OISD-STD-141 (Revised) FOR RESTRICTEDCIRCULATION DESIGN AND CONSTRUCTION REQUIREMENTS FOR CROSS COUNTRY HYDROCARBON PIPELINES OISD-STD-141 First Edition, April 1990 Amended Edition, September 2001 Revised Edition, September 2003 OIL INDUSTRY SAFETY DIRECTORATE Government of India Ministry of Petroleum & Natural Gas OISD-STD-141 Amended Edition, September 2001 Edition, September 2003 First Edition April 1990 Revised FOR RESTRICTED CIRCULATION DESIGN AND CONSTRUCTION REQUIREMENTS FOR CROSS COUNTRY HYDROCARBON PIPELINES Prepared by COMMITTEE ON DESIGN AND INSPECTION OF PIPELINES 7th FLOOR, “NEW DELHI HOUSE” 27, BARAKHAMBA ROAD NEW DELHI -110001 OIL INDUSTRY SAFETY DIRECTORATE NOTE OISD publications are prepared for use in the oil and gas industry under Ministry of Petroleum & Natural Gas. These are the property of Ministry of Petroleum & Chemicals and shall not be reproduced or copied and loaned or exhibited to others without written consent from OISD. Though every effort has been made to assure the accuracy and reliability of the data contained in these documents. OISD hereby expressly disclaims any liability or responsibility for loss or damage resulting from their use. These documents are intended to supplement rather than replace their prevailing statutory requirements. standards and practices are in vogue. 27-Barakhamba Road. This standard is meant to be used as a supplement and not as a replacement for existing codes and practices.FOREWARD The Oil Industry in India is 100 years old. Factory Inspectorate or any other Statutory body which must be followed as applicable. This standard is based on the accumulated knowledge and experience of industry members and the various national and international codes and practices. the then Ministry of Petroleum and Natural Gas in 1986 constituted a Safety Council assisted by Oil Industry Safety Directorate (OISD) staffed from within the industry in formulating and implementing a serious of self regulatory measures aimed at removing obsolescence. It is hoped that the provision of this standard if implemented objectively. Suggestions are invited from the users after it is put into practice to improve the standard further. emphasised the need for the industry to review the existing state of art in designing. coupled with feed back from some serious accidents that occurred in the recent past in India and abroad. With this in view. operating and maintaining oil and gas installations. The present standard on “Design and Construction Requirements for Cross Country Hydrocarbon Pipelines” was prepared by the Functional Committee on “Design and Inspection of Pipelines”. Committee on Inspection of “Design and Inspection of Pipelines”. This standard in no way supersedes the statutory regulations of Chief Controller of Explosive (CCE). New Delhi House. . standardising and upgrading the existing standards to ensure safer operations. may go a long way to improve the safety and reduce accidents in the Oil and Gas Industry. This. New Delhi-110 001. 7th Floor. Standardisation in design philosophies and operating and maintenance practices at a national level was hardly in existence. Due to various collaboration agreements. Users are cautioned that no standard can be a substitute for the judgement of responsible and experienced engineer. Suggestions for amendments to this standard should be addressed to:The Coordinator. Oil Industry Safety Directorate. a variety of international codes. Accordingly OISD constituted a number of Functional Committees comprising of experts nominated from the industry to draw up standards and guidelines on various subjects. G. Sh.f June/89 on Shri Karode’s retirement from Oil India Ltd).K.K.M Bhumgara 7. Sh. several other experts from the industry contributed in the preparation. .E.COMMITTEE ON DESIGN AND INSPECTION OF PIPELINES ( First Edition April 1990 ) ------------------------------------------------------------------------------------------------------Name Organisation ------------------------------------------------------------------------------------------------------- Leader 1.N. Sh. Sh.S. Dhadda 9. Char 6. Mulla 8. Dutta 11.K.K. Karode 2. Sh. Sh. ** (Took over as Leader w. Bhandari Oil Industry Safety Directorate ------------------------------------------------------------------------------------------------------In addition to the above.V.R.V.Rao Rudravajala 4.R. Sh.T.K.C.A. review and finalisation of this document.e. Sh.S. Goyal 5. Baruah Indian Oil Corporation Limited Oil and Natural Gas Corporation Limited Oil and Natural Gas Corporation Limited Hindustan Petroleum Corporation Limited Hindustan Petroleum Corporation Limited Engineers India Limited Gas Authority of India Limited Oil India Limited Oil India Limited Member Coordinator 12.M. Sh.K. Sh. Shanbhag ** Oil India Limited Indian Oil Corporation Limited Members 3. Sh. Saiprasad 10. Sh.R.R. N. Sh. review and finalisation of this document. Soman Bharat Petroleum Corporation Limited Bharat Petroleum Corporation Limited GAIL India Limited Indian Oil Corporation Limited Kochi Refineries Limited Member Coordinator 7. Sh. several other experts from the industry contributed in the preparation.S.Mittal Oil Industry Safety Directorate ------------------------------------------------------------------------------------------------------In addition to the above.COMMITTEE ON DESIGN AND INSPECTION OF PIPELINES ( First Revision September 2003 ) ------------------------------------------------------------------------------------------------------Name Organisation Leader 1. Sengupta Indian Oil Corporation Limited Members 2. Sh. . Wankhede 3.Patel 5.S..A.S.P. Sh.K.KBS Negi 4.G.Pal 6. Sh.K.R.C. Sh. Sh. 2 6.3 7.4 7.1 5.0 3.2 4.5 4.6 7.4 4.6 4.2 7.0 2.7 4.8 5.0 4.1 7.3 4. Miters and Elbows Installation of Pipe in the Ditch Special Crossings Pump Station. Tank Farm and Terminal Construction .7 INTRODUCTION SCOPE DEFINITIONS DESIGN Dynamic Effects Weight Effects Corrosion Design of Components Valves Threaded Joints Stress Values Design of Pipe supporting Elements MATERIALS Steel Materials for Sour Multiphase Service DIMENSIONAL REQUIREMENTS CONSTRUCTION. 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 4 4 4 5 6 PART .I 1.0 5. Stringing and Storing Ditching Bends. Hauling.1 4. WELDING AND ASSEMBLY Location Handling.No ITEM DESCRIPTION PAGE NO.DESIGN AND CONSTRUCTION REQUIREMENTS FOR CROSS COUNTRY HYDROCARBON PIPELINES CONTENTS Sl.5 7.0 4.0 7.0 7. 1 10.0 16.4 16.0 10.3 10.2 8.3 8.0 12. INSTALLATION AND TESTING General Provisions Population Density Index Corrosion Allowance Cover Requirements for Pipelines Clearance Between Pipelines or Mains and other underground Structures 11 11 11 12 12 12 12 13 15 15 15 15 16 16 16 16 .1 15.1 16.5 16.4 Storage and Working Tankage Storage Pre-Operational Stresses INSPECTION AND TESTING Type and Extent of Examination Required Testing Commissioning Record OPERATION AND MAINTENANCE PROCEDURES CORROSION CONTROL Protective Coating Cathodic Protection System Electrical Isolation Temporary Cathodic Protection System PART – II 6 6 6 6 7 7 7 7 8 8 8 8 8 11.1 8.2 16.7.0 14.3 15.0 10.0 15.0 15.2 15.0 8.4 15.3 16.2 10.8 7.0 13.9 8.4 9.5 DESIGN PIPING SYSTEMS MATERIALS AND EQUIPMENT WELDING PIPING SYSTEM COMPONENTS AND FABRICATION DETAILS Valves and Pressure Reducing Devices Expansion and Flexibility Combined Stress Calculations Supports and Anchorage for Exposed Piping Pre-Operational Stresses DESIGN. 9 16.3 18.2 18.6 18.15 17. Roads or Streets Bends.0 18.0 18.0 20.1 18.13 16. Requirements under Rail Roads.8 16.7 19.12 16. Highways.4 18.0 Casing.6 16.14 16.5 18.10 16.11 16. Elbows and Miters in Steel Pipelines and Mains Miscellaneous Operations involved in the Installation of Steel Pipelines and Mains Water Crossings Crossing of / or by Utilities Testing after Construction Control and limiting of Gas Pressure Valves Pipe Book OPERATING AND MAINTENANCE PROCEDURES CORROSION CONTROL Coating Requirements Electrical Isolation Electrical Connections and Monitoring Points Electrical Interference Existing Installations Temporary Cathodic Protection System Internal Corrosion Control MISCELLANEOUS REFERENCES 16 16 17 17 18 18 20 20 21 21 21 21 21 21 22 22 22 23 23 23 .16. e) SHOULD 3. stations. natural gasoline. assembly.0 INTRODUCTION Safety in petroleum installations and pipelines comes through continuous efforts at all stages and as such it can be ensured by observing that installations and pipelines are designed.17 is defined as 'Onshore'.4'. inspection.Areas beyond the line of ordinary high water.4.8 herein after is referred' as 'B 31. The definition of 'Offshore' as per B 31. tank farms.4 clause 400. For the purpose of this standard. truck and rail) and other delivery and receiving points. commissioning. materials.8 clause 803. multiphase fluids are considered to be low vapour pressure fluids. maintenance and safety aspects of cross country pipelines – onshore. constructed and tested as per recognised engineering standards and they are periodically inspected and maintained. refineries. (A) transporting liquids such as crude oil.0 DESIGN Design of cross country pipelines – onshore shall be as per ANSI/ASME B31.2Definitions is defined as 'Onshore'.8'. PART-I Multiphase fluids means oil. Areas not covered by 'Offshore' as defined in B 31.4 herein after is referred' as 'B 31. operation.0 DEFINITIONS a) MULTIPHASE FLUIDS The word 'Should' is used to indicate that the provision is recommendatory as sound engineering practices.0 SCOPE This standard outlines the minimum requirements for design. The definitions of 'Offshore' as per B 31. between producer lease facilities. along that portion of the coast that is in direct contact with the open seas and beyond the line marking the seaward limit of inland coastal waters’.8 is reproduced hereunder for easy reference: 'Offshore-Areas beyond the line of ordinary high water. and 'ASME/ANSI Code B 31. Areas not covered by 'Offshore' as defined in B 31. b) ON PIPELINES SHORE – LIQUID LIQUID PETROLEUM TRANSPORTATION SYSTEMS 4. condensate. gas or water in any combination produced from one or more oil wells or recombined oil well fluids that may have been separated in passing through treatment/processing facilities. terminals (marine. and liquid petroleum products (B) transporting Natural Gas. natural gas liquids.' d) SHALL The word 'Shall' is used to indicate that the provision is mandatory.DESIGN AND CONSTRUCTION REQUIREMENTS FOR CROSS COUNTRY HYDROCARBON PIPELINES 1. c) ON SHORE – GAS PIPELINES 2. 4. along that portion of the coast that is in direct contact with the open seas and beyond the line marking the seaward limit of inland coastal waters.4 is reproduced hereunder for easy reference: ‘Offshore . testing. For convenience 'ASME/ANSI Code B 31. construction. natural gas processing plants.1 DYNAMIC EFFECTS . 2 WEIGHT EFFECTS Live Loads Weight of water during hydrostatic testing shall also be considered while designing. SOUR MATERIALS FOR MULTIPHASE SERVICE Definition NACE Standard MR-OI-75 'Sulfide Stress Corrosion Cracking Resistant Metallic Materials for Oil Field Equipment defines limiting concentrations on hydrogen sulphide in the fluid transported' for it to be considered as sour service. . 4.1.8. 4.Other Loadings 4. 4.1 5.1 5. adequate precautions shall be taken to prevent corrosion at or near the contact points.3 Mill Hydrostatic Testing of line pipe is recommended as 90% of SMYS irrespective of grade of pipe material. where D = outside diameter of pipe. Further.1 MATERIALS STEEL Carbon Equivalent shall be calculated based on the formula given below: CE = C + Mn + Cr+Mo+V + Ni+Cu 6 5 15 Carbon Steels having a specified carbon content in excess of 0.0 5. all connections welded to the pipe shall be made to a separate cylindrical member which completely encircles the pipe.1 Unusual loadings such as those caused by scour. If a pipeline is designed to operate at stress level of more than 50% of the specified minimum yield strength of the pipe.2. Braces and Anchors 5.65% shall be preheated. The pressure hold period should be 15 sec.2 Additional test requirements shall be as per Appendix-A of Part-I of this standard for steel pipes manufactured by Electric Resistance Welding and/or Electric Induction welding. API-1104 shall be referred for guidance.4 DESIGN OF COMPONENTS 4. 4.8 DESIGN OF PIPE SUPPORTING ELEMENTS Supports.4. 4. 4.3 CORROSION Whenever internal or external corrosion is expected during the design life of the pipeline. and this encircling member shall be welded to the pipe by continuous circumferential welds at both ends.1 STRAIGHT PIPE The least nominal wall thickness (tn) for steel pipe. 4. 5.6 THREADED JOINTS Threaded joints shall not be used in cross country pipelines. soil movement and slides.8.1 shall not be less than the dimensions indicated in the specifications for line pipe approved by B 31.2 5.1.1.1.4 Wherever non integral attachments.32% or a carbon equivalent in excess of 0. pipe having a D/tn ratio greater than 150 shall not be used.2 5.4. 4. installation forces. Ultrasonic testing for pipe skelp and weld seam is 100%.5 VALVES Valves made of cast iron or ductile iron shall not be used.4 clause 404. erosion. as indicated in B 31.7 STRESS VALUES Consideration shall be given to the use of lower allowable design stress if there is likelihood of repeated stress changes giving rise to fatigue conditions. Ultrasonic testing for pipe ends is mandatory. such as pipe clamps and ring girders are used. 5. a suitable corrosion allowance shall be made at the design stage.1. vortex shedding and other phenomena shall also be considered and provided for in accordance with sound engineering practice. congregate or assemble.4 Chapter IV shall apply.3 of this standard.2.4 and this standard.0 DIMENSIONAL REQUIREMENTS All provisions of B 31.3.1 CONSTRUCTION.0 metres from the existing underground pipeline when heavy conventional construction equipment is excepted to be utilized.3 7.0 7. all materials used in sour multiphase service shall meet the following requirements.0 metres of any private dwelling or any industrial building or place of public assembly in which persons work.3 Pipes made of cast iron. ductile iron. such as carbon dioxide in the gas and salt in the water or larger amounts of free water or gas. Minimum cover for Buried Pipelines 7. a) Pipe. bronze and other copper based materials shall not be used in sour multiphase service.2 General In addition to the applicable requirements of B31. The acceptance criteria shall be based on current established industry practice.2 6. No pipeline should be located within 15. may cause problems to occur at lower concentrations of hydrogen sulphide.0 of this standard. fittings.2. 7. Pipelines shall be buried below ground level. unless it is provided with at least 300 mm of cover in addition to that provided in Table 7. 7. should be at a minimum clear distance of 5. 7. 5. STRINGING AND STORING Pipe shall not be strung along the right of way in rocky areas where blasting may be required. the Sulphide Stress Corrosion Cracking (SSCC) and Hydrogen Induced Cracking (HIC) tests should be conducted as per NACE standards referred in Clause 20. flanges bolting and other equipment exposed to or which are necessary to contain sour multiphase fluids may be susceptible to stress corrosion cracking and hydrogen induced stepwise cracking and thus due consideration shall be given to material selection in design.1 DITCHING The width of trench shall be such that a minimum clear distance of 200mm for trench in normal soil and 300mm for trench in rock is maintained between edge of pipe and the trench wall at the bottom of trench. valve. until all blasting is complete and the area cleared of all debris. c) Pressure containing components (excluding pipe) intended for sour multiphase service shall be fully identified with a permanent marking.3. Depending upon the service and the materials involved. unless construction above ground is found to be desirable for exceptional technical. In any case the minimum clear distance shall not be less than 3. b) Materials for sour multiphase service shall conform to the requirements of NACE Standard MR01-75. when running parallel to an existing underground pipeline. 7. Material other than line pipe shall not be strung on the right of way but shall be transported to site for use only at the time of installation. WELDING AND ASSEMBLY LOCATION The location of a new underground pipeline. 'Sulphide Stress Corrosion Cracking Resistant Metallic Material for Oil Field Equipment'. These areas shall be distinctly identified on ground during construction. 5. This distance may be reduced after careful assessment of construction methodologies so that it does not result in unsafe conditions during construction.Note: While past experience has indicated this to be the accepted minimum concentration at which sulphide stress corrosion cracking may occur.3.3 . HAULING. economic or topographical reasons. the presence of other constituents in the phases making up the multiphase fluid.3.2 HANDLING.0 metres. a complete check of the pipe coating and field joint coating shall be carried out and all damages repaired.4 (3) 1.5 metre) shall be provided below the predicted scour profile expected during the life time of the pipeline.3 The minimum radius of field cold bends shall be as follows: ________________________________ Nominal Pipe Minimum Radius of size In Bend in Pipe Diameter ________________________________ NPS 12 and smaller 21D NPS 14 u/i 18 30D NPS 20 and larger 40D MITERED BENDS A mitered bend is not permitted with the exception of deflections upto 3 degrees that are caused by misalignment. particular attention shall be paid to the suitability of the trench to allow the pipeline to be lowered without the coating being damaged and to give a reasonably even support to the pipeline. TABLE 7. When already coated pipes are being lowered. Wherever pipeline is laid under tension as a result of an assembly error (for example incorrect positioning of bends.2 (3) 7.5 (4) 1. the trench shall be rectified or in exceptional cases a new assembly shall be carried out so that it fits the excavation and the laying bed.3 given below.4. the deformation caused during the raising of the pipe from the support does not exceed the values for the minimum allowable radius of elastic (1) The above mentioned minimum cover requirements shall be valid for all class locations.4. Canal and other Minor water crossings Drainage ditches at Roadways and railroads Rocky Areas Uncased/Cased Road Crossings Railroad Crossings Other Areas 1.0 1. which are prone to scour and erosion.1 The ends of each bent length shall be straight and not involved any way in the bending. (4) In case of rivers/water bodies. (3) Cover shall be measured from the top of road or top of rail.0 (2) and Residential Areas Stream.3.4. either horizontal or vertical).3.3 Minimum Cover for Buried Pipelines ________________________________ Location Minimum Cover in metre ________________________________ Industrial. 7. adequate safe cover (minimum 1. 7. Tangents approximately 1 metre in length shall be provided on both ends of cold bends. The length of the straight . or top of graded working strip. as the case may be. Fill material in working strip shall not be considered to add to the depth of cover. INSTALLATION OF PIPE IN THE DITCH Before lowering operations are commenced.The minimum cover shall be as per table 7.0 (2) 1.5 section shall permit easy jointing.2 Pipes with longitudinal welds shall be bent in such a way that weld lies in the plane passing through neutral axis of the bend which shall be installed positioning the longitudinal weld in the upper quadrants.4 BENDS. BENDS MADE FROM PIPE 7. (2) Minimum depth of cover shall be measured from the top of pipe coating to the top of undisturbed surface of the soil.0 (2) 7. whichever is lower. Commercial 1. Care must be taken that during laying. MITERS AND ELBOWS Bends made from pipe 7.4.4 1. Where it is not practicable to obtain the above mentioned clearance. b) The pipeline at such crossings shall be installed with extra depth of cover. d) A heavier wall thickness pipe shall be provided for the river crossing section.6 7. so as to keep the stresses in the steel pipe and on the coating within safe limits. In laying parallel pipelines in the same trench. e) A minimum separation of 3.3 All crossings shall be made in such a manner that the angle between the centerline of the railway.6.6. special design and construction shall be used. c) To ensure the stability of the underwater pipeline. potentially scouring bed. large erodable flood plain and wide water course (high water mark to high water mark) both during the design and installation of such crossings. extra precaution shall be taken to ensure the maximum possible clearance and to prevent future contact.curvature. If pipelines and communication and / or power utilities share the same trench. river.6. the minimum clear distances between the pipelines shall be 500 mm. The cover provided shall be adequate to prevent exposure of the pipeline for the entire design life of the pipeline. the section of the pipeline corresponding to the river crossing should before installation be subjected to hydrostatic pre-testing. 7. ground cables and counter poise. scour of bed and erosion of banks and to obtain all other parameters related to design and installation of such crossings. conductors or conduit. a) Hydrological and geotechnical surveys to establish the river bed and water current profiles to predict the behaviour of the river with respect to change of course. 7. For river crossings such as those described and established above the following additional requirements are to be considered. Regardless of separation. Where these clearances cannot be maintained. along or near underground power and / or communication cables. the above clearance shall be maintained with the pipeline preferably at a lower level. stream. the complete pipeline corresponding to river crossing shall be tested after installation. canal or utility being crossed and the centerline of the pipeline shall .1 SPECIAL CROSSINGS Water crossings Special considerations shall be required for submerged crossings which are characterized by their perennial nature.2 f) Whenever considered desirable. Crossing of or by Utilities a) A minimum clearance of 300mm shall be maintained at the point of crossing and the utility or pipeline shall be installed at a uniform depth for the full width of the right of way.0 metre should be maintained between pipeline and transmission tower footings. However. other systems through the application of cathodic protection shall be dealt by mutual action of the parties involved. d) When laid parallel to. meandering course. highway. it may be necessary to add weight to sink and hold the pipeline in position. underground pipes shall maintain a vertical clearance of at least 300 mm. steep and potentially erodable banks. consideration should always be given to lightning fault current protection of pipelines and safety of personnel. taking into consideration the effect of all loads during laying and it shall be ensured that the stresses remain within permissible limits in accordance with B 31. or from. b) A clearance sufficiently large to avoid electrical fault current interference shall be maintained between the pipeline and the grounding facilities of electrical transmission lines. 7. c) Interference with.4. e) A detailed stress analysis for the pipe section for river crossings should be carried out. If moisture is present on the surface of the pipe. but not restricted to. The designer shall ensure that preoperational stresses are controlled and that they are non-injurious to the pipe. Unless special procedures can be taken.1. The gauging plate shall have a diameter of 95% of the internal diameter of the pipeline. no coating materials shall be applied.9 PRE-OPERATIONAL STRESSES It is desirable to limit stresses during pre-operational manipulation of the pipe so as to avoid damage that might impair the operability of the line. Method for Underground Storage of National Gas Liquids 7.1.3 Test Pressure Hydrostatic Testing Pressure Piping of Internal f) hydrostatic test pressure loads (particularly when the pipeline is constructed as an above ground installation or is buried in unstable The test pressure shall be decided as . selected backfill. 8. 7. e) Field bending. 8. the effect of the following pre-operational loads: a) Transportation and stockpiling of the pipe. b) Stringing. Such chambers shall be constructed and operated in accordance with GPA Publication 8175. if required.0 8.1 PUMP STATION. Yard-coated pipe shall be examined after field bending to ensure that the quality of the coating has not been impaired.8 STORAGE AND WORKING TANKAGE STORAGE Underground Storage Prior to design and construction of an underground storage chamber.1.2.2 8. All sections which have been previously hydrostatically tested viz.be as close as possible to 90 degree but in no case less than 45 degree .. Water used for testing should be dozed with suitable corrosion inhibitor. TESTING A gauging pig shall be passed through the pipeline to prove the internal diameter of the entire line.1 soils). coating wrapping. no coating shall be applied when the ambient temperature might have a detrimental effect on the coating either during or after application. and ditch padding shall be taken where conditions are such that damage to the pipe coating could occur.1 8. and 8. c) Backfilling. and laying. TANK FARM AND TERMINAL CONSTRUCTION Location Minimum distances from property lines and road allowance limits to buildings and equipment etc. OF 8. Consideration shall be given to.5 8.2 8. rock shield. Any cutting or removal of the coating shall be promptly and carefully repaired.7.1. shall meet the requirements of OISD Standard 118 "Layouts for Oil and Gas Installations". an engineering and geological investigation shall be carried out to determine the feasibility of such a system at the proposed site.2.1 INSPECTION AND TESTING TYPE AND EXTENT EXAMINATION REQUIRED Construction Field pipeline coating shall be applied on a properly prepared surface and visually inspected during application.1.7 7. Additional precautions such as double coating.3 8.2 d) Loads imparted by construction traffic. 7.2.4 8. road/rail crossings and river crossings shall be retested alongwith the completed mainline sections. 0 10.2 CATHODIC PROTECTION SYSTEM a) Existing Bare Pipelines Systems Investigation shall be made to determine the extent or effect.6 Pre. welder number.1 CORROSION CONTROL PROTECTIVE COATING a) Coatings shall electrically isolate the external surface of the piping system from the environment. 8. of corrosion on existing bare pipeline systems.7 Preservation of Pipeline If the pipeline is to be preserved for a specified duration before it can be commissioned.2.4-Chapter-VII and OISD-STD-138 shall apply. Each item shall be recorded by its identification number.4.5 Termination of Testing The pipeline shall be slowly depressurized at a moderate and constant rate. In cases where the water has to be cleared from the pipeline before commissioning because of possible chemical or physical action between the water and the liquid to be transported.2 . 8.2. 10. Location of each weld including weld number. fittings.3. the pipeline shall be filled with the liquid. and other fittings installed in the project. After drying. damages to fields under cultivation and/or existing structures and interference with the traffic. During dewatering. Care shall 8. scraper traps. corrosion control measures or other remedial action shall be undertaken. repairs and tie-ins shall be coated with a material compatible with the existing coating.2. b) Cathodically Protected Pipeline Systems Temporarily Out of service Cathodic Protection system shall be maintained on any pipeline that is temporarily out of service. The purpose of the pipe book shall be to indicate and maintain as a permanent record the exact position in the pipeline of each pipe length and each pipeline material like valves. flanges.3. 8.1 COMMISSIONING Commissioning shall consist of displacing the hydrostatic test water from the pipeline by pumping in the liquid to be transported. 8. 8. RECORD Pipe Book A pipe and welding book shall be maintained for all projects. Batching pigs or spheres shall be used not only to minimize mixing at the interface but also to enable the progress of the interface to be followed. weld treatment and details of equipment used for radiography shall be recorded in the pipe book. When these investigations indicate that continuing corrosion will create a hazard. the pipeline shall be first drained and then dried as thoroughly as possible.3 8. 9. 10.2. The duration of hydrostatic proof test shall be minimum 24 hours.tested Pipe Pipe used for making repairs shall be pre-tested to a pressure equal to or greater than the original pipeline strength test pressure. 8. bends.4 be taken to clear pockets of water from valves and fittings. care shall be taken to properly dispose the discharging water in order to avoid pollution. the pipeline shall be completely filled with water with sufficient quantities of corrosion inhibitors depending upon the quality of water and the period of preservation and at a suitable pressure.per B31.4 Acceptance of Test The test is successful when the pipeline has withstood the strength and leak tests and during the test period there is no observable drop in pressure that cannot be accounted for by temperature changes. b) All joints. type of welding and electrode.0 OPERATION AND MAINTENANCE PROCEDURES All provisions of B 31. 4 (D-t) t ------------e(D-2t)-1. A = 2R = 1. they shall be properly rated for temperature.1425 ASTM A 135 B 0.0900 ---------------------------------------------------b) Procedure The mandrel is to be plugged into the specimen. pressure.1175 API 5L X.1100 API 5L X.1325 API 5L X-52 0.1025 API 5L X. D . and radius of APPENDIX .4 .4t -t 10. . electrical properties.80 0. with the weld in contact with mandrel.70 0.Strain Minimum values of 'e' shall be as follows: ---------------------------------------------------Grade of Steel Min 'e' value ---------------------------------------------------ASTM A53 B 0.Peaking factor e .10.1425 API 5L B 0. stray current interference from foreign objects at HT pipeline crossings.56 0.1425 API 5L X-42 0. a) Selection of Mandrel The reverse bend test shall be carried out with a mandrel.1 Reverse Bend Tests Reverse bend tests shall be performed on the pipe piece cut from the crop end from the front end of the first length and the back end of the last length produced from each coil.1. B1).60 0. whose radius(R). The temporary CP system shall preferably be installed simultaneously keeping pace with the pipeline laying / installation work and shall be monitored periodically.1125 API 5L X.4 TEMPORARY CATHODIC PROTECTION SYSTEM When considered necessary a temporary cathodic protection system with sacrificial anodes shall be installed to ensure adequate protection of pipeline from external corrosion from the time the pipeline is laid in the trench till the permanent cathodic protection system is commissioned. to such a depth that the angle of engagement between mandrel and specimen reaches 600 (see Fig.1375 API 5L X-46 0. If the combination of diameter and wall thickness of pipe.A ADDITIONAL REQUIREMENTS FOR ELECTRIC RESISTANCE/ELECTRIC INDUCTION WELDED LINE PIPE B.5 Safety appliances shall be provided against lightning. and shall be resistant to the commodity carried in the pipeline systems. 10. wall thickness and grade with the formula.3 ELECTRICAL ISOLATION Whereas such insulating devices are installed. where.1275 API 5L X. width(A) shall be calculated for any combination of diameter. The specimen shall be 100mm to 115mm long and shall be reverse bend tested in accordance with procedure given below and Figure B.65 0.Outside diameter of pipe t .Wall thickness of pipe 1. 2 Micrographic and Hardness Examination A test specimen shall be taken across the longitudinal weld from one length of finished pipe from each lot of maximum 50 lengths from the same heat manufactured from the same process.2 in accordance with ASTM E-32. B. c) Acceptance Criteria A specimen which fractures completely prior to the specified engagement of mandrel and specimen. . shall be rejected. B. The Manufacturer shall make hardness measurements on each specimen as indicated in Fig.mandrel is such that the angle of engagement does not reach 600. or which reveals cracks and ruptures in the weld or heat affected zone longer than 4mm. The examinations shall provide evidence that heat treatment of weld zone is adequate and there is no untempered martensite left. Cracks less than 6mm long at the edges of the specimen shall not be cause for rejection. the mandrel shall be plugged into the specimen until opposite walls of the specimen meet. The maximum difference in hardness between base material and any reading taken in the heat affected zone shall be less than 80 points Vicker's HV10. These specimens shall be polished and etched for micro-examinations. 13. the effect of the time-temperature relationship on the mechanical properties of the pipe shall be determined and taken into consideration.3. proven notch toughness properties are not mandatory.3.2.0 DESIGN Design of cross country pipelines – onshore shall be as per ANSI/ASME B31. TEMPERATURE AND NOTCH TOUGHNESS REQUIREMENTS 13.PART-II GAS TRANSPORTATION SYSTEMS 11.1 Carbon Equivalent Carbon Equivalent shall be calculated based on the formula given below: CE = C + Mn + Cr+Mo+V + Ni+Cu 6 5 15 Carbon Steels having a specified carbon content in excess of 0.C (250 deg.2 13.0 12.2 For steel pipes and associated steel components of size 2" NPS and larger. All cross country pipelines shall be piggable. The pressure hold period should be 15 sec.3.3. having due regard to past recorded temperature data and the minimum gas temperature that may occur.2 12. Pipe diameter 4” and above shall be used for cross country pipelines. 13.2 If steel pipe is intended to be heated during fabrication and/or installation.4 Mill Hydrostatic Testing of line pipe is recommended as 90% of SMYS irrespective of grade of pipe material.1 PIPING SYSTEMS The Pipe wall thickness less than 6.3 13. 13. 13. having due regard to past recorded temperature data and the possibilities of higher temperatures occurring. particular attention shall be given to the tensile properties of the material to ensure that the derating for temperature is adequate.2. 13. 12.1 For steel pipes smaller than 2" NPS and steel valves. 13. b) The maximum design temperature shall be taken as the highest expected operating pipe or metal temperature. Notch toughness valves (minimum absorbed energy valves) shall be specified based on the design operating stress and the minimum design temperature.3 MATERIAL SPECIFICATIONS 12.4 mm should not be used for cross country pipelines in the city limits.0 13. fittings and flanges smaller than 2" NPS.3 The minimum and maximum design temperatures shall be determined as follows: a) The minimum design .65% shall be preheated.8. Part-I of this standard for steel pipes manufactured by Electric Resistance Welding and/or Electric Induction Welding. Notch toughness values shall be determined to provide protection against fracture initiation and propagation. OPERATING CONDITIONS. API-1104 shall be referred for guidance. 13. The minimum design temperature shall take into account the effect of lower air or ground temperatures in the area.1 MATERIALS AND EQUIPMENT When the maximum design temperature exceeds 120 deg. F).32% or a carbon equivalent in excess of 0.2. temperature shall be taken as the lowest expected operating pipe or metal temperature when the hoop stress exceeds 50 MPa (7000 psi).3 Additional test requirements shall be specified as per Standards / Guidelines mentioned in Appendix-A. 13.4.2 EXPANSION AND FLEXIBILITY 15.2.1 14.0 PIPING SYSTEM COMPONENTS AND FABRICATION DETAILS VALVES AND REDUCING DEVICES PRESSURE Valves made of cast iron or ductile iron shall not be used in gas piping systems.8 and this standard. The acceptance 15. API-1104 shall be referred for guidance. whereas buried pipelines adjacent to bends or unanchored end caps could be regarded as restrained or .2 General a) In addition to the applicable requirements of B 31. such as CO2 and Salts in water. 13.1 This section is applicable to both above ground and buried piping and covers all classes of materials permitted by this standard.32% or a carbon equivalent in excess of 0. flanges. c) All materials used in sour gas service shall conform to the material requirements of NACE standard MR01-75. Note: While the limiting conditions defined in NACE standard MR-01-75 for considering gaseous hydrocarbons as sour is the normally accepted minimum concentration of hydrogen sulphide at which material problems occur. move laterally. shall be calculated based on the following formula: CE = C + Mn + Cr+Mo+V + Ni+Cu 6 5 15 Carbon Steels having a specified carbon content in excess of 0. "Sulphide Stress Corrosion Cracking Resistant Metallic Material for Oil Field Equipment".4. the presence of other constituents in the gas stream. e) Cast iron line pipe shall not be used to convey sour gas. Note : For the purpose of this standard. 15.1 Definition NACE standard MR-01-75 "Sulphide Stress Corrosion Cracking Resistant Metallic Material for Oil Field Equipment" defines specific conditions. Depending upon the service and the materials involved. may cause problems at lower concentrations of hydrogen sulphide. long straight lengths of buried pipe and above ground pipe on closely spaced rigid supports are classified as restrained. b) Pipe.0 of this standard. 'unrestrained' means that the pipe is able to strain along its length. d) Pressure containing components (excluding pipes) intended for sour gas service shall be fully identified with a permanent marking. bolting and other equipment exposed to or which are necessary to contain sour gas may be susceptible to Sulphide Stress corrosion cracking and hydrogen induced step-wise cracking and thus due consideration shall be given to material selection in design. Formal calculations shall be required where reasonable doubt exists as to the adequate flexibility of the piping. the Sulphide Stress Corrosion Cracking (SSCC) and Hydrogen Induced Cracking (HIC) tests should be conducted as per NACE standards mentioned in Clause 20.3. or both. all materials used in sour gas service shall also meet the following requirements. Ultrasonic testing for pipe ends is mandatory.65% shall be preheated. 13.5 Ultrasonic testing for pipe skelp and weld seam is 100%.0 WELDING Carbon equivalent (CE) wherever referred in this chapter. valves. fittings. 13. which a gaseous hydrocarbon shall be considered to be sour. 15. Typically.4 REQUIREMENTS FOR SOUR GAS SERVICE criteria shall be based on current established industry practices. Pipe that does not meet both of the above requirements is referred to as 'restrained'. it may be necessary to calculate the longitudinal.2 EXPANSION AND FLEXIBILITY a) Expansion calculations are necessary for buried lines if significant temperature changes are expected. or bellows type. anchors or ties of sufficient strength and rigidity shall be installed to provide for end forces due to fluid pressure and other causes.3. depending on specific circumstances. (e) Static wind loads and static fluid loads. The pipeline cover will be decided considering the above factor. Unless such movements are restrained by suitable anchors. 15. the torsional stresses. Consideration shall also be given to. Thermal expansion of buried lines may cause movement at points where the line terminates. and bending stresses. axial. different limits on allowable longitudinal expansion (b) Thermal contraction. 15.2(i) above. loops. 15. support (d) Self-weight and gravity dead loads. Buoyancy. where applicable. b) Means of providing Flexibility If expansion is not absorbed by direct axial compression of the pipe. (d) Dynamic and seismic loads: Seismic load consideration for earthquake prone areas should be taken after proper seismic survey to determine liquefaction factor of soil.2. to the service conditions to which the pipe and support system are to be subjected. wave loadings and all significant fluid loads to which a submerged line might be submitted). If expansion joints are used. In calculating these stresses and reactions and the effects of various loadings on the piping the designer shall use established fundamental analysis methods. but not necessarily limited to the effects of the following additional loadings: (a) (b) (c) Overburden loads. ball joint. changes in direction. the necessary flexibility shall be provided. loss of support. the stress interactions and the reactions at significant points in the system.8. 15. (e) Cyclic and vibratory loads including the effect of Stress Intensification. the hoop stresses. Therefore. (f) Internal pressure fluctuations. and thermal effect of the pipeline on soil properties).unrestrained.3.3 COMBINED STRESS CALCULATIONS (c) Differential movements. ii) In addition to the requirements of Clause 15.3 Stress Values i) Consideration shall be given to the stresses and reactions caused by. consideration shall be given. or changes in size. (h) Geotechnical loads (including slides.2 Loading Considerations (g) External hydrostatic pressure (including collapse.3. or offsets or provision shall be made to absorb thermal strains by expansion joints or couplings of the slip joint.3. . but not necessarily limited to the following loadings:(a) Internal pressure. Live loads. Factors on the fatigue life of components. 15.1 General In addition to satisfying the requirements of clause 841 of B 31. flexibility shall be provided by the use of bends. differential settlement. expansion and a) General There are fundamental differences in loading conditions for the buried. or similarly restrained positions of the piping and the above ground portions not subject to substantial axial restraint. psi (MPa) T1 = Temperature at time installation degrees F(degrees C) T2 = Maximum or operating temperature F(degrees C) of SE = Sq. Sb = Sq. (N. The sum of the longitudinal stresses . Root of{( i1 M1)2 + ( i0 M0)2}/Z =equivalent bending stress.m) Mt = torsional moment. psi (MPa) a = Linear coefficient of thermal expansion. SE. with modulus of elasticity for the cold condition. c) Unrestrained Lines Stresses due to expansion for those portions on the piping without substantial axial restrain shall be combined in accordance with the following equation: The maximum computed expansion stress range. such as elbows or tees. longitudinal pressure c) the longitudinal bending stress due to external loads. inch per inch per degree F (mm per mm per degree C) v = Poisson's ratio = 0. based on 100 per cent of the expansion. or transverse. calculated for nominal pipe wall thickness. for the latter the moments in the header and branch portions are to be considered separately) in. psi(MPa) M1 = Bending moment in plane of member (for members having significant orientation. b) Restrained Lines The net longitudinal compressive stress due to the combined effects of temperature rise and fluid pressure shall be computed from the equation: SL = Ea (T2-T1) . The total of the following shall not exceed the specified minimum yield strength. minimum degrees E = Modulus of Elasticity of steel. Beam bending stresses shall be included in the longitudinal stress for those portions of the restrained line which are supposed above ground. SE without regard for fluid pressure stress.8 Appendix E) io = stress intensification factor under belonging out of.lb. This equivalent tensile stress shall not be allowed to exceed 90 per cent of the specified minimum yield strength of the pipe. (N.30 for steel Note that the net longitudinal stress becomes compressive for moderate increases of T2 and that according to the commonly used maximum shear theory of failure. or transverse to.m) ii = stress intensification factor under bending in plane of member (B 31. Root of (Sb2 + St2 ) Where. this compressive stress adds directly to the hoop stress to increase the equivalent tensile stress available to cause yielding. wind etc.m) M0 = bending moment out of. SE = Stress due to expansion. shall not exceed 0.stresses are necessary.v Sh in which.to plane of member. plane of member (B 31. in lb. in lb. S.8 Appendix E) Z = Section modulus inch 3(mm3) of pipe. psi (MPa) St = Mt/2Z = torsional stress. such as weight of pipe and contents. psi(MPa) Sh = Hoop stress due to internal fluid pressure. b) the stress.72 times the specified minimum yield strength of the pipe. SL = The longitudinal compressive stress. (N. a) the combined stress due to expansion. It is not necessary to consider wind and earthquake as occurring concurrently. and laying.due to pressure. e) Field bending. c) Backfilling. 16. but not restricted to. shall not exceed 80 per cent of the specified minimum yield strength of the pipe. distribution Onshore or offshore pipeline. such as wind or earthquake.75 time the allowable stress in the hot condition.5.1 DESIGN. It is not necessary to consider other occasional loads. coating and wrapping. together with the environment in which the pipeline is to be installed.1 In laying parallel pipelines in the same trench. INSTALLATION AND TESTING GENERAL PROVISIONS The selection of design for pipeline system shall be based on the following evaluation of the properties and required flow rate of the fluid to be transported.4 SUPPORTS AND ANCHORAGE FOR EXPOSED PIPING Attachment of supports on Anchors Due consideration shall be given to the effect of such attachments on possible fatigue failures and local stress concentrations. such as wind and earthquake. f) hydrostatic test pressure loads (particularly when the pipeline is 16.0 16.3 CORROSION ALLOWANCE Whenever internal or external corrosion is expected during the design life of the pipeline. live and dead loads. 7.4 COVER REQUIREMENTS PIPELINES Refer Table requirements.5 PRE-OPERATIONAL STRESSES It is desirable to limit stresses during pre-operational manipulation of the pipe so as to avoid damage that might impair the operability of the line. b) Stringing. 15. The designer shall ensure that preoperational stresses are controlled and that they are non-injurious to the pipe.2 system. pressures and c) Gathering transmission system. system.3. single or multiphase flow conditions. dead and test loads existing at the time of test. a) Sweet or sour natural gas. Consideration shall be given to. d) 16. or service lines. 15.5 constructed as an above grade installation or is buried in unstable soils). weight. . the effect of the following pre-operational loads: a) Transportation and stockpiling of the pipe. The sum of the longitudinal stresses produced by pressure. 16.3 for FOR cover CLEARANCE BETWEEN PIPELINES OR MAINS AND OTHER UNDERGROUND STRUCTURES 16. the minimum clear distances between the pipelines shall be 500 mm. 16. d) Loads imparted by construction traffic. b) Operating temperatures. and other sustained external loadings shall not exceed 0. Stresses due to test conditions are not subject to the above limitations. as occurring concurrently with the live. and those produced by occasional loads. a suitable corrosion allowance shall be made at the design stage. POPULATION DENSITY INDEX A Class 4 location ends 220 metre from the nearest building with 4 or more stories above ground. vapour phase LPG. and Stringing Pipe shall not be strung on the Rightof-Way in rocky areas where blasting may be required. Highways.4 of this standard. Roads or Streets shall be done in accordance with the provisions of "Recommended Practice for Liquid Petroleum Pipelines Crossing Railroads and Highways" API RP 1102 and applicable clauses of B31.6 CASING. 16. or any industrial building or a place of public assembly in which persons work. The length of the straight section shall permit easy jointing. 16. 16. 16. congregate or assemble. This distance may be reduced after a careful assessment of construction methodologies. REQUIREMENTS UNDER RAILROADS.8. No pipeline should be located within 15. unless it is provided with atleast 300 mm of cover in addition to that provided in clause 16. which do not result in unsafe conditions during construction. ROADS. until all blasting is complete and the area cleared of all debris. HIGHWAYS. In any case the minimum clear distance shall not be less than 3. Hauling. BENDS. 16.4 Field-cut segments of elbows NPS 12" and larger are not recommended.8.0 meter.0 metre of any private dwelling. a complete check of the pipe 16. when running parallel to an existing underground pipeline should be at a minimum clear distance of 5. particular attention shall be paid to the suitability of the trench to allow the pipeline to be lowered without the coating being damaged and to give a reasonably even support to the pipeline.1 The ends of each bent length shall be straight and not involved anyway in the bending. economic or topographical reasons.16.9.8. Material other than line pipe shall not be strung on the Right-of-way but shall be transported to site for use only at the time of installation. When already coated pipes are being lowered. unless construction above ground is found to be desirable for exceptional technical. Before lowering operations are commenced.9 MISCELLANEOUS OPERATIONS INVOLVED IN THE INSTALLATION OF STEEL PIPELINES AND MAINS 16. 16.8.2 Pipes with longitudinal welds shall be bent in such a way lies in the plane passing through neutral axis of the bend which shall be installed positioning the longitudinal weld in the upper quadrants.5. These areas shall be distinctly identified on ground during construction.7 Design and construction of gas pipelines crossing Railroads. 16.0 metre from the existing underground pipeline when heavy conventional construction equipment is expected to be utilized.2 The location of a new underground pipeline. ELBOWS AND MITERS IN STEEL PIPELINES AND MAINS The minimum radius of field cold bends shall be as follows: _______________________________ Normal Pipe Minimum Radius of Size (in) Bending in Pipe Diameters _______________________________ NPS 12 and smaller 21 D NPS 14 u/i 18 30 D NPS 20 and larger 40 D _______________________________ 16.8 .9.2 Installation of Pipe in the Ditch Pipelines shall be buried below ground level. A field bend shall not be made within two pipe diameters of a field weld.2 metre away (vertically) from aerial electrical wires and shall be suitably insulated from underground conduits carrying electric wires on railway land.3 A mitered bend is not permitted with the exception of deflections upto 3 degrees that are caused by misalignment.8 and this standard.1 Handling. Tangent lengths should not be reduced in the field. Tangents approximately 1 metre in length shall be provided on both ends of cold bends. casing pipe and vent pipes shall be at least 1. OR STREETS Pipeline. Whenever considered desirable. where it is not practicable to obtain the above mentioned clearance. Care must be taken that the deformation caused during the raising of the pipe from the supports does not exceed the valves for the minimum allowable radius of elastic curvature. However. (c) To ensure the stability of the underwater pipeline. the complete pipeline corresponding to river crossing shall be tested after installation. Where these clearances cannot be maintained. the following requirements are to be considered: (a) Hydrological and geotechnical surveys to establish the river bed and water current profiles. before installation. maintain a vertical clearance of at least 300mm. 16. the trench shall be rectified or in exceptional cases a new assembly shall be carried out so that it fits the excavation and the laying bed. special design and construction shall be used. large erodable flood plain and wide water course (high water mark to high water mark) both during the design and installation of such crossings: For river crossings such as those described and established as above. potentially scouring bed. The width of trench shall be such that a minimum clear distance of 200mm for trench in normal soil and 300mm for trench in rock is maintained between edge of pipe and the trench wall at the bottom of trench. A heavier wall thickness pipe shall be provided for a river crossing section.11. provided that.10 WATER CROSSINGS Special considerations shall be required for submerged crossing by pipelines of rivers which are characterized by their perennial nature. other systems through the application of Cathodic Protection shall be dealt with by mutual action of the parties involved. to predict the behaviour of the river with respect to change of course. The pipeline at such crossings shall be installed with extra depth of cover. conductors. underground pipes shall. it may be necessary to add weight to sink and hold the pipeline in position.2 A clearance sufficiently large to avoid electrical fault current interference shall be maintained between the pipeline and the grounding facilities of electrical transmission lines.11.3 Interference with. so as to keep the stresses on the steel pipe and on the coating within safe limits.8 and this standard. or from. steep and potentially erodable banks. extra precaution shall be taken to ensure the maximum possible clearance and to prevent future (b) .11 16.coating and field joint coating shall be carried out and all damages repaired. The cover provided shall be adequate to prevent exposure of the pipeline for the entire design life of the pipeline. A detailed stress analysis for the pipe section for river crossings should be necessary taking into consideration the effect of all loads during laying and it shall be ensured that the stresses remain within permissible limits in accordance with B 31.11. meandering course. incorrect positioning of bends. scour of bed and erosion of banks and to obtain all other parameters related to design and installation of such crossings. 16. Wherever pipeline is laid under tension as a result of an assembly error (for example. either horizontal or vertical). the section of the pipeline corresponding to the river crossing should. CROSSING OF / OR BY UTILITIES (d) (e) (f) 16.1 A minimum clearance of 300mm shall be maintained at the point of crossing and the utility or pipeline shall be installed at a uniform depth for the full width of the right-of-way.11. 16. or conduit.4 When laid parallel to along or near underground power and/or communication cables. 16. be subjected to hydrostatic pretesting. except as provided for in (b) below. d) Where testing of offshore platform gas piping and pipe riser cannot be accomplished separately from the main offshore pipeline.25 times the maximum operating pressure. gas or water to at least 1. the above clearance shall be maintained with the pipeline preferably at a lower level. the guaging plate having a diameter of 95% of the internal diameter of the pipeline. All sections. stream.4 times the maximum operating pressure. which have been previously hydrostatically tested viz. the piping components shall be pretested to atleast 1. A guaging pig shall be passed through the pipeline to prove the internal diameter of the entire line.12. but in no case less than 45 deg. b) Pipelines and mains located in class 1 and class 2 location shall be tested with air. road/rail crossings and river crossings. The test pressure for above ground piping and .contact.1 General Provisions a) All Pipelines. during which time the piping shall be inspected for leaks. Sour gas shall not be used as a test medium. b) Tie-ins For pipelines intended to operate at hoop stresses of 30% or more of the specified minimum yield strength pretested pipe shall be used in tie-in sections and for those sections where in-place testing is not practicable. the test pressure shall be maintained for a period of 24 hours after temperature stabilization and stabilization of surges from pressurizing operations. 16.2Test Required to Prove Strength of Pipelines and Mains to Operate at Hoop Stresses of 30% or More of the Specified Minimum Yield Strength of the Pipe: a) All test assemblies used in testing shall be fabricated and installed in accordance with provisions of B 31.e. If pipelines and communication and/or power utilities share the same trench. shall be retested along with the completed mainline sections.11 6 All crossings shall be made in such a manner that the angle between the centreline of the railway.12. i. ground cables and counter poise. 16.0 metre should be maintained between pipeline and transmission tower footings. the test pressure shall not exceed 1. canal or utility being crossed and the centreline of the pipeline shall be as close as possible to 90 deg. shall be by means of water rather than a gaseous medium. and service lines shall be tested in place after construction. 16. Where a gaseous medium is used. regulator station and measuring station gas piping.5 A minimum separation of 3. shall be used.8 and all such piping is retested with the main offshore pipeline to class 1 location test requirements.11.25 times the maximum operating pressure.12 TESTING AFTER CONSTRUCTION offshore platform piping shall be maintained for a minimum period of 4 hours. inhibited water. Regardless of separation consideration should always be given to lightning fault current protection of pipelines and safety of personnel. For all buried and submerged piping. mains.8 covering permanent assemblies and fabrications. highway.5) shall be tested to atleast class 3 location test requirements. wherever practicable. provided that all final welds are inspected in accordance with the provisions of B 31. c) Compressor station. 16. water to which suitable doses of corrosion inhibitors are added depending upon quality of water. including the piping connecting the station to valving employed for isolating the station from the pipeline and designed in accordance with Type-C construction (Design factor = 0. When water is used as the test medium. Testing. river. e) Test Requirements for Pipelines and Mains to Operate at Hoop 16. g) Records The operating company shall maintain in its file for the useful life of each pipeline and main.5 of this standard do not apply. Test pressure at lowest elevation. Test duration. if ix. if applicable. Minimum. a corresponding reduction in prescribed test pressure may be made as indicated in the pressure Test Prescribed. vii. viii.25 times the maximum operating pressure shall be made and the limitations on operating pressure imposed by Table 16. vi. Pressure and temperature recording charts. ii. However.12. Elevation profile and the location of the test section and testing points.2. If an operating company decides that the maximum operating pressure will be less than the design pressure. Pipe Specifications of sections under test. iii. if applicable. Location of leaks or failures and description of repair action taken. column. records showing the procedures used and the data developed in establishing its maximum allowable operating pressure. the Maximum operating pressure cannot later be raised to design pressure without retesting the line to the test pressure prescribed in the Pressure Test Prescribed. Time and data of Test. f) In such cases an air test to 1. chart. iv.Stresses of 30% or More of the Specified Minimum Yield Strength of the Pipe GENERAL NOTES: mop = Maximum operating pressure (not necessarily the maximum allowable operating pressure) dp = design pressure tp = test pressure This table brings out the relationship between test pressures and maximum allowable operating pressures subsequent to the test. if this reduced test pressure is used. Pressure-Volume applicable. Testing medium used. The record shall contain at least the following information: i. v. h) Acceptance of Test The test is successful when the . 8 Chapter V and OISDSTD-138 shall apply. b) Where insulating devices are installed to provide electrical isolation of pipeline systems to facilitate the application of corrosion control. 16.0 18.3 Termination of Testing The pipeline shall be slowly depressurized at a moderate and constant rate. 16. During dewatering.5 of this standard shall be adhered to. and flanges and other fittings installed in the project. bends. sectionalizing block valves equipped with automatic closing devices should be provided for sour gas pipelines in order to minimize the volume of hydrogen sulphide that could be released in the event of a pipeline failure.15 PIPE BOOK A pipe and welding book shall be maintained for all projects. non-toxic gas and at a suitable pressure. 16.12. c) Be ductile to resist cracking. they shall be properly rated for .2. 16. damages to fields under cultivation and/or existing structures and interference with the traffic. 18. 16. or with a non-flammable.14 VALVES Notwithstanding the foregoing provisions of this clause. and during the test period there is no observable drop in pressure that cannot be accounted for by temperature changes. weld treatment and the details of used equipment for radiography shall be recorded in the pipe book. 16. 17. Each item shall be recorded by its identification number. type of welding and electrode.5 Preservation of Pipeline If the pipeline is to be preserved for a specified duration before it can be commissioned. care shall be taken to properly dispose the discharging water in order to avoid pollution. e) Be compatible with cathodic protection system. d) Have a strength or otherwise be protected to resist damage due to normal handling (including concrete coating application.0 OPERATING AND MAINTENANCE PROCEDURES All provisions of B 31.12. 18. where applicable) and soil stress. or river weight installation. the pipeline shall be completely filled with water with sufficient quantities of corrosion inhibitors. scraper traps.12.4 Pre-tested Pipe Pipe used for making repairs shall be pre-tested to a pressure equal to or greater than the original pipeline strength test pressure.pipeline has withstood the strength test.1 CORROSION CONTROL COATING REQUIREMENTS Coatings shall: a) Electrically isolate the external surface of the pipeline system from the environment. The purpose of the pipe book shall be to indicate and maintain as a permanent record the exact position in the pipeline of each pipe length and each pipeline material like valves.13 CONTROL AND LIMITING OF GAS PRESSURE Maximum Allowable Operating Pressure for Steel or Plastic Pipelines or Mains Consistent with Table 16.2 ELECTRICAL ISOLATION a) This clause shall not take precedence over recognized electrical safety practices and codes. welder number. depending upon the quality of water and the period of preservation. Location of each weld including weld number.12. b) Have sufficient adhesion to effectively resist underfilm migration of moisture. generating stations or other facilities that have high short circuit current-carrying grounding networks. Attaching test leads directly to the pipe by other methods of brazing is prohibited. d) Provision shall be made to prevent harmful galvanic action at below-grade or submerged connections between copper and steel piping.3. Consideration should be given to: i) Installing an insulated coupling or insulating gasket set between the copper and steel.4 ELECTRICAL INTERFERENCE 18.2 The following paragraph is added: When a thermit welding process is used for electrical lead installation on pressurized pipelines. or when personnel are in contact with the pipelines.4 of this standard) c) Pipeline system shall be installed so that the belowgrade or submerged portions are not in electrical contact with any casing.3. 18. precautions shall be taken to avoid possible failure of the pipeline during installation due to loss of material strength at the elevated welding temperatures. 18. or ii) Protecting the piping with an insulating coating material to provide a spatial separation of not less than 0. stray current interference from foreign objects at HT pipeline crossings.4.3 Safety Requirements .1 Fault Current Interference Fault current interference shall be taken into consideration. c) Safety appliances shall be provided against lightning.temperature.1 Where a higher current carrying capacity is required. foreign piping systems or other metallic structures. (Refer Clause 18.1 above. NOTES: a) Fault current resulting from lighting or upset conditions of electrical facilities could result in serious damage to coating and pipe wall and danger to personnel. Each group shall be attached to pipe with a separate charge.5m between bare copper and steel. and shall be resistant to the commodities carried in the pipeline systems. 18. pressure.4. remedial measures may be necessary to control the effect of these fault currents in order to reduce the resultant rise in potential gradient in the earth near the pipeline system to an acceptable level.4. a) When studies or tests show that alternating current potentials will be or are being induced on a buried pipeline system. and electrical properties. b) Where a buried pipeline system is close to grounding facilities. Consideration shall be given to other methods of Pipelines paralleling alternating current electrical transmission lines are subject to induced potentials as well as the effects mentioned in Notes to Clause 18. These devices shall not be installed in enclosed areas where combustible atmospheres are likely to be present unless precautions are taken to prevent arcing.3 ELECTRICAL CONNECTIONS AND MONITORING POINTS installation. 18. Where a thermit welding process is not deemed suitable. b) When such pipelines are under construction.6 AWG. 18.4.2 Induced Potential Interference 18. These adverse effects may occur where a pipeline is close to the grounding facilities of electrical transmission line structures. sub-stations. This shall not preclude the use of electrical bonds where necessary. devices shall be installed to reduce these potentials to a tolerable level. a multistrand conductor shall be used and the strands shall be arranged into groups no larger than No. special precautions shall be taken to nullify the possible effects of induced alternating current potentials. 7.5 EXISTING INSTALLATIONS INTERNAL CORROSION CONTROL 18.7. unless tests or experience indicate otherwise.7. 18.6 TEMPORARY CATHODIC PROTECTION SYSTEM When considered necessary. 18. Corrosion Protection Tapes and Heat Shrinkable Sleeves.2 Existing Bare Pipeline Systems Investigations shall be made to determine the extent or effect of corrosion on existing bare pipeline systems.8 Chapter VII shall apply.7 a) Employ blowdown connections that will direct the gas away from the electric conductors. 18. unless tests or experience indicate otherwise.2 Any gas whose water dew point exceeds the minimum pipeline operating temperature is considered to be corrosive.shall be monitored periodically.1 Existing Coated Pipeline Systems Cathodic Protection shall be applied and maintained on all existing coated pipeline systems.0 MISCELLANEOUS All provisions of B 31.5. 18. 18. corrosion. 20.5. unless tests or experience indicate otherwise. 30672 AWWA C203-86 Standard for Coal-Tar Protective Coatings and Linings for Steel Water Pipelines-Enamel and Tap-Hot Applied. corrosion control measures or other remedial action shall be undertaken.7. 18. c) Make a study in collaboration with the electric company on the common problems of personnel safety. b) Install bonding across points where the pipeline is to be separated and maintain this connection while the pipeline is separated.Coatings made from Corrosion Protection Tapes and Heat Shrinkable Sleeves for Underground Pipelines. is considered to be non-corrosive.3 Any gas containing hydrogen sulphide or carbon dioxide whose water dew point exceeds the minimum pipeline operating temperature is considered to be corrosive. electrical interference and lighting problems. unless tests or experience indicate otherwise. a temporary Cathodic Protection system with sacrificial anodes shall be installed to ensure adequate protection of pipeline from external corrosion from the time the pipeline is laid in the trench till the permanent Cathodic Protection system is commissioned. Where these investigations indicate that continuing corrosion will create a hazard.3 Cathodically Protected Pipeline Systems Temporarily out of Service Cathodic Protection systems shall be maintained on any pipeline system temporarily out of service. or is suitably inhibited.1 Any gas whose water dew point is at all times below the minimum pipeline operating temperature is considered to be non-corrosive.4 Any gas containing hydrogen sulphide or carbon dioxide whose water dew point is maintained below the minimum pipeline operating temperature by dehydration.0 REFERENCES DIN 30670 Polyethylene Sheathing of Steel Tubes and of Steel Shapes and Fittings. BSI BS 4146 Specifications for Coal-Tar Based Hot . 18.5. 18. The temporary cathodic protection system shall preferably be installed simultaneously keeping pace with the pipeline laying/installation work and 19. Following precautions shall be taken: 18. Colorado 80235 . MR-01-75 Sulphide Stress Corrosion Cracking (SSCC) Resistant Metallic Material for Oil Field Equipment Name and address of the AWWA American Water Works Association 6666 West Quincy Avenue.1987 Applied Coating Materials for protecting iron and Steel. DIN: Deutsches Institute for Normung Obtainable from: Foreign Standards Distribution Beuth Verlag GmbH Burggrafen Strasse 4-10 D-1000 BERLIN 30 British Standards Institution 2. organisation whose standards and specifications appear above. Park Street. London : WIA 2BS Telephone : 01-6299000 Telex : 266933 NACE TM-01-77 Testing of Metals for Resistance to Sulphide Stress Cracking at Ambient Temperatures. BSI TM-02-84 Testing of Metals for Resistance to Stepwise Cracking. including suitable Primers where required. Denver.