BS 6990:1989

Foreword
Committees responsible
Code of practice
Section one. General
1 Scope
2 Definitions
3 Information, items to be approved and items to be
    agreed and to be documented
Section two. Safety considerations
4 Legal requirements
5 Preliminary considerations
6 Factors affecting safety
Section three. Welding
7 Pipe thickness, temperature and internal pressure
8 Pipe material
9 Fitting material
10 Welding equipment
11 Electrodes and filler metals
12 Shielding gases
13 Approval and testing of welding procedures
14 Approval and testing of welders
15 Preparation of pipe
16 Inspection of fittings
17 Fusion faces
18 Preparation for encirclement fitting
19 Preparation for set-on fitting
20 Alignment of flanged fittings
21 Working clearance
22 Stray arcs
23 Weather conditions
24 Preheating
25 Sequence of welding
26 Inter-run cleaning
27 Inspection
28 Non-destructive testing acceptance criteria
29 Rectification of welds
Tables
1 Welding procedure details
2 Changes affecting procedure approval (essential
    variables)
Figures
1 Typical fittings
2 Typical longitudinal weld preparation for fitting:
    dimensions and tolerances
3 Attachment of run-on/run-off plates to backing
    material
4 Typical yoke-type clamp for encirclement tee
    fittings

Covers details prior to, during and after all operations relating to and involving the safe arc welding on ferritic and austenitic steel land or offshore pipelines and process plant pipework which contain or have contained a process fluid and which are at least 5 mm thick.

This code covers operations relating to and involving arc welding on ferritic steel and austenitic stainless steel land or offshore pipelines and process plant pipework which contain or have contained a process fluid and which are at least 5 mm thick. It gives details of procedures prior to, during and after all these operations. NOTE 1 Welding on pipes of thickness below 5 mm is not covered by this code although it can be undertaken. The code covers manual, semi-automatic and mechanized arc welding by the following processes or combination of processes: manual metal-arc welding; MIG/MAG welding; TIG welding; flux cored arc welding; non-shielded welding. It is essential that the items listed in clause 3 should be fully documented and followed. Welding operations needing post-weld heat treatment for adequate weld quality are not within the scope of this code. This code is not applicable to a pipeline or pipework that has been fully isolated and decontaminated or has not been commissioned. These are covered by other standards such as BS 2633, BS 4677 and BS 4515. This code does not relate to a pipeline or pipework containing a process fluid or its residuals that will become explosively unstable upon the application of heat or will affect the pipe material by rendering it susceptible to ignition, stress corrosion cracking or embrittlement. NOTE 2 The titles of the publications referred to in this code are listed on the inside back cover.