fullencirclement sleeves. for example. lowhydrogen electrodes should be stored in heated. G4 Specifications Several pertinent aspects related to equipment and materials for welding of pipelines and related facilities are specified in this section. Examples of active gases include carbon dioxide and oxygen.1 PROCEDURE QUALIFICATION The phrase “before production welding is started” has no specific time limit. and other industry codes.S Department of Transportation. More specifically. PR-185-04508." Final Report to Pipeline Research Council International and U. Other welders then may qualify to perform the same welding procedure. 5 G5. the diameter and wall thickness ranges listed in a WPS may be different from the mandatory diameter and wall thickness groups in 6. Cellulosic-coated electrodes (AWS EXX10-type) should not be allowed to dry out excessively prior to use. API 1104 also refers to the latter as a coupon test report.2. it is common practice for the company to approve each qualified WPS that will be used for production welding. "Evaluation of Hydrogen Cracking in Weld Metal Deposited using Cellulosic-Coated Electrodes.3. for both to include a space for a revision number.1 General Only the welding variables that are applicable to the welding process and welding method to be used Revision 1 – April 30. Columbus. A WPS can be supported by more than one PQR. and Boring. A PQR ‘supports’ a WPS. A. Figure 2 is a sample PQR. Never try to force one kind of gas into a cylinder containing another. which may be required eventually. A WPS need not be established and qualified by the company itself. Drying/reconditioning ovens are capable of attaining temperatures well in excess of those attainable in electrode storage ovens and have the capability for air circulation.2.2.3 Shielding Gases G4. The gas.2.. It is common.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities reconditioning guidelines specified by the manufacturer for the particular brand of electrode being used should be followed. G5. Fiore. Figure 1 in API 1104 is a sample WPS. It is common.3.2.. S. See additional guidance provided in G5. It is only necessary that the welding procedure specification (WPS) to be used for production welding be established and qualified sometime prior to the start of production welding.3 G4. Examples of inert gases include argon and helium.2. Note that the qualification of a welder who performs a test joint for a procedure qualification may be limited by the essential variables of a single qualification in 6. Cellulosic-coated electrodes that have been allowed to dry out are known to produce welds that are susceptible to weld metal hydrogen cracking. which can also be used as a welder qualification test record (WQTR). Edison Welding Institute. must have adequate purity and dryness for welding. G5. but not mandatory. The use of Figures 1 and 2 is not mandatory.3. Ohio.2.2 Storage and Handling A crucial prohibition with respect to shielding gases involves field intermixing.3. or mixture of gases.1 Types Active gases combine with the weld to contribute to weld properties. Inert gases protect the weld but do not combine with the weld. although forms similar to these should be used. Other codes and standards require that welding procedures be requalified if they are transferred to and used by a different company. including manufacturers. Electrode drying/reconditioning should be carried out in a purpose-built oven. General guidelines for the use and handling of low-hydrogen electrodes are available from a variety of sources.3 PROCEDURE SPECIFICATION G5 Qualification of Welding Procedures for Welds Containing Filler-metal Additives The word “additives” in the title of this section refers to filler metal in general and is intended to differentiate between welding procedures covered by this section and welding procedures for autogenous (no filler metal added) welding. but not mandatory to list the PQRs that support a particular WPS. or bring gases to the arc in multiple hoses. 3 G5. June 2009.3. G4. M.2. PHMSA Research and Development for PRCI Project No. However. A welder who performs a test joint that qualifies a WPS becomes qualified to perform that procedure provided that all of the testing required for a welder qualification is performed and passed.2 RECORD A qualified welding procedure consists of a WPS and a procedure qualification record (PQR). 2010 . 2. for some applications (e.2 Pipe and Fitting Materials It is common.3 and the basis for selecting the welding consumables to be used.e.2. high longitudinal strains).1. G5. which is more likely to contain imperfections than the pipe material. and combinations of these methods. mechanized. The latter establishes the basis for the tensile strength requirements in 5. Changes to welding variables that are not listed in 5.2. A revised WPS should be identified by a revision number. All of the applicable welding variables described in 5.2 Specification Information G5.6. Welding methods (or methods of application) include manual. Wall thickness is an essential variable for procedure qualification. However..2.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities need be documented.” This presumably refers to ASTM specifications that are acceptable to the company. It may be beneficial to select diameter and wall thickness groups for a WPS based on the diameter and wall thickness groups that are essential variables for single qualification of welders in 6. For example.3 Diameters and Wall Thicknesses The suggested groupings shown in 6. However.1 Process Eight possible welding processes are listed in 1. For material with a SMYS higher than 56. the test joint must be made using the material with the highest specified minimum yield strength (SMYS) in the group.2.3.2. some codes limit wall thickness to which the procedure is applicable from some minimum thickness to 2t. a welding procedure qualified for use on X42 is acceptable provided that the material is being used as X42. it is good practice but not mandatory to document the carbon equivalent for all base materials used in the procedure qualification.2. G5.4. Many of these variables are limited by the essential variable changes given in 5. the size of the wall thickness range to which the procedure is applicable often depends on the actual value of t and the welding process that will be used.2. Table G-1 in Section G1 shows which methods of application are generally applicable to which welding processes. it could be confusing to welders.3.2. Not all welding methods are applicable to all welding processes. Guidance can be found in a variety of other codes and standards. More specifically.4 Joint Design The joint type (fillet. For example.3. It is only necessary to use a welding procedure qualified for use on the grade for which the material will be used.2. inspectors.4 are allowed by simply revising the WPS without the need for requalification. For production welding that involves joining base materials from two different strength groups. although sound engineering judgment should be used.3 refers to the diameter and wall thickness of the branch and header piping.g. if the diameter and wall thickness groups in a WPS are different from these essential variable groups for single qualification.2. Base materials and base material groupings are addressed in 5. or a combination of fillet and groove) should be specified. A branch weld Revision 1 – April 30. etc. as well as the grade of the base material. whereas diameter is not. a WPS for the higher strength material must be employed. for pipe certified to both API 5L X42 and X52. but not mandatory. semiautomatic. To qualify a WPS for an entire group. a welder with single qualification might be qualified to weld only a portion of the joints permitted by a WPS..3.2 must be included in the WPS. For pipe that meets the requirements of more than one pipe grade (i. G5. Other groupings can be used provided that there is technical justification for doing so based on sound engineering judgment. pipe that is ‘multi-graded’ 6 or ‘dual or triple stenciled’).4. it is good practice to at least match the actual yield strength of the pipe. contractors. groove. 5. The use of filler metal with yield strength that matches or overmatches the actual yield strength of the pipe material prevents longitudinal strains from accumulating in the weld region. While control of this sort of situation is possible. where t is the wall thickness used for procedure qualification.3. items d and e are just that – suggested groupings.3.000 psi (386 MPa).2.3. 2010 . It is not clear what constitutes an “acceptable ASTM specification. to specify the industry standard or specification to which the base material was manufactured. or automatic. For branch connections. G5. it is not necessary to use a welding procedure that is qualified for the highest grade to which the pipe is certified. for the bevel angle tolerances to be specified also. stringer beads. it is good practice to indicate this and to specify pulse parameters.. it is good practice.3. E6010 has a SMUTS of 60. weave beads. but not mandatory. However. etc. it is normally necessary to specify the use of welding consumables with a higher designation than the pipe material (e.. (e. While not required. it is good practice to consider the addition of a backweld to be an essential variable for procedure qualification). backwelds are relatively small beads that are deposited at relatively low heat input levels.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities can consist of a groove and/or fillet weld.000 psi). The WPS is not required to contain a sketch of the sequence of beads. It is good practice but not mandatory to specify the welding technique that should be used – e. The ranges should not be so wide that operating at the edges of the ranges produces an unacceptable weld.. it is common practice. but not mandatory. If pulsed current is to be used. depositing a weld pass from the inside to repair or otherwise make the root region of the weld G5. The required root opening may be expressed as an approximate value or a specific value with applicable tolerances. it is common practice.3. For example. In addition to specifying the required size of the root face. the trade name of the filler metal can also be listed for information purposes. Ranges for amperage and voltage specified by the electrode manufacturer can be used for guidance. if desired. it is considered a combination fillet and groove weld. The limits of the range should be based on sound engineering judgment. The ranges specified should be wide enough so that the qualified welding procedure can be implemented in the field.e. X60 has a SMYS of 60. If the welding procedure covers a range of wall thicknesses and a combination of techniques. whereas filler metals (i. Current can be either alternating current (AC) or direct current (DC). this should be specified. Backwelds are normally deposited last and do not benefit from the tempering associated with the thermal cycle from subsequent passes. If backwelding is to be permitted. it is appropriate to include the minimum number of beads for each wall thickness.. If the welding procedure covers a range of wall thicknesses. welding consumables) are designated by their specified minimum ultimate tensile strength or SMUTS. G5. polarity can be either electrode negative (straight polarity) or electrode positive (reverse polarity). A branch connection that includes the use of a beveled branch and a full penetration weld is considered a groove weld. Such tolerances may vary depending upon the type of bevel (machine-cut or torch-cut). If backwelding (i.2. If it also includes a fillet weld reinforcement. 2010 . the allowable range for amperage and voltage should be no larger than the median value +/. The specified range should reflect the minimum and maximum values that produce an acceptable weld (or a weld with desired toughness properties for example. the sequence of beads must somehow be designated. or a combination of both. To achieve matching or overmatching strength girth welds.000 psi). Unlike cap passes. voltage. In addition to specifying the required bevel angle. Heat input takes into account the collective effect of amperage. it is insufficient to list trade name only Line pipe materials are designated by their specified minimum yield strength or SMYS (e. but not mandatory. It is permissible to list more than one filler metal diameter for each welding pass when the procedure will be qualified using only one diameter since filler metal diameter is not an essential variable for procedure qualification. at least E7010 electrodes for X60 pipe material). not the calculated Revision 1 – April 30.20%. to specify a heat input range for each welding pass.g. The specified range should reflect the minimum and maximum heat input values that produce an acceptable weld.g.. the weld width (or wall thickness) at which the transition from one technique to another should occur should also be specified. For DC. if required). it is good practice but not mandatory to weld and test joints with and without backwelds (i... It is good practice to list an amperage and voltage range for each filler metal type and size.g.g. However. In addition to ranges for amperage.6 Electrical Characteristics 7 acceptable) is to be prohibited. for the root face tolerances to be specified.e.2. and travel speed. voltage.e. and travel speed on the thermal cycle of the weld.5 Filler Metal and Number of Beads The filler metal to be used should be identified by its AWS (or other) specification and classification numbers. 2.2. G5. When determining what value to specify on a WPS for time between passes. The information specified in the WPS should comply with the requirements/recommendations given in 7... voltage.3. the time-dependant nature of hydrogen cracking should be considered.12 Cleaning and/or Grinding It is good practice. The time between the completion of the root bead and the start of the second bead is most critical since the weld has less cross-sectional area at this stage. etc.3.3.3. it would seem to be prudent to indicate that here. For manual or semiautomatic welding.3. power brushing only for the remaining passes).2. API 1104 has traditionally been used for construction of cross country pipelines.).g. ‘stacked and tacked’) and for a lineup clamp to be specified for production welding. G5.g. Flame characteristics include carburizing (also called reducing). Requirements/recommendations for root bead completion prior to lineup clamp removal are given in 7.g. side.4.8). which involves girth welding with the pipe in the horizontal position.13 Pre.7 Flame Characteristics The term “flame characteristics” refers to oxyfuel welding. The use of the phrase “as required” is common. oxidizing.2. G5. and travel speed range. and neutral. or some position in between).Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities minimum and maximum values from the amperage. G5.3. in which an excess of fuel gas results in a carbon-rich flame.2.2.15..g. G5.2. or bottom of the pipe). although it would seem to be prudent to indicate that here.2. in which an excess of oxygen results in an oxygenrich flame.3. the direction of welding is horizontal. low-hydrogen electrodes. For branch connection welding. G5.8 Position A definition for “roll welding” is provided in 3. The possibility of unforeseen delays or interruptions during welding should also be considered when specifying the maximum allowable time between the completion of the root bead and the start of the second bead (see guidance in G5.11 Type and Removal of Lineup Clamp Information pertaining to the type and removal of a lineup clamp in this section generally applies to production welding. Actual values for amperage and voltage used during the procedure qualification test need not be recorded in the WPS. 2010 .and Post-heat Treatment Preheat is the minimum specified temperature of the entire weld zone immediately prior to the start of welding. If welding is to be performed with the pipe in a position other than horizontal. vertical. Roll welding refers to rolling the pipe while the weld metal is being deposited. there is no requirement in API 1104 to designate the position of the branch (e. only the ranges need to be specified. it is common for no lineup clamp to be used during the procedure qualification test (i. horizontal. G5. Specifying a maximum-allowable time between passes does this by a) preventing the weld from cooling excessively between passes and b) providing less time for 8 cracking to occur.. Shorter times decrease the chance that cracking can occur prior to the completion of the weld. See guidance in G7. grinding for the root pass.e.2.3. Also for manual or semiautomatic welding. The actual values used during the procedure qualification test should be recorded in the PQR. In a multipass weld. top. it is also the temperature immediately before the second and Revision 1 – April 30.10 Time between Passes The primary intent of this requirement is to prevent the weld from experiencing hydrogen cracking prior to completion. but not mandatory. Longer times can be justified when the probably of cracking is low (e. as well as the probability of the weld to cracking.3. it is common for an external lineup clamp to be used during the procedure qualification test and for an internal lineup clamp to be specified for production welding.9 Direction of Welding If welding is to be performed with the pipe in the vertical position. in which the mixture being burned contains a balance of fuel gas and oxygen.. to specify the extent of cleaning/grinding required for the weld bevel prior to welding and for each pass type (e.3. higher preheat/interpass temperatures. There is no requirement in API 1104 to designate the position of the pipe material (e. A minimum-required preheating temperature is normally specified. Weave motion perpendicular to the direction of weld progression is not included in the travel speed measurement. Additional information pertaining to the application of pre. such as air cooling or accelerated cooling 9 with water. it is also common to specify a maximum-allowable interpass temperature. slowing the weld cooling rate somewhat. Preheating does this by driving off moisture and other contaminants prior to welding. should be specified. Revision 1 – April 30. the type of weld cooling after welding.3. and induction heaters (induction methods). 2010 . post-weld heat treatment (PWHT) can also temper hard weld microstructures and relieve residual welding stresses.and post-heating is provided in the guidance material for 7.32/A5. and the maximumallowable cooling rate from this temperature. the hold time at the PWHT temperature range (usually expressed in hours per unit of wall thickness).e.16 Speed of Travel It is good practice to list a travel speed range for each filler metal type and size.4 ESSENTIAL VARIABLES G5. The specified range should reflect the minimum and maximum values that produce an acceptable weld. not just the first weld bead).32M also provides purity requirements for the listed gases and mixtures. the allowable range for travel speed should be no larger than the median value +/. AWS A5. and allowing hydrogen to diffuse from the weld during welding and after completion..15 Shielding Flux Shielding flux type refers to submerged arc welding.20%.2.4. The range specified should be wide enough so that the qualified welding procedure can be implemented in the field. For some applications. Travel speed is measured in the direction of weld progression. preheating is specified only when the ambient or pipe surface temperature is below a certain value. departures from variables that affect the mechanical properties or soundness of completed welds are not allowed without requalification by preparing and testing another weld. Once welding begins. a maximumallowable heating rate from this temperature to the PWHT temperature range. The specified range should reflect the minimum and maximum values that produce an acceptable weld.14 Shielding Gas and Flow Rate AWS A5. It is unacceptable to list the travel speed as ‘manual’. G5.” or the temperature of the weld zone during welding of any weld bead (i. G5. These latter variables are referred to as essential variables.32/A5.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities subsequent passes. The range should not be so wide that operating at the edges of the range produces an unacceptable weld. electric resistance heaters (conduction methods). For example. G5.. and temperature indicating crayons (e. this temperature is generally referred to as the interpass temperature.1 General API 1104 allows some degree of departure from the variables used to qualify a WPS.2. However. Common methods used to preheat pipelines prior to welding include gas torches and quartz lamps (radiation methods). Post-heating and slow cooling can also have a beneficial effect on welds by allowing hydrogen diffusion after welding. If used to expedite nondestructive testing (NDT) and/or joint coatings. The maximum metal temperature at which accelerated cooling is applied should also be specified.11. If carried out at high enough temperatures. PWHT parameters for stress relief often include a temperature to which the joint can be heated without controlling the heating rate. which has a beneficial effect on the weld microstructures that develop. For some applications.3. Common methods for temperature measurement include contact thermometers (digital or analog).2.g. Tempilsticks™). It may be useful to think of preheat temperature as the “arc start temperature.32M Specification for Welding Shielding Gases provides standard AWS classifications for common shielding gasses and gas mixtures that can be used in preparation of procedure specifications. The primary reason for preheating is to prevent the weld from experiencing hydrogen cracking during welding or soon after completion. non-contact infrared pyrometers.3. G5. 4 Position See guidance provided in G5. expressed in US Customary units.8.50% of the nominal value without the need for requalification. Revision 1 – April 30. thus requiring that a new procedure be qualified.4.2. G5.3.2. G5.3. it would make little sense to perform two identical qualification tests (i..3. An example of a base material compatibility factor that might be considered within one of the grouping specified is carbon equivalent level. X65 to X65. However.4. For a pipe material of a given grade. Therefore. for welding full-encirclement sleeves that involve only fillet welds.2. However.2. whereas diameter is not.4. G5.. a successful procedure qualification test qualifies the procedure for use in welding X70 to X70.2. G5.2 should be based on nominal strength levels.3 Joint Design API 1104 does not define what constitutes a minor change in joint design. G5.4. A procedure qualified using a combination of materials only qualifies the procedure for that combination of materials. In addition to numerous AWS specifications listed in Table 1.4. additional information pertaining to filler metal. higher carbon equivalent materials generally have reduced weldability compared to lower carbon equivalent materials.000 psi (448 MPa) and above..g. one considering it to be X65 and the other considering it to be X70) on the exact same material. Part C.2. does not qualify for welding X42 to X42 or X65 to X65).6 Filler Metal If a filler metal is not listed in one of the groups of Table 1 in API 1104. it is not necessary to consider that API 5L-X42 now has an actual specified minimum yield strength. not all combinations of X42 and X65 (i.2. if the range specified in the WPS for any of those variables is exceeded. or a new procedure qualified. See the note under Table 1. Using the example of pipe certified to both X65 and X70. The strength level grouping listed in 5.2. a branch connection can consist of a groove weld and a fillet weld. Section II. a welding procedure qualified by welding a full encirclement sleeve (fillet weld only) is not sufficient for welding a branch connection that includes a groove weld.5). of 42. For welding procedure qualification tests conducted on multi-graded or dual or triple stenciled pipe (e. G5.5 Wall Thickness See guidance provided in G5.3.1.2. Regarding the note provided in 5. electrode. and X65 to X70.2.4.2 requires a separate qualification test for materials with a SMYS of 65. and flux designations can be found in ASME Boiler and Pressure Vessel Code. pipe certified to both API 5L-X65 and X70) the test results can be used to support WPSs pertaining to any of the grades to which the pipe is certified.2 Base Material To qualify a welding procedure for an entire group.4.2.2.e.3.1 Welding Process or Method of Application See guidance provided in G5. a welding procedure qualified by welding API 5L-X42 to X65 only qualifies for welding X42 to X65. It would seem reasonable to allow changes to the bevel angle of up to + 20%/-5% of the nominal value and changes to the root opening or land of up to +/.e.100 psi). thus requiring that a new procedure be qualified. sound engineering judgment should be used when determining the compatibility of the base materials.2. Wall thickness is an essential variable for procedure qualification.4. For example..e.4. a welding procedure qualified for a branch connection (groove and fillet weld) is sufficient.4. Even though 5. It is good practice but not mandatory to consider the addition of a backweld as an essential variable for procedure qualification (see guidance provided in G5.2 Changes Requiring Requalification Essential variables are those that require the procedure to be requalified. it requires separate qualification. A change from a fillet weld to a groove weld of a branch connection is also a major change in joint design. the procedure qualification must be carried out on the material with the highest specified minimum yield strength in the group.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 10 G5. A change from a butt weld to a fillet weld is a major change in joint design.2. The actual strength levels that are now specified in API Spec 5L (Forty-fourth Edition) as the result of normalization need not be considered (i. 2010 . 4.4. This is intended to account for the more-favorable conditions that generally exist when welding procedures are normally qualified (e.4.g.3.6. G5.. G5. the WPS should be revised accordingly to reflect the actual parameter ranges that were used to make the test joint. cooling should also be applied to the test joint.6 TESTING OF WELDED JOINTS-BUTT WELDS It should be noted that some acceptance criteria for imperfections discovered during procedure qualification testing in 5.3. Consequently.3. one common practice during procedure qualification is to delay welding of the hot pass after completion of the root pass by an appropriate amount of time.9. in an enclosed welding shop as opposed to on a pipeline Revision 1 – April 30. G5.11 Shielding Flux See guidance provided in G5.5 WELDING OF TEST JOINTS-BUTT WELDS There is no requirement for minimum length of the pipe nipples. G5.20% of the nominal value without the need for requalification.2.4. If after-weld cooling is to be used during production welding to expedite NDT and/or joint coatings. 2010 .2.13.7 Electrical Characteristics See guidance provided in G5. sound engineering judgment should be used when determining the compatibility of the filler metals within the groups specified in Table 1.2. Even if a change in the shielding gas flow rate does not visually affect the weld (e. does not result in porosity).g.2.2. is not necessary to test the limits of the range. welds made by what may be the most highly skilled welders available.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities Regarding the note provided in 5. Where a range is specified for a given parameter. Exceeding the maximum allowable value specified in the welding procedure for time between the completion of the root bead and the start of the second bead during production welding is grounds for rejection of that weld. G5. G5.4. The target value for welding parameters during welding of the test joint should be near the middle of the range specified. Target value for preheat temperature should be near the minimumrequired value.2. the weld properties (e. Test joints should be made using parameters that are specified in the WPS. whereas the maximum time between the completion of the second bead and the start of other beads is not.2.. It would seem reasonable to allow changes of up to +/.6.9 Direction of Welding See guidance provided in G5.g. API 1104 does not define what constitutes a major change in shielding gas flow rate.2.8 Time between Passes The maximum time between the completion of the root bead and the start of the second bead is an essential variable for procedure qualification. G5. to allow hydrogen diffusion after welding) does not constitute post-weld heat treatment (PWHT) and should not be considered an essential variable for procedure qualification.2.4.13 Pre-heat 11 The addition of preheat or an increase in the preheat temperature is not an essential variable for procedure qualification.. strength and toughness) may be adversely affected. G5. If the values recorded during welding of the test joint are outside the ranges specified in the WPS.3.6 are more stringent than those for imperfections discovered by nondestructive testing of production welds in Section 9.10 Shielding Gas and Flow Rate A change from one shielding gas to another refers to nominal composition. G5.15.12 Speed of Travel See guidance provided in G5.2..2. However.2.4. Maintaining preheat temperature following the completing of welding (e.16.2.4.14 Post-weld Heat Treatment (PWHT) See guidance provided in G5.3.2. G5.g. the pipe nipples should be long enough so that adequate restraint and thermal mass are provided and that specimens of adequate length can be extracted.4. the imperfection observed is not representative of the weld. Specimens must have parallel edges so that questionable results are avoided.3. However.2 is performed in the longitudinal direction and the longitudinal tensile strength of some line pipe materials can be lower than the transverse tensile strength. if the quality of the weld in the area from which a failed specimen was taken is determined to be not representative of the weld).6. The weld reinforcement is not removed and the specimen is full width and not a reduced section specimen.. 4 12 G5.6. some pipeline designs (e.2 Tensile-strength Test G5.g. on pipe nipples as opposed to full joints of pipe. The use of filler metal with yield strength that matches or overmatches the actual yield strength of the pipe material prevents longitudinal strains from accumulating in the weld region. This becomes problematic if requalification (or testing of production welds) produces unacceptable results. etc. There is currently disagreement among industry experts as to the acceptability of the practice of retesting specimens that fail to meet the minimum requirements during procedure qualification testing. However. in the opinion of the company.5 if. retesting of failed test specimens during procedure qualification is allowed. If a tensile test specimen is inadvertently tested with the weld reinforcement removed.6.3 (see guidance provided in G5.g. There are no specific provisions in Section 5 of API 1104 for retesting during procedure qualification should any of the test specimens fail to meet the minimum requirements. Such requirements should be specified in the contract documents.6. If a test joint is found to be unacceptable because the welding parameters that were used to make the weld were inadequate. the test joint should be considered unacceptable if either of the replacement specimens fails to meet the minimum requirements. high longitudinal strains) require matching or overmatching strength girth welds. often on a twofor-one basis. Revision 1 – April 30.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities right-of-way.1 Preparation Figure 4 illustrates the tensile-strength test specimen. G5.3 Requirements It is acceptable according to API 1104 for the measured tensile strength across the weld to be less than the actual tensile strength of the pipe material. Since retesting of specimens other than tensile test specimens is not specifically addressed in Section 5.2 that would seem reasonable involves test results that are determined to be invalid. Specimens may fail because the parameters that were used to make the test joint were inadequate. (219.5. G5.2. One exception to the no retesting requirement in 5. the inadequacy should be diagnosed and revised welding parameters should be specified and used to weld a new test joint. Retesting of bend test specimens is allowed during welder qualification in 6. This can be problematic since API Spec 5L only requires that tensile strength requirements be met in the transverse (circumferential) direction for welded line pipe 8-5/8 in.6..6. G5. In other codes and standards. no retesting is allowed.3). and the results meet the minimum tensile strength requirement. it is also evaluated as if it is a nick-break test specimen. 2010 .). which is more likely to contain imperfections than the pipe material.4 If it is determined that retesting of specimens (other than tensile test specimens) on a two-for-one basis is appropriate (e.6.2. sound engineering judgment should be used when determining the acceptability of this practice. If the specimen breaks below the specified minimum tensile strength of the pipe material. Because the API 1104 tensile test specimen does not utilize an In the past.2.1 Preparation No guidance material required. The cross-weld tensile test required in 5. particularly if there are pipelines already built using the procedures in question. some regulators in the US have required operators to re-qualify a procedure that was originally qualified based on retesting of failed test specimens or to perform testing on production welds removed from the pipeline..2 Method No guidance material required.6. Specimens may also fail because the location from which they were taken contains an imperfection that exceeds the acceptance criteria in 5. retesting of failed tensile test specimens during procedure qualification is specifically prohibited by 5.1 mm) diameter and larger. If a tensile test specimen breaks in the weld. then the results should be considered valid.6.2.2. even though the parameters that were used are capable of producing acceptable production welds.6. it would seem reasonable to allow a retest of a replacement specimen removed adjacent to the original specimen.6. G5. Typical fisheyes are shown in Figure G1. The term “nick-break” refers to the saw-cut notch that initiates fracture.6.6.3. The sooner nick-break specimens are tested after welding the more likely fisheyes are to appear due to the presence of hydrogen in the weld. Figure 5 illustrates a nick-break test specimen with instructions on how to prepare the nick. Consideration should be given to replacing the grips if this becomes problematic for a particular testing machine. would also seem to be appropriate provided that an adequate fracture surface results. Figure G1 – Typical Fisheyes on Fracture Surface of Nick-Break Specimen (photo courtesy of Lincoln Electric Company) Revision 1 – April 30.3..3 Requirements Figure 8 illustrates the exposed surface of such a specimen after breaking. not the entire fisheye. G5.3.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities area of reduced cross section. making the specimen easier to break. it would seem to be appropriate to allow the specimen to be nicked with a narrow disk grinder as well. The hydrogen that causes fisheyes will generally diffuse out of the weld over time. It is not appropriate to “nick” the specimens using an oxy-fuel torch.1 Preparation The nick-break test is a subjective test that judges the soundness of a weld by fracturing the specimen through the weld so the fracture surfaces can be examined for the presence of imperfections. other convenient methods.2 Method 13 The intent of this test is to provide an adequate fracture surface for subsequent examination. the grips deform or otherwise cause a stress concentration in the pipe material). Fisheyes are features on exposed fracture surfaces caused by the presence of hydrogen in the weld. test specimens will occasionally fail at a low value in the area of the grips (i. 2010 . G5. Only the actual imperfection in the center of the fisheye needs to be considered when evaluating nick-break test specimens. such as supporting one end and bending the other end with a lever (a length of small-diameter pipe) or bending in alternating directions in a load frame.3 Nick-break Test G5. While methods for breaking the specimens are prescribed in this section.6.e. While nicking the specimen with a hack saw is preferred. A fisheye consists of a small imperfection or defect that is surrounded by a circular or ellipticalshaped shiny or dull grey area. In cases such as this. G5. It should be noted that the diameter of the plunger and die are specified and not determined by material thickness and strength as in other codes. G5.6.g. This is intended to account for the more-favorable conditions that generally exist where welding procedures are normally qualified (e.e. Note that weld reinforcement must be removed prior to testing. To qualify a welding procedure for a branch connection.4 Root.6. which is different from other codes.8 TESTING OF WELDED JOINTS-FILLET WELDS It should be noted that some acceptance criteria for imperfections discovered during procedure qualification testing are more stringent than those for imperfections discovered by nondestructive testing of production welds. The required thickness of side-bend test specimens is 1/2 in.6.g.2.6.7 mm).6. Figure 7 illustrates a side-bend test specimen.4.1 Preparation The root. The current wording in 5.5.3.4. (12. a procedure for butt welding cannot be used for fillet welding. Note that the weld reinforcement must be removed. G5. provided that the branch connection consists of a groove weld and a fillet weld reinforcement.7 WELDING OF TEST JOINTS-FILLET WELDS Figure 10 shows three possible configurations. G5.6.6. Unlike other codes.and face-bend test..Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 14 G5. 2010 .5 Side-bend Test G5. The top configuration shows a branch connection that consists of a groove weld and a fillet weld reinforcement.and Face-bend Test G5. causing the specimen to bend into a U shape.. The use of the wrap around method is actually preferred when testing specimens when there is a significant difference in weld and base material yield strength as non-uniform bending (kinking) is avoided. G5. API 1104 Figure 6 illustrates a root.2 Method Figure 9 illustrates an example of a guided bend test jig. Deep scratches or grinding marks that are parallel to the weld (i. perpendicular to the specimen) may cause an otherwise acceptable weld to fail. (12.3 Requirements See guidance provided in G5.7 mm).2 Method See guidance provided in G5.6. G5.and face-bend test is for pipes with a wall thickness less than or equal to 1/2 in. (12. In API 1104.5.4. a change from a butt weld to a fillet weld is a major change in joint design.1 Preparation The side-bend test is similar to the root.6. It is not permissible to grind or machine to below the surface of the specimen (e. G5.5.6. porosity. incomplete fusion or penetration. respectively. although the use of this method would seem to be reasonable from a practical point of view. The side-bend test is for pipes with a wall thickness greater than 1/2 in. thus requiring that a new procedure be qualified.6.and face-bend testing involves determining the soundness and ductility of a weld by placing a test specimen across the shoulders of a die. the testing requirements for both the groove and fillet portion of the weld are the same as those for a fillet weld.and facebend test specimen. Revision 1 – April 30.4. except that the bending occurs on the cross section surface of the specimen.4. cracks. and/or trapped slag.4. The plunger is forced toward the die. A plunger is positioned such that the area of interest is opposite the plunger.2 would seem to prohibit the use of guided bend test machines that employ the alternative ‘wrap-around’ method. A welding procedure qualified for a branch connection will also qualify for welding a fullencirclement sleeves that involves only fillet welds. to remove undercut).3 Requirements Causes of failure may include lack of ductility. in an enclosed welding shop as opposed to on a pipeline right-of-way). The bottom two are fillet welds typical of those used for a full-encirclement reinforcing sleeve and a belland-spigot joint. The root.7 mm).. Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities G5. 2010 .1 General The use of the word “plane” in 6.2 allows a welder to make welds within the limits of the essential variables described in 6.3 Requirements No guidance material required.2. the “pace” or “elapsed time” for a production weld will tend be different from a qualification weld. vertical. When the welder is qualifying in the fixed position. Each welder must weld the entire wall thickness of a particular segment when qualifying. that welder is limited by the essential variables listed in 6. The requirements for Revision 1 – April 30. it would seem to be appropriate to allow a duplicate specimen removed adjacent to the original to be used for a retest. vertical.8.2. AWS designations are typically used to describe pipe positions. G6 Qualification of Welders G6. The phrase “before any production welding is performed” has no specific time limit.2. G5.2.2. A multiple qualification in accordance with 6. as long as the requirements in Section 6 are also met. Required welder requalification intervals are left to the discretion of the user and are addressed in a variety of other codes and regulations. However. • Vertical. A welder who makes a procedure qualification weld is also qualified as a welder.1 can be confusing. the welder should follow the requirements of the previously qualified procedure as outlined in the WPS. Consequently. The travel speed used by the welder during a welder qualification test should be within the range specified in the WPS. and overhead positions of the weld made by each welder. the position is 2G (whether the pipe is fixed or rotated). G5. API 1104 does not address time intervals over which a welder qualification is valid. not the suitability of the welding procedure. If a welder qualifies by making a weld in accordance with 6.2 SINGLE QUALIFICATION A single qualification accordance with 6. The qualification of two welders in this manner is typically referred to as the “brother-in-law” technique.. If the specimen does not break through the weld because the flame and hacksaw cuts were not sufficient. and a welder may be inclined to take more care with a qualification weld than some production welds. The phrase “segments of pipe nipples” refers to a single qualification in accordance with 6.8. • Horizontal. however. It is only necessary that welders to be used for production welding be qualified sometime prior to the start of production welding. Two welders can be qualified on a single pipe nipple as long as an appropriate number of test specimens are removed and tested from the typical flat. the position is 1G. During the welder qualification test. G6.2.2 Method This is a subjective test that judges the soundness of a weld by fracturing the specimen through the weld so the fracture surfaces can be examined for the presence of imperfections.1 GENERAL This section refers to the use of previously qualified procedures because a welder qualification test is intended to evaluate welder skill. or inclined from horizontal at an angle of not more than 45°. thin-wall pipe through the weld can present challenges. A welder need not be qualified by the company itself. The word “speed” applies to the “pace” or “elapsed time” of welding. Each welder must weld the entire wall thickness of their particular segments. and the pipe is fixed. It is not appropriate for two welders to weld in combination to fill up one weld groove.2.8. and the pipe is fixed. and the pipe is rotated. • 45° incline from the horizontal.3 allows a welder to make welds over a wider range of applications.1 Preparation The flame and hacksaw cuts shown in Figure 11 must be sufficient to ensure that the specimen breaks in the weld. the axis of the pipe shall be horizontal. If the axis of the pipe is: • Horizontal. 15 satisfactory welder qualification welds are more stringent than for production welds. Breaking specimens from relatively highstrength. welders must be qualified in the presence of a representative that is acceptable to the company. the position is 5G.2. G6. the position is 6G. Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 16 G6. 2010 . this does not qualify that welder to make complete welds using only one of those processes. 5G or horizontal-fixed position) to make production welds with the pipe inclined an angle of up to +/.2 Scope While the title of this section is “Scope”.2.250 in. uniform workmanlike appearance”.2. joint designs. which require that the welder be requalified if changes beyond the limits listed are exceeded. b. While “neat. See guidance material below. If a welder qualifies using a combination of filler metals (e. A change in joint design constitutes an essential variable..1 General See guidance pertaining to pipe positions in G6. Except as indicated in “f” above. that allow welders who are qualified to make butt welds to also make fillet welds without a separate qualification. g. and not contain burn-throughs exceeding the size limits of 6. and fittings.2. A welder who qualifies for butt welds in the 6G position is qualified not only to make butt welds in all positions. c. a welder qualified for only butt welds is not qualified for fillet welds.. The branch must be located at the 6 o’clock position.. it is common to apply the visual examination standards given in 6. Wall thickness is an essential variable for both welder and welding procedure qualification. such as ASME Section IX. 1.625 in.4. If the welder qualifies using a combination of processes. A revised WQTR should be identified by a revision number. cut.3. cut.3. A welder who qualifies in any position other than the 6G position is only qualified for that particular position. It should be noted that the essential variables for welder qualification are different than those for welding procedure qualification. Pipe diameter is an essential variable for welder qualification but not for procedure qualification. The nominal diameter of the branch must match the nominal diameter of the run pipe and the hole in the run pipe must be the same size as the inside diameter of the branch. it contains a list of essential variables for welders with a single qualification. A change from a butt weld to a fillet weld is a change in joint design. although sound engineering judgment should be used. which requires the welder to lay-out.15° from that position without the need for requalification. root pass from Group 1 or 2 and fill and cap from Group 3).3 mm) and a minimum wall thickness of 0. Successful qualification requires that the completed weld “exhibit a neat.3 MULTIPLE QUALIFICATION Multiple qualification allows a welder to weld in all positions. four nick-break specimens Revision 1 – April 30. this does not qualify that welder to make complete welds using electrodes from only Group 1 or 2 or from only Group 3.1. this requirement seems to refer to the wall thickness of both the branch and the header piping. For branch connections. this requirement appears to refer to the diameter of both the branch and the header piping. The eight possible welding processes are listed in 1.3. and fit the two pipes together and make the weld. as appropriate. G6. on all wall thicknesses. (6. In addition to vertical uphill and vertical downhill. but is also qualified to make lap fillet welds. the direction of welding is horizontal if welding is to be performed with the pipe in the vertical position.e. Specific guidance for each item listed. Multiple qualification requires the welder to complete two tests: • A butt weld test with the pipe fixed in the 5G or 6G position on pipe with a minimum outside diameter of 6. and on all pipe diameters within the limits of the essential variables described in 6. For branch connections. • A branch-on-pipe connection test (i. is provided below. Changes to variables that are not listed in 6. That is contrary to some other standards.g. (168. It would seem reasonable to allow a welder who has qualified in a particular position (e. G6. f. 2. d.g. In addition. e. The welder performing the test must lay-out. a set-on branch). No backing strip may be used.2 are allowed by simply revising the welder qualification test record (WQTR) without the need for requalification. API 1104 does not define tolerances for changes in position.4 mm). uniform workman-like appearance” is not defined. and fit two pipes together in the form a branch connection.2.1. Qualification using a combination of filler metals only qualifies the welder to make welds using that combination. the welder can qualify using that combination of processes or the welder can qualify using each process separately. a. To be qualified to make a weld with a combination of processes.1. the direction of welding is horizontal if welding is to be performed with the pipe in the vertical position. 1. this does not qualify that welder to make complete welds using electrodes from only Group 1 or 2 or from only Group 3. To be qualified to make a weld with a combination of processes. rejection is automatic and no additional testing need be performed. this does not qualify that welder to make complete welds using only one of those processes.375 in (60.8.3 mm). inadequate penetration. root pass from Group 1 or 2 and fill and cap from Group 3).5. A welder who makes a procedure qualification weld is also qualified as a welder.. is provided below.3 The phrase “using qualified procedures” refers to both tests. The essential variables for multiple qualification are also different than those for single qualification. The locations of the specimens shown in Figure 12 are rotated in accordance with Note 1 in Figure 12 so that the appropriate number of specimens is obtained from each welder’s segment of the pipe. 2010 . Revision 1 – April 30. b. Qualification using a combination of filler metals only qualifies the welder to make welds using that combination.g. two test welds must be made to obtain the required number test specimens. which require that the welder be requalified if changes beyond the limits listed are exceeded. The phrase “shall be free from” indicates that there is no acceptable extent for cracks. G6.3. however. as appropriate. G6. G6. a. This is intended to account for the more-favorable conditions that generally exist where welders are normally qualified (e.g. In addition to the objective criteria for rejection.4 VISUAL EXAMINATION Visual examination of the test weld is a requirement for welder qualification and generally 17 precedes preparation and testing of samples for mechanical testing. in an enclosed welding shop as opposed to on a pipeline right-ofway).2 are allowed by simply revising the welder qualification test record (WQTR) without the need for requalification.3. the welder can qualify using that combination of processes or the welder can qualify using each process separately. which shows sample locations for procedure qualification welds. In addition to vertical uphill and vertical downhill. Changes to variables that are not listed in 6. the total number of specimens specified in Table 3 is required for each welder and the locations of test specimens for each welder must be representative of each location illustrated in Figure 12. G6. This figure is very similar to and should not be confused with Figure 3.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities removed from locations described in Figure 10 must be tested and meet the requirements of 5. c.. If the visual examination reveals that the weld contains imperfections that exceed the limits given in 6.1. If a welder qualifies using a combination of filler metals (e. a weld may be rejected at the discretion of the inspector based on poor workmanship or if too much filler wire protrudes into the interior of the pipe (also called whiskers). If the welder qualifies using a combination of processes.1 Sampling of Test Butt Welds Figure 12 shows sample locations for welder qualification welds. which shows sample locations for procedure qualification welds. The eight possible welding processes are listed in 1. and burn-through. The phrase “segments of pipe nipples” refers to the qualification of two welders on a single pipe nipple using the “brother-in-law” technique. it contains a list of essential variables for welders with a multiple qualification. If two welders are qualified on a single pipe nipple. 2. See guidance material below. Table 3 shows sample locations for welder qualification welds. although sound engineering judgment should be used.2 Scope While the title of this section is “Scope”. as long as the requirements in Section 6 are also met. It should be noted that the essential variables for welder qualification are different than those for welding procedure qualification.5 DESTRUCTIVE TESTING It should be noted that some acceptance criteria for imperfections discovered during welder qualification testing are more stringent than those for imperfections discovered by nondestructive testing of production welds.4. A revised WQTR should be identified by a revision number. If the pipe diameter is less than 2. This table is very similar to and should not be confused with Table 2. Specific guidance for each item listed. Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities If the pipe diameter is less than 1.315 in (33.4 mm), a tensile test of one full pipe section specimen may be substituted for the root-bend and nick-break specimens. If the tensile test specimen breaks in the weld, it is also evaluated as if it is a nick-break test specimen. G6.5.2 Tensile-strength, Nick-break, and Bend-test Procedures for Butt Welds See guidance pertaining to tensile strength, nickbreak, and bend testing provided in G5.6. For welder qualification, it is not necessary to measure tensile strength since a welder qualification test is intended to evaluate welder skill, not the suitability of the welding procedure. At the option of the user, the specimens designated for tensile testing may be subjected to the nick-break test instead. G6.5.3 Tensile-strength Test Requirements for Butt Welds It is permissible for the tensile strength test specimen to break in the weld. If the specimen breaks in the weld, it is evaluated as if it is a nickbreak test specimen. G6.5.4 Nick-break Test Requirements for Butt Welds See guidance provided in G5.6.3.3. G6.5.5 Bend Test Requirements for Butt Welds See guidance provided in G5.6.4.3. However, for a welder qualification test, it is permissible for bend test specimen for welds in high-test (i.e., high tensile strength) materials to break in the weld before they bend into a full U shape. If the specimen breaks in the weld, it is evaluated as if it is a nick-break test specimen. See guidance provided in G5.6.3.3. The statement in 6.5.5 pertaining to bend test specimens that do not bend to a full U shape does not imply that specimens do not have to be tested to the full extent of the jig. Retesting of one bend test specimen is allowed during welder qualification if, in the opinion of the company, the imperfection observed is not representative of the weld. Retesting is allowed only once. 18 G6.5.6 Sampling of Test Fillet Welds The phrase “segments of pipe nipples” refers to the qualification of two welders on a single pipe nipple using the “brother-in-law” technique. For fillet welds made on pipe in the horizontal fixed position, one full circumferential weld completed by two welders is sufficient to test both welders. For fillet welds made on pipe in the 6F position (inclined at 45 degrees), each welder must complete one half of the up hill fillet weld and one half of the downhill fillet weld in order to provide test specimens representing all of the fillet weld orientations for each welder. G6.5.7 Test Method and Requirements for Fillet Welds See guidance provided in G5.8. G6.6 RADIOGRAPHY-BUTT WELDS ONLY G6.6.1 General For butt welds, the company may elect to use radiography for evaluation of welder qualification welds instead of destructive testing. However, some regulatory codes require that welders be qualified by destructive testing when they are to make production welds in certain locations, (e.g., welders who weld compressor station piping to meet the requirements of 49 CFR Part 192). Since radiography is the only nondestructive test method mentioned as an alternative to destructive testing, the use of other test methods, such as automated ultrasonic testing, is not currently allowed. G6.6.2 Inspection Requirements See guidance pertaining to acceptance standards in G9.3. The use of radiography results to choose good or bad portions of the weld for subsequent destructive testing for the purpose of qualifying or disqualifying a welder is prohibited. G6.7 RETESTING If a welder fails a qualification test because of unavoidable conditions or conditions beyond the control of the welder, that welder may be given a second opportunity to qualify. If that welder fails the second time, acceptable proof of additional welder Revision 1 – April 30, 2010 Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities training must be submitted before taking the test again. G6.8 RECORDS Records of detailed test results for each welder must be maintained. The level of detail required is not specified and is left to the discretion of the user. Figure 2 is a sample welder qualification test record (WQTR), which can also be used as a procedure qualification record (PQR). The use of Figure 2 is not mandatory, although a form similar to this should be used. It is common, but not mandatory, to include a space for a revision number, which may be required eventually. A list of welders and the procedures for which they are qualified must also be maintained. API 1104 does not address time intervals over which a welder qualification is valid. Required welder requalification intervals are left to the discretion of the user and are addressed in a variety of other codes and regulations. At the discretion of the company, a welder may be required to re-qualify if the competence of that welder comes into question. 19 (WQTR). Documentation of a qualified welding procedure consists of a WPS and a procedure qualification record (PQR). API 1104 also refers to the latter as a coupon test report. A PQR ‘supports’ a WPS. A WPS can be supported by more than one PQR. It is common, but not mandatory to list the PQRs that support a particular WPS. It is good practice to ensure that copies of welder and welding procedure documentation are available in the field during production welding. For pipe that meets the requirements of more than one pipe grade (i.e., pipe that is ‘multi-graded’ or ‘dual or triple stenciled’), it is not necessary to use a welding procedure that is qualified for the highest grade to which the pipe is certified. It is only necessary to use a welding procedure qualified for use on the grade for which the material will be used. For example, for pipe certified to both API 5L X42 and X52, a welding procedure qualified for use on X42 is acceptable provided that the material is being used as X42. However, for some applications (e.g., high longitudinal strains), it is good practice to at least match the actual yield strength of the pipe. The use of filler metal with yield strength that matches or overmatches the actual yield strength of the pipe material prevents longitudinal strains from accumulating in the weld region, which is more likely to contain imperfections than the pipe material. Since there is no requirement in API 1104 to designate the position of the pipe material during procedure qualification (e.g., horizontal, vertical, or some position in between), there are no limits on the use of a qualified welding procedure in applications where the axis of the pipe is displaced significantly from that which was used during procedure qualification. Sound engineering judgment should be used when determining the applicability of a qualified welding procedure when the axis of the pipe is displaced significantly from that which was used during procedure qualification. For a welder who has a single qualification to 6.2, however, there are welder qualification limits for position. See guidance provided in G6.2.2f. G7.2 ALIGNMENT When lining up for girth welding, API 1104 allows for some degree of offset between adjoining edges of the pipe. Since the word should is used to describe the 1/8 in. (3 mm) maximum offset specified, this is a recommended practice and not a requirement. Offsets larger than this are allowed provided that they are the result of pipe end dimensional variations that are within the limits of Revision 1 – April 30, 2010 G7 Design and Preparation of a Joint for Production Welding Section 7 gives guidance on the use of qualified welding procedures during production welding. Much of this section simply indicates that the qualified welding procedure specification (WPS) must be followed (i.e., welders must follow the qualified welding procedure). Changes to a qualified welding procedure are allowed provided that an essential variable is not violated. Changes to welding variables that are not essential variables are allowed by simply revising the WPS without the need for requalification, although sound engineering judgment should be used. A revised WPS should be identified by a revision number. Revisions to a qualified welding procedure must be authorized by the company. Welders are not permitted to weld outside of the ranges specified in the qualified welding procedure even if an essential variable is not violated. There are many instances of the word “should” in Section 7 of API 1104. The word “should” indicates a recommended practice, whereas the word “shall” indicates a mandatory requirement. G7.1 GENERAL Documentation of a qualified welder usually consists of a welder qualification test record Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities the specification to which the pipe was purchased and that the offset has been distributed uniformly around the circumference. Pipe end dimensional variations that can result in offset include pipe diameter tolerances, out-of-roundness tolerances, and wall thickness tolerances. It is recommended that offsets larger than 1/8 in. (3 mm) that are due simply to misalignment not be allowed. Acceptable end preparations for butt welds between pipe having unequal wall thickness, unequal yield strength, or both are provided in a variety of other codes and standards. API 1104 does not address the placement of longitudinal seams or the separation of longitudinal seams on adjacent pipes during girth welding. However, it is common practice to place the longitudinal seams in the top half of the pipeline and to stagger the longitudinal seams on adjacent pipes. G7.3 USE OF LINEUP CLAMP FOR BUTT WELDS If allowed by the WPS, the lineup clamp can be removed prior to the completion of the root bead provided that the completed part of the bead is in approximately equal segments and is spaced approximately equally around the circumference. When using an internal lineup clamp, if preventing pipe movement will be difficult or if the weld will be unduly stressed, the clamp must be left in place until the root bead is complete. When using an external lineup clamp, root-bead segments should be uniformly spaced around the circumference and the root bead should be at least 50% complete before the clamp is removed. The word should in the previous sentence denotes a recommended practice and not a requirement. For highly-stressed welds (e.g., tie-in welds), it is preferable that as much of the root bead be completed as possible before the clamp is removed. G7.4 BEVEL G7.7 CLEANING BETWEEN BEADS G7.4.1 Mill Bevel The design and dimensions of mill bevels must conform to the qualified WPS G7.4.2 Field Bevel Pipe ends for butt welding may be beveled in the field by any convenient machine method. Machining or machine oxygen cutting produces a higher quality bevel that manual methods such as grinding and hand 20 oxygen cutting. The word should indicates a preference for machining or machine oxygen cutting. The use of manual methods requires company authorization. The design and dimensions of field bevels must conform to the qualified WPS. G7.5 WEATHER CONDITIONS Inclement weather conditions that can have an adverse affect of weld quality include low temperatures, moisture in the air (e.g., precipitation, high humidity, etc.), high winds, etc. Preheating is often specified in a WPS when the ambient temperature is lower than a specified value. When the surface temperature is below the ambient dew point, moisture will condense on the pipe surface, which, if welded over, will contribute to increased weld hydrogen levels. The use of preheating will eliminate moisture and other contaminants (e.g., coating residue) prior to welding. High winds can disrupt the shielding of the molten weld metal, which can lead to porosity. Low temperatures can cause increased weld cooling rates, which can lead to the development of crack-susceptible weld microstructures and can cause hydrogen to become trapped in the weld. Preheating can also slow weld cooling rates somewhat and allow hydrogen diffusion following welding. During inclement weather, temporary shelters can be used to protect the weld and its immediate surroundings. Responsibility for determining how and when to conduct welding operations in inclement weather conditions lies with the company. G7.6 CLEARANCE When welding above ground or in a trench, adequate clearance should be provided for the welder so that movement around the pipe is not obstructed. Since the word should is used to describe the 16 in. (400 mm) minimum clearance specified, this is a recommended practice and not a requirement. Cleaning of the weld groove prior to welding and between beads must be carried out as specified in the qualified WPS. Hand or power tools may be specified. Between pass grinding is specifically required to remove surface imperfections when using semiautomatic or mechanized welding. When silicon in the weld puddle forms heavy glass deposits (primarily when using the GMAW process), these must be removed between passes when requested by the company. Revision 1 – April 30, 2010 Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 21 G7.8 POSITION WELDING In position welding, the pipe or assembly is stationary (i.e., not rotating) while the weld metal is being deposited. Welding while the pipe is stationary, rolling the pipe, and then welding again (sometimes referred to as quarter welding) is also position welding (not roll welding). G7.8.1 Procedure During position welding, adequate support and clearance must be provided. A change in position from position welding to roll welding, or vice versa, constitutes an essential variable for procedure qualification. G7.8.2 Filler and Finish Beads The thickness of weld passes on the top and bottom of a stationary pipe tend to be greater than for the sides. Therefore, stripper beads may be required to even out the weld cross-sectional thickness prior to depositing the cap pass. Stripper passes, commonly required in the 2 to 4 o’clock positions, are typically deposited using welding parameters for fill passes. Since the word shall is used to describe the minimum height of the weld crown (at least flush with the parent metal), this is a requirement. The word should is used to describe the 1/16 in. (1.6 mm) maximum cap height and the weld width of at least 1/8 in. (3 mm) wider than the original groove, however, making these recommended practices and not requirements. The start/stop location for a subsequent bead should not coincide with the start/stop location of a previous bead. It is not permissible to leave slag deposits on completed welds, as this interferes with visual inspection. G7.9 ROLL WELDING Roll welding refers to rolling the pipe while the weld metal is being deposited. Welding while the pipe is stationary, rolling the pipe, and then welding again (sometimes referred to as quarter welding) is position welding (not roll welding). G7.9.1 Alignment The ability to use roll welding is left to the discretion of the company, although adequate support must be provided. However, a change in position from roll welding to position welding, or vice versa, constitutes an essential variable for procedure qualification. G7.9.2 Filler and Finish Beads While not prohibited, stripper passes are generally not required for roll welds. Since the word shall is used to describe the minimum height of the weld crown (at least flush with the parent metal), this is a requirement. The word should is used to describe the 1/16 in. (1.6 mm) maximum cap height and the weld width of at least 1/8 in. (3 mm) wider than the original groove, however, making these recommended practices and not requirements. While not required for roll welds, the start/stop location for a subsequent bead should not coincide with the start/stop location of a previous bead to reduce the chance of accumulating start/stop imperfections in a particular location.. It is not permissible to leave slag deposits on completed welds, as this interferes with visual inspection. G7.10 IDENTIFICATION OF WELDS The method by which each welder must identify his (or her) work is left to the discretion of the company. This typically involves the use of a system of paint marker markings. If die stamping is specified, low-stress type dies (e.g., dot style or round face) should be used. G7.11 PRE- AND POST-HEAT TREATMENT Material conditions that may necessitate the use of pre- or post-heating include heavy wall thickness and/or high carbon equivalent values. Weather conditions that may necessitate the use of pre- or post-heating include low temperatures and/or moisture in the air (e.g., precipitation, high humidity, etc.). Pre- and/or post- heating must be carried out as prescribed in the WPS. Preheating carbon steel to a precise temperature is generally not required. It is usually acceptable to exceed the minimum-required preheat temperature by approximately 100°F (56°C). However, maximumallowable interpass temperature requirements should not be violated. Common methods used to preheat pipelines prior to welding include gas torches and quartz lamps (radiation methods), electric resistance Revision 1 – April 30, 2010 the heat from the welding operation is sufficient to maintain the desired temperature without the continuous external application of heat.. preheating should be reapplied until the minimum-required preheat temperature is reestablished. If preheating is specified in the welding procedure.2 METHODS OF INSPECTION Production welds may be inspected using nondestructive testing (e. welding should be interrupted and preheat should be reapplied. Production welds can also be sampled (i.5 are more stringent than those in Section 9. If the welding operation is interrupted. Other codes. This results in the need to repair the area from which the sample was taken. to allow hydrogen diffusion). not just the first weld bead). standards. Once welding begins. (75 mm) in all directions from the point of welding. the post-weld heating must be applied prior to the onset of cracking. When possible. and when and how often it will occur. removed using a hole saw).. Inspection during welding may include visual inspection or nondestructive testing. For many welding applications.e. 22 When using post-heating (or post-weld preheat maintenance) to minimize the risk of cracking (i. Temperature measurement methods commonly used include contact thermometers (digital or analog). Acceptance criteria for imperfections discovered by destructive testing are those contained in 6.g.e. the preheat temperature could fall to below the minimum-required temperature before an individual weld pass is completed.e. Revision 1 – April 30. Preheating should be applied in a manner that ensures that the full material volume surrounding the joint is thoroughly heated to above the specified minimum temperature. and induction heaters (induction methods).. The minimumrequired interpass temperature should be equal to the minimum-required preheat temperature unless otherwise indicated. cut out) for destructive testing. Acceptance criteria for imperfections discovered by nondestructive testing are those contained in Section 9 (or Appendix A). It should be noted that some acceptance criteria in 6. Trepanning involves removing and destructively testing a portion of the weld (e.” or the temperature of the weld zone during welding of any weld bead (i. General preheating guidance suggests that the material should be thoroughly heated for a distance equal to the thickness of the material being welded. which makes it impractical for pipeline girth welding applications. and temperature indicating crayons (e. heat should be applied to the side opposite of that which is to be welded. it should also be applied when tack welding.. the temperature should be measured on the opposite side of that which is heated). non-contact infrared pyrometers. See guidance provided for Appendix A. the hold time at PWHT temperature range (usually expressed in hours per unit of wall thickness).5. If this occurs. this temperature is generally referred to as the interpass temperature. radiography or other methods specified by the company) provided that the method can produce indications of imperfections that can be accurately interpreted and evaluated. Parameters for post-weld heat treatment (PWHT) for stress relief often include a temperature to which the joint can be heated without controlling the heating rate. a maximum-allowable heating rate from this temperature to the PWHT temperature range...1 RIGHTS OF INSPECTION The company may dictate what type of inspection will occur.e. Where this is impractical. and the maximum-allowable cooling rate from this temperature. 2010 . G8.g.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities heaters (conduction methods). Cracks that develop in tack welds that are not completely consumed by the final weld can initiate cracks in the final weld. G8 Inspection and Testing of Production Welds G8.g. time should be allowed for the temperature to equalize after removal of the heat source before the temperature is measured. For girth welds in large diameter pipe. The use of Appendix A is for girth welds only and requires extensive analysis and testing prior to use. The minimum-required preheat temperature should be maintained throughout the welding operation. and regulations may set minimum requirements for inspection. It may be useful to think of preheat temperature as the “arc start temperature. Tempilsticks™). but not less than 3 in.. and measurements should be made on the surface adjacent to the joint (i. etc. visual inspection generally precedes other inspection methods. If a weld is rejected on the basis of visual inspection. and ultrasonic testing methods. For example.9 mm). shape.2 Record The company must keep detailed records pertaining to certification of nondestructive testing personnel. the imperfection is considered a defect should any one of the listed conditions exist. When performing a nondestructive examination.5 in.. In other words.) to the acceptance standards in Section 9. during. For detection of imperfections that would be cause for rejection according to the acceptance standards contained in Section 9. To determine the disposition of a particular imperfection.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities The company may require that inspectors demonstrate the effectiveness of the inspection procedures being used. ASNT requires inspectors to have specified levels of education and training. Requirements for nondestructive personnel are contained in 8. or for rejection on other grounds (e. magnetic particle. G8.g. When qualifying welders in accordance with 6. Visual inspection involves examining materials. Visual inspection can be performed before.g.1 Procedures Certification of nondestructive testing personnel is covered in American Society for Nondestructive Testing (ASNT) Recommended Practice No.. the inspector must compare the attributes of that imperfection (e. aggregate length within any continuous 12 in.4. No specific examination is required. (300 mm) of weld length. all defects are imperfections but not all imperfections are necessarily defects.3 QUALIFICATION OF INSPECTION PERSONNEL The level of education. For a given imperfection type. the expense of more costly nondestructive test methods can be avoided. size. aggregate length expressed as a percentage of the total weld length. Acceptance standards are given in terms of absolute length. (88.4. SNTTC-1A and the ASNT Central Certification Program.4 CERTIFICATION OF NONDESTRUCTIVE TESTING PERSONNEL G8. However. G8. changes in some detectable way. experience.5. and for pipe with an outside diameter less than 3. the inspector may find imperfections that may or may Revision 1 – April 30. it is not acceptable to select specific welds for destructive testing based on nondestructive testing results. orientation. The acceptance standards in Section 9 also apply to imperfections detected by visual inspection. Other nationally recognized programs for certification may also be used with company approval. and their ability to use those procedures. G9. welding procedure was not followed). An imperfection is not considered a defect until it has been compared to an acceptance standard and found to be non-conforming. the definition of linear indication for magnetic particle and liquid penetrant testing (length more than three times the width) should not be applied to porosity indications in radiographic applications. experience. Where multiple standards are given for a specific imperfection.4. the company must keep records pertaining to qualification of welding inspection personnel. G8. which are interruptions or irregularities in an otherwise uniform structure. liquid penetrant. with or without magnification or remote examination devices such as mirrors or fiber optics. G9 Acceptance Standards for Nondestructive Testing Nondestructive testing detects imperfections in a component or structure. and performance on qualification exams. and training required for welding inspection personnel is left to the discretion of the company. it is not necessary or advisable to consider or apply acceptance standards for different nondestructive test methods (except for visual inspection as described below). and after welding operations. location. Each has a source of probing energy or a medium that. All components and structures contain imperfections. upon encountering an imperfection in weld (or base material). 2010 .1 GENERAL Section 9 presents acceptance standards for imperfections detected by radiographic. testing 23 not require rejection. 3. API 1104 differentiates between IF (incomplete fusion open to the surface) and IFD (incomplete fusion below the surface). material that is thicker or more dense will produce a lighter image. G9. In both cases. Only the depth of an imperfection is mentioned in 9.3 Inadequate Cross Penetration Inadequate cross penetration occurs when welding is being performed from both sides of the joint and the two beads do not meet within the joint. improper joint configuration. Volumetric imperfections.3.3. For example.. G9. G9. Conversely. Imperfections cause patterns of lightness or darkness. A light image on a radiograph is described as being less dense than a dark image. also called incomplete joint penetration.2 Inadequate Penetration Due to Highlow See guidance provided in G9.4 Incomplete Fusion Incomplete fusion is a weld imperfection in which fusion does not occur between weld metal and fusion faces or adjoining weld beads. such as porosity and slag inclusions may be easily detected by radiography while some planar (i. When considering density.1. length) could be included as well. Material that is thinner or less dense will produce a darker image.4.2 RIGHTS OF REJECTION A weld that passes nondestructive testing may still be rejected by the company if in their opinion the imperfection can be detrimental to the weld. crack-like) imperfections may be more difficult to detect if not oriented parallel to the path of the penetrating radiation. Causes of ICP include improper technique and improper joint configuration.6 Internal Concavity Internal concavity (also called suck-back) is a root surface condition in which the weld bead surface is somewhat below the inside surface of the pipe Revision 1 – April 30.3 are summarized in Table G2.5 Incomplete Fusion Due to Cold Lap See guidance provided in G9. producing lighter image. Radiographic images of IF and IFD typically appear as a dark line or lines oriented in the direction of the weld. the acceptance standards for RT contained in 9. Areas where material is thinner or less dense will transmit more radiation to the film. producing darker images. which radiographic inspectors are trained to interpret and evaluate. can occur with or without high-low. 2010 . G9. A dark image on a radiograph is described as being more dense than a light image. For the sake of convenience. Radiographic films produce negative images. or improper fit-up.3 RADIOGRAPHIC TESTING Radiographic testing (RT) is based on the distinction between transmission and absorption of xray and gamma radiation.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 24 G9.1 Inadequate Penetration without Highlow High-low refers to misalignment of adjoining pipe sections. a crack oriented in the through-wall direction may be detected much more easily than a mid-wall lamination of similar size.3.2. Radiographic images of IP and IPD typically appear as a dark area with well defined straight edges that follow the root face down the center of the weld.e. be aware of the difference between density of the radiographic image and density of the material.3. Causes of IP include improper technique. Inadequate penetration. the most common causes included improper manipulation of electrode by the welder and improper joint configuration.3.. but it would seem reasonable that other attributes of the imperfection (e. producing images captured on film or other media. The acceptance standards for IPD are generally less stringent than for IP. G9.g. Detectability of imperfections is significantly affected by the shape and orientation of the imperfection when subjected to radiographic RT. G9. The acceptance standards for IFD are generally less stringent than for IF. G9. The radiographic image of ICP typically appears as a dark straight line in the center of the weld.3. IP and IPD are joint root conditions where the weld metal does not extend entirely through the thickness of a groove weld joint and one or both of the root faces of the weld bevel are not completely consumed. reflecting lower density.3. areas where material is thicker or denser will transmit less radiation to the film. 1 Porosity is the result of gas entrapment in the solidifying metal.3. G9.7. Two kinds of slag inclusion are recognized in 9. The radiographic image of IC typically appears as a darker area with irregular edges and is quite wide in the center of the image.4 Any elongated porosity indication in the root pass should be considered to be hollow bead. Porosity can be elongated and may have the appearance of having a tail. acceptable length for ESI.9.3.1 A slag inclusion is an entrapment of nonmetallic solid in the weld metal or between the weld metal the parent material.2 apply. G9. depends on wall thickness.2 No guidance material required. If part c of 9.3. (60.3 Only one acceptable BT is allowed for pipe with an outside diameter less than 2. G9.10 Cracks A crack.9. or in rows. and improper travel speed.3. improper shielding of the welding arc. and excessive heating and melting of the root pass during the welding of the second pass. The detectability of cracks is strongly influenced by their orientation relative to the path between the radiation source and the film (or detector). and hollow bead porosity (HB). Revision 1 – April 30. the criteria in 9.375 in.3.8. Provided that the welding procedure is followed. 2010 . G9.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities wall.2. G9. elongated (ESI) and isolated (ISI). G9.9. the only cracks that may be acceptable without repair are shallow star or crater cracks. is a linear imperfection with sharp end conditions.3. and insufficient cleaning of weld beads. Causes of porosity include contaminants or moisture in the weld zone.9 distinguishes between individual or scattered porosity (P). and acceptable length and width of ISI.3.2 a and b) and amount (9.8.3.3 If cluster porosity cannot be proven to be in the finish pass.3.3. In judging the amount. The radiographic image of BT typically appears as dark spots often surrounded by light areas.9.9.9. It takes many shapes on a 25 radiograph but often appears as dark. which appear at the end of a weld bead.3. and whether they develop during welding (hot cracks) or after cooling (cold cracks). in clusters. Section 9.8 Slag Inclusions G9. reference is made to Figures 19 and 20. The radiographic image of SI typically appears as dark jagged asymmetrical shapes within the weld or along the weld joint areas. the formation of cracks in general is usually indicative of a deficiency in the welding procedure for the particular materials being welded and the particular conditions under which the procedure is being used. size of the individual pores (9. then Figures 19 and 20 must be used even if the indication on the radiograph has been identified as cluster porosity. which provide schematic representations of porosity that are used for comparison purposes.3.3.8 mm).9.3. Cracks parallel to the radiation path are more likely to be detected than cracks oriented at a sharp angle to the radiation path. G9. (60. While other defect types depend on the skill of the welder. (0.3 See guidance provided in G9.2 Acceptance or rejection of porosity is based on two factors.3. excessive amperage. G9. G9. Causes of SI include improper technique. Causes of BT include improper technique.2 c).3 mm).7.9 Porosity G9. In API 1104. either longitudinal or transverse. cluster porosity (CP).7 Burn-through Not to be confused with “burning through” during welding onto an in-service pipeline where the welding arc causes the pipe wall to be breached and allows the contents to escape.3. G9.3.3 mm). Causes of IC include improper technique.8. improper manipulation of the electrode.8. The radiographic image of a crack typically appears as jagged and often faint irregular lines.7. For pipe with an outside diameter less than 2. round or irregular spots or specks appearing singularly.9. and improper joint configuration. G9.3. Cracks are the most critical imperfection because of their tendency to grow and propagate under stress.2 Wagon tracks typically occur in pairs and are treated as a single indication unless the width of either ‘track’ exceeds 1/32 in. Cracks are characterized by their location within the weld (heat-affected zone or weld metal).375 in.3. insufficient current.1 A burn-through is a localized collapse of the molten pool leaving a depression or crater type imperfection in the root area of the weld. cracks tend to occur if the necessary conditions are met regardless of welder skill. G9.3.2 applies.8.3. For example. Internal or root undercut occurs in the base metal adjacent to the root of the weld. In MT.3. while AC current typically finds only surface imperfections.4. Depending on their nature and size. the acceptance standards for MT contained in 9. This leakage attracts the particles of iron powder.4. because linear indications are more prone to propagation. These are considered separately in Paragraphs 9. it will appear as a dark irregular line offset from the centerline of the weld.11 should be used in conjunction with the visual acceptance standards for undercutting in 9.11 Undercutting Undercutting is a groove melted into the base metal during welding. When a magnetic field encounters an obstruction.2 If the inspector is not sure what an indication is.1 When using MT. In the radiograph. G9. the imperfections may cause the item to be rejected or explored further. In the radiograph.g. by dressing the toe of a weld by grinding) and reexamined.13 Pipe or Fitting Imperfections If radiography discloses defects in pipe or fittings. they must be reported to the company.3.4. such as abrupt changes in thickness at the toe of girth weld caps or the toe of a lumpy fillet weld can also result in particle accumulations. G9. Examples include wet fluorescent MT and the use of colored (usually black) particles in a liquid suspension applied to a surface that is first sprayed with a thin layer of white contrast paint. in some cases. excessive amperage.3. 2010 .1. G9. the surface should be conditioned (e.3 The inspector must ascertain which relevant imperfections are linear and which are rounded. the inspector identifies locations where particles accumulate.4 are summarized in Table G3.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities G9. Causes of undercutting include improper manipulation of the electrode by the welder. External undercut occurs in the base metal adjacent to the face of the weld and is also readily detectable by visual examination.2 Acceptance Standards If MT gives ambiguous results. metallurgical differences between weld metal and heat-affected zones may cause perturbations in the magnetic field that result in accumulations of particles at or near the fusion line.3. When both methods are used.3. the magnetic field ‘leaks’ into the atmosphere.12 Accumulation of Imperfections When considering accumulation of imperfections within a given weld length.1.1. Generally. mechanical measurements made in conjunction with visual inspection govern. G9. For the sake of convenience. it appears as a dark irregular line along the outside edge of the weld. 26 Generally. such as an imperfection or defect. the length of undercutting and incomplete penetration due to high low are not included. The length criteria in 9. External undercut is normally detected visually prior to radiographic testing. G9. MT only detects imperfections that are at or very close to the surface being inspected. which improves the mobility of the particles and allows them to be more easily attracted to small imperfections.4 MAGNETIC PARTICLE TESTING Magnetic particle testing (MT) employs magnetizing current and iron powder to locate imperfections in ferromagnetic materials. and improper travel speed. Dressing the toe of a weld by grinding or similar mechanical means can improve inspectability. those accumulations are somewhat less distinct than accumulations resulting from the presence of imperfections.4. other nondestructive testing methods may be used to determine the disposition of the weld.. the more sensitive methods use magnetic particles suspended in a carrier liquid. Sound materials that do not contain defects or imperfections and do not leak magnetic current do not attract iron powder.3.7 to determine whether an instance of undercutting is acceptable or rejectable. G9. G9.4. the inspector should be careful to distinguish between relevant accumulations of particles due to defects and irrelevant accumulations due to inherent characteristics of the weld.1 Classification of Indications G9. Undercut is not as straight as lack of penetration because it does not follow a ground or prepared edge. Geometric irregularities. Revision 1 – April 30. DC current may be capable of finding subsurface imperfections close to the surface. Various forms of MT have been developed to improve detectability of imperfections.11.2 and 9. Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities G9. because linear indications are the most prone to propagation. power wire brushing and some other mechanical methods of cleaning can smear metal over the surface opening of small imperfections and interfere with penetrant absorption.1.4 See guidance provided for imperfection types and causes in G9.6.6. Then a contrast medium (developer) reveals the penetrant remaining in the voids and crevices.6. the inspector should be careful to distinguish between relevant indication due to imperfections or defects and irrelevant indications due to characteristics of the weld.1 No guidance material required. For the sake of convenience. The inspector compares them to a reference standard to determine acceptability. they must be reported to the company. other nondestructive testing methods may be used to determine the disposition of the weld. the surface must be conditioned and reexamined.1. because linear indications are more prone to propagation.5. and volumetric indications.5 LIQUID PENETRANT TESTING Liquid penetrant testing (PT) relies on the ability of certain types of liquids to enter into surface voids and crevices by capillary action. 2010 .2 See guidance provided for imperfection types and causes in G9. the acceptance standards for PT contained in 9.2 Acceptance Standards If PT gives ambiguous results. G9.3 See guidance provided for imperfection types and causes in G9. G9.2 Acceptance Standards The inspector must distinguish between linear.3. G9.3 The inspector must ascertain which relevant imperfections are linear and which are rounded. various various various G9. G9. other nondestructive methods may be used to determine the disposition of the weld. the inspector should be careful to distinguish between relevant indications due to imperfections or defects and irrelevant indications due to the geometry of the weld. thus preventing detection. and volumetric indications.6 ULTRASONIC TESTING Ultrasonic testing (UT) involves the propagation of sound waves through materials. G9.2 If the inspector is not sure what an indication is.3 Pipe or Fitting Imperfections 27 If PT discloses defects in pipe or fittings.6. Anomalous or uncertain results can be obtained if excess penetrant is not thoroughly cleaned from the surface prior to the application of the developer. G9.1.3.1. they must be reported to the company. and remain there when the surface liquid is removed. G9. transverse. Revision 1 – April 30. G9.5 are summarized in Table G3 at the end of this section. and capture of the reflected echo from density changes in the material being inspected.4. G9.3. However. the acceptance standards for UT contained in 9.1 Classification of Indications The inspector must distinguish between linear. G9.5.1.1.1.6.3 Pipe or Fitting Imperfections If magnetic particle testing discloses defects in pipe or fittings.5.5.5. G9. The contrast medium may be a powder in liquid suspension or ultraviolet light. G9.1 When using UT. because linear indications are the most prone to propagation.6. However.5 If ultrasonic testing gives ambiguous results.5. Failure to appropriately clean the surface to be inspected before the application of the penetrant can also interfere with the ability to subsequently remove excessive penetrant before the developer is applied.1 Classification of Indications G9.6. These changes appear on a display screen as peaks and valleys.1 When using PT. G9.6.1. For the sake of convenience. transverse. G9.2.6 are summarized in Table G4. excessive cleaning can inadvertently remove penetrant from the actual imperfections. 1] SYMBOL IP INDIVIDUAL INDICATION SIZE Length shall not exceed 1 in. Incomplete Fusion Due to Cold Lap [9.3. (50 mm) in any continuous 12 in. and the density in any portion of the BTs image exceeds that of the thinnest adjacent parent material. whichever is less.375 in. (25 mm). Burn-through – Pipe OD ≥ 2.3. (50 mm). 2010 .3] Incomplete Fusion [9. (50 mm). Aggregate length shall not exceed 3 in. Maximum dimension shall not exceed 1/4 in.3.375 in.4] IPD ICP IF Length shall not exceed 2 in.3 mm) [9. or aggregate length shall not exceed 8% of the weld length. Any weld less than 12 in. aggregate length shall not exceed 8% of the weld length. Any weld less than 12 in. Length shall not exceed 2 in. (13 mm) in any continuous 12 in. (25 mm).3. (6 mm) or the thinner of the nominal wall thicknesses joined.3. TOTAL INDICATION SIZE Aggregate length shall not exceed 1 in. Aggregate length shall not exceed 2 in.7.5] IFD Length shall not exceed 2 in. (300 mm) in length. (75 mm).3. Inadequate Penetration Due to High-Low [9. length of weld. Length shall not exceed 1 in. length of weld. Aggregate length shall not exceed 2 in.3. length of weld or the total weld length. aggregate length shall not exceed 8% of the weld length.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 28 Table G2 – Summary of Radiographic Testing Acceptance Standards INDICATION TYPE Inadequate Penetration without High-Low [9. For areas that exceed the density of the thinnest adjacent parent material.3 mm) [9. Sum of the maximum dimensions of separate BTs exceeds that of the thinnest adjacent parent material shall not exceed 1/2 in. (50 mm). Aggregate length shall not exceed 1 in. (25 mm) in any continuous 12 in.3. (300 mm) in length. (50 mm). (60. and the density in any portion of the BTs image exceeds that of the thinnest adjacent parent material.1] BT Revision 1 – April 30.2] Inadequate Cross Penetration [9. (60.6] IC Any length is acceptable provided the density of the radiographic image of the IC does not exceed that of thinnest adjacent parent material.7. Internal Concavity [9. (6 mm) or the thinner of the nominal wall thicknesses joined.1] BT Burn-through – Pipe OD < 2. More than one BT of any size is present and the density in any portion of the BTs image exceeds that of the thinnest adjacent parent material. (25 mm). the criteria for burn-through are applicable. Maximum dimension shall not exceed 1/4 in. 1] Elongated Slag Inclusion – Pipe OD < 2. (60. (13 mm).1] Isolated Slag Inclusion – Pipe OD ≥ 2. (50 mm) in length or 1/16 in. ESI Length shall not exceed 3 times the thinner of the nominal wall thicknesses joined or width exceed 1/16 in. Aggregate length shall not exceed 1/2 in.3.9. (60. ISI Isolated Slag Inclusion – Pipe OD < 2. (3 mm) or 25% of the thinner of the nominal wall thicknesses joined. (60.3.1] P Cluster Porosity (Finish pass only).8. (3 mm) in any continuous 12 in.3 mm) [9.8. Maximum dimension of individual pore shall not exceed 1/8 in.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 29 Table G2 – Summary of Radiographic Testing Acceptance Standards INDICATION TYPE Elongated Slag Inclusion – Pipe OD ≥ 2. Aggregate length of ESI and ISI shall not exceed 8% of the weld length. (13 mm) in any continuous 12 in. Aggregate length shall not exceed 1/2 in. (3 mm). (1. TOTAL INDICATION SIZE Aggregate length shall not exceed 2 in.8.3] CP All Rights Reserved Revision 1 – April 30. 2010 . (13 mm) or more than four ISI indications with the maximum width of 1/8 in. Aggregate length shall not exceed 2 times the thinner of the nominal wall thicknesses joined and maximum width shall not exceed one-half the thinner of the nominal wall thicknesses joined.375 in.9. Diameter of cluster shall not exceed 1/2 in.375 in. (300 mm) length of weld. (60. Aggregate length of ESI and ISI shall not exceed 8% of the weld length.1] ISI Porosity (Individual or scattered.3 mm) [9.6 mm).6 mm).3. (50 mm) or width exceed 1/16 in.375 in. Maximum distribution of scattered porosity shall not exceed concentration shown in Figures 19 or 20. Maximum width shall not exceed 1/8 in.3 mm) [9.375 in. including cluster porosity in any pass except the finish pass) [9.3.3.6 mm).8.3 mm) [9. (1. Aggregate length of ESI and ISI shall not exceed 8% of the weld length.1] SYMBOL ESI INDIVIDUAL INDICATION SIZE Width shall not exceed 2 in. [9. Aggregate length of ESI and ISI shall not exceed 8% of the weld length. (300 mm) length of weld.3. (1. except a shallow crater crack or star crack with a length 5/32 in. 2010 .3.12] AI Note: 1.13 are based on negative images. shall not exceed 2 in.3. 2. Revision 1 – April 30. in any combination. they shall be considered separate indications. or exceed 8% of the weld length.8 mm). or the aggregate length of all HB indications shall not exceed 8% of the weld length. or less (4 mm) is permitted. TOTAL INDICATION SIZE Aggregate length shall not exceed 2 in. or exceed one-sixth of the weld length.3. excluding IPD and EU or IU. (13 mm) in length. Cracks [9. (300 mm) length of weld. Accumulation of Imperfections [9. Aggregate length. (50 mm) in any continuous 12 in. (300 mm) length of weld.9.1 through 9. (50 mm) in any continuous 12 in. shall be separated by less than 2 in. Aggregate length of EU and IU. All densities referred to in 9. (50 mm). In that event.10] Undercutting (Internal External) [9.3.4] SYMBOL HB INDIVIDUAL INDICATION SIZE Individual indication shall not exceed 1/2 in. (0. (6 mm) in length.3. (300 mm) length of weld.3. Individual HB indications.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 30 Table G2 – Summary of Radiographic Testing Acceptance Standards INDICATION TYPE Hollow Bead [9.11] or C IU or EU None permitted of any size or location in the weld. Parallel ESI indications separated by approximately the width of the root bead (wagon tracks) shall be considered a single indication unless the width of either of them exceeds 1/32 in. shall not exceed 2 in. each greater than 1/4 in. (50 mm) in any continuous 12 in. 3. 2. (13 mm). (300 mm) length of weld or 8% of the weld length. (25 mm) in a continuous 12 in. Any indication with a maximum dimension of 1/16 in. the maximum dimension of a rounded indication shall be considered its size. verification may be obtained by using other nondestructive testing methods.6 mm) or less shall be classified as nonrelevant. Diameter of cluster porosity shall not exceed 1/2 in. except a shallow crater crack or star crack. Maximum dimension of individual pore shall not exceed 1/8 in. (3 mm) or 25% of the thinner of the nominal wall thicknesses joined. Maximum distribution of scattered porosity shall not exceed concentration shown in Figures 19 or 20. None permitted of any size or location in weld. © Revision 1 – April 30. (1. For evaluation purposes. Total length shall not exceed 1 in. (13 mm) in any continuous 12 in. (4 mm). When doubt exists about the type of imperfection being disclosed by an indication. Aggregate length of cluster porosity shall not exceed 1/2 in.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 31 Table G3 – Summary of Magnetic Particle and Liquid Penetrant Testing Acceptance Standards RELEVANT INDICATION TYPE Crater Cracks or Star Cracks Cracks Incomplete Fusion C IF SYMBOL INDIVIDUAL INDICATION SIZE Length shall not exceed 5/32 in. (300 mm) length of weld. TOTAL INDICATION SIZE Rounded Indications Notes: 1. 2010 . 2010 . (300 mm) length of weld or exceed 8% of the weld length. (300 mm) length. or exceed 8% of the weld length. 3. Maximum dimension shall not exceed 1/8 in. (300 mm) length of weld. (13 mm). Vertical height (through-wall) dimension shall not exceed one quarter of the wall thickness. (25 mm) in any continuous 12 in. (300 mm) length of weld or exceed 8% of the weld length. whichever is less. Aggregate length shall not exceed 1 in. When doubt exists about the type of imperfection being disclosed by an indication. (3 mm). Aggregate length shall not exceed 2 in.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 32 Table G4 – Summary of Ultrasonic Testing Acceptance Standards RELEVANT INDICATION TYPE Cracks Indications SYMBOL C INDIVIDUAL INDICATION SIZE None permitted of any size or location in weld. Maximum dimension shall not exceed 1/4 in. (13 mm) in any continuous 12 in. (6 mm) or the nominal wall thickness. 2. verification may be obtained by using other nondestructive testing methods. Revision 1 – April 30. (50 mm) in any continuous 12 in. (50 mm) in any 12 in. Aggregate length shall not exceed 2 in. Total length shall not exceed 1/2 in. Evaluate using the criteria for volumetric indications Maximum dimension shall not exceed 1/2 in. Multiple indications at the same circumferential location with a summed vertical height (through-wall) dimension exceeding one half the wall thickness. Linear buried indications are interpreted to be subsurface with in the weld and not ID or OD surface-connected. TOTAL INDICATION SIZE Linear Surface cracks) Linear Buried cracks) (other than LS (other than LB Transverse (other than cracks) Volumetric Cluster Volumetric Individual Volumetric Root (open to the ID surface) Accumulation of Indications (above level) Relevant evaluation T VC VI VR AR Notes: 1. Linear surface indications are interpreted to be open to the ID and OD surface. 2. the original welding procedure is sufficient.3 Pipe or Fitting Imperfections If ultrasonic testing discloses defects in pipe or fittings. G9.2.11.6.7.7 VISUAL ACCEPTANCE STANDARDS FOR UNDERCUTTING Visual inspection involves examining materials.3. repair welds tend to be susceptible to hydrogen cracking. G10.2.2. G9.6.1 Cracks The only cracks that may be acceptable after further evaluation and repair are shallow star or crater cracks that do not exceed 5/32 in. This often involves the use of low-hydrogen electrodes and/or preheat and interpass temperatures that are higher than those used to make the original weld. G9. For repair welding procedures.6.6 No guidance material required. the repair is authorized Revision 1 – April 30. G9. When repairing a crack. Cracks other than shallow star or crater cracks may be repaired if the total length of the crack is less than 8% of the weld length.2.11.7 No guidance material required. 2010 . restraint provided by surrounding weld metal (higher levels of residual stress). G9.2.8 No guidance material required.2.3. (4 mm). but need not authorize repair of cover pass defects.2 Defects Other Than Cracks The company must authorize repair of defects in the root and filler beads.1 AUTHORIZATION FOR REPAIR G10. the deficiencies of the procedure used to make the original weld should be rectified.2 No guidance material required.1. they must be reported to the company. For procedures that will only be used for repair welding.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities G9. G10.1 through 10. A qualified repair procedure must include the minimum requirements listed in 10. For other repairs. consideration should be given to the use of lowhydrogen electrodes and/or increased preheat and interpass temperatures.4 No guidance material required.1 General Visual examination requirements for welder qualification welds are contained in 6.6.5 No guidance material required. The extent of testing is left to the discretion of the company. G9. G9. G9. Destructive testing is necessary to demonstrate that the procedure is adequate.2. the formation of cracks in general is usually indicative of a deficiency in the welding procedure for the particular materials being welded and the particular conditions under which the procedure is being used. G9.1.7. As a result. Factors that make repair welds more challenging to make include excavation geometries (produced by hand grinding). it is common for segments of weld repairs to be made on a full circumference weld and to G10 Repair and Removal of Defects G10. and when a previously repaired area is repaired again.6.4. with or without magnification or remote examination devices such as mirrors or fiber optics.3 The acceptance standards for buried indications are generally less stringent than for surface breaking indications. the acceptance standards based on mechanical measurements given in Table 4 supersede those in 9. whenever mechanical measurements are made in conjunction with visual inspection.6. 33 by the company. Two conditions are noted that require the use of a qualified repair welding procedure for defects other than cracks: when the repair employs a welding process different from that of the original weld.2 REPAIR PROCEDURE Repair welds are often made under more challenging conditions than production welds. G9.6.2.2 Acceptance Standards As noted here and in G9. Provided that the original welding procedure was followed during production welding.6. particularly for the root region of through-wall repairs. and an approved and qualified repair welding procedure is used.6. Surface breaking imperfections are more prone to propagation than buried imperfections. and thermal severity (faster weld cooling rates) caused by surrounding weld metal. such as porosity and slag inclusions.4.1 describe how to produce radiographic images using low-energy nonparticulate radiation (x-rays or gamma radiation).2. Conversely.2.3. It is common for mechanized welds originally inspected using automated ultrasonic testing (AUT) and evaluated using alternative acceptance criteria developed using Appendix A to be repaired and inspected using RT and evaluated using the workmanship-based acceptance criteria in Section 9. G10.3 Examples of methods to confirm complete removal of the defect include visual inspection and nondestructive examination (e.1 Examples of methods of exploration include carbon arc gouging. it must be inspected in the same manner as the original weld and meet the acceptance criteria contained in Section 9.4.3. At the discretion of the company.5 WELDER G10. Material that is thinner or less dense will produce a darker image. G10.2 Examples of methods for defect removal include carbon arc gouging. When considering density.4 SUPERVISION G10. For example. producing lighter images.1 No guidance material required. all residue should be removed prior to resuming welding. G10. etc. Revision 1 – April 30.5. partial-wall repairs. producing images captured on film or other imaging media. grinding.2. Areas where material is thinner or less dense will transmit more radiation to the film. be aware of the difference between density of the radiographic image and density of the material. so does nondestructive testing. Detectability of imperfections is significantly affected by the shape and orientation of the imperfection when subjected to RT.1 RADIOGRAPHIC TEST METHODS Radiographic testing (RT) is based on the distinction between transmission and absorption of xray and gamma radiation.3). etc.2.2. G11. and multiple repairs. procedures can be developed for backwelding (see guidance provided in G5.2.g. G10.. A dark image on a radiograph is described as being more dense than a light image. At the discretion of the company. G11 Procedures for Nondestructive Testing Just as welding requires the use of a written procedure. If liquid penetrant testing is used.1 No guidance material required. A WPS can be supported by more than one PQR. A PQR ‘supports’ a WPS.e. It is common. 2010 .2. Imperfections cause patterns of lightness or darkness. G10. API 1104 also refers to the latter as a coupon test report. Radiographic films produce negative images.1 Once a weld is repaired. only the repaired area can be inspected or the entire weld can be re-inspected. crack-like) imperfections may be more difficult to detect if not oriented parallel to the path of the penetrating radiation.. which RT inspectors are trained to interpret and evaluate. magnetic particle testing).g.2. The subsections listed under 11. a crack oriented in the through-wall direction may be detected much more easily than a mid-wall lamination of similar size. through-wall repairs. Volumetric imperfections. areas where material is thicker or denser will transmit less radiation to the film.4 The use of sufficiently-high preheat and interpass temperatures is particularly important considering that repair welds tend to be more highly restrained than the original weld..2. may be easily detected by radiography while some planar (i.3.6 Examples of interpass nondestructive testing methods include visual inspection and nondestructive examination (e. producing darker images.3 ACCEPTANCE CRITERIA G10. all residue should be removed prior to repair welding. G10. If liquid penetrant testing is used.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities extract and test specimens from the repaired locations.5 and G5. grinding. A light image on a radiograph is described as being less dense than a dark image. material that is thicker or more dense will produce a lighter image.5 See guidance provided in G5. G10. but not mandatory to list the PQRs that support a particular WPS. 34 G10. G10. magnetic particle testing). A qualified welding procedure consists of a welding procedure specification (WPS) and a procedure qualification record (PQR). The essential wire diameter indicates which of the wires on the IQI must appear clearly across the entire area of interest. G11. When placing the IQI across the weld is impractical due to weld reinforcement or profile. It is placed on the weld prior to radiography and various attributes must be visible when viewing the resulting film.1.1..1. Knowing the weld thickness and the required IQI type. and most common.1. The essential wire cannot be obscured by lead letters or numbers. finer grain Class I radiographic film offers better resolution than higher-speed. artifacts. G11. It is only necessary that the radiographic procedure or procedures to be used be established and qualified sometime prior to the start of production radiography. The use of hole-type penetrameters is no longer allowed.5 Selection of Image Quality Indicators (IQI) IQIs are chosen for a particular application based on the thickness of the weld.2.4 Type of Image Quality Indicators (IQI) An image quality indicator (IQI) is a device used to measure the quality of radiographic images.2 Film Radiography All of the applicable details described in 11. The company has the option to choose between either ASTM or ISO type IQIs.1 General Only the details that are applicable to the method that will be used (i. Single-wall exposure for single-wall viewing (SWE/SWV) is the preferred method over doublewall exposure for single-wall viewing (DWE/SWV) or double-wall exposure for double-wall viewing (DWE/DWV) when the inside of the pipe is accessible.2 Details of Procedure G11.1. spaced equally around the pipe on the source side or film side of the pipe. plus any weld reinforcement (internal plus external combined). G11. is to place the IQI across the weld.1.6 Placement of Image Quality Indicators (IQI) Three different IQI placement options exist.1 describe how to produce radiographic images using either x-rays or gamma rays.2 for film radiography must be recorded in the radiographic procedure. a separate block of similar material (also called a shim) is used to elevate the IQI to a height equal to the top of the weld reinforcement.1. G11.1.3 Exposure Geometry 35 Exposure geometry is the relationship between the radiation source.3 Other Imaging Media All of the applicable details described in 11. and the film (or other imaging media).1.1. G11. G11.e.1.1.3.2. IQIs were previously referred to as penetrameters in API 1104.2 Other Imaging Media No guidance material required. G11.1 General The subsections listed under 11. Also.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities API 1104 Standard does not specify the conditions under which x-ray or gamma radiography should be used. Revision 1 – April 30. water stains. placing the IQI on a heat shield.3 for radiography using other imaging media must be recorded in the radiographic procedure. API 1104 does not specify the conditions under which x-ray or gamma radiography should be used.2.1.2. etc. the weld being inspected. The resulting images are what determine the acceptability of the method chosen. The resulting image quality is what determines the acceptability of the method chosen.2. The x-ray technique offers better radiographic sensitivity (sharper image and higher contrast for better detection of planar imperfections) compared to the gamma radiation technique.1 Film Radiography No guidance material required. the inspector can use Tables 5 and 6 to determine the essential wire diameter for the application. G11. G11. The phrase “prior to the performance of production radiography” has no specific time limit. G11. The third location option.3. film radiography or radiography using other imaging media) need to be recorded. is used primarily to radiograph hot materials. coarser-grain Class II film. The first. 2010 . The characteristics of suitable film viewing facilities are also described. G11.10 Film Density The light area representing the image of a weld on a film must provide enough contrast from the dark area representing the image of the base metal.1.10. G11.10. effective shielding requires distance.2 MAGNETIC PARTICLE TEST METHOD Magnetic particle testing (MT) employs magnetizing current and iron powder to locate imperfections in ferromagnetic materials.11 Image Processing 36 The company may request that the film be readily viewable for at least three years. G11. G11.6.7 Production Radiography Technicians interpreting radiographic images must be certified to Level II or Level III according to the requirements of the ASNT Recommended Practice SNT-TC-1A or equivalent. lead. RT work areas must be properly posted and cleared of all nonessential personnel.6. This is particularly important when a single weld is represented by multiple radiographs because the identification markers will distinguish between the end of one radiograph and the start of the next.e. Radiographic film can also be digitized and the electronic files can be maintained indefinitely. G11. that are determined to be defects) according to 9.1. Radiographic film can be photographed if images are to be maintained for very long times.1.13 Radiation Protection The radiographer is responsible for all aspects of radiation safety.1. The requirements for film storage and the recognizable characteristics of film damaged due to improper storage are provided in this section.1. G11. G11.2 Other Imaging Media No guidance material required.1 Film No guidance material required. G11.1. G11.1.9.10. MT only detects imperfections that are at or very close to the surface being inspected.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities G11.9. the images should include a scale for size reference and.6.1 Film Density No guidance material required. DC current may be capable of finding subsurface imperfections close to the surface.1. Because the gamma ray and x-ray radiation used in RT is nonparticulate electromagnetic radiation unaffected by gravity.1. if possible.10. G11. such as an imperfection or defect. the magnetic field ‘leaks’ into the atmosphere. Sound materials that do not contain imperfections or defects and do not leak magnetic current do not attract iron powder.. This leakage attracts the particles of iron powder. or a significant thickness of concrete or steel. When a magnetic field encounters an obstruction.1.1. Various forms of MT have been developed to improve detectability of imperfections. 2010 . Revision 1 – April 30. G11. G11.1. include the radiographic image of the IQI.1.1.12 Image Processing Area All of the RT equipment and the area where image processing occurs must be kept clean.1. The best way to view radiographic film is with equipment that transmits light through the film to help the inspector see the image of the weld being inspected.8 Identification of Images Lead letters or numbers must be placed on the weld being inspected to identify the image.2 Other Imaging Media No guidance material required. while AC current typically finds only surface imperfections. Unless the company requests reporting of all imperfections. The requirements for determining that adequate density exists to ensure proper viewing of the film’s image are provided in the subsections listed under 11.3 Film Viewing Facilities No guidance material required.2 Film Viewing Equipment No guidance material required.9 Storage of Film and Other Imaging Media G11. G11. the inspector must report only imperfections that are rejectable (i. however.1 Film Improper storage can damage unexposed film. In MT. A detailed procedure must be developed. However. published by the American Society for Testing and Materials. G11. G11. 37 A procedure for PT must be written. the inspector identifies locations where particles accumulate.4. the imperfections may cause the item to be rejected or explored further. The choice of these is left to the discretion of the user. both are necessary for comprehensive guidance on the methods and quality control requirements for PT. Depending on their nature and size. The MT procedure must comply with ASTM E 709. G11. Although API 1104 does not mention the latter document. A procedure for MT must be written. the inspector should be careful to distinguish between relevant indication due to defects and irrelevant indications due to characteristics of the weld. both are necessary for comprehensive guidance on the methods and quality control requirements for MT. G11. ASTM E 165 is a tutorial that supports ASTM E 1417.3 LIQUID PENETRANT TEST METHOD Liquid penetrant testing (PT) relies on the ability of certain types of liquids to enter into surface voids and crevices by capillary action.4. Although API 1104 does not mention the latter document. Failure to appropriately clean the surface to be inspected before the application of the penetrant can also interfere with the ability to subsequently remove excessive penetrant before the developer is applied.2 Details of Procedure The required details of a written procedure for UT of welds are provided in the subsections listed under 11. and remain there when the surface liquid is removed. power wire brushing and some other mechanical methods of cleaning can smear metal over the surface opening of small imperfections and interfere with penetrant absorption. API 1104 does not specify the required inspection techniques to be used within automated ultrasonic testing (AUT) systems such as pulse-echo or time-of-flight diffraction (TOFD). Required mapping techniques or techniques for coupling control are not specified either. qualified by demonstration. Standard Practice for Liquid Penetrant Testing. The contrast medium may be a powder in liquid suspension or ultraviolet light. The pipe being inspected with UT must be uncoated and the inspector should be aware of surface conditions that can interfere with scanning. and capture of the reflected echo from density changes in the material being inspected. Standard Practice for Magnetic Particle Testing. Examples include wet fluorescent MT and the use of colored (usually black) particles in a liquid suspension applied to a surface that is first sprayed with a thin layer of white contrast paint. However. Standard Guide for Magnetic Particle Examination. The PT procedure must comply with ASTM E 165. published by the American Society for Testing and Materials. and accepted by the company prior to use.4 ULTRASONIC TEST METHODS Ultrasonic testing (UT) involves the propagation of sound waves through materials.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities Generally.1 General This section applies to both new and in-service circumferential butt welds (groove welds in a butt joint). The inspector compares them to a reference standard to determine acceptability. Anomalous or uncertain results can be obtained if excess penetrant is not thoroughly cleaned from the surface prior to the application of the developer. When using PT. qualified by demonstration. and agreed upon by the contractor and company. excessive cleaning can inadvertently remove penetrant from the actual imperfections. Standard Test Method for Liquid Penetrant Examination. ASTM E 709 is a tutorial that supports ASTM E 1444.2.2.4. Then a contrast medium (developer) reveals the penetrant remaining in the voids and crevices. 2010 . qualified by demonstration. These changes appear on a display screen as peaks and valleys. G11. thus preventing detection.1 General The procedures furnished to the company should include all of the variables for UT and should include Revision 1 – April 30. the more sensitive methods use magnetic particles suspended in a carrier liquid which improves the mobility of the particles and allows them to be more easily attracted to small imperfections. and accepted by the company prior to use.4. differences within portions of a weld. The specific characteristics of the scanning process necessary to ensure scanning of the entire surface so the returning echo can be evaluated should be described. is provided below. k. and tee.4. etc. The UT procedure must specify when to calibrate. The method of recording the inspection results must be identified. Base materials should be listed according to the requirements of Section 4. the speed at which the weld is scanned. G11. and the required steps involved with calibration. and the sensitivity settings of the instrument. Destructive testing can be required by the company to resolve differences in detection results between UT and RT of demonstration welds. g. such as joint configuration and repaired areas. The demonstration involves creation of reference welds similar to production welds. Sketches and crosssectional views of these standard blocks must be provided.4 Demonstration of the Testing Procedure Prior to a UT procedure being used. m. a. groove. Where discrepancies exist between detection results from UT and RT.2 for UT must be recorded in the UT procedure. In the manual mode of UT. what calibration reference standards to use. are then used to demonstrate that the UT procedure will effectively find the conditions deliberately created in the reference weld.4. An indication of whether the UT process is to be applied manually (where the operator has full control of scanning) or automatically (where the operator applies no manual scanning techniques) must be specified. as appropriate. it must be demonstrated and accepted by the company. l. should be specified. the gel-like substance that lubricates the surface of the material to be scanned and provides an airtight bond between the transducer and the surface. The return echoes appear on the equipment screen as peaks. specifically designed with defects and geometrical differences.2 Ultrasonic Procedure All of the applicable details described in 11. a weld may be scanned in many ways. Transducers for various types of materials and for different angles at which sound can be projected through the material are available from a variety of UT equipment manufactures. n. scanning patterns. and inspection results. which must include qualification by demonstration. Acceptable and rejectable height levels for a return echo peak must be established and recorded. 38 j.2. G11. The manufacturer of the UT equipment should be identified and the specifications for all instruments and accessories should be listed. d. Welding and fabrication involves many steps where UT may be required. A sample inspection reporting form must be provided. Sound waves projected into a weld will bounce back to their source from different portions of the weld at different times. Types of joints include butt. destructive testing results should govern. Calibration of UT equipment is essential to verify that the UT equipment and procedures are working properly and to provide standard points of reference to compare echoes from actual inspections to those performed on reference standards during calibration.4. These characteristics include angle and frequency of sound waves. the temperature of the material. Revision 1 – April 30. and reference points or markings identifying the geometric characteristics of the joint. c. These reference welds. G11. sensitivity-level requirements to achieve. scanning patterns.3 Ultrasonic Testing Personnel Requirements Only Level III UT inspectors are qualified to develop application techniques and procedures. The procedure should clearly define the stage of the welding or fabricating operation at which examination is to be performed. 2010 . Materials should be identified by their ASTM or API specification number. Reference standards of similar material and geometry should be used to qualify techniques and calibrate the UT process. lap. The manufacturer and product number of the couplant. f. so the surfaces of materials subject to UT must be free from such things as spatter or weld reinforcement. b. using an approved welding procedure. The amount of sensitivity (sound is measured in decibels) above what was used on the reference standard must be recorded. as detected using radiographic testing (RT). During UT.4. h. Specific guidance for each item listed. which will vary in screen height depending on their strength.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities sketches for such things as joint design. and these return echoes depict geometric differences in the weld. e. Types of welds include fillet. i.2. the transducer must slide freely across the base material. G11. consideration should be given to including indication height sizing in the list of required capabilities.6 Parent Material Ultrasonic Testing Before UT of a completed weld.4.4. For new construction applications. G11.7.7.4. G11.) in practice. G11. No clear requirements are given regarding size of these flat bottom holes except that the diameter should be approximately equal to the thickness of one welding fill pass.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities If destructive testing of the reference weld indicates that a particular imperfection (e. no acceptance criteria are specified. 2010 .7 Scanning and Evaluation Level The subsections listed under 11.4. Since vertical height (through-wall dimension) of an indication is part of the acceptance criteria listed in 9.6..2.039 in.4.18.. For new construction applications. The principals of probability of detection (POD) can be used to determine the most appropriate nondestructive testing method for the welding process being used.e. In the case of interfering reflectors. and for manual and automated testing of welds.3 Automated Ultrasonic Weld Testing Scanning and evaluation level requirements are the subject of some debate. the inspector must report only imperfections that are rejectable (i.4. G11. Revision 1 – April 30.25 times the longest surface skip distance can be difficult to achieve. that are determined to be defects) according to 9. G11. The term “should” indicates a recommended practice.4.4. it is not mandatory to dynamically scan the reference standard containing the required calibration reflectors.0 mm (0. the UT inspector must conduct a compression wave test on the parent metal adjacent to the weld to locate any reflectors in the parent material that may interfere with the weld metal inspection. the requirement to scan the parent material with coverage 39 of 1.6. Flat bottom holes may also be used for calibration purpose in addition to the N10 notches at the ID and OD surface.2 Manual Ultrasonic Weld Testing No guidance material required. The peaks on the instrument screen that return echoes from these notches must be 80% of the screen height.4.1.9 Identification of Reported Indications No guidance material required. the measurement of attenuation and transfer would seem to be redundant.7. it is not clear when and why the plus 4dB sensitivity needs to be applied in relation to the evaluation level screen height. The use of techniques other than pulse-echo may be used if demonstrated to be adequate. Inspection of the parent material and inspection of the weld must be performed and documented independently. Consideration should be given to dynamically scanning the calibration standard.2 identify the scanning techniques and screen height requirements for manual compression wave testing of the parent material.8 Production Ultrasonic Testing Unless the company requests reporting of all imperfections. As indicated in 3. which will eliminate the need for transfer and attenuation measurements.5 API Sensitivity Reference Standard The sensitivity reference standards for use in measuring the screen height of return echoes from known geometric conditions (the notches in the calibration block) must be made of materials similar to those in production applications. “shall” is a term that indicates a mandatory requirement.1 Parent Material Ultrasonic Testing No guidance material required. G11.2. lack of fusion) is detectable by UT and not by RT. G11.g. In practice. While Figure 21A implies that notch depths of 10% of the actual WT can be used. then it would seem reasonable to for the company to strongly prefer the use of UT over RT for the inspection of production welds. Since the calibration block must be made of materials similar to those in production applications. the depth of N10 notches is generally limited to 1. G12. Many of these variables are limited by the essential variable changes given in 12. The welding processes that are generally applicable to mechanized welding are shown in Table G1 in the guidance provided in G1. A revised WPS should be identified by a revision number. inspection of production welds. Section 12 requires both destructive and nondestructive testing whereas Section 5 requires only destructive testing. and to Section 9 for nondestructive testing requirements. FCAW. but not mandatory to list the PQRs that support a particular WPS.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 40 G12 Mechanized Welding with Filler Metal Additions Mechanized welding is a method of application where welding process parameters and torch guidance are controlled mechanically or electronically but may be manually varied during welding to maintain the specified welding conditions. although forms similar to these should be used. equipment and operator qualification.1 only if they are performed in a mechanized mode. Examples of the ‘type of welding technology’ that may be utilized include GMAW with pulsed Revision 1 – April 30. Changes to welding variables that are not listed in 12. It is common.2 must be included in the WPS.1.1 ACCEPTABLE PROCESSES Section 12 applies to the processes listed in 12. G12. A PQR ‘supports’ a WPS.4 PROCEDURE SPECIFICATION G12. For some of these topics. Figure 1 in API 1104 is a sample WPS. Section 5 applies to these processes they are performed in a manual or semiautomatic mode. G12. it is common practice for the company to approve each qualified WPS that will be used for production welding. It is only necessary that the welding procedure specification (WPS) to be used for production welding be established and qualified sometime prior to the start of production welding.2. This section combines the requirements for procedure qualification. G12.3 RECORD A qualified welding procedure consists of a WPS and a procedure qualification record (PQR). which may be required eventually. although sound engineering judgment should be used. GTAW. acceptance standards.1 General Only the welding variables that are applicable to the welding process and welding method to be used need to be documented. A welder who performs a test joint that qualifies a WPS becomes qualified to perform that procedure provided that all of the testing required for a welder qualification is performed and passed. for both to include a space for a revision number. G12.2 PROCEDURE QUALIFICATION The phrase “before production welding is started” has no specific time limit. A WPS can be supported by more than one PQR. It is common. reference is also made to other sections of API 1104.4. Other welders then may qualify to perform the same welding procedure. The use of Figures 1 and 2 is not mandatory.2.5 are allowed by simply revising the WPS without the need for requalification. Section 12 refers to Section 5 for destructive testing requirements.4. See additional guidance provided in Section 5. it would seem that Section 12 is more applicable than Section 5.4. Some mechanized welding system employ a manual or semi-automatic root pass (or possibly a root and hot pass). except that nick-break testing is not required. For these systems. and repair for mechanized welding into a single section. However.4.2 Specification Information G12. API 1104 also refers to the latter as a coupon test report. A WPS need not be established and qualified by the company itself. and PAW. GMAW.1 and include SAW. which can also be used as a welder qualification test record (WQTR). 2010 .5. Procedure qualification requirements in Section 12 for mechanized welding are similar to those in Section 5 for manual or semiautomatic welding. but not mandatory.1 Process Eight possible welding processes are listed in 1. Figure 2 is a sample PQR. All of the applicable welding variables described in 12. 2.g.000 psi (386 MPa). 41 If the welding procedure covers a range of wall thicknesses. it is common practice.2. or a combination of both. Base materials and base material groupings are addressed in 5. It is not clear what constitutes an “acceptable ASTM specification.g.3 and the basis for selecting the welding consumables to be used. the weld width (or wall thickness) at which the transition from one technique to another should occur should also be specified. ER70S-6 electrode on X80 line pipe) are commonly used with mechanized vertical-down GMAW. A description of the equipment to be utilized could include the manufacturer and model number of the internal welder and external welding bugs. no suggested groupings for outside diameter are provided. G12. the trade name of the filler metal can also be listed for information purposes. no suggested groupings for wall thickness are provided.4. for the root face tolerances to be specified.4. the test joint must be made using the material with the highest specified minimum yield strength (SMYS) in the group. For production welding that involves joining base materials from two different strength groups. G12.. higher strengths are typically observed on the mechanized low heat input vertical-down welds. copper backing shoes). The WPS is not required to contain a sketch of the sequence of beads. the sequence of beads must somehow be designated.2 Pipe and Fitting Materials It is common.6. and the version number of the software control program.2. Backup can be either consumable (e.4..2. The latter establishes the basis for the tensile strength requirements in 5. to specify the industry standard or specification to which the base material was manufactured. The welding parameters for a mechanized vertical-down narrow-groove GMAW pipeline girth weld are significantly different than those used for the AWS filler metal classification test plate weld. However. For material with a SMYS higher than 56. a WPS for the higher strength material must be employed.4. Using the same filler metal. weave beads.” This presumably refers to ASTM specifications that are acceptable to the company. The range of wall thicknesses over which the procedure is applicable is left to the user to define.2.3 Diameters Unlike Section 5. To qualify a WPS for an entire group. if desired. If the welding procedure covers a range of wall thicknesses and a combination of techniques. 2010 .6 Filler Metal The filler metal to be used should be identified by size and its AWS (or other) specification and classification numbers.2.g.4. it is insufficient to list trade name only. Guidance can be found in a variety of other codes and standards.4 Wall Thickness Group and Number and Sequence of Beads Unlike Section 5. Guidance can be found in a variety of other codes and standards.g. The range of outside diameters over which the procedure is applicable is left to the user to define. Revision 1 – April 30..2. It is good practice but not mandatory to specify the welding technique that should be used – e. for the bevel angle tolerances to be specified. it is common practice. but not mandatory. In addition to specifying the required size of the root face.5 Joint Design In addition to specifying the required bevel angle. Lincoln Invertec STT II with STT Waveform Control and CSC MIG Weld Process Controller from Miller Electric’s Jetline division). but not mandatory. While not required.2. as well as the grade of the base material.4.g.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities current (GMAW-P) or advanced waveform power supplies (e. The required root opening may be expressed as an approximate value or a specific value with applicable tolerances. G12. stringer beads. it is good practice but not mandatory to document the carbon equivalent for all base materials used in the procedure qualification. G12.. Filler metals with lower classified strength levels than the line pipe (e. However. but not mandatory. it is appropriate to include a range for the number of beads required for each wall thickness. G12. consumable inserts) or non-consumable (e. G12. When determining what value to specify on a WPS for time between passes.2. voltage. etc. as well as the probability of the weld to cracking. 2010 . it is good practice to indicate this and to specify pulse parameters. Actual values for amperage and voltage used during the procedure qualification test need not be recorded in the WPS.15. When using welding power sources generating waveform output (e. Specifying a maximum-allowable time between passes does this by a) preventing the weld from cooling excessively between passes and b) providing less time for cracking to occur. The time between the completion of the root bead and the start of the second bead is most critical since the weld has less cross-sectional area at this stage. and sampling rate. The ranges specified should be wide enough so that the qualified welding procedure can be implemented in the field. only the ranges need to be specified.. For DC.7 Electrical Characteristics Current can be either alternating current (AC) or direct current (DC).). The ranges should not be so wide that operating at the edges of the ranges produces an unacceptable weld.4. voltage. and travel speed. An amperage and voltage range for each filler metal type and size must be specified. not the calculated minimum and maximum values from the amperage. etc. but not mandatory. the time-dependant nature of hydrogen cracking should be considered. also.2. the voltage and amperage measurements may vary significantly depending on the type and brand of meter used. G12. If pulsed current is to be used. it is good practice to record where these values were obtained (welding power source display. and travel speed range.2. API 1104 has traditionally been used for construction of cross country pipelines.20%. brand and type of meter used. For mechanized welding however. Ranges for amperage and voltage specified by the electrode manufacturer can be used for guidance.9 Direction of Welding If welding is to be performed with the pipe in the vertical position. horizontal.g. Revision 1 – April 30. GMAW-P).).2.4. The specified range should reflect the minimum and maximum heat input values that produce an acceptable weld. it would seem to be prudent to indicate that here.10 Time between Passes The primary intent of this requirement is to prevent the weld from experiencing hydrogen cracking prior to completion. meter settings. the allowable range for amperage and voltage should be no larger than the median value +/. For example. Commercially available meters are generally not designed to measure fluctuating high-amperage welding outputs and the welding equipment meters are commonly used instead. The actual values used during the procedure qualification test should be recorded in the PQR. The specified range should reflect the minimum and maximum values that produce an acceptable weld (or a weld with desired toughness properties. the direction of welding is horizontal. The limits of the range should be based on sound engineering judgment. Heat input takes into account the collective effect of amperage. polarity can be either electrode negative (straight polarity) or electrode positive (reverse polarity). it is common for the lineup clamp that will be used for production welding to be used during the procedure qualification test.4. or some position in between). if required). Longer times can be justified when the probably of cracking is low (e. higher preheat/interpass temperatures.. etc. Roll welding refers to rolling the pipe while the weld metal is being deposited. in addition to the volts and amps.g. voltage.2.8 Position A definition for “roll welding” is provided in 3.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 42 G12.11 Type of Lineup Clamp Information pertaining to the type and removal of a lineup clamp generally pertains to production welding. to specify a heat input range for each welding pass.4. which involves girth welding with the pipe in the horizontal position. There is no requirement in API 1104 to designate the position of the pipe material (e. In addition to ranges for amperage. G12. Shorter times decrease the chance that cracking can occur prior to the completion of the weld. low-hydrogen welding process. it is good practice.4. When using waveform welding processes. If welding is to be performed with the pipe in a position other than horizontal.g. G12. vertical.2. and travel speed on the thermal cycle of the weld. 2.2. The information specified in the WPS should comply with the requirements/recommendations given in 7. G12. Tempilsticks™). The primary reason for preheating is to prevent the weld from experiencing hydrogen cracking during welding or soon after completion..32M also provides purity requirements for the listed gases and mixtures.2.32/A5.3. non-contact infrared pyrometers. G12. preheating is specified only when the ambient or pipe surface temperature is below a certain value.4. G12. It may be useful to think of preheat temperature as the “arc start temperature. a maximum-allowable heating rate from this temperature to the PWHT temperature range. This section requires the user to specify the width of the weld zone.4. In a multipass weld. For some applications. and the maximum-allowable cooling rate from this temperature. The benefits of PWHT must be weighed against the loss of desirable materials attributes when PWHT is applied.. post-weld heat treatment (PWHT) can also temper hard weld microstructures and relieve residual welding stresses. Once welding begins. and allowing hydrogen to diffuse from the weld during welding and after completion. a temperature to which the joint can be heated without controlling the heating rate. Additional information pertaining to the application of pre.12 Cleaning The extent of cleaning required for the weld bevel prior to welding and between each weld pass must be described.15 Shielding Gas and Flow Rate AWS A5. it is also the temperature immediately before the second and subsequent passes. G12. This section also requires the user to specify the width of the zone to be heated. 2010 . and quartz lamps. and temperature indicating crayons (e. the hold time at PWHT temperature range (usually expressed in hours per unit of wall thickness). induction heaters.g. Modern microalloyed and control-rolled line pipe steels can be very sensitive to temperature above approximately 400ºF (200ºC). If carried out at high enough temperatures.13 Pre-heat Treatment Preheat is the minimum specified temperature of the entire weld zone immediately prior to the start of welding. which has a beneficial effect on the weld microstructures that develop. The maximum metal temperature at which accelerated cooling is applied should also be specified. and induction heaters (induction methods). Revision 1 – April 30. such as air cooling or accelerated cooling with water. slowing the weld cooling rate somewhat.14 Post-heat Treatment Post-heating and slow cooling can have a beneficial effect on welds by allowing hydrogen diffusion after welding.e.4. Common methods used to preheat pipelines prior to welding include gas torches and quartz lamps (radiation methods). electric resistance heaters (conduction methods). If used to expedite nondestructive testing (NDT) and/or joint coatings. Temperature measurement and control during post-weld heat treatment is normally accomplished using welded thermocouples and dedicated control units.2. PWHT parameters for stress relief often include the width of the area to be heated.11. this temperature is generally referred to as the interpass temperature. not just the first weld bead). A minimum-required preheating temperature is normally specified. AWS A5.” or the temperature of the weld zone during welding of any weld bead (i.32/A5.3. Preheating does this by driving off moisture and other contaminants prior to welding.3. should be specified. Common methods used for post-weld heat treatment of pipeline girth welds include electric resistance heaters. the type of weld cooling after welding.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 43 Requirements/recommendations for root bead completion prior to lineup clamp removal are given in 7. Common methods for temperature measurement include contact thermometers (digital or analog). See guidance in G7. For some applications.32M Specification for Welding Shielding Gases provides standard AWS classifications for common shielding gases and gas mixtures that can be used in preparation of procedure specifications. it is also common to specify a maximum-allowable interpass temperature.4.and post-heating is provided in the guidance provided in G7. if the range specified in the WPS for any of those variables is exceeded. 2010 .e. such as air cooling or accelerated cooling with water. A procedure qualified using a combination of materials only qualifies the procedure for that combination of materials.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities The specified range should reflect the minimum and maximum values that produce an acceptable weld. The trade name or number of the shielding flux should also be listed.2. which are not covered in the preceding sections.4. Travel speed is measured in the direction of weld progression.20%. should be specified.2 should be based on nominal strength levels. G12.2.2. Procedures for mechanized welding are often qualified in accordance with this section but also in conjunction with Appendix A when alternative acceptance standards based on engineering critical assessment will be used. departures from variables that affect the mechanical properties or soundness of completed welds are not allowed without requalification by preparing and 44 testing another weld.100 psi).5. Revision 1 – April 30. The actual strength levels that are now specified in API Spec 5L (Forty-fourth Edition) as the result of normalization need not be considered (i.5.5 ESSENTIAL VARIABLES G12.4.5. or a new procedure qualified. The specified range should reflect the minimum and maximum values that produce an acceptable weld. higher carbon equivalent materials generally have reduced weldability compared to lower carbon equivalent materials.5.17 Speed of Travel The travel speed range for each pass must be specified.2.2. The shielding flux should be identified by its AWS (or other) specification and classification numbers.2. it is insufficient to list trade name only.5. G12.16 Shielding Flux Shielding flux type refers to submerged arc welding. it is not necessary to consider that API 5L-X42 now has an actual specified minimum yield strength.4. However.1 General API 1104 allows some degree of departure from the variables used to qualify a WPS.2 Changes Requiring Requalification Essential variables are those that require the procedure to be requalified.1. G12. If used to expedite NDE and joint coatings.18 Other Factors The purpose of this section is to allow aspects of the specific process being used. of 42. However. The range specified should be wide enough so that the qualified welding procedure can be implemented in the field.5. The strength level grouping listed in 12. These latter variables are referred to as essential variables..4. Regarding the note provided in 12. Weave motion perpendicular to the direction of weld progression is not included in the travel speed measurement. For a pipe material of a given grade. the allowable range for travel speed should be no larger than the median value +/. the more stringent essential variable requirements in Appendix A supersede some of those listed in this section. Several examples are provided. G12.2. An example of a base material compatibility factor that might be considered within one of the groupings specified is carbon equivalent level.1 Welding Process See guidance provided in G. G12. sound engineering judgment should be used when determining the compatibility of the base materials.2.2. expressed in US Customary units. the procedure qualification must be carried out on the material with the highest specified minimum yield strength in the group.2 Pipe Material To qualify a welding procedure for an entire group. to be specified. the type of weld cooling after welding. The range should not be so wide that operating at the edges of the range produces an unacceptable weld. G12. G12. For these applications. For example. The maximum metal temperature at which accelerated cooling is applied should also be specified. g. a decrease in the specified minimum preheat temperature should constitute an essential variable.2. Regarding the note provided in 12. G12. one common practice during procedure qualification for mechanized GMAW is to delay welding of the hot pass for up to 48.4 Wall Thickness See guidance provided in G12.g.6 Filler Metal If a filler metal is not listed in one of the groups of Table 1 in API 1104. G12.5. Even if a change in the shielding gas flow rate does not visually affect the weld (e. etc.4.4. API 1104 does not define what constitutes a major change in shielding gas flow rate.5.2. G12.4.3 G12.6 QUALIFICATION OF WELDING EQUIPMENT AND OPERATORS The purpose of this section is to allow welding operators to demonstrate their ability to make acceptable welds using the qualified procedure and Revision 1 – April 30. if specified.2.5.20% of the nominal value without the need for requalification.2. For preheating.4.10 Shielding Gas and Flow Rate A change from one shielding gas to another refers to nominal composition.2. Consequently.13 and G12.5..2.14 Electrical Characteristics See guidance provided in G12.6.and Post-heat Treatment Requirements See guidance provided in G12.2. .8 Time between Passes The maximum time between the completion of the root bead and the start of the second bead is an essential variable for procedure qualification. G12.4.2. G12.2. The addition of preheat or an increase in the specified minimum preheat temperature should not require the procedure to be requalified unless toughness properties.5.5 Pipe Diameter See guidance provided in G12. G12.2.5. the weld properties (e. Exceeding the maximum allowable time between the completion of the root bead and the start of the second bead during production welding is grounds for rejection of that weld.2. strength and toughness) may be adversely affected. sound engineering judgment should be used when determining the compatibility of the filler metals within the groups specified in Table 1. G12.12 Speed of Travel See guidance provided in G12.2.2. See the note under Table 1.6.2.2. are thought to be affected.5.4. whereas the maximum time between the completion of the second bead and the start of other beads is not..5. It would seem reasonable to allow changes of up to +/.5.2. the addition of PWHT or a change from the ranges or values specified in the procedure should each constitute an essential variable.4. For PWHT. This extended delay is to accommodate significant delays between passes during production welding that could be caused by equipment failure. G12.5. G12.17.4. For mechanized welding.9 Direction of Welding No guidance material required.5.7.5.3 Joint Design API 1104 does not define what constitutes a minor change in joint design. it would seem reasonable to allow changes to the bevel angle of up to + 10%/-5% of the nominal value and changes to the root opening or land of up to +/.15 Orifice Diameter or Orifice Gas Composition No guidance material required. G12.5.13 Pre.11 Shielding Flux No guidance material required.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 45 G12. does not result in porosity).5. or even 72 hours after completion of the root pass.2.2. G12. 2010 G12.7 Size of Filler-metal Wire See guidance provided in G12.2.2.2.14.20% of the nominal value without the need for requalification. it requires separate qualification. 9. Since this section allows for evaluation of the completed test weld by destructive methods only. nondestructive methods. Section 6. See guidance provided in G12.5. Qualification requirements for welding operators in Section 12 are similar to those in Section 5 for welder qualification except that Section 12 does not require nick-break testing. i. j.5.6.5. It is not appropriate to substitute nick-break tests for tensile strength tests and then to use the language in 12.8 INSPECTION AND TESTING OF PRODUCTION WELDS See guidance provided in Section G8. a change in mode of transfer (e. Figure 2 in API 1104 is a sample PQR. A change from solid wire or metal cored wire to a flux cored wire is also a change of process. Revision 1 – April 30.8. or both.6 for evaluation by nondestructive methods. AUT could be used to supplement destructive testing at the option of the user. as appropriate.1 are different from the essential variables for procedure qualification in 12.2 is intended only for manual and semi-automatic welding.2. See guidance provided in G12. Even though AUT is not mentioned in Section 8. e. g.2. While it would seem that the use of a qualified automated ultrasonic testing (AUT) system would not only be appropriate but preferred for evaluation of mechanized GMA welds..g. A welding bug is a mechanized device that provides movement of the welding torch around the pipe. b. or a change in polarity.3.9 ACCEPTANCE STANDARDS FOR NONDESTRUCTIVE TESTING See guidance provided in Section G9 or Appendix A. which can also be used as a WQTR.6 specifically states that radiography can be used in lieu of destructive methods. c. it contains a list of essential variables for welding operators. The phrase “Prior to the start of production welding” has no specific time limit.6 to eliminate these nick-break tests. which may be required eventually.6. The essential variables for welding operators listed in 12. In 6.2.5.1 Scope While the title of this section is “Scope”. this is not intended to preclude the use of AUT on mechanized pipeline girth welds. The essential variable is a change from one welding process to another process or combination of 46 processes. It refers to Section 6. d. G12.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities the equipment that will be used in production welding.5. The company must also maintain a list of operators and the procedures for which they have qualified. The use of Figure 2 is not mandatory.4. It would appear that the period after the word “established” is in error and that the word “For” should not be capitalized. It is common. No guidance material required. although a form similar to this should be used. substitution of nick-break tests for tensile strength tests is allowed. This provision allows the company to qualify welding operators for specific weld passes without having that operator complete an entire weld. short circuit transfer to spray transfer). which require that the welding operator be requalified if changes beyond the limits listed are exceeded. For mechanized welding.2. The substitution clause in 6. but not mandatory. a. G12. This section allows for evaluation of the completed test weld by destructive methods. 2010 .2 for manual and semiautomatic welding) and thus omitted. No guidance material required.2. The preferred method of inspection for many mechanized welds is automated ultrasonic testing (AUT). G12. to include a space for a revision number. the use of AUT only would seem to be prohibited for the qualification of welding operator by this section. h. The first sentence of 8. is provided below.7 RECORDS OF QUALIFIED OPERATORS The company must maintain records of test results for each welding operator. as appropriate. f.2 indicates that nondestructive testing may consist of radiographic testing (RT) or another method specified by the company. See guidance provided in G12. G12. Welding operator shall qualify on the heaviest nominal wall thickness of the ranges established in the applicable WPS.4. the tensile strength tests should not be replaced by nick-break tests (as allowed in 6. It is only necessary that the welding operators to be used for production welding be qualified sometime prior to the start of production welding. Specific guidance for each item listed. 6.metal Additions G13. some pipeline designs require matching or over-matching strength girth welds.1 ACCEPTABLE PROCESSES This section applies only to the flash buttwelding process. and includes instructions on how to prepare the nick.2.11 RADIOGRAPHIC TESTING For RT.6. this is not intended to preclude the use of UT on mechanized pipeline girth welds. G13.2. G13. and repair for flash butt-welding into a single section.3. As in Section 5. reference is also made to other sections of API 1104. It is only necessary that the welding procedure specification (WPS) to be used for production welding be established and qualified sometime prior to the start of production welding.2 Method See guidance provided in G5.2.1.3. The term “nick-break” refers to the saw-cut notch Revision 1 – April 30.1 Preparation Figure 25 illustrates a nick-break test specimen for flash butt welding.1 General No guidance material required.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 47 G12.2.10 REPAIR AND REMOVAL OF DEFECTS See guidance provided in Section G10. G13. Such requirements should be specified in the contract documents.3 Requirements It is acceptable according to API 1104 for the measured tensile strength across the weld to be less than the actual tensile strength of the pipe material.2.2.3.3 Mechanical Testing of Butt-welded Joints G13.11.3 Nick-break Test G13.3. acceptance standards.3. 13. see guidance provided in G11. it is common practice for the company to approve each qualified WPS that will be used for production welding. however the specimens for flash butt welding are wider and more specimens are required.3. UT is the preferred method for many mechanized welds and should be performed in accordance with 11. This section combines the requirements for procedure qualification. equipment and operator qualification. it is also evaluated as if it is a nick-break test specimen.2 Tensile-strength Tests G13.2 Radiography Prior to Mechanical Testing Mechanical testing must be preceded by RT. The nick-break test is a subjective test that judges the soundness of a weld by fracturing the specimen through the weld so the fracture surfaces can be examined for the presence of imperfections. G12.2 PROCEDURE QUALIFICATION Procedure qualification requirements in Section 13 for flash butt-welding are similar to those in Section 5 for manual or semiautomatic welding and Section 12 for mechanized welding except that at least two test welds are required and destructive testing must be proceeded by radiographic testing (RT). G13.3. 2010 G13 Automatic Welding Without Filler.1.2. quality assurance. which is wider than that described in Section 5. Macro-etching of nickbreak test specimen for flash butt welding is required to locate the fusion line. G13. A WPS need not be established and qualified by the company itself. The number of test specimens required for flash butt welding depends on the outside diameter of the pipe.1. .1 Procedure The phrase “before production welding is started” has no specific time limit. If a tensile test specimen breaks in the weld. G13.2.2. G13.1 Preparation See guidance provided in G5. For some of these topics.2.2. nick-break testing is required.2. with larger pipe diameters requiring more specimens.2.2.3. However.4 Even though UT is not mentioned in 12.2. However. for both to include a space for a revision number. Since no range of acceptability is given in this section for the essential variables for flash butt welding. 2010 . which may be required eventually.3. A PQR ‘supports’ a WPS. Essential variables are those that require the procedure to be requalified.5 apply.2.2.6. Since this section provides that both the equipment and the operator are qualified at the same time.6.3. G13.3. departures from variables that affect the mechanical properties or soundness of completed welds are not allowed without requalification by preparing and testing another weld.1 General 48 Many of these variables are limited by the essential variable changes given in 13. It is not appropriate to “nick” the specimens using an oxy-fuel torch. although sound engineering judgment should be used.2.2 Method See guidance provided in G5.4.3 Requirements No guidance material required.3. A welder who performs a test joint that qualifies a WPS becomes qualified to perform that procedure provided that all of the testing required for a welder qualification is performed and passed.2. welding operators to be used for production welding should be qualified sometime prior to the start of production welding.2.5. Changes to welding variables that are not listed in 13. These latter variables are referred to as essential variables. G13.6.5. However. it would seem to be appropriate to allow the specimen to be nicked with a narrow disk grinder as well. G13.2. any change to these variables requires requalification of the procedure.1. the essential variables specified in Section 13. Revision 1 – April 30.2.3. G13.3. or a new procedure qualified.4 must be included in the WPS.2 Method See guidance provided in G5. It is common.1 Preparation See guidance provided in G5.5. but not mandatory.4 PROCEDURE SPECIFICATION All of the applicable welding variables described in 13.2 Changes Requiring Requalification G13.5.5 ESSENTIAL VARIABLES API 1104 allows some degree of departure from the variables used to qualify a WPS. G13. making the specimen easier to break. G13.3. G13. A WPS can be supported by more than one PQR. G13.6 QUALIFICATION OF EQUIPMENT AND OPERATORS The purpose of this section is to allow welding operators to demonstrate their ability to make acceptable welds using the qualified procedure and the equipment that will be used in production welding.5.4. This section does not specify any essential variables for qualification of welding operators.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities that initiates fracture.3 RECORD A qualified welding procedure consists of a WPS and a procedure qualification record (PQR).3.2. but not mandatory to list the PQRs that support a particular WPS. While not specifically indicated.3 Requirements See guidance provided in G5.5 are allowed by simply revising the WPS without the need for requalification.4 Side-bend Test G13. While nicking the specimen with a hacksaw is preferred.5. G13. G13. API 1104 also refers to the latter as a coupon test report.3. It is common. if the range specified in the WPS for any of those variables is exceeded. A revised WPS should be identified by a revision number.6.3.4. It calls for each welding unit (machine) and each operator to be qualified simultaneously through both radiography and destructive testing. Other welders then may qualify to perform the same welding procedure. Since no reference is made to acceptance criteria for other imperfections. Acceptance criteria for porosity.9 ACCEPTANCE STANDARDS FOR NONDESTRUCTIVE TESTING For flash butt welds. which may be required eventually. appears to be in error. G13. G13.10.8. which contain acceptance criteria for slag inclusions detected by radiography.3.8. The company must also maintain a list of operators and the procedures for which they have qualified. monitoring the welding sequence using a strip chart recorder.2 and 9. G13.2 Defects No guidance material required.3. to include a space for a revision number.4 Rejection Based On Reinforcement No guidance material required.3. G13. G13.3 Rejection Based on Nondestructive Testing No guidance material required.9. G13. G13.2.9. and monitoring post-weld heat treatment using a strip chart recorder. G13.8.3.1 Rights of Inspection No guidance material required.10. G13.8 QUALITY ASSURANCE OF PRODUCTION WELDS Quality assurance of production welds made using the flash butt-welding process is normally accomplished by removing and testing selected production welds.9. G13. although a form similar to this should be used.7 RECORDS OF QUALIFIED OPERATORS The company must maintain records of test results for each welding operator.1.8. Figure 2 in API 1104 is a sample PQR. nondestructive testing.8.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 49 G13. are contained in 9. acceptance criteria are provided only for isolated slag inclusions. It is common. The use of Figure 2 is not mandatory.8.1 Repairs Permitted See guidance provided in Section G10.2 Rejection Based on Strip Chart No guidance material required.10 REPAIR AND REMOVAL OF DEFECTS G13. Revision 1 – April 30.1 General See guidance provided in G13.5 Rejection Based on Post-heat Treatment No guidance material required. which can also be used as a WQTR.10.9.2 and 9. G13.2 Repairs Not Permitted Reference to 9. to which 13.8. these appear to be unacceptable regardless of their size. measurement of reinforcement height. G13.3.11 RADIOGRAPHIC PROCEDURE See guidance provided in G11.2 pertains. but not mandatory. 2010 .3.9. 7 Wang..e. 6 Revision 1 – April 30. When the use of Appendix A is selected. Y. D. Provided that the welding procedures are properly qualified.1 General Workmanship vs. Minimum CTOD Toughness and its Significance In the previous versions of Appendix A. The minimum required CTOD here only implies that the alternative defect acceptance criteria are suitable when this minimum value is achieved. More detailed background information on Options 1 and 2 may be found in a paper by Wang. It is important to recognize that the minimum required CTOD toughness in Appendix A is entirely different from the minimum toughness requirement a company may set in its material qualification.” 6th International Pipeline Conference. Alberta. 2006.2. The workmanship criteria were originally developed on the basis of achievable level of sound workmanship by skilled welders using properly maintained equipment and executing properly qualified welding procedures. In the July 2007 Errata version of Appendix A. IPC2006-10491. both flaw height and length are correlated to the measured CTOD toughness. These issues may indicate inadequate design or inappropriate selection of line pipe material and welding processes. This approach allows for more consistent levels of conservatism across the entire range of CTOD toughness. Calgary. Selection of Options For consistency the use of Option 1 or 2 is mandatory6 when the fatigue loading spectrum is within the limit defined in A. The minimum required CTOD in this appendix should not be used as a material qualification standard.-Y. Horsley. et al. Canada. September 25-29. More rigorous testing is required to apply the alternative acceptance criteria. The The use of API 1104 Appendix A is at the option of the Company. The allowable flaw length was a function of either pipe wall thickness or diameter. Workmanship A company has the option of selecting the workmanship acceptance criteria of Section 9 or the alternative acceptance criteria of Appendix A. The extent of material qualification tests is different for these two types of acceptance criteria. Although the allowable flaw length from the alternative acceptance criteria is frequently greater than that of the workmanship acceptance criteria for most onshore pipeline projects.7 Selection of Appendix A vs. the workmanship criteria remain the same for all pipeline projects.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 50 APPENDIX A—ALTERNATIVE ACCEPTANCE STANDARDS FOR GIRTH WELDS5 GA. the allowable flaw length from the alternative acceptance criteria may be smaller than that of the workmanship criteria.1 of Appendix A. In contrast the alternative acceptance criteria are based on the philosophy of fitness-for-service. 2010 . The acceptance criteria are not altered by the weld properties and expected loads on the pipeline girth welds. The term “mandatory” here is applicable when the use of API 1104 Appendix A is selected. only the allowable flaw height was dependent on the 5 This guidance is specifically written for API 1104 Appendix A 20th Edition July 2007 Errata. the reduction in the minimum required CTOD toughness in this version of Appendix A does not imply a reduced conservatism in any way. Liu.2. i. “A Tiered Approach to Girth Weld Defect Acceptance Criteria for StressBased Design of Pipelines. In certain offshore applications. this is not always the case. It is generally not possible to rigorously compare the relative conservatism between the workmanship and alternative acceptance criteria. Pipelines built to either acceptance criteria have shown excellent records of safety when these criteria are applied consistently.... M. the fitness of the particular welds for the intended purposes. Examples of unexpected issues may include extremely low CTOD toughness and high fatigue flaw growth rates. The level of field quality control may be different as well. and Bauman. G. Paper No.. Alternative Acceptance Criteria The basis of the workmanship acceptance criteria in Section 9 and the alternative acceptance criteria in Appendix A is quite different. As the allowable flaw size is adjusted and correlated to measured CTOD toughness as a continuous function. it is not advisable to switch to workmanship acceptance criteria when the welds are determined to not meet the standards of Appendix A. measured crack tip opening displacement (CTOD) toughness. Consequently the acceptance level in the alternative acceptance criteria is correlated to the weld properties and expected loads on the girth welds for a particular project of interest or a specific section of a pipeline. Alberta. 2010 . e. it is advisable to limit the total number of repairs in any single girth weld. Weld Quality Considerations in Implementing the Flaw Acceptance Criteria Depending on the CTOD toughness and the longitudinal stress/strain. can not be used to justify going beyond the limits set in Appendix A. the allowable flaw size produced by Appendix A may be quite large.-Y. “Stress Analysis of Pipe Lowering-in Process during Construction. G. Sound engineering practice dictates that having appropriate flaw accumulation rules is a good engineering practice. unsupported span for offshore pipelines. IPC2008-64630. September 29 – October 3.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities underlining causes for such issues should be investigated and rectified. Necessary Conditions for Using Appendix A All of the prerequisite conditions outlined in the list at the end of Section A. such as the difference between the actual yield strength and the specified minimum yield strength (SMYS). Revision 1 – April 30. the allowable flaw height needs not be more than 2 to 3 times the weld bead height.8 8 Liu. and (2) providing the maximum magnitude of longitudinal stress as an input for the determination of the allowable flaw size. Estimation of Static Stresses Under normal onshore construction conditions. For offshore pipelines high static stress may occur in pipelay operation from pipelay tension and bending along the firing line and stinger. et al.2 Stress Analysis GA. It is advisable to establish the total number and the accumulative length of all non-interacting flaws in a single girth weld. Calgary.g. hence appropriate analysis options that may be used for developing defect acceptance criteria. such as in the case of washout or ground movement. Wang. high static stresses may also occur in service when large displacement is imposed on the pipelines. 51 GA.2. However.. For heavy wall pipes. The cyclic stresses are usually induced by the temperature and pressure fluctuations of the pipelines.1 AXIAL DESIGN STRESS Purpose of the Stress Analysis The stress analysis serves two purposes: (1) determining the fatigue spectrum severity. Appendix A does not presently cover flaw accumulation rules. These rules would have governed the total number or accumulative length of all flaws in a single girth weld. Excessive number of repairs in any single girth weld may be indicative of welding quality control issues. and the interaction between the pipe and surrounding soil (including friction). 2008. Paper No.. In most instances of well-controlled weld processes. the allowable flaw size could be reduced so sound welding quality control is exercised.. The statistical distribution of material properties.. The flaw acceptance criteria should not be viewed as a substitute for sound welding quality control. Y. the highest static stresses generally occur during construction. Overly generous allowable flaw size may not be necessary. M. except in cases of short flaw length under limited circumstances. the longitudinal stresses are predominantly controlled by the lift height of the pipe relative to the bottom of the trench. Canada. pull force.1 must be met to apply Appendix A. More details of the stress analysis may be found in a paper by Liu.” Proceedings of the 7th International Pipeline Conference. Appendix A currently covers flaw acceptance criteria of individual flaws. Interacting flaws that are re-categorized as a single flaw are effectively treated as a single flaw. The static stresses may come from construction and service conditions. At the option of the company. Stresses on Pipeline Girth Welds The stresses affecting the integrity of pipeline girth welds may be broadly divided into static and cyclic (alternating) stresses. the maximum allowable flaw height of nearly 50% wall thickness could be quite large. and Rogers. The stresses from horizontal directional drill (HDD) can be estimated from the curvature of the pipe path. Since repair welds generally have inferior quality than mechanized welds. For onshore pipelines. . the frequency of such fluctuation is small. 9 It is this author’s view that the limit on the use of Appendix A “when the concentration of either CO2 or H2S exceeds typical historical levels” is only applicable to Options 1 and 2.e.2. GA.2 CYCLIC STRESS GA. t is pipe wall thickness.9 GA.2. The appropriate fatigue growth curves must be used in the evaluation. i.. cyclic stresses in the longitudinal direction of pipelines may come from pressure and temperature fluctuations. resulting in longitudinal stresses. The pressure fluctuation in natural gas pipelines is generally small. σ =ν p D − Eα (T − T0 ) . Offshore pipeline installations could impose significant cyclic stresses. The construction temperature is typically the zero-stress temperature. The pressure fluctuation may be a part of normal operation or shutdown and startup. a tensile longitudinal stress is formed due to the thermal contraction of the pipeline. such as in startup and shutdown conditions. One of the most significant sources of fatigue for offshore pipelines is VIV from free span in ocean current. and the heat transfer between the fluid and the soil. Large pressure fluctuations may occur. The stress range ∆σ i is therefore controlled mostly by thermal cycles.e. This interpretation is however inconsistent with the text of Appendix A.2. soil temperature. Some special installation techniques may impose cyclic stresses on girth welds.1 Analysis Sources of Cyclic Stresses In a typical onshore pipeline operation. either during normal laying or in the event of work stoppage due to weather and other conditions. A-1 in Appendix A.2 Environmental Effects on Fatigue The use of Option 3 is recommended when the concentration of either CO2 or H2S exceeds typical historical levels experienced in non-corrosive pipelines.3 SUSTAINED-LOAD CRACKING No guidance material required. E is Yong’s modulus. The influence of the pressure fluctuation should be properly considered. Consideration of Residual Stresses It is generally not necessary to consider residual stress in computing the fatigue spectrum per Eq. The fatigue spectrum of the affected girth welds must be evaluated for such special circumstances.4 DYNAMIC LOADING No guidance material required. The longitudinal cyclic stresses could cause the girth weld flaws to grow. temperature at which the pipeline is stress-free.2. Onshore pipeline installations usually do not impose significant cyclic stresses. Revision 1 – April 30. The pressure fluctuation in liquid pipelines can be greater than that in gas pipelines. D is pipe diameter. The change in the pipeline temperature can come from the changes of the fluid temperature.2. One example is pneumatically assisted pull-back in HDD installations. GA. The pressure and temperature variations effectively produce ∆σ i in Eq. and T0 is the construction temperature (assumed stress-free temperature). 2t (1) where ν is Poisson’s ratio. Pressure fluctuations induce longitudinal stresses due to the Poisson’s effects. A fatigue analysis typically starts from the anticipated or postulated temperature and pressure histories. α is the thermal expansion coefficient. The fatigue cycles applied to the flaw acceptance criteria should be correlated to allowable span limits and remediation schedules during the operation of the pipelines.2. i. When the pipeline operating temperature is lower than the construction temperature. Temperature changes cause thermal contraction or expansion of the pipe. it is necessary to assume a zero-stress temperature.2. Cyclic Stresses from Temperature and Pressure Fluctuation In determining the overall temperature effect. The stresses from these conditions must be evaluated accordingly. A-1 of Appendix A. The longitudinal stress (σ) is related to the pressure (p) and temperature (T) through the following relation. 2010 . there are few cycles. The relative motion of the pipelay vessel and the pipe off the stinger could generate significant fatigue cycles. However the effects of residual stresses may be considered in Option 3.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 52 GA. Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 53 GA. Any parameter that could potentially affect the thermal history may influence the weld properties. 2010 . Therefore a good “match” between the base materials and the weld processes is necessary to achieve satisfactory HAZ properties. The significance of the essential variables listed in Appendix A is shown in reference to their influence on the initial state of the materials and cooling rate in Table G5. the composition of the deposited weld metal may be influenced by “dilution” and the application of shielding gas. Weld and HAZ Properties Line pipe steels and welds are made of polycrystalline grains. the properties of the deposited weld metal and heat-affected zone (HAZ) are of importance. The company must be vigilant about signs of field weld quality problems. From the viewpoint of structural integrity of a weld. etc. There could be other parameters that affect weld properties. the gain size and orientation prior to the application of weld thermal cycles. In comparison to the base line pipe material. GA. standards. Significance of the Essential Variables in Appendix A The properties of welds are primarily affected by the initial state of the material (chemical composition. The potential impact of these unknown and/or uncontrollable parameters is generally dealt with by applying a safety factor in design practice and weld acceptance criteria.2. The dilution generally refers to the transportation of elements between the weld metal and the base metal. Revision 1 – April 30. its properties are affected by the chemical composition of the welding consumable and the thermal history experienced by the weld metal. In a large pipeline construction project. grain size. For the deposited weld metal. In addition to the “native” composition of the welding consumables.) and the cooling rate. line pipe materials from different manufacturers are welded with a variety of welding processes. The properties of the HAZ are affected by the chemical composition of the base pipe material. these essential variables are known and controllable parameters.1 GENERAL Assumptions and Rationale of the Welding Procedure Qualification The use of the welding procedure qualification test data in the development of flaw acceptance criteria of field production welds assumes that the field welds will be produced in a similar manner thus having similar mechanical properties as the procedure qualification welds. Objectives of Welding Procedure Qualification The primary objective of welding procedure qualification is to establish that a welding procedure can reliably produce welds with the necessary properties to meet or exceed the requirements set forth by relevant codes. and/or company specifications. A rigorous quality control program for the field welds is necessary to ensure such assumptions are met. For the purpose of welding procedure qualification. either through the fluid stir of the molten weld pool or diffusion processes. even though such repairs are allowed for the purpose of applying the flaw acceptance criteria.3. Therefore it is necessary to establish the applicable range of a qualified procedure. The weld properties are expected to remain largely the same within the applicable range of the qualified procedures. including reheating by subsequent welding passes. The thermal history experienced by the weld metal can be affected by a large number of parameters. such as excess repair rates. Concept of Essential Variables To ensure a qualified procedure is applied within its applicable range. The characteristics of these grains and their relative arrangement determine the performance of these materials. but not yet known or controllable.5 RESIDUAL STRESS No guidance material required. these regions tend to have inferior properties.3 Welding Procedure GA. The essential variables are parameters that are known to affect the weld property. and the welding thermal cycles. Thermal history has a major impact on the properties of deposited weld metal and the HAZ through its effects on the phase transformation of steels. it is necessary to understand the essential variables. 2.8 12.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 54 Table G5 – Essential Variables and Their Influence Approximately Equivalent Essential Variables in Section 12 Section ID Essential Variable in Appendix A Cooling Rate Initial Microstructure Condition Chemical Chemical Initial Grain Composition.2. For high Revision 1 – April 30.2.2.13 Not listed 12. it is necessary to conduct toughness tests of the deposited weld metal and each individual HAZ. 2010 . i.12 x x x x x x x P P Possible Additional Notes on Essential Variables Essential Variable b When the same grade of pipe is sourced from different pipe manufacturers or the skelp is sourced from different plate/coil manufacturers for the same pipe mill.2.5 12.5. It is not necessary to qualify joints A-A.4 12.2. If (a) multiple pipe mills source the plate/coils from the same manufacturer. for instance. or method of application Pipe grade. the pipes can be treated as different materials defined by their source.5. it is sufficient to consider the pipes as one single material.5.2.5.e.2. Materials A.2.5. In the case where multiple materials are used for the same project.6 & 12. Composition. plate/coil manufacturers.5. and (b) the plates/coils are made to different specifications. and heat number of fill metal Time between the completion of root bead and the start of the second bead Welding direction Type of current Pre-heat temperature Interpass temperature Pipe diameter Heat input 1 12.5. type. the HAZ toughness may be obtained by placing notches into Side A and Side B of a joint A-B.9 12. or having different basic chemical compositions among the plate/coils manufacturers. it is normally necessary to qualify each material individually.1 x b c d e f 12.5.3 Not listed 12.g. or using the different process routes. Size.2 12. and (c) the manufacturing processes of the pipe mills are substantially the same. mode of arc transfer. B-B.14 12... (b) the plates/coils are made to the same specification using the same process route and have the same basic chemical composition.2.7 x x x x x x x g h l m n p q Note: 12.5. low heat input solid wire GMAW processes). Base Deposited Base Pipe Pipe Material Weld Metal Material P1 ID Description a Welding process. and B.5. and A-B individually. chemical composition Joint Design Welding position Pipe wall thickness Size.5. For low-dilution welding processes (e.5.2. If (a) multiple plate/coils manufacturers supply the skelp to the same pipe mill.2. manufacturing process of pipe material. it may be necessary to qualify welds in joints A-A. T. six at each o’clock position. Eds. Carrasco. 1999.” ASME PVP Conference.. If the heat input were to vary around the o’clock position of a weld. Ferregut. G.3.1 Weld Tensile Properties GA. Y.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities dilution processes.2. The reported tensile strength could be affected when this failure location occurs.10. D. pp.. M. Denys.2 Charpy Impact Energy GA. New Welding Processes and Essential Variables The list of essential variables in Appendix A reflects the current consensus understanding from fundamental welding metallurgy and practical experience. R. Appendix A therefore requires the tensile specimens with a reduced gage section.1 Specimen Preparation A total of 18 specimens.3. C. BB. Essential Variable q The microstructure and the mechanical properties of welds (deposited weld metal and HAZ) are strongly affected by the thermal history experienced by the material. V.3. “Incorporating Weld Metal Mismatch into Structural Integrity Assessment. Essential Variable f For practical considerations. The weld properties from these new materials and welding processes could be affected by additional parameters (such as electrode/torch spacing) not currently listed in Appendix A. Montreal. Gordon. pp. Kirk.” in Pipeline Technology. and Pisarski.1 Specimen Preparation and Testing The cross-weld tensile specimens without a reduced gage section as those in Section 12 could sometimes fail near the test machine grips. W. The benefits of PWHT must be weighed against the loss of desirable attributes of the materials when PWHT is applied. These processes produce different thermal history from the traditional single-wire GMAW process.” in Probabilistic and Environmental Aspects of Fracture and Fatigue. Essential Variable o Some modern microalloyed and control-rolled line pipe steels can be very sensitive to temperature above approximately 200ºC (392ºF).3.2.. 12 Warke. Wang. 1995. J. Vol. The welding heat input is a key essential variable.2.-Y.2 Requirements Further information on the assessment of weld strength mismatch can be found in other publications.. For the HAZ notched specimens. The notch location is referenced to the fusion boundary for the easy location of the notch position.-Y.. 2010 . Y. H.2.2. 1996. GA.1. R.3. M.3.11.2. 89-99 10 Revision 1 – April 30.. Elsevier Science B. Essential Variable n The interpass temperature is intended to establish the maximum temperature of the material at the start of a welding pass. “A Structural Assessment Procedure for Welded Structures with Weld Metal Strength Mismatch. GA.-Y. All process parameters that affect 55 the thermal history experienced by the weld must be controlled and the correlation must be established between the procedure qualification welds and the field production welds. C. J.2 MECHANICAL PROPERTY TESTING GA.3. R. New line pipe materials and welding processes are being introduced continuously to meet new pipeline requirements and to increase the costeffectiveness of new pipeline constructions. and A-B individually. T. J.2. are required. 1. Edited by S. “A FAD-Based Method for Probabilistic Flaw Assessment of Strength-Mismatched Girth Welds. ASME PVP-Vol.. and Kirk.12 GA. Wang.2.. July 22-26. 475-486. such as submerged arc welding. GA. 386.2 Testing No guidance material required. Y.1. it is advisable to ensure that sufficient quantities of consumables of the same heat number are available for the intended number of welds when applying the qualified procedure of the same heat number.. Some examples of new welding procedures are multi-wire GMAW and laser-GMAW hybrid processes.. the current notch location is intended to have the notch intersect the grain-coarsened HAZ in the middle one-third of the specimen thickness. the 10% limit on the variation must be applied to the o’clock-position-specific nominal heat input of the qualified procedure. 11 Wang. Rahman. and Horsley.. 4 Re-Testing Previous versions of Appendix A allowed for retesting if the toughness were too low to meet the minimum toughness requirements. 2006. Due to the lowered minimum toughness requirement.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 56 GA. Modern GMAW welds frequently have much higher impact energy at the upper shelf of the transition curves than the minimum required values.3.. Welds having difficulty meeting the minimum energy requirements could indicate quality issues that must be examined by qualified experts. Cold weather construction may justify low temperature tests.3.. the lowest expected pipe lowering-in temperature.13.2. GA.” 6th International Pipeline Conference.4 Qualification of Welders No guidance material required. GA. These alternative approaches are not formally endorsed by Appendix A.3. 13 Annex C. 2007. GA. Paper No. Special permits may be required from appropriate regulatory authorities. in this case. CSA Z662-2007 Annex C provides procedures to derive more appropriate low-constraint CTOD toughness from standard highconstraint CTOD test results.3. D.2. GA. The equivalent requirement of the shear area is that the temperature corresponding to the mid-point of the transition curve must be less than the minimum design temperature.” Canadian Standards Association.3 Requirements The determination of shear area is sometimes subjective and difficult for weld samples. Liu. the test temperature must be the lowest expected temperature for the postulated critical state at which the allowable flaw sizes would be the smallest. This version of Appendix A does not allow retesting for the sole purpose of hoping to generate higher toughness values. Y. The application of the CSA procedures and the low-constraint tests should be advised by qualified fracture mechanics experts. “A Quantitative Approach to Tensile Strain Capacity of Pipelines.. 2010 .3 Fracture Toughness Testing GA.2.2. The requirements for the Charpy shear area are meant to ensure ductile behavior. the required minimum and average impact energy values in Appendix A were sufficient to ensure ductile behavior for lower grade welds (X52 and lower) made before the advent of microalloyed and control-rolled steels.-Y. 14 Wang. the postulated critical state is often the pipe lowering-in processes when the girth welds are expected to experience the highest longitudinal stress/strain. “Oil and Gas Pipeline Systems. Frequently these energy values would be on the lower transition part of the Charpy energy transition curves.3. IPC2006-10474. The selection of this test temperature should be balanced by the consideration of the potential over-conservatisms of the traditional high-constraint CTOD test.3. J. For modern high strength welds. Historically.2 Specimen Preparation High-quality macros are often necessary to identify un-tempered grain coarsened HAZ. Given the natural variations in fracture toughness. GA. The alternative is using the transition curve of the Charpy impact energy.2.3 CTOD Toughness Testing The minimum design temperature is often defined by pipeline design engineers. Calgary. Canada.2.2. Revision 1 – April 30. most welds are expected to meet the minimum toughness requirements. this would have effectively allowed somewhat selective use of test data for the same welds. Horsley.5 Requirements This requirement is different from pervious versions of Appendix A. GA. CSA Z662-2007.1 General No guidance material required. Alberta. The corresponding CTOD test temperature would be. these required minimum and average impact energy values are quite low..3.3. M.3.3.2. and Zhou.3. The underlying cause of the low toughness should be examined if a weld fails to meet the minimum toughness requirements. For onshore pipelines.14 An alternative approach is selecting low-constraint tests such as shallow-notched CTOD specimens or single edge notch tension (SENT) specimen.3. September 25-29. As CTOD toughness can have strong dependence on test temperature. Toughness Transferability.4.1.1 Structure of the Procedures to Determine the Maximum Acceptable Imperfection Size No guidance material required.2 Fatigue Flaw Growth Appropriate fatigue growth curves must be selected based on the internal and external conditions Revision 1 – April 30. 2c/t < 1. GA. although this is a subject of great complexity. .2 Example of Option 1 Application The imperfection allowance curve similar to that in Figure A-9 may be converted to an allowance table for a range of flaw height.1.2.1.1 Background More information on the application of the failure assessment diagram may be found in a publication by Wang et al. Such realignment cannot occur as easily in full-scale pipes when the remaining circumference would impose considerable restraint for such realignment.1 PLANAR IMPERFECTIONS GA.. and Weld Misalignment in the Strain Based Design of Pipelines. i. GA. GA.5. The use of actual strength is not permitted.3..1.2 Determination of Acceptable Imperfection Size by Option 1 Girth weld high-low misalignment has shown to be detrimental to girth weld stress and strain capacity. M.5.-Y. For very short and deep flaws.5.-Y. July 1-6.3 Determination of the Key Components in the FAD Procedure The solution of Fb was not intended to be used for very short flaws.” Special Issue of the Proceedings of “Pipeline Technology Now and Then” at the 8th International Welding Symposium.5. GA. Lisbon.1.5. GA. It is advisable to seek the assistance of fracture mechanics experts on the treatment of high-low misalignment.5.4 Determination of Acceptable Imperfection Size by Option 3 Option 3 is permitted only when the fatigue spectrum severity exceeds the limit set for Options 1 and 2. GA. Japan.5. the KI values near the free surface could be higher than that of the deepest point when a small D/t pipe is under global bending.1.e. Y.5. The flaw acceptance criteria should not be developed per Appendix A for such flaws. 2010 Wang.5. 15 ..0. The increment of the flaw height can be selected to best match the setup of NDT equipment. November 16-18.” Proceedings of the 17th International Offshore and Polar Engineering Conference (ISOPE 2007).3.4 and the references cited in the publication.16. and Liu.1. the procedure must be followed in its entity.2. The current formulation assumes the deepest point of a flaw is the most critical location. GA. The effects of high-low misalignment on the flaw acceptance criteria are not explicitly considered in Appendix A.5. 8WS.4. Y. “Weld Integrity from the Perspective of Strain-Based Design of Large Diameter and High Strength Pipelines. “The Role of Anisotropy.5. Published work is available on the effects of misalignment on weld integrity15. GA. 16 Wang.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 57 GA. GA. A cross-weld tensile test used in a typical welding procedure qualification is not sufficient to verify the detrimental effects of misalignment for an actual full-scale pipe. When a qualified assessment procedure is selected.1. Such a test with misalignment is non-conservative in predicting full-scale pipe behavior as the misaligned weld is easily re-aligned during the test of such small specimens. 2007. M. Such a scenario is not considered in Appendix A.1 General Various available procedures may incorporate safety factors at different stages of the assessment process.5 Inspection and Acceptable Limits GA. Portugal. Welds without the benefits of realignment are expected to behave more poorly than welds that could be realigned during a test..1.5. Kyoto.1.3 Determination of Acceptable Imperfection Size by Option 2 GA. 2008.1.1 Computation of the Load Level Pr The parameter Pr must be computed from specified minimum values.2 Determination of Critical Imperfection Size No guidance material required. and Liu. Appropriate KI solutions from other sources may be applied for such short flaws.3. These procedures are not provided in Appendix A currently. 2010 .1. repair on repairs. Revision 1 – April 30. Since the transverse planar flaws are of limited length. GA. GA. ranging from material properties and pipeline stresses under various construction and service conditions.5. Regardless of the causes of the transverse planar flaws. Some may have the opinion that the occurrence of transverse planar flaws is the result of improperly executed welding procedures. the significance of the flaws can be assessed using qualified fitness-forservice procedures.1. The records of both accepted and non-accepted flaws are useful in future quality control and construction cost estimation.3 ARC BURNS No guidance material required. they become significant if the toughness or the ductility of the material is very low. not the longitudinal stress that drives the girth weld flaws being considered in all other parts of Appendix A. This is particularly important when the static peak load may occur before the expected end of the fatigue life. GA. GA. and the total number of permissible repairs on any single girth weld.2 ACCEPTABLE LIMITS OF VOLUMETRIC IMPERFECTIONS No guidance material required.3 Inspection Error and Safety Factor on Allowable Imperfect Size The treatment of inspection error should follow the selected assessment procedure. Others may think that the discovery of transverse planar flaws is associated with statistical occurrence.4. The assessment of the significance of transverse planar flaws can be a source of different opinions.5.5. GA. GA.7 Repairs Weld repair procedures must be established and qualified for realistic repair scenarios. The company should establish rules on minimum repair size. GA.5 Transverse Planar Imperfections The driver for any potential failures from transverse planar flaws is the hoop stress. The data can become a valuable source of information during the operation and maintenance of the pipeline.4 IMPERFECTION INTERACTION Appropriate flaw sizing accuracy and probability of detection must be considered in applying the imperfection interaction rules.8 Nomenclature No guidance material required.6 Record The development of the imperfect acceptance criteria involves a large amount of data.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities the pipe material is exposed to so any acceleration of fatigue growth from a normal benign environment is properly accounted for.5. All static failure models must be checked simultaneously when the flaw is allowed to grow from the cyclic loads. 58 GA.5. API 1104 refers to burnthrough as “burning through” to distinguish it from a “burn-through” (excessive root penetration in a butt weld) described in 9.1 General This section combines the requirements for procedure qualification.7. “shall” is a term that indicates a mandatory requirement. or have not been commissioned. A burnthrough. An illustration of a typical burnthrough is shown in Figure G2. except for the alternative/additional requirements that are specified in Appendix B.2. For welding onto thinner inservice pipelines (i. the requirements in the main body of API 1104 should apply instead of those in Appendix B..18. The term “shall” does not appear in Appendix B.125-in. In other words. For welds that do not contact the carrier pipe. will occur when welding onto a pressurized pipe if the unmelted area beneath the weld pool has insufficient strength to contain the internal pressure of the pipe. such as longitudinal seam welds of full-encirclement fittings that include the use of backing strips or filletwelded overlapping side strips. For some of these topics. Figure G2 – Typical Burnthrough on 0. Type B full-encirclement repair sleeves. less than 0. pressurecontaining tees. welding practices. fabricated branch connections. and repair for in-service welding into a single section. The term “should” indicates a recommended practice. For pipelines and piping systems that have been fully isolated and decommissioned. etc.e. the use of a welding procedure that limits heat input may be necessary. inspection. The risk of burnthrough will increase as the pipe wall thickness decreases and the weld penetration increases. [6.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 59 APPENDIX B—IN-SERVICE WELDING GB.4 mm] thick). welder qualification.3. As indicated in 3. The background section prominently indicated that the requirements for fillet welds in the main body of API 1104 should be applied to in-service welds that contact the carrier pipe. A burnthrough typically results in a small pin-hole in the bottom of what was the weld pool.250 in. Examples of appurtenances include branch fittings. The requirements in the main body of API 1104 should apply instead of those in Appendix B. In-service welds are defined as those that fuse directly into the wall of an in-service pipeline or piping system. reference is also made to other sections of API 1104. 2010 . Appendix B is not a stand-alone document and must be used in conjunction with the main body of API 1104. it is not necessary to consider these to be in-service welds. (3. or blowout as it is sometimes referred. acceptance standards.2-mm) Thick Pipe Revision 1 – April 30. 2. prior to welding.g. The primary benefit of preheating is to allow the weld to cool more slowly. the essential variable is carbon equivalent level.2. the use of a temper bead deposition sequence.2. the strength of the completed weld should meet or exceed the specified minimum yield strength of the pipe and fitting material. hermetically sealed cans are ideally suited for in-service welding.1 Pipe and Fitting Materials Appendix B allows procedures for in-service fillet welding to be qualified in accordance with carbon equivalent level groupings as opposed to specified minimum yield strength groupings. As added assurance against hydrogen cracking.1. Recommendations are provided in B. See guidance provided in GB.1 PROCEDURE SPECIFICATION GB. GB. the use of preheating.2.4.1 Specification Information General requirements for developing a welding procedure specification (WPS) are provided in 5. procedures should be qualified in accordance with carbon equivalent levels as opposed to strength level groupings. packaged in small-quantity. In appendix B. The additional and/or alternative specification information for inservice welding are given in B.g. welding procedures that minimize the formation of crack-susceptible microstructures should be developed and followed. whereas. Procedure options for minimizing the formation of crack susceptible microstructures include the use of a sufficiently-high heat input level. therefore. This provision is included because hydrogen cracking susceptibility is more a function of carbon equivalent level than it is to specified minimum yield strength. the presence of which can increase weld hydrogen levels. For in-service welds.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities A common first step toward avoiding hydrogen cracking in welds made onto in-service pipelines is to minimize the hydrogen level by using low-hydrogen electrodes or a low-hydrogen welding process. In the main body. or some combination of these. most 1950s-vintage X52 materials have a high carbonequivalent value. [6. While the effective use of preheating for this purpose during in-service welding is difficult for some pipeline operating conditions.1.250 in. For inservice welds. the essential variable is strength level.2. and carbon equivalent level can vary widely depending on pipe manufacturer and vintage. less than 0.2 Qualification of In-service Welding Procedures As noted above. a modern API 5L-X52 material that has been thermo-mechanically processed may have a low carbon-equivalent value (and. these models can be useful for determining starting parameters prior to procedure qualification and for interpolating between qualified thermal severity levels and material carbon equivalent levels.1.1.1.. While the use of thermal analysis models is not a substitute for procedure qualification. An example of a conflict between the main body of API 1104 and Appendix B is the essential variable 60 for material groupings for procedure qualification. For in-service welds other than fillet welds.. GB. See guidance provided in GB. See guidance provided in G5.1. preheating does tend to burn off moisture and other contaminants. Lowhydrogen electrodes with the H4R supplemental designator (e.1. For example. Appendix B does not preclude the use of cellulosic-coated electrodes (e. AWS E7018-H4R).4.4.2. AWS EXX10-type).2.4 mm] thick) where the use of a high heat input level represents a risk of burnthrough. The specified minimum yield strength of the materials to which the procedure applies should also be specified in the WPS.1. The maximum-allowable carbon equivalent Revision 1 – April 30. GB. Appendix B contains alternative requirements to those specified in Section 5 and additional requirements beyond those specified in Section 5. although specified minimum yield strength is not an essential variable for in-service fillet welds. a high resistance to hydrogen cracking). The requirements for fillet welds in Section 5 should be the basis on which procedures for in-service welding should be qualified. Temper bead procedures are also useful for welding onto thin-wall in-service pipelines (i. Temper bead sequences rely on the heat from subsequent passes or layers to temper and refine the HAZ of previous passes or layers. However.4.. 2010 .e. Appendix B is not a stand-alone document. as long as the welding procedures have been qualified in accordance with the requirements of this section and are used within the qualified range of essential variables. The sequence in which welds are made for some appurtenances can affect stresses acting on the weld. August 8. The provision for allowing a given welding procedure (i. Other carbon equivalent formulas may be used provided that the same formula is used for procedure qualification and production welding.g. Heat input takes into account the collective effect of amperage.. Guidance can be found in Appendix A of the PRCI Pipeline Repair Manual by Jaske. a heat input range for each welding pass should be specified for in-service welding procedures that rely on the use of a sufficiently high heat input level.” Final Report to Pipeline Research Council International. These procedures are generally referred to as temper bead procedures.g. voltage.. 2006. O. and if the pipe contents are a gas. The specified range should reflect the measured minimum and maximum heat input values that produce an acceptable weld. portable optical emission spectrometer). The use of thermal analysis models is permitted for interpolating between qualified thermal severity levels and material carbon equivalent levels provided no increase in the risk of hydrogen cracking results. pressure. C.2. etc. voltage..). an increase in the predicted HAZ hardness can be interpreted to represent an increase in hydrogen cracking risk. “Pipeline Repair Manual.e.2. and travel speed. for example.g.2 Pipeline Operating Conditions For in-service welds. temperature. ranges for wall thickness. DNV Columbus. This applies to both the pipe material and the appurtenance material. Weld cooling rates depend on welding parameters and the thermal severity of the pipeline operating conditions. et al. it may be appropriate to allow that procedure to be used for higher carbon equivalent materials without an increase in the risk of hydrogen cracking.4 Weld Deposition Sequence As an alternative to the use of a sufficiently high heat input level to overcome the effect of the flowing contents. since it is generally appropriate for most older line pipe materials to which in-service welding is commonly applied. For in-service welding procedures that rely on Revision 1 – April 30. For in-service welding. For a given material chemical composition. the procedure should document the condition under which the procedure was qualified and the actual conditions to which the procedure applies (e.1. voltage. Control of heat input level is an important aspect of assuring adequate tempering for procedures intended to overcome the effect of heat removal by the contents by using temper bead deposition sequence (temper bead procedures).3. Hart. GB.17 61 GB. a given set of welding parameters) to be used for higher carbon equivalent materials than the material used for procedure qualification is intended to allow the use of thermal analysis models to evaluate tradeoffs that can be made between the carbon equivalent of the materials and thermal severity levels. by direct analysis using portable equipment (e. Arlington. a procedure will be used under less severe thermal conditions than those used for procedure qualification. Inc.. If. B.1. filings removed using a high-speed rotary file) for laboratory analysis. GB.. but also on the pipeline operating conditions such as the thermal properties and temperature of the pipe contents. W.. 2010 17 Jaske. A. pipe contents.g. Inc.2. also on the pressure (thermal conductivity of gasses change with pressure).. In addition to ranges for amperage.3 Heat Input Range The most common procedures for in-service welding rely on the use of a sufficiently high heat input level to overcome the effect of the flowing contents. The development of crack-susceptible weld microstructures depends on the chemical composition or carbon equivalent of the materials being welded and on weld cooling rates. Chemical composition of an in-service pipeline can be determined by interrogating records from when the pipeline was built (e.1. or by removal of samples (e.2. the thermal severity (in terms of weld cooling rates that result) depends not only on wall thickness. not the calculated minimum and maximum values from the amperage. the flow rate. See guidance provided in GB. mill test reports).Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities of the materials to which the procedure applies should also be specified in the WPS.. Dublin. E. Temper bead procedures typically involve depositing a first layer or "buttering" layer using stringer beads that are deposited within the acceptable heat input range for preventing burnthrough. and Bruce.. procedures designed to make use of tempering from subsequent passes can be used to minimize the development of crack-susceptible weld microstructures.1. and travel speed range..1. Virginia. flow rate. The IIW (International Institute of Welding) carbon equivalent formula is provided in the footnote. Contract PR-186-0324. Subsequent passes are deposited in such a way as to maximize the amount of grain refinement and tempering of the buttering layer. and travel speed on the thermal cycle of the weld. Ohio. .1. 1. However. unrealistically slow weld cooling rates result.1.5 in.2.1. wall thickness should be considered along with pipeline operating conditions as it affects 62 thermal severity.2. if the range specified in the WPS for any of those variables is exceeded. For in-service welds other than fillet welds. This applies to the thickness of both the pipe material and the appurtenance material. while it is not necessary to consider pipe wall thickness itself as an essential variable.1. the strength of the completed weld should meet or exceed the specified minimum yield strength of the pipe and fitting material. the WPS should be revised to show the revised number of beads.3. See guidance provided in GB.2. instead of pipe wall thickness. While not explicitly stated in B2. A change in the bead spacing beyond the limits in the procedure specification should be considered an essential variable.2.2.2.1 Changes Requiring Requalification Essential variables are those that require the procedure to be requalified. See guidance provided in G5.2.7 mm) for typical applications.2.2.2.2. It is not necessary to consider the addition of buttering layer passes (e.1. which removes heat from the pipe wall. an increase in the thermal severity of the pipeline operating conditions above the group qualified constitutes an essential variable. to reduce gaps between a pipeline and a full-encirclement fitting) as an essential variable provided that the passes are deposited using parameters specified in the qualified welding procedure. the testing requirements for both the groove and fillet portion of the weld are the same as those for a fillet weld. the thermal severity (in terms of weld cooling rates) depends not only on wall thickness.2 Pipeline Operating Conditions For in-service welds. in addition to different solidification characteristics of the weld.1 Pipe and Fitting Materials Appendix B allows procedures for in-service fillet welds to be qualified in accordance with carbon equivalent level groupings as opposed to specified minimum yield strength groupings.1.2.2. Welds made onto thin-wall pipelines are made in close proximity to the flowing pipeline contents. To qualify a welding procedure for a branch connection.1. 2010 .4 Weld Deposition Sequence If the procedure relies on the use of a temper bead deposition sequence to minimize the development of crack-susceptible weld microstructures.2 ESSENTIAL VARIABLES General requirements for essential variables are provided in 5.3. the required weld deposition sequence should be specified. GB.g.1. the user has the option to qualify a procedure for either a sleeve weld or a branch weld. GB.2.3. The additional and/or alternative essential variables for in-service welding are given in B.2.2.1. but also on the pipeline operating conditions.e.2.1.1. When performing a procedure qualification for in-service welding..2.2. GB. The additional and/or alternative requirements for in-service welding are given in B. Without simulating the ability of the in-service pipeline to remove heat from the pipe wall. This effect becomes less prominent as pipe wall thickness exceeds some critical value.3 Pipe Wall Thickness For in-service welding.7. up to and including the most severe in-service welding applications).2. carbon equivalent of the materials being welded should be considered an essential variable for in-service welding as opposed to specified minimum yield strength. GB.2. GB. (12. GB.1.1. thought to be approximately 0. that sequence should be followed during production welding. The note provides guidance on how to easily simulate in-service conditions and indicates that procedures qualified with flowing water inside the pipe are suitable for most typical in-service applications (i.3 WELDING OF TEST JOINTS General requirements for welding of test joints for fillet welds are provided in 5.2. GB. and reverts back to a conventional relationship due to the thermal mass of the pipe wall itself at greater thicknesses.. For in-service welds. The weld deposition sequence should include tolerances for bead spacing to assure proper tempering of the previous passes. See guidance provided in GB.7. except for the provision provided in B. The note also Revision 1 – April 30.1. See guidance provided in G5. or a new procedure qualified.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities the use a temper bead deposition sequence. . less than 0. which will qualify the procedure for that position only.e.4.2. using thermal analysis models or by procedure qualification under less severe thermal conditions with pressure inside the pipe). the risk of burnthrough should be assessed independently (e.250 in.g.8. 2010 GB. This test position qualifies the procedure for all positions. . and the tests to which they are to be subjected are given in B.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities indicates that other media (e. Figure G3 – Typical Setup for Welding Procedure Qualification under Simulated In-Service Conditions To qualify a welding procedure for a branch connection. For in-service welding. See guidance provided in G5.4 TESTING OF WELDED JOINTS It should be noted that some acceptance criteria for imperfections discovered during procedure qualification testing are more stringent than those for imperfections discovered by nondestructive testing of production welds. This is intended to account for the more-favorable conditions that generally exist where welding procedures are normally qualified (e.. It is good Revision 1 – April 30. It should be noted that the pipe is not required to be aligned at approximately 45 degrees as indicated in Figure B-2.1. motor oil) may be used to simulate less severe thermal conditions (e.4.g. the locations.. low-pressure.. the testing requirements for both the groove and fillet portion of the weld are the same as those for a fillet weld.2. Tests may be performed in other positions. the weld cooling rate can exceed the cooling rate of test welds made on water-filled pipe of moderate wall thickness. For in-service welds made on very thick-wall pipe or fittings.8.g. [6.g. Thermal analysis modeling can be used to compare the estimated cooling rate of qualification welds with the estimated cooling rate of actual in-service conditions to verify that the test setup produced cooling rates that are representative of actual service conditions.4 mm]) in-service pipelines operating at 63 less severe thermal conditions. The use of procedures qualified with flowing water inside the pipe may represent a risk of burnthrough when applied to thin-wall (i.1 Preparation General requirements for testing of fillet welds are provided in 5. thinner-wall natural gas pipelines operating at low flow rates). For these applications. GB.. The use of this technique is illustrated in Figure G3.2. minimum number of specimens. in an enclosed welding shop as opposed to on a pipeline right-of-way). If the specimen is cut using a thermal process (e.. Brinell. overnight) prior to removing specimens so that any cracking that is going to occur has time to do so.2.2. The macro-section test 64 also allows hardness testing in the HAZ to be performed.6 mm (0.6. polishing the face of the weld and heat-affected zone.008 in. Longitudinal seams of full-encirclement sleeves or fittings that consist of butt welds should be tested in accordance with 5.4. The preferred procedure involves making hardness measurements at the toe of the weld in the coarse-grained HAZ on the pipe material side of the joint. the indent produced is an appropriate size for weld heat-affected zones).2.. and examining the surface for imperfections.8. dilute nitric acid in methanol (e. GB.2 Visual Examination While not required.1. GB.8. including assessment for the risk of hydrogen cracking.6 and G5. GB. which are typically made in conjunction with the qualification of procedures for in-service welding of full-encirclement sleeves and fittings. (203 mm) diameter.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities practice to allow the test weld to sit for some time (e.4 Macro-section Tests—Branch and Sleeve Welds The macro-section test involves cutting a welded test joint through its cross section.2.625 in. it is common for prepared macro-section specimens to be examined with a magnifying device. This technique is illustrated in Figure G4.3 Hardness Testing Hardness testing is often used as a performance indicator for welds. as this commonly used for weld heat-affected zones (i. 2010 .g. are provided in Appendix B for convenience only. The width of the heataffected area from the cut using a thermal process is typically 1/4 in.6. it may be difficult to obtain the required number of specimens when the branch is smaller than 8.) from each other and 0. longitudinal seams that consist of filletwelded overlapping side strips should be tested in accordance with 5.4.4. See guidance provided in G5.2 mm (0. Nital) can be used. In addition to ammonium persulfate or dilute hydrochloric acid.4. It is good practice to polish the specimen sufficiently so that the fusion line can be clearly distinguished. See guidance provided in G5. both the groove and fillet portion of the weld are treated as a fillet weld. Appendix B also specifies the macro-section test and face-bend test for in-service branch and sleeve welds. It is not appropriate for the Rockwell. GB. In addition to the nick-break test specified in 5.8. GB. oxy-fuel cutting).024 in.4. Recommendations for testing these welds.2.2.2. (6 mm) or less. or other large-scale hardness methods to be used and the results converted to the Vickers scale. For a branch connection.2. The phrase “to at least a 600 grit finish” refers to the abrasiveness of the sandpaper that should be used. Revision 1 – April 30. the heat-affected area from the cut must be removed by a non-thermal process.3 Branch and Sleeve Welds General requirements for testing of fillet welds are provided in 5. See guidance provided in G5.e.4..4..4.8. Five Vickers 10-kg indents are spaced 0. GB.8.2 Longitudinal Seam Welds General requirements for testing of butt welds are provided in 5. The results for these five measurements in the area of maximum hardness are then averaged. While not explicitly stated in B.1 Preparation Machine cutting is preferred. It should be noted that for qualification testing of branch welds. The etchant should be applied using a swab until the weld structure becomes clearly visible.g..) from the fusion line.6.4. The Vickers hardness testing method using a 10kg load is specified. butt welds that include the use of a backing strip or fillet-welded overlapping side strips) are not considered in-service welds according to the definition in B. Longitudinal seams that do not contact the carrier pipe (e.g.4.g. (9.e.375-in.4 Requirements The widely-used limit of 350 HV is conservative for some applications (and may be non-conservative for others – e. 2010 . B. Carman. In addition.. A. Dublin. Arnett. A.19 This work also showed that HAZ hardness is a lesseffective performance indicator for welds in modern microalloyed and control-rolled line pipe steels. Recommended hardness limits for materials in the 0. V.. If the weldability of the appurtenance material is less favorable than that of the pipe material (i.5-mm) thickness range with a carbon content greater than 0. Etheridge. Closer control of hydrogen level 18 Bruce. Dublin. Ohio.2." Final Report to U. A.5 Face-bend Test—Branch and Sleeve Welds The primary purpose of the face-bend test is to expose any hydrogen cracks that may be present. allows higher hardness to be tolerated. 2008. or the hardness level below which hydrogen cracking is not expected.g. The results are then reported as an average for this region of anticipated maximum hardness... IPC2008-64003. particularly at the weld toe area.4. Critical hardness level.4. W. depends on the hydrogen level of the welding process being used and on the chemical composition (carbon content and carbon equivalent level) of the materials being welded..Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 65 Figure G4 – Suggested Procedure for HAZ Hardness Measurement HAZ hydrogen cracks tend to occur in areas where hard microstructures coincide with stress concentrations. DNV Columbus. For in-service welds. Consideration can be given to excluding measurements that deviate significantly from the median value. "Development of Heat-Affected Zone Hardness Limits for In Service Welding. GB. averaging the results of the five measurements taken in the coarsegrained region of the HAZ near the weld toe has been found to be appropriate. DNV Columbus. A.” Proceedings of the 7th International Pipeline Conference. September 2009. September 29-October 3. Inc. Calgary. and Carman. GB. Inc. and Nolan. lower carbon content materials tend to crack at lower hardness levels and higher hardness can be tolerated when welding higher carbon content materials.10% are provided in a paper by Bruce. W.. R.S Department of Transportation..18 Limits that take the effect of material thickness into account have also been proposed. Canada. C.. Agreement #DTPH56-07-T-000004. if the appurtenance material has a higher carbon equivalent than the pipe material). In order to assess the overall hydrogen cracking susceptibility of in-service welds. Paper No. consideration should also be given to making hardness measurements in the coarse-grained HAZ on the appurtenance material side of the joint. 19 Bruce.4. “Heat-Affected Zone Hardness Limits for In-Service Welding. et al.. Project #216. where weld hydrogen levels are not controlled). PHMSA Research and Development. C. D. Alberta... Revision 1 – April 30. Ohio.. B. these areas tend to occur at the toe of the weld in the pipe material. Etheridge.2. . GB. porosity. testing of face-bend test specimens should not occur immediately after welding.2. the heat-affected area from the cut must be removed by a non-thermal process.500 in.2 Method Hydrogen cracking. can take some time to occur. 2010 . Testing of face-bend test specimens taken from branch and sleeve welds is similar to that for butt welds specified in 5.5. Also.2. Where wall thickness is greater than 0. Therefore. A typical hydrogen crack at the toe of a sleeve fillet weld in a face-bend test specimen is shown in Figure G5. although care should be taken to ensure that sanding or grinding to below the surface of the specimen (e. cracks. Machine cutting is preferred. If the specimen is cut using a thermal process (e. this remaining portion can be used for the face-bend test.4. See guidance provided in G5. Time delay prior to inspection of production welds for hydrogen cracking is addressed in B. (12.3 Requirement Causes of failure may include lack of ductility.4.6. (12. oxy-fuel cutting).6.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities 66 GB.4. incomplete fusion or penetration..1 Preparation Because of the geometry associated with branch and sleeve welds. GB. See guidance provided in G6.4.5.. to remove undercut) is avoided. GB.7 mm).6.5.5. which is also referred to as delayed cracking.4. perpendicular to the specimen) may cause an otherwise acceptable weld to fail.e. preparation of face-bend test specimens is different than that for butt welds specified in 5.500 in.g.4.5.2. The additional and/or alternative requirements for in-service welder qualification are given in B. Figure G5 – Typical Hydrogen Crack at Toe of Sleeve Fillet Weld in Face-Bend Test Specimen Revision 1 – April 30.g. The note provided in B.3 In-service Welder Qualification General requirements for welder qualification (single qualification) are provided in 6.3. deep scratches or grinding marks that are parallel to the weld (i.7 mm) by machining the inside surface The weld reinforcement can be removed using a belt sander or by grinding. and/or trapped slag. A time delay of at least 24 hours is specified. If the nickbreak test can be performed without introducing a notch in the pipe material side of the specimen.1is intended to allow both the nick-break test and the face-bend test to be performed on the same specimen. it may be reduced to 0.2.4.2.2. are provided in Appendix B for convenience only..3 and the in-service qualification to B. that welder can perform a 67 welder qualification test using one technique and demonstrate the other using another method (e.3 (in-service qualification).1. A welder who has an existing multiple qualification to 6. The last sentence in B. For in-service welding. While not explicitly stated in B..g.1 WELDING OF TEST JOINT Without simulating the ability of the in-service pipeline to remove heat from the pipe wall. low-pressure. longitudinal seams that consist of filletwelded overlapping side strips should be tested in accordance with 5.g. if any..5. AWS EXX10-type). Procedure selection for avoiding hydrogen cracking is often made based on the chemical composition (carbon equivalent) of the pipe material. the company can require that a welder perform a qualification test using heat inputs at the upper end of the anticipated range of specified heat inputs. portable optical emission spectrometer).g.3 is intended to allow for the multiple qualification of an in-service welder. The note provides guidance on how to easily simulate in-service conditions and indicates that welders qualified with flowing water inside the pipe are suitable for most typical in-service applications (i.3 must be for filler metals from Group 3. mill test reports).3 should apply. operating pressure. Similarly..3. the existing multiple qualification to 6. 2010 . The scope of testing of the second weld. Additional guidance specific to in-service welding can also be found in Appendix A of the PRCI Pipeline Repair Manual by Jaske. and an in-service qualification to B. relevant parameters such as pipe material. filings removed using a Revision 1 – April 30.3.g. using plate material arranged for lap fillet welds) provided that the company considers this to be satisfactory.1.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities Longitudinal seams that do not contact the carrier pipe (e.g. up to and including the most severe in-service welding applications). Multiple qualification of an in-service welder is limited by the essential variables in 6.. GB.17 Prior to in-service welding. and all wall thicknesses using filler metals from Group 3.2. is at the discretion of the company. which are typically made in conjunction with the qualification of welders for in-service welding. or by removal of samples (e.2.3 (multiple qualification) and B.2 TESTING OF WELDED JOINTS See guidance provided in G6. See guidance provided in Section G7. See guidance provided in G5. Chemical composition of an in-service pipeline can be determined by interrogating records from when the pipeline was built (e. Recommendations for testing these welds. GB. and all wall thicknesses using filler metals from Group 3. The phrase “to the satisfaction of the company” is intended to preclude the need to perform multiple welder qualification tests. If a welder is to be qualified for both heat input control and temper bead deposition procedures. For an in-service welder to be qualified for all positions.3. by direct analysis using portable equipment (e.8. Additional and/or alternative requirements for in-service welding are given in B.2.g.3 are less restrictive than those in 6. pipe contents.3 RECORDS See guidance provided in GB. essential variables for pipe diameter for in-service welder qualification in B.g.g. Longitudinal seams of full-encirclement sleeves or fittings that consist of butt welds should be tested in accordance Table B-2.3 using filler metals from Group 3 (e. GB.3.3 using filler metals from Group 1 or 2 in Table 1 (e.4 and G6... The essential variables for pipe diameter for inservice welder qualification in B. The welding procedure that will be used should be appropriate for the specific application. AWS EXX18-type).3.8. and wall thickness at the location of the welding should be determined.e. butt welds that include the use of a backing strip or fillet-welded overlapping side strips) are not considered in-service welds according to the definition in B. in addition to different solidification characteristics of the weld. flow conditions. unrealistically slow weld cooling rates result.4.. GB. thinner-wall natural gas pipelines operating at low flow rates). and then demonstrate the ability to make welds at lower heat inputs using a second weld of some type using heat inputs at the lower end of the heat input range. et al. all diameters. should not be considered an in-service welder for all positions..g.. motor oil) may be used to simulate less severe thermal conditions (e. The note also indicates that other media (e.4 Suggested In-service Welding Practices General requirements for production welding are provided in Section 7. all diameters. Guidance can be found in Appendix A of the PRCI Pipeline Repair Manual by Jaske. it is important to follow the specific electrode manufacturer’s recommendations for storage and handling. While excessive gap is not defined.1. The most common method of facilitating proper fit up the use of chains and hydraulic jacks. Appendix B does not address safety during welding aspects directly. a test plate should be used by the welder prior to depositing welds on an in-service pipeline to 68 ensure that the proper heat input level is being achieved. GB. it may be necessary to maintain a heat input above a minimum-required value.4. For Type A full-encirclement repair sleeves (reinforcement only) and for full-encirclement reinforcement of stub-on hot tap branch connections. Using this scheme. it may be necessary to maintain a heat input within a specified range (i.2 WELDING SEQUENCE For full-encirclement sleeves and fittings requiring circumferential fillet welds. et al. and then one end before the other) should be used to minimize stresses. The sequence described in B. it may be necessary to maintain a heat input below a maximum-allowable value. For welding onto inservice thin-wall pipelines. Low-hydrogen electrodes should be properly stored and handled to ensure that low hydrogen levels result. This increases the effectiveness of the reinforcement provided by the repair sleeve or fitting and minimizes the complications associated with fillet welding in the presence of a gap..1 Fit-up Care should be taken to ensure that full encirclement repair sleeves and fittings fit snugly around the pipe. the length of weld deposited is specified as some percentage of the electrode length consumed. Since different low-hydrogen electrodes behave differently with respect to moisture absorption. GB. Accurate measurement of heat input levels can be achieved using conventional equipment (amp tongs. Regardless of the method chosen to control heat input levels. 2010 . For some applications.2 Root Opening—Longitudinal Seam Welds For full-encirclement sleeves and fittings.4.2 (i. the longitudinal seams should be fitted with a mild steel back-up strip or suitable tape to prevent penetration of the weld into the carrier pipe. Weld metal build-up (buttering layers) can be used when other methods are insufficient. An ultrasonic wall thickness check can also be used to investigate for the presence of defects.13 Wall thickness should be determined using appropriate ultrasonic testing equipment to ensure that corrosion or erosion has not greatly affected the actual wall thickness from the nominal value. it is common to limit gaps to 1/16 to 1/8 in.2 mm) maximum.1. the sequence in which welds are made can affect stresses acting on the welds because welds contract as they solidify and cool. Moisture can be absorbed by the electrode coating during storage and handling. (1. The run-out ratio scheme can also be used to control heat input levels. even though the longitudinal seams made with backing strips are not required to be qualified in accordance with Appendix B.1 ALIGNMENT GB. However. It is not necessary to consider the addition of buttering layer passes as an essential variable provided that the passes are deposited using parameters specified in the qualified welding procedure.4. voltmeter. Cellulosic-coated electrodes should not be indiscriminately substituted for low hydrogen welding practices for the longitudinal seams.e. the WPS should be revised to show the revised number of beads. For procedures that are intended to overcome the effect of the flowing contents by using a sufficiently high heat input. etc. The ability to accurately control heat input levels is an important aspect of being able to safely weld onto in-service pipelines.e. GB.. Revision 1 – April 30.6 to 3. but refers to API RP 2201 instead. stopwatch.4.4. Purpose-built clamps are also available for this purpose. Penetration of the longitudinal butt weld into the carrier pipe is undesirable since any crack that might develop is exposed to the hoop stress in the carrier pipe.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities high-speed rotary file) for laboratory analysis. longitudinal seams first. between a minimum-required and a maximumallowable value).) or purpose-built arc monitoring equipment. It should be noted that the performance of circumferential fillet welds deposited using lowhydrogen electrodes can be influenced by the use of cellulosic-coated electrodes for making the longitudinal seam welds of full-encirclement fittings. preheating and post-heating). saddle-. and immediate inspection may be justified. Prior to inspection for hydrogen cracking.. Revision 1 – April 30. as well as the expected susceptibility of the weld to cracking. The reason for this is that time is required for the hydrogen to diffuse to areas with crack susceptible microstructures. Longer times should be considered for thicker materials (e. B-10. During execution of a temper bead procedure. Bead sequence is not an essential variable provided that the passes are deposited using parameters specified in the qualified welding procedure. MT has the ability to detect imperfections that are located slightly below the surface (if DC magnetization is used). The sequence in which individual beads within a given weld are made can also affect the weld microstructures that result.] and/or heavy-wall fittings) and/or for lower ambient temperatures. GB. and thus the importance of determining an appropriate delay time.5 in. GB. an inspection method that is capable of detecting these cracks. should be used.Guidance Material for API Standard 1104 – Welding of Pipelines and Related Facilities (Figures B-8. the WPS should be revised to show the revised bead sequence. 69 thin layer of white contrast paint tend to perform equally well.6 Standards of Acceptability: Nondestructive Testing (Including Visual) See guidance provided in Section G9. Some companies.. the beads should be stacked away from the carrier pipe material. When determining appropriate delay times prior to inspection. 2010 . The longitudinal seam welds provide the necessary reinforcement. To do this. the beads should be deposited is such a way as to maximize tempering.5 Inspection and Testing of Inservice Welds General requirements for inspection and testing are provided in Section 8. if the hydrogen in the weld is allowed to diffuse away after welding by the continuous application of preheating (i. For example. Between-pass inspection should be carried out to assure proper bead placement. requires time to occur. The use of magnetic particles suspended in a carrier liquid is generally more sensitive than the use of dry powders. The additional and/or alternative specification information for in-service welding is given in B. which is also referred to as delayed cracking. Both wet fluorescent MT and the use of colored (usually black) particles over a surface that is first sprayed with a GB. The probability of cracking.g.7 Repair and Removal of Defects General requirements for repair and removal of defects are provided in Section 10. Ultrasonic testing (UT) can be used to supplement MT results. Since in-service welds that contact the carrier pipe can be particularly susceptible to hydrogen cracking. the welder should be thoroughly familiar with the proper sequence. the probability of cracking is significantly reduced. However. a sufficient delay time should be allowed to elapse. can be minimized by using more conservative welding procedures. however. particularly at the carrier pipe weld toe. and B-11). the time-dependant nature of hydrogen cracking should be considered. The successful application of UT for the typical geometries associated with inservice welds has been shown to be highly dependent on operator skill. Care should always be taken when grinding on an in-service pipeline to prevent an area of reduced wall thickness that is larger than what is appropriate for the operating pressure in the pipeline from being produced. The ability of a temper bead sequence to reduce hydrogen cracking risk is dependent upon proper placement of the weld beads.7 mm [0.e. For welds that contact the carrier pipe. particularly at the weld toes. See guidance provided in Section G8. Hydrogen cracking. it is not necessary to fillet weld the ends to the pipeline provided that the full-encirclement fits tightly around the pipeline. pipe wall thickness greater than 12. See guidance provided in Section G10. Magnetic particle testing (MT) has been shown to be more effective than liquid penetrant testing (PT) for detecting hydrogen cracks at the toe of sleeve-. and branch-to-carrier pipe welds. A delay time of twelve hours would seem to be a reasonable time for the range of thicknesses that are encountered during most typical in-service welding applications. Longer delay times decrease the chance that cracking can occur after inspection has been completed. weld the ends to prevent further corrosion. which can also be accomplished using an effective coating system. Excavation of defects in in-service welds should be limited to grinding only.5. whereas PT does not. even for non-temper-bead procedures.