NES 862 Part 1 Fasteners

Ministry of DefenceDefence Standard 02-862 (NES 862) Issue 1 Publication Date 01 April 2000 Fasteners Part 1 General Incorporating NES 862 Category 2 Issue 1 Publication Date March 1994 AMENDMENT RECORD Amd No Date Text Affected REVISION NOTE This standard is raised to Issue 1 to update its content. HISTORICAL RECORD This standard supersedes the following: Naval Engineering Standard (NES) 862 Part 1 Issue 1 dated March 1994. Signature and Date Ministry of Defence Naval Engineering Standard NES 862 Part 1 Issue 1 (Reformatted) FASTENERS PART 1 GENERAL March 1994 This NES Supersedes NES 730 PART 1 ISSUE 1 Record of Amendments AMDT 1 2 3 4 5 6 7 8 9 10 INSERTED BY DATE . Foxhill. Bath BA1 5AB i .NAVAL ENGINEERING STANDARD 862 FASTENERS PART 1 ISSUE 1 (REFORMATTED) GENERAL The issue and use of this Standard is authorized for use in MOD contracts by MOD(PE) Sea Systems and the Naval Support Command ECROWN COPYRIGHT Published by: Director of Naval Architecture Procurement Executive. Ministry of Defence Sea Systems. ii . iii .NES 862 Part 1 Issue 1 (Reformatted) SCOPE 1. This NES specifies the general requirements for threaded fasteners used on HM ships and submarines. It also specifies the standards which define the detailed requirements of particular types of fasteners. NES 862 Part 1 Issue 1 (Reformatted) iv . directly applicable to a particular contract are to be dealt with as specified in the contract. This NES comprises: Fasteners Part 1 General Part 2 Ferrous Part 3 Non-Ferrous Part 4 Ferrous (Submarine First Level Quality Assured) 3. has been compiled from the rationalized and updated information contained in the eleven Parts of NES 730 and thereby supersedes it. 2. approved. reference in this NES to approval. No alteration may be made to this NES except by the issue of an authorized amendment. in four Parts. 4. 11. Proposals for amendments which are: a. Section NA 115. means by the Ministry of Defence in writing. 9. not directly applicable to a particular contract are to be made to the Sponsor of the NES. If it is found to be unsuitable for any particular requirement the Sponsor is to be informed in writing with a copy to Director Naval Architecture (DNA) NA 145. Unless otherwise stated. This Naval Engineering Standard (NES) is sponsored by the Procurement Executive. This document is Crown Copyright and the information herein may be subject to Crown or third party rights. authorized or similar terms.NES 862 Part 1 Issue 1 (Reformatted) FOREWORD Sponsorship 1. Deletions will be indicated by 000 appearing at the end of the line intervals. Extracts from British Standards quoted in this NES are included with the permission of the British Standards Institution. Conditions of Release General 10. b. v . It is not to be released. 12. Director Naval Architecture. 5. (DNA). its servants or agents) for any loss or damage however caused where the NES is used for any other purpose. negligence on the part of the Crown. The Crown hereby excludes all liability (other than liability for death or personal injury) whatsoever and howsoever arising (including but without limitation. Any significant amendments that may be made to this NES at a later date will be indicated by a vertical side line. Ministry of Defence. This Naval Engineering Standard (NES) has been prepared for the use of the Crown and of its contractors in the execution of contracts for the Crown. 8. reproduced or published without written permission of the MOD. 7. The Crown reserves the right to amend or modify the contents of this NES without consulting or informing any holder. 6. NES 862. Any user of this NES either within MOD or in industry may propose an amendment to it. British Standards British Standards Institution. It refers only to technical suitability and in no way absolves either the supplier or the user from statutory obligations relating to health and safety at any stage of manufacture or use. Llanelli. When NES are incorporated into MOD contracts. 15. standards and drawings. Dyfed SA14 8YP d. Defence Standards Directorate of Standardization and Safety Policy.3. Note: Tender or Contract Sponsor can advise in cases of difficulty. Other documents Tender or Contract Sponsor to advise. vi . substances and/or procedures that may be injurious to health if adequate precautions are not taken. Enquiries in this connection may be made of the local MOD(PE) Quality Assurance Representative or the Authority named in the tender or contract. 65 Brown Street. Prime Contractors are responsible for supplying their subcontractors with relevant documentation. including specifications. London W4 4AL b. those quoted may not necessarily be exhaustive. Compliance with an NES does not of itself confer immunity from legal obligations. including related documents. Kentigern House. Naval Engineering Standards CSE3a. In the tender and procurement processes the related documents listed in each section and Annex A can be obtained as follows: a. or submission of the tender. users are responsible for their correct application and for complying with contracts and any other statutory requirements. Health and Safety Warning 19. Cadmium Plating 20. 14. relevant to each particular tender or contract. This NES may call for the use of processes. CSE Llangennech. All applications to Ministry Establishments for related documents are to quote the relevant MOD Invitation to Tender or Contract Number and date.6c. in connection with which it is issued. Glasgow G2 8EX c.6a. Stan 1. Related Documents 16. Where attention is drawn to hazards. This NES is the property of the Crown and unless otherwise authorized in writing by the MOD must be returned on completion of the contract.NES 862 Part 1 Issue 1 (Reformatted) MOD Tender or Contract Process 13. the user is to ensure that he is in possession of the appropriate version of each document. 18. together with the sponsoring Directorate and the Tender or Contract Sponsor. When this NES is used in connection with a MOD tender or contract. 17. See Clause 1. to 1. Cadmium and its corrosion products are toxic. 389 Chiswick High Road.3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Wire Thread Inserts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reuse . .5 1. . . . . Health and Safety . . . . . . . . . . . . . . . . . . . . .2 1. . . Submarine Pressure Hull Fasteners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 USE OF FASTENERS . . . . . . . .4 1. . . . . . . . . . . . .4 1. . . . . . . . . . . . . . . .2 1. A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 1. . . . . . . . . . . . Aluminium Silicon Bronze . . . . . . . . . . . . . . . . . . . . . Brass . . . . . . . . . . . . . . . . . . . . . Use of Washers on Nickel Aluminium Bronze Flanges and Headers . . . . . . . . . . . . . . . . . v v v v vi vi vi vi vi CONTENTS . . General . .1 1. . . . . . General . . . .1 1. . . . .6 1. . . . . . . . . . Compounds Used with Fasteners . . Cadmium Plating . . . . . . . . . . . . . . . . . . . . . . . . SECTION 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 1. . .3. . . . . . Conditions of Release . . . . . . . . . . . . . . . . Electro-Chemical Compatibility . . . . . . . Material . . . . . . . . . .4 1. . . . . . . . . . . . . . . Shock . . . .5 1. . . . . . . . Service Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 1. .4 . . . . . . . . . . . . RELATED DOCUMENTS . .3. . . . . . . . . . . . . . . . Stainless Steel . . . .4 1.3 1. . . . . . . . . . . . . . .4 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3. . . . . . . . . . . . . . . . .2 1. . . . . . . . .3. . . . . . . . . . . . .4 1. . . . B. . . . .4 1. . . . . Thread Protrusion . . . . .3 1. . . . . . . . . . . .3 1. . . . . . . . . . . . . . . . . . QUALITY ASSURANCE . . . . . . . . . . . . . . . . . . . . Warning . . . . . . . . . . . . . . . . . . . . . . . . . . Zinc Plated Steel Fasteners . . . . . . . . . Locking of Fasteners . . . . . . .3 1. . . . . . . . . . . . . . . . . .1 1. . . . . . . . . . . . . . .6 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . Assembly Instructions . . . . . . . . . . . . . . . .8 1. . . . . . . . . . . . .3 1. . . . . .3 1. Thread Form and Fastener Dimensions . . . . . . . . . . . .2 1. . . . . . .3. . . .7 1. . Sponsorship . . . . . 1. . .2 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 1. . . . . . . . i SCOPE . . . . . . .11 1. . . .1 1. . . . . . . . . . . . . . . . . . . . . . . . . . .NES 862 Part 1 Issue 1 (Reformatted) CONTENTS Page No TITLE PAGE . . .7 1. . .8 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 1. . . . . . .2 1. . . . .3. MOD Tender or Contract Process .2 1. . . . . . . . . . . . . . . . . . .3. . . iii FOREWORD . . . . . . . . . . . . Tightening . . . . . . . . . . . . . . . . . .10 vii 1. . . . . vii SECTION 1. .1 ANNEX A. . . . . . . . . . . . . . . . .3 1. . . .12 1. . . . . . . . . . . . . . . . . . . . . . Cadmium Plating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. . . . . . . . . . . . . . . . . . . . . . . Fluids Which May Adversely Affect Fasteners . . . . . . . . DEFINITIONS AND ABBREVIATIONS . . . . . . . . . . . . . . . .2 1.3. . . . . . . . . . . . . Related Documents .1 ANNEX B. . . . . . . . . . . . . . C.2 ILLUSTRATIVE CORRECTION FACTORS FOR SURFACE FINISH . . . . . . . .3 . . . . . . C. . . TABLE D. . . .3 ANNEX D. . .2 D. . C. . . . . .3 SPECIFICATIONS FOR NON-FERROUS FASTENERS USED IN NAVAL APPLICATIONS . . GRADE 8. . . . . . DRY. . . . .3 ILLUSTRATIVE CORRECTION FACTORS FOR BOLT GRADE . . . . . . .1 TABLE C. TABLE D. . .1 D. . . FASTENER STANDARDS AND SPECIFICATIONS .1 TABLE C. . . . . . . . . . . . .1 ILLUSTRATIVE RELATIONSHIP BETWEEN BOLT LENGTH AND THE AMOUNT OF TURN REQUIRED TO TIGHTEN A FASTENER . . . . . TABLE D. C. . . . ALPHABETICAL INDEX viii D. .NES 862 Part 1 Issue 1 (Reformatted) ANNEX C. . . . . . . .1 ILLUSTRATIVE RELATIONSHIP BETWEEN TIGHTENING TORQUE AND FASTENER SIZE FOR UNPLATED. FIGURE D. .1 A SELECTION OF BRITISH STANDARDS RELATED TO FASTENERS .8 STEEL FASTENERS TIGHTENED TO A PRE-LOAD OF 75% OF THE PROOF LOAD .2 D. . . . . . . . . . . . . . . . .2 TABLE C. . . . . . . . TIGHTENING FASTENERS . . . . . . . .1 D. . . .2 SPECIFICATIONS FOR STEEL FASTENERS USED IN NAVAL APPLICATIONS . 1. (11) wire thread inserts. Although a reasonable fit seems apparent. before non-preferred or non-standard sizes are considered. When fasteners are used the aspects listed below are to be considered. a selection of fastener specifications relating to metric and imperial fasteners is listed in Annex C. (3) service temperature. (2) Whitworth and British Standard Fine (BSF) fasteners are not to be used unless there is no acceptable alternative. Advice on avoiding this problem is given in BS PD 6494.1 . when an assembly uses fasteners with more than one thread form. (4) Fasteners available in Naval Stores should be used wherever possible (see BR 320D for further information).NES 862 Part 1 Issue 1 (Reformatted) 1. the following principles apply when selecting the thread form and dimensions of fasteners: (1) Metric fasteners are to be used in preference to imperial fasteners. 1.1 General a. (7) reuse. (2) material. These aspects are expanded in Clauses 1. b.1b. (5) shock. b. c. (10) submarine pressure hull fasteners. (9) use of washers on nickel aluminium bronze flanges and headers. To minimize the range of fasteners in service and ensure ease of supply. thread engagement and strength are greatly affected. USE OF FASTENERS 1. Thread Form and Fastener Dimensions a. and the Metric Coarse pitch series is to be used in preference to the Metric Fine pitch series. (4) locking of fasteners. to 1.2 Further guidance on the selection of fasteners for general purposes is given in Def Stan 53−11.13a. (3) Fasteners are to be selected from standard or preferred ranges specified in the appropriate standard. (12) tightening. For information. (6) assembly instructions.: (1) thread form and fastener dimensions. Care is to be taken to avoid thread mismatch. (8) thread protrusion. b.3. 1. high performance stainless steels are available which have a superior resistance to crevice corrosion. 1. Aluminium Silicon Bronze a.3. typically zinc plating is to BS 3382 Part 2. expensive.NES 862 Part 1 Issue 1 (Reformatted) 1.2 . although Type 316 and other grades of stainless steel which contain a minimum of 2% molybdenum may be used on weather decks. or subjected to sea spray or heavy condensation. For information. These include not using Type 316 austenitic stainless steel below the water line. The electro-chemical compatibility of materials can be checked by referring to BS PD 6484. This can be controlled by insulating the materials from each other. Austenitic stainless steels are suitable for applications requiring a low magnetic permeability. They are regarded as materials for specialist applications requiring individual assessment. Zinc Plated Steel Fasteners a. Brass a.1 Electro-Chemical Compatibility a. Zinc plated steel fasteners are not to be used for applications where the temperature may rise above 60° C because the electro-chemical polarity of zinc and steel reverses so that the zinc no longer protects the steel sacrificially but actively promotes rusting. additional protection such as a paint system is required to prevent corrosion. 1. however the material can become slightly magnetic when cold worked. c.5 When dissimilar materials are used for fasteners and adjacent material in the presence of an electrolyte. 1. Aluminium silicon bronze is only to be used where a low magnetic permeability is required and no acceptable alternative is available.4 Brass fasteners are not to be used in applications where they will be in contact with sea water because the material suffers from dezincification which will reduce strength.3.3 Material 1. c. Precautions are to be taken against crevice corrosion if stainless steel fasteners are liable to come into contact with sea water. galvanic corrosion may occur. or DEF STAN 03−20 for thread diameters up to and including 18 mm (or ¾!) and to BS 1706 Grade Fe/Zn8 c2 for fasteners with a thread diameter over 18 mm (or ¾!). For information. Washers are typically zinc plated to BS 1706.2 1. Since zinc plating is very thin and offers little protection to fasteners immersed in fresh or salt water. or the assembly can be suitably protected (eg by a paint system). For information. b. fasteners in compliance with BS 6105 Grade A4−80 are manufactured from Type 316 stainless steel.3.3 Stainless Steel a.3. or DEF STAN 03−19 for thread diameters up to and including 18mm (or ¾!) and to BS 1706 Grade Fe/Cd8 c2 for fasteners with a thread diameter over 18mm (or ¾!). b. Where cadmium plated fasteners are used. Fasteners are not to be used where they could come into contact with fluids which would adversely affect them. Service Temperature a.6 Cadmium Plating a. All fasteners are to be assembled in accordance with the relevant design specification.4 Size: 45mm ¢ 12mm.NES 862 Part 1 Issue 1 (Reformatted) 1. Fasteners are not to be used for applications where the temperature goes outside the temperature range applicable to the particular fastener.. two anodized aluminium backed tallies with self adhesive aluminium foil labels warning of the presence of cadmium are available from Naval Stores: c. NSN 0617/7690−99−062−9609. c. Compounds in Naval Stores are listed in BR 320D. Locking of Fasteners A means of locking all fasteners liable to work loose is to be provided. Def Stan 53−32 gives information on a selection of locking techniques.5a.2. Compounds are available for corrosion protection.8 (1) General guidance on the design requirements for fasteners to minimize the risk of damage due to non-contact underwater explosion is given in BR 8470.5 For information. Assembly Instructions a.3. typically cadmium plating is to BS 3382 Part 1. 1. b. preventing seizure and locking assembled fasteners in position. drawing or manufacturer’s instructions. NSN 0617/7690−99−372−3734.3. TABLE C. 1. therefore cadmium plating is only to be used where it has been demonstrated that there is no acceptable alternative. Service temperature ranges for steel fasteners manufactured to other parts of this NES are given in Annex C. a. Prevailing-torque type nuts with non-metallic inserts to BS 4929 Part 1 or Part 2 are not to be used in applications where the service temperature will exceed 120° C.3. Cadmium and its corrosion products are toxic. All metal prevailing-torque type nuts to the same specifications are only to be used up to 300° C. For information. 1. Shock a. The maximum service temperature for zinc plating is given in Clause 1.6 (2) Fluids Which May Adversely Affect Fasteners a. an appropriate warning tally is to be fitted in a prominent location.7 Size: 60mm ¢ 17mm. 1. 1. 1. Compounds Used with Fasteners a. Washers are typically plated to BS 1706. In particular prevailing torque-type nuts with nylon inserts are not to be used in fuel tanks.3.3 .7 1. b. Requirements for the reuse of submarine pressure hull fasteners are specified in NES 136. the requirements are to be in accordance with NES 136. For general applications the minimum permitted thread protrusion is half a thread. Non-First Level fasteners may be reused providing they are in a serviceable condition. surface texture or area. 1.13 On nickel aluminium bronze flanges and headers. there is no requirement to fit washers under bolts or nuts. b. Information on wire thread inserts is given in DEF STAN 53−82.8 1. BR 8472 and BR 8473 are to apply when thread protrusion affects shock clearances. Additional information is given in Annex D. Use of Washers on Nickel Aluminium Bronze Flanges and Headers a. However. c. The maximum permitted thread protrusion is 2½ threads.4 .9 1. or NES 862 Part 4 are clearly visible. where the spot facing is inadequate by casting design.10 Reuse a. except for prevailing torque type nuts. 1. Wire Thread Inserts a. 1. When specified. SM−M or those specified in NES 862 Part 3. in which case the minimum permitted thread protrusion is one thread. NES 136 is to apply for the thread protrusion of submarine pressure hull studs.NES 862 Part 1 Issue 1 (Reformatted) 1.12 Where applicable.11 Submarine Pressure Hull Fasteners a. Thread Protrusion a. washers may be used to ensure even loading. 1. fasteners are to be tightened by the specified method to achieve the specified pre-load. These First Level Quality Assured fasteners are only to be reused if the identification marks NS/M. Tightening a. (3) Submarine First Level Quality Assured Fasteners as defined in SSCP 25 are given in NES 862 Part 3 for non-ferrous fasteners and NES 862 Part 4 for ferrous fasteners.1 . 2. Class I 0−300° C and Class III 0−520° C are given in NES 862 Part 2. The Quality Assurance requirements for: (1) steel fasteners for use at high temperatures. (2) non-ferrous fasteners for non-first level applications are given in NES 862 Part 3. QUALITY ASSURANCE a.NES 862 Part 1 Issue 1 (Reformatted) 2. 2 .NES 862 Part 1 Issue 1 (Reformatted) 2. Part 1: General purpose studs Annex C. RELATED DOCUMENTS A. Normal series (Obsolescent) Annex C. aluminium alloys for general engineering purposes: rivet.1 The following documents and publications are referred to in this NES: See Clause BS 2TA 3 Specification for Bar and section for Annex C. BS 1769 Specification for unified black hexagon bolts.1 ANNEX A.3. BS 2470 Specification for hexagon socket screws and wrench keys. extruded round tubes and sections BS 1580 Specification for unified screw threads Parts 1 & 2: Diameters ¼in and larger Annex C. BS 1706 Method for specifying electroplated coatings of zinc and cadmium on iron and steel 1. . Specification for nickel and nickel alloys: bar Annex C. Part 3: Diameters below ¼in Annex C. Heavy Series (Obsolescent) Annex C.NES 862 Part 1 Issue 1 (Reformatted) ANNEX A. screws and nuts (UNC and UNF threads). bolt and screw stock BS 1474 Specification for wrought aluminium and Annex C. Inch series Specification for screwed studs Annex C. BS 1981 Specification for unified machine screws and machine screw nuts Annex C.6c.3.. aluminium alloys for general engineering purposes: plate. machining of commercially pure titanium (tensile strength 390−540N/mm 2) (Obsolescent) BS 57 Specification for BA screws bolts and nuts (Obsolescent) Specification for BA screw threads with tolerances for sizes O BA to 16 BA (Obsolescent) BS 93 Annex C. Annex C. BS 1470 Specification for wrought aluminium and Annex C. BS 1768 Specification for unifed precision hexagon bolts. sheet and strip BS 1473 Specification for wrought aluminium and Annex C.5c. screws and nuts (UNC and UNF threads). 1. BS 2693 BS 3076 A. aluminium alloys for general engineering purposes: bars. NES 862 Part 1 Issue 1 (Reformatted) BS 3382 BS 3409 BS 3410 BS 3643 Specification for electroplated coatings on threaded components Part 1: Cadmium on steel components 1. Part 2: Specification for selected limits of Annex C. Annex C. Annex C. BS 4882 Specification for bolting for flanges and pressure containing purposes Annex C. BS 4183 BS 4190 BS 4278 BS 4320 BS 4463 ANNEX A.6c. Annex C. BS 4377 Specification for tapping of holes to receive wire thread inserts (ISO metric threads) Annex C.3. Metric series Annex C. A. Specification for the tapping of holes to receive wire thread inserts (UNC and UNF threads) Part 1: Diameters ¼in and over (Obsolescent) Part 2: Diameters below ¼in (Obsolescent) Specification for metal washers for general engineering purposes (Obsolescent) BS 4168 BS 4174 Annex C. Metric series Specification for crinkle washers for general engineering purposes (metric series) Annex C. hexagon bolts. screws and nuts Hexagon socket screws and wrench keys Annex C. size Specification for ISO metric precision Annex C. Annex C. ISO metric screw threads Part 1: Principles and basic data BS 3692 Annex C.2 Annex C. BS 4439 Specification for screwed studs for general purposes.3. BS 4464 Specification for spring washers for general engineering and automobile purposes. screws and nuts Specification for eyebolts for lifting purposes Specification for metal washers for general engineering purposes. Part 2: Zinc on steel components 1.5c. metric series Specification for self-tapping screws and metallic drive screws Specification for machine screws and machine screw nuts: metric series Specification for ISO metric black hexagon bolts. Metric series Annex C. Annex C. Annex C. . Annex C. 1. 2.5c. Requirements for the Watertight Integrity of HM Submarines Requirements for Nickel Aluminium Bronze: Part 1: Sheet.2c.4b. NES 862 Part 4: Ferrous (Submarine First Level Quality Assured) 1.8a.. 1. Part 2: Forgings. Sections Fasteners Part 2: Ferrous 2. 1.8a.a. DEF STAN 53−11 Guide to selection bolts..3. Annex C.. NOTE: *In course of preparation. Part 2: Forgings. Until published.. Part 2: Unified (inch) series (Obsolescent) 1. Annex B. Rods and Annex C.a. 1. Rods and Annex C. coiled wire thread 1.8a.5a. Forging Stock. A.2b. Annex C. . Forging Stock. screws and nuts.a. Annex C. *NES 862 Part 3: Non-Ferrous 1. BS PD 6494 Specification for corrosion-resistant stainless steel fasteners Fasteners..1b..9c. screwed thread.1a. Strip and Plate 1.NES 862 Part 1 Issue 1 (Reformatted) BS 4929 Specification for steel hexagon prevailing torque type nuts Part 1: Metric series 1. DEF STAN 03−20 Electro-deposition of zinc 1..6c. Annex C.3.3. guidance is to be sought from Section NA 115.. 1. Annex C. Annex C.12a.4b.3. Annex C...3 ANNEX A. Strip and Plate NES 862 Annex C. metric. Clearance holes for bolts and screws Commentary on corrosion at bimetallic contacts and its alleviation Mismatch of screw thread systems DEF STAN 03−19 Electro-deposition of cadmium 1. BS 6105 1.11a.. Sections Requirements for Aluminium Silicon Bronze: Part 1: Sheet. BS EN 20273 BS PD 6484 DEF STAN 53−82 NES 136 NES 833 NES 834 1. general purpose use DEF STAN 53−32 Guide to the methods of locking screwed fasteners Inserts. 2. BR 8472 Naval Standard Range Mounts for Equipment Installation (to Attenuate Mechanical Shock or Vibration) 1.2a.a. A.NES 862 Part 1 Issue 1 (Reformatted) ANNEX A.9b. BR 320D Descriptive Catalogue of Naval Stores 1.. SSCP 25 Quality Assurance for Safety in Submarines 2. 1..7a. BR 8473 Miscellaneous Mounts for Equipment Installation (to Attenuate Mechanical Shock or Vibration) 1.3.6a. Annex B.9b.4 . BR 8470 Shock and Vibration Manual 1. ‘Rotabolt’ is the trademark of the company Rotabolt Ltd. Typically nuts are either square or hexagonal and are tightened with a spanner. Pre-load The tensile force in an externally threaded fastener equal to the clamping force applied immediately after the fastener assembly has been tightened. Nuts. the cap touches the end of the fastener so that it can no longer rotate. Typically the full length of the shank is not threaded. Prevailing Torque Type A nut with a feature which makes it frictionally resistant to rotation with the intention of preventing the nut from working loose once assembled. Typically. intended to take a nut at each end. Screw A fastener with the head integral with the shank and which is threaded at the opposite end. Fastener Bolts. . Stud A fastener threaded at both ends. Studbolts A fastener threaded at both ends or threaded for the whole of its length. This is a headed pin anchored to the base of a hole made along the axis of the fastener. Submarine First Level Quality Assured fasteners. Typically the full length of the shank is threaded. studbolts. Washer A component assembled under nuts and the heads of bolts and screws which may incorporate a feature for keeping the adjacent fastener tight. B. Stud Hole A threaded hole which accommodates the metal end of a stud. studs. When the design load is applied. screws. used in the pressure hull and forming part of the boundary resisting ambient sea water pressure.1 ANNEX B.) Hull Fasteners Nuts An internally threaded fastener used with bolts and screws.NES 862 Part 1 Issue 1 (Reformatted) ANNEX B. one end of which (the metal end) is screwed into parent metal and the other end of which (the nut end) takes a nut. (See NES 136 for further information. The headed end retains a cap which is free to rotate. as defined in SSCP 25. washers are annular in shape. Examples include nuts with a nylon ring insert. DEFINITIONS AND ABBREVIATIONS B.1 For the purpose of this NES the following definitions apply: Bolt A fastener with the head integral with the shank and which is threaded at the opposite end. nuts and washers for general engineering purposes. Rotabolts Bolts or studs which have a built-in mechanical strain gauge to ensure that the design load is achieved when the fastener is assembled. B.2 .NES 862 Part 1 Issue 1 (Reformatted) ANNEX B. Metric Unified BA Precision hexagon bolts. Procurement Specifications or Standards for steel and non-ferrous fasteners for naval applications are contained in TABLE C. head and machine screw nuts BS 4183 BS 1981 BS 57 Hexagon socket screws and wrench keys BS 4168 BS 2470 − Self-tapping screws BS 4174 − − Lifting eye bolts BS 4278 − − Screwed studs for general purposes BS 4439 BS 2693 Pt 1 − Studs.1 A selection of British Standards which relate to metric and imperial fasteners is given in TABLE C. FASTENER STANDARDS AND SPECIFICATIONS C. countersunk raised countersunk head.NES 862 Part 1 Issue 1 (Reformatted) ANNEX C.1.2 and TABLE C. countersunk.1 ANNEX C. screws and nuts BS 3692 BS 1768 BS 57 BS 4190 BS 1769 − Machine screws—cheese.1 A SELECTION OF BRITISH STANDARDS RELATED TO FASTENERS C. pan. screws and nuts Black hexagon bolts. . studbolts and nuts for flanges and pressure consuming purposes Prevailing torque type nuts BS 4882 BS 4882 − Description BS 4929 Pt 1 BS 4929 Pt 2 − Washers for general purposes BS 4320 BS 3410 BS 3410 Spring washers for general purposes BS 4464 − − Crinkle washers for general purposes BS 4463 − − Tapping of holes to receive wire thread inserts Screw threads BS 4377 BS 3409 − BS 3643 BS 1580 BS 93 BS EN 20273 − − Clearance holes for bolts and screws TABLE C.3 respectively. See Clauses 1.5a.2 .3.8 BS 4439 BS 4882 BS 1768 Steel Grade S BS 2693 BS 4882 Hexagon nuts Under 60° C BS 3692 Steel Grade 8 BS 1768 Steel Grade 1 Washers Under 60° C BS 4320 BS 3410 NOTE: Zinc plated to an appropriate Standard.5c. to 1. is required.NES 862 Part 1 Issue 1 (Reformatted) Purpose Submarine First Level Quality Assured steel fasteners Pipe systems and ot e app cat o s other applications with i h hi high h service i temperature where steel fasteners are spec ed specified General purpose use below 60° C where a High Tensile Strength of about 50 tonf/in 2 or 800 N/mm 2. For use within the temperature range −50° C to under 60° C. (See Note) Fastener Hex Bolts Hex Screws Studs Studbolts Hex Nuts Grade or Class Temperature Range Grade SM1−M or SM1−U Under 60° C (See Note) Grade SM2−M or SM2−U 0−300° C Grade SM3−M orSM3−U 0−520° C Procurement Specification Metric Unified NES 862 Part 4 NES 862 Part 4 Washers Under 60° C (See Note) BS 4320 BS 3410 Washers 0−520° C NES 862 Part 2 NES 862 Part 2 NES 862 Part 2 NES 862 Part 2 Hex Bolts e Screws Sc ews Hex S d Studs Studbolts Class I 0−300° C Class III 0−520° C Hex Nuts Class A 0−300° C Class B 0−520° C Washers 0−520° C Hexagon bolts Hexagon Screws Studs Studbolts Under 60° C BS 3692 Steel Grade 8. TABLE C. C. for details.2 SPECIFICATIONS FOR STEEL FASTENERS USED IN NAVAL APPLICATIONS ANNEX C.3. NES 862 Part 1 Issue 1 (Reformatted) Purpose Material Specification Fastener Submarine First Level Quality Assured fasteners where specified to be high strength nickel alloy.3 SPECIFICATIONS FOR NON-FERROUS FASTENERS USED IN NAVAL APPLICATIONS C. . Nickel copper alloy to BS 3076−NA13 Hex nut Nickel copper aluminium alloy to BS 3076−NA18 Stud bolt In ships and services where the pparticular material i l is i specified ifi d Nickel copper alloy to BS 3076−NA13 Nickel copper aluminium alloy to BS 3076−NA18 Hex nut Titainum to Aerospace BS 2TA 3 Aluminium Silicon Bronze to NES 834 Pt 2 Nickel Aluminium Bronze to NES 833 Pt 2 Aluminium Alloy to BS 1473−6082−TF or BS 1474−6082−T6 Hex bolt Hex screw Stud Studbolt Nut Titanium to Aerospace BS 2TA 3 Aluminium Silicon Bronze to NES 834 Pt 1 Nickel Aluminium Bronze to NES 833 Pt 1 Aluminium Alloy to BS 1470−5251−H22 Washers Procurement Specification NES 862 Pt 3 NES 862 Pt3 Hex bolt Hex screw Stud Studbolt TABLE C.3 ANNEX C. NES 862 Part 1 Issue 1 (Reformatted) ANNEX C. C.4 . Relating Nut Turn to Pre-load D. creep and high temperatures contribute. or the final tightening torque. or if a component is bent out of shape.3 The pre-load of a fastener assembly cannot be maintained because relaxation of the fastener causes a reduction in the clamping force. Calibration is required for these techniques. Tighten the bolt and nut so that all slackness in the assembly is taken up then tighten further as in TABLE D. but when it is it may be established by measuring. gaskets. the amount of turn applied once the fastener starts to stretch. spring washers. Relaxation D. TIGHTENING FASTENERS D. before any of these techniques may be used it is necessary to have data relating them to pre-load. in practice the relationship will be affected by the points of contact between. In practice a realistic relationship may only be established by carrying out trials on each type of bolted assembly considered.1 This Annex is only intended as a brief guide on tightening fasteners and is not a mandatory part of the NES.4 Measuring fastener stretch is the most direct and therefore the most accurate method. In some cases relaxation may cause a fastener to work loose shortly after tightening. Relating Fastener Stretch to Pre-load D.1. Text books are available if more detailed information is required. In the short term this is due to ‘bedding in’. all components clamped by the fastener. However. providing there is a linear relationship between load and extension. vibration. Pre-load D. while in the longer term factors such as corrosion. Bolt length between bolt head and nut expressed as a number of bolt thread diameters Up to and including 2 Amount of turn 180° Above 2 and up to and including 3 240° Above 3 and up to and including 4 300° Above 4 and up to and including 8 360° Above 8 420° TABLE D. However.2 Pre-load is often unspecified. Proprietary devices are available for measuring extension including Rotabolts and computerized ultrasonic equipment. .NES 862 Part 1 Issue 1 (Reformatted) ANNEX D. fastener stretch. and the compressibility of. This approach is very difficult if the components include disk washers.1 ANNEX D. and the yield stress has not been exceeded.5 It is easy to derive formulae relating the amount of turn to stretch or load in linearly elastic fasteners from the pitch.1 ILLUSTRATIVE RELATIONSHIP BETWEEN BOLT LENGTH AND THE AMOUNT OF TURN REQUIRED TO TIGHTEN A FASTENER D. The trials may produce the following type of procedure: a. dry.3 ILLUSTRATIVE CORRECTION FACTORS FOR BOLT GRADE ANNEX D.9 bolt and a phosphated and oiled nut: Tightening torque from FIGURE D.15 Cadmium Plated 0.00 0.2 ILLUSTRATIVE CORRECTION FACTORS FOR SURFACE FINISH Bolt Grade 6.1 = 24kg m Correction factor for surface finish from TABLE D.41 = 23. as well as the accuracy of the torque spanner used.00 Phosphate and Oil 0.6 6. formulae can be derived relating torque to pre-load.85 0.6 Using final tightening torque to measure pre-load overcomes the problems created by points of contact between components and the compressibility of components.8 steel fasteners tightened to a pre-load of 75% of the proof load.41 Therefore.9 Correction Factor 0.35 1.2 and TABLE D. corrected tightening torque = 24 ¢ 0. D.NES 862 Part 1 Issue 1 (Reformatted) Relating Tightening Torque to Pre-load D. TABLE D.15 1.70 0.80 0.70 0.90 1.1 for plated or lubricated fasteners in other grades.90 Zinc Plated 1. D.65 0. A worked example is given below for an unplated.70 Correction factor for bolt grade from TABLE D. but it is affected by coefficients of friction between the surfaces in contact with the underside of the nut and the thread of the nut.69 TABLE D.1 illustrates the type of relationship which may be produced by trials for unplated.20 1.2 .7 FIGURE D.75 1.9 12.3 = 1.41 1.00 1.7kg m Surface Condition of Bolt Surface Condition of Nut Unplated Zinc Plated and Unlubricated Cadmium Plated Phosphate and Oil Unplated and Unlubricated 1.3 illustrate how correction factors may be used to adapt FIGURE D.8 10.2 = 0.56 0. M16. grade 8.20 1. Grade 10. but trials are necessary to establish a meaningful relationship for each fastener assembly.8 8.70 ¢ 1.75 TABLE D.00 1. As with measuring the amount of nut turn. NES 862 Part 1 Issue 1 (Reformatted) FIGURE D.8 STEEL FASTENERS TIGHTENED TO A PRE-LOAD OF 75% OF THE PROOF LOAD D.1 ILLUSTRATIVE RELATIONSHIP BETWEEN TIGHTENING TORQUE AND FASTENER SIZE FOR UNPLATED. GRADE 8. DRY.3 ANNEX D. . 4 .NES 862 Part 1 Issue 1 (Reformatted) ANNEX D. D. 1.1 Fluids.2 Assembly. 1. 1. 1. 1.2 British Standard Fine (BSF).1 E Electro-chemical compatibility. B. 1.1 Compounds. 1. B.1 Dezincification. 1.1 INDEX . B. 1.2 Hull fasteners.3 Coarse pitch. 1.3 H Health and Safety.2 F Fastener definition.3 Corrosion crevice.2 Electrolyte. 1.1 INDEX. 1. 1.NES 862 Part 1 Issue 1 (Reformatted) ALPHABETICAL INDEX A Aluminium Silicon Bronze.1 Brass. B. 1.3 B Bolt. 1.2 Dimensions.2 galvanic.1 C Cadmium plating.4.2 D Definitions. 1.1 Fine pitch. 1.1 I Imperial. 1. 1. C.1 N Nickel Aluminium Bronze. 1.3 Shock. 1.1 Seizure.2 Metric.1 Studbolts. 1. 1. 1. B.NES 862 Part 1 Issue 1 (Reformatted) L Locking. 2. B.1 R Rationalized Ranges. 1. prevention. B. 1.1 Nuts.1 P Paint system. 1. B. 1.1.4.1 Submarine First Level Quality Assured. B. D.1 S Screw.1.3 M Magnetic permeability. 2. 1.4 Nuts.3 Specifications.2 Stud.3. B.2 Stores.1 Stainless steel. 1.4 Rotabolts.1 Strength.1.1 INDEX INDEX. 1. 1.2 Q Quality assurance. B. B.2 . 1.1 Studhole.1 Reuse. 1.1. Prevailing torque. 3 INDEX .4 Z Zinc plating.1 Wire thread inserts. 1.1 W Warning.1 protrusion.2. 1.4.NES 862 Part 1 Issue 1 (Reformatted) T Temperature. D.4. 1.4 Tightening.3 Thread form. 1.1 Whitworth. 1.2 Washers. 1. 1. B.3 INDEX.1 Tolerances. 1. 1. 1.1 mismatch. 1. 1. 4 .NES 862 Part 1 Issue 1 (Reformatted) INDEX INDEX. Inside Rear Cover . © Crown Copyright 2000 Copying Only as Agreed with DStan Defence Standards are Published by and Obtainable from: Defence Procurement Agency An Executive Agency of The Ministry of Defence Directorate of Standardization Kentigern House 65 Brown Street GLASGOW G2 8EX DStan Helpdesk Tel 0141 224 2531/2 Fax 0141 224 2503 Internet e-mail enquiries@dstan. 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