BS 2971:1991

Committees responsible
Foreword
Section 1. General
1. Scope
2. Information and requirements to be agreed and to be
     documented
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
     welds
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
Appendices
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
Tables
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
Figures
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.

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.