Welding Processes, Procedures, and Qualification
The document chain
Learn the chain cold: PQR → WPS → welder performance qualification. The PQR is a record of a test that proved a procedure; the WPS is the production instruction written from it; the performance qualification proves the individual. Essential variables must be requalified if changed; nonessential variables may be changed within the WPS ranges without requalification. Typical essential variables: process, filler classification (F-number/A-number), base metal group, thickness range, position, preheat and interpass temperature, PWHT, and - for GMAW - mode of metal transfer. AWS D1.1 permits prequalified joints when base metal, filler, thickness, and joint detail all comply; otherwise the procedure needs qualification testing.
Process points candidates miss
SMAW is limited by electrode coating and operator skill; FCAW gives high deposition with slag that must be cleaned before the next pass; GMAW short-circuit is a low-heat, thin-material mode; SAW needs flux handling and is flat-position only; GTAW is clean and precise but slow. FCAW is not GMAW - mixing them up is a common distractor.
Traps
- Conflating procedure qualification with welder qualification.
- Assuming a 3G-qualified welder is qualified in 4G.
- Assuming thickness reciprocity is symmetric; it is not.
Worked example
Under ASME IX, a 1/2-in groove test coupon (no impact testing required) qualifies a production range of 3/16 in minimum to 2T = 1 in maximum, because T ≥ 3/8 in. Below 3/8 in, the minimum drops to 1/16 in with the same 2T maximum.