BS-1821-1982.pdf

BRITISH STANDARD BS 1821:1982 Incorporating Amendment Nos. 1 and 2 Specification for Class I oxy-acetylene welding of ferritic pipework for carrying fluids ICS 25.160.10 Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:21:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1821:1982 This British Standard, having been prepared under the direction of the Welding Standards Committee, was published under the authority of the Board of BSI and comes into effect on 26 February 1982 © BSI 04-1999 First published January 1952 First revision February 1957 Second revision February 1982 ISBN 0 580 12506 8 Committees responsible for this British Standard The Welding Standards Committee, under whose direction this British Standard was prepared, consists of representatives from the following: Aluminium Federation Associated Metal Workers Union Associated Offices Technical Committee* British Compressed Gases Association British Constructional Steelwork Association British Railways Board British Shipbuilders British Steel Industry* Crown Agents for Oversea Governments and Administrations Health and Safety Executive* Institution of Civil Engineers Institution of Electrical Engineers Institution of Production Engineers Institution of Structural Engineers Lloyds Register of Shipping Ministry of Defence Process Plant Association Society of British Aerospace Companies Limited Society of Motor Manufacturers and Traders Limited Water-tube Boilermakers Association* Welding Institute* Welding Manufacturers Association* The organizations marked with an asterisk in the above list, together with the following, were directly represented on the Technical Committee entrusted with the preparation of this British Standard: British Gas Corporation British Non-ferrous Metals Federation Electricity Supply Industry in England and Wales Engineering Equipment Users Association Heating and Ventilating Contractors Association Institute of Plumbing Institution of Gas Engineers Institution of Mechanical Engineers Joint Industry Board for Plumbing Mechanical Engineering Services in England and Wales Oil Companies Materials Association Power Generation Association Stainless Steel Fabricators Association of Great Britain United Kingdom Atomic Energy Authority Individual firms Amendments issued since publication Amd. No.Date of issueComments 9738February 1998Indicated by a sideline in the margin Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:21:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1821:1982 © BSI 04-1999i Contents Page Cooperating organizationsInside front cover Forewordiii Section 1. General 1Scope1 2References1 3Parent metals1 4Filler rods1 5Equipment1 6Welding technique1 7Proximity of welds1 8Fusion faces1 9Assembly for welding1 10Cold pull2 11Heat treatment2 12Inspection2 Section 2. Butt joints 13General2 14All types of butt joint2 15Gusseted bends3 Section 3. Branches 16General5 17All types of branches5 18Set-on branches6 19Set-in branches6 20Extruded branches10 21Forged fittings10 Section 4. Sleeve joints and socket-welding fittings 22General10 23Sleeve joint details10 24Socket joint details10 Section 5. Structural attachments 25General11 26Welding procedure11 Section 6. Welding neck flanges 27General11 Section 7. Inspection requirements 28Requirements for visual examination of completed welds12 29Non-destructive testing13 Section 8. Rectification of faulty welds 30Removal of faults15 31Preparation for re-welding15 32Re-welding15 Section 9. Welding procedure approval 33General16 34Attachments to thin pipes16 35Branch welds16 Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:21:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1821:1982 ii © BSI 04-1999 Page Section 10. Welder approval 36General16 36Text deleted17 37Attachments to thin pipes17 Appendix A Classes of operating conditions18 Appendix B Items for agreement between the contracting parties18 Appendix C Welding techniques18 Appendix D Image quality indicator sensitivities21 Table 1 Parent metals and filler rods1 Table 2 Sizing and alignment2 Table 3 Drifting of pipe ends3 Table 4 Preparation of ends4 Table 5 External weld reinforcement12 Table 6 Penetration of root bead12 Table D.1 Image quality and indicator sensitivities (types I and II)21 Figure 1 Thick to thin sections3 Figure 2 Segmental bends4 Figure 3 Cut-and-shut bend5 Figure 4 Curved or “easy sweep” branch joint6 Figure 5 Minimum height of flanged branches7 Figure 6 Details of set-on branches8 Figure 7 Details of set-in branches9 Figure 8 Extruded branch10 Figure 9 Forged fittings for branch joints10 Figure 10 Sleeve joints11 Figure 11 Fillet welds for sleeve joint11 Figure 12 Socket joint11 Figure 13 Welding neck flange12 Figure 14 Partial cut-out in rectification of faulty welds15 Figure 15 Rightward (or backward) technique19 Figure 16 Blowpipe and rod angles for all-position right-ward technique19 Figure 17 Leftward technique20 Figure 18 Multi-layer technique. Pipe horizontal20 Figure 19 Block-welding technique20 Publications referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:21:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1821:1982 © BSI 04-1999iii Foreword This revision of this British Standard has been prepared under the direction of the Welding Standards Committee. It embodies the technical developments that have taken place since the previous edition was published in 1957. BS 1821:1957 is now withdrawn. On common aspects the standard has generally been aligned with BS 2633. Although for carbon steels with not more than 0.25 % carbon, either this standard or BS 2640 may be used according to whether class I or class II welding is required, it is recommended that carbon steels with a carbon content exceeding 0.25 % and the low alloy steels covered by this standard be welded in accordance with the requirements of this standard irrespective of the operating conditions. Because of its increased use for quality control purposes, non-destructive testing has been introduced together with the allied acceptance levels. The relevant application standard, where it exists, should specify whether class I welding of pipework is required, but the factors to be taken into account in coming to such a conclusion are the operating conditions of the pipework, the degree of inspection and the acceptance requirements. (See also Appendix A.) The following are companion standards to this standard: BS 2633, Class I arc welding of ferritic steel pipework for carrying fluids. BS 2640, Class II oxy-acetylene welding of carbon steel pipework for carrying fluids. BS 2971, Class II arc welding of carbon steel pipework for carrying fluids. BS 4204, General requirements for the flash welding of steel pipes and tubes for pressure and other high duty applications. BS 4677, Class I arc welding of austenitic stainless steel pipework for carrying fluids. Inspecting authority. The term “inspecting authority” refers to that competent independent body or association which verifies compliance with this standard. Pipe and tube. In this British Standard the word “pipe”, alone or in combination, is used to mean “pipe” or “tube”, although these terms are often used for different categories of product by different industries. Pipe dimensions. Unless otherwise qualified, for the purposes of this British Standard “pipe diameter” relates to the specified value of the outside diameter and “pipe thickness” relates to the specified value of the wall thickness of the pipe in the as supplied condition. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages 1 to 22, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:21:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:21:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1821:1982 © BSI 04-19991 Section 1. General 1 Scope This British Standard specifies requirements for both shop and site class I oxy-acetylene welding of joints in ferritic steel pipework of a thickness not exceeding 10 mm intended to carry fluids. Attention is particularly drawn to Appendix B which lists items for agreement between the contracting parties. 2 References The titles of the publications referred to in this standard are listed on the inside back cover. 3 Parent metals This standard relates to pipes and attachments made from the types of steels listed in Table 1. The use of equivalent alternative steels to those complying with the standards stated in Table 1 is permitted. The material used for pipes and fittings shall be fully suitable for the service conditions. While the requirements and limitations of this standard apply also to the welding of cast parts, additional precautions in inspection and welding procedure that may be necessary to deal with the presence of non-metallic inclusions or porosity, shall be subject to agreement between the purchaser and the manufacturer. 4 Filler rods Filler rods of the types specified in Table 1 complying with the requirements of BS 1453 shall be used. 5 Equipment All welding equipment shall be in good condition and such as to enable the welder to maintain the correct neutral flame at all times. Where necessary, staging and protection from the weather shall be provided to enable the welding operation to be performed properly. 6 Welding technique Welding shall be carried out by any of the techniques described in Appendix C, subject to the limits imposed in Table 4. 7 Proximity of welds The design of joints shall be such as to provide adequate access for the deposition of weld metal to meet the requirements of this standard. Joints where more than two welded seams meet should be avoided. If the design cannot avoid this, then appropriate precautions shall be taken which shall be agreed between the manufacturer, the purchaser and the inspecting authority. Table 1 Parent metals and filler rods 8 Fusion faces The fusion faces and the adjacent material shall be free from moisture, scale, rust, paint, grease or other foreign matter immediately prior to welding. Certain proprietary protective coatings are specially formulated with the intention that they should not interfere with subsequent welding. The use of such coatings is not excluded by the requirements of this clause, but if so required by the purchaser the manufacturer shall demonstrate by means of specimen welds that the coating does not affect the quality of the weld. 9 Assembly for welding To maintain the specified alignment and gap during welding (see Table 2 and Table 4) the pipes to be welded shall be securely held in position by mechanical means, welded-on bridge pieces or tack welding. If tack welding is adopted, the tack welds shall be either melted out during welding or made as part of the main weld and of the same quality as that weld. It is appreciated that there may be difficulty in complying strictly with the specified requirements for the root gap. Slight modifications imposed by practical considerations shall be subject to agreement between the purchaser and the manufacturer. Material classification Pipe standardsTypes of filler rod to BS 1453 Carbon steel 0.25 C BS 3059-1320 BS 3059-2360 and 440 BS 3601320, 360 and 430 BS 3602-1360, 430 BS 3602-2430 BS 3603430LT BS 3606320 and 440 A2 or A3 C-MoBS 3059-2243 BS 3606243 and 261 A6 or A7 1 Cr ½ Mo 1 ¼ Cr ½ Mo BS 3059-2620 BS 3604620 BS 3606620 BS 3604621 BS 3606621 A32 Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 06:21:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1821:1982 2 © BSI 04-1999 10 Cold pull Where the effects of thermal expansion in service are to be counteracted by “cold pull” during erection of the pipe assembly, the “cold pull” shall be maintained during welding, post-weld heat treatment (if any) and cooling. Before applying “cold pull” to a joint, all other joints in the pipe assembly shall have been welded, subjected to any post-weld heat treatment, inspected and accepted. 11 Heat treatment It is advisable for the purchaser in all cases to inform the manufacturer of the use to which the pipework will be put. Normalizing or other post-weld heat treatment is not required for welded joints in pipework covered by this standard, unless the purchaser states in the enquiry and order that welds are to be heat treated, in which case all details relating to such heat treatment shall be agreed between the contracting parties. 12 Inspection The purchaser or his representative shall have access at all reasonable times to those parts of the works or site engaged on the preparation, fabrication and testing of the pipe assemblies which he has ordered. Section 2. Butt joints1) 13 General Section 1 of this standard details the basic procedure requirements with which all welded joints between pipes and fittings shall comply. These basic requirements are supplemented by the specific requirements detailed in this section 2. Both section 1 and section 2 of this standard shall be applied in determining the full procedure requirements. 14 All types of butt joint 14.1 Matching of ends. The bores of the ends of adjacent pipes shall preferably, for welding purposes, match exactly, but in any case shall not differ at any diameter by more than the amounts specified in Table 2, whilst the alignment shall be within the limits specified in that table. NOTE 1The difference in thickness that can be tolerated between adjacent pipes for oxy-acetylene welding decreases with increasing pipe thickness. NOTE 2It is recognized that the ends of pipes and welding fittings are supplied to standard tolerances and may not match, especially if placed together at random. Additional workmanship may therefore be required to ensure the alignment specified in Table 2. The welding of pipe joints in accordance with this standard shall include the proper sizing or matching by the welding contractor of the pipe ends at each joint, if necessary, before welding. (See also Figure 1(a).) Matching shall be effected by selection, drifting, machining or the use of a suitable expander. If drifting is employed, a slow taper drift shall be used under the conditions specified in Table 3. When drifting or expanding hot, the pipes shall be heated to a temperature either within the range 900 °C to 975 °C or within the range 500 °C to 620 °C. Wherever the thickness is reduced by drifting, machining or expanding, the thickness at every