If welding is to be performed according to a welding procedure specification, it is possible that changing the electrode manufacturer will invalidate the approval of the procedure to the code/standard on which it was based. The manufacturer or ‘trade name’ of the electrode can be classed as an essential variable in a given weld procedure. The extent to which re-qualification is necessary will vary from code to code.
For example, in EN ISO 15614-1 and in the UK standard BS 4515:2004, approval is only restricted to the specific make of electrode if impact testing is required as part of the procedure qualification. On the other hand, DNV OS-F101 states that on changing the brand of consumable, the welding procedure is to be considered invalid, and would need to be re-qualified (see table C-2).
In ASME IX (QW-404.12, supplementary essential variable), the trade name is considered only if the electrode is not covered by an SFA specification or if the designation has a ‘G’ suffix within an SFA specification. In such cases and if impact testing is required, a change in the trade designation of the filler metal requires requalification.
If the code/standard permits use of another electrode brand, or if welding is not being carried out to a specific procedure, provided there have been no problems with their use, it is still advisable to stick with the consumables used in the code/standard or that which is normally used. This is because electrode classification does not take into account ‘usability’. Different brands of electrode (of the same specification) often weld differently, and many welders are sensitive to differences in quality and operating characteristics of electrodes from various manufacturers. On occasion, differences have been identified in electrode performance for the same brand or source of electrode coating materials, which has resulted from a change in the plant where the electrodes are made. Whilst there may be no way of avoiding this, for the other reasons highlighted above the adage ‘if it isn’t broke, don’t try to fix it’ is sometimes the best advice regarding changing electrode brands.
- BS EN ISO 15614-1:2004+A2:2012 ‘Specification and qualification of welding procedures for metallic materials – Welding procedure test’.
- BS 4515-1:2009 ‘Specification for welding of steel pipelines on land and offshore’.
- Det Norske Veritas, Offshore Standard DNV-VOS-F101 ‘Submarine Pipeline Systems’, October 2010.
- ASME B&PV, Section IX, ‘Welding and Brazing Qualifications’, 2011a edition.