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BS 2971:1991



The latest, up-to-date edition.

Specification for class II arc welding of carbon steel pipework for carrying fluids

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Published date


Committees responsible
Section 1. General
1. Scope
2. Information and requirements to be agreed and to be
3. Parent metal
4. Weld metal
5. Gases for shielding and purging
6. Equipment
7. Welding processes
8. Backing rings
9. Joint preparations
10. Proximity of welds
11. Fusion faces
12. Assembly for welding
13. Purging
14. Damage to parent metal by arc strikes
15. Inter-run cleaning
16. Cold pull
17. Preheating for cutting and welding
18. Heat treatment after welding
Section 2. Butt joints
19. General
20. All types of butt joint
21. Gusseted bends
Section 3. Branches and small bore connections
22. General
23. Branches
Section 4. Sleeve joints and socket-welding fittings
24. General
25. Sleeve joint details
26. Socket joint details
Section 5. Structural attachments
27. General
28. Welding procedure
Section 6. Flanges
29. General
30. Welding neck flanges
31. Welded-on flanges
Section 7. Inspection
32. Requirements for visual examination of completed
33. Testing of completed welds
34. Non-destructive testing
35. Flaw limitations
Section 8. Rectification of unacceptable welds
36. Removal of flaws
37. Preparation for rewelding
38. Rewelding
Section 9. Welding procedures
39. General
40. Attachments to thin pipes
Section 10. Welder approval
41. General
42. Attachments to thin pipes
A. Classes of operating conditions
B. Grades of steel in British Standards and similar
     grades for pipe in ASTM and DIN standards
C. Typical joint preparations
1. Methods of making initial root runs in butt joints
2. Typical limits for bore difference and alignment
     for manual welding
3. Classes of operating conditions
4. Grades of steel in British Standards
5. Grades in ASTM and DIN standards of similar
     weldability to British Standard grades of pipe
1. Segmental bends
2. Cut-and-shut bend
3. Sleeve joints
4. Fillet welds for sleeve joints
5. Socket joint details
6. Welding neck flange
7. Typical butt joint preparations for use with
     backing rings
8. Typical butt joint preparations for use without
     backing rings
9. Typical set-on branch without weld preparation
10. Typical preparation and assembly of set-on branches
     without backing
11. Typical preparation and assembly of set-on right-
     angle branches with temporary backing
12. Typical set-in branch without weld preparation
13. Typical curved or 'easy sweep' branch joint
14. Typical set-on (shaped) small bore connections
15. Typical set-in small bore connection
16. Typical small bore connections for pressures over
     10 bar or for refrigerants or corrosive fluids
17. Typical 'slip-on' welded-on flange
18. Typical 'slip-on' hubbed welded-on flange

Welding using manual, automatic or semi-automatic processes. Welding consumables, preparation for welding, butt joints, branches, attachments, flanges, testing and inspection, acceptance requirements for optional non-destructive testing, procedure and welder approval tests.

Supersedes 90/71692 DC, 95/706852 DC and BS 2971(1977). (07/2005) Reviewed and confirmed by BSI, December 2011. (11/2011)
British Standards Institution

This British Standard specifies requirements for both shop and site class II arc welding of joints in carbon steel pipework intended to carry fluids. It covers manual, automatic or semi-automatic arc welding or combinations of these processes, but it also allows joints to be made with an oxy-acetylene root run without a backing ring by agreement between the contracting parties.

NOTE1 For details of oxy-acetylene welding see BS2640.

This standard is only applicable where there is adequate access available for welding and, when required, non-destructive testing.

NOTE2 In cases of poor access, a mechanical connection could be used.

In addition to the definitive requirements, this standard also requires the items detailed in clause2 to be documented. For compliance with this standard, both the definitive requirements and the documented items have to be satisfied.

NOTE3 The titles of the publications referred to in this standard are listed on the inside back cover.

BS EN 760:1996 Welding consumables. Fluxes for submerged arc welding. Classification
BS 3923-1:1986 Methods for ultrasonic examination of welds Methods for manual examination of fusion welds in ferritic steels
BS 2640:1982 Specification for Class II oxy-acetylene welding of carbon steel pipework for carrying fluids
BS EN 60974-12:2011 Arc welding equipment Coupling devices for welding cables
BS EN 439:1994 Welding consumables. Shielding gases for arc welding and cutting
BS EN 287-1:2011 Qualification test of welders. Fusion welding Steels
BS 1821:1982 Specification for class I oxy-acetylene welding of ferritic steel pipework for carrying fluids
BS 3606:1978 Specification for steel tubes for heat exchangers
BS EN 288-2:1992 Specification and approval of welding procedures for metallic materials Welding procedures specification for arc welding
BS 5289:1976 Code of practice. Visual inspection of fusion welded joints
BS 1640-3:1968 Specification for steel butt-welding pipe fittings for the petroleum industry Wrought carbon and ferritic alloy steel fittings. Metric units
BS 7084:1989 Specification for carbon and carbon-manganese steel tubular cored welding electrodes
BS 1560-3.1:1989 Circular flanges for pipes, valves and fittings (Class designated). Steel, cast iron and copper alloy flanges Specification for steel flanges
BS 1965-1:1963 Specification for butt-welding pipe fittings for pressure purposes Carbon steel
BS EN 60974-11:2010 Arc welding equipment Electrode holders
BS 1387:1985 Specification for screwed and socketed steel tubes and tubulars and for plain end steel tubes suitable for welding or for screwing to BS 21 pipe threads
BS 6084:1981 Method of test for comparison of prefabrication primers by porosity rating in arc welding
BS 3602-1:1987 Specification for steel pipes and tubes for pressure purposes: carbon and carbon manganese steel with specified elevated temperature properties Specification for seamless and electric resistance welded including induction welded tubes
BS 6693-2:1986 Diffusible hydrogen Method for determination of hydrogen in manual metal-arc weld metal
BS EN 288-3:1992 Specification and approval of welding procedures for metallic materials Welding procedure tests for the arc welding of steels
BS EN 499:1995 Welding consumables. Covered electrodes for manual metal arc welding of non alloy and fine grain steels. Classification
BS EN 756:2004 Welding consumables. Solid wires, solid wire-flux and tubular cored electrode-flux combinations for submerged arc welding of non alloy and fine grain steels. Classification
BS EN 50078:1994 Torches and guns for arc welding
BS 4504-1:1969 Circular flanges for pipes, valves and fittings (PN designated) Ferrous
BS EN ISO 9000:2015 Quality management systems. Fundamentals and vocabulary
BS EN 288-1:1992 Specification and approval of welding procedures for metallic materials General rules for fusion welding

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