Quality Assurance, Procedure and Welder Qualification
What you must know
Distinguish quality control (inspection and testing) from quality assurance (planned systems ensuring requirements are met). Understand the welding procedure specification, procedure qualification record, and welder performance qualification, and how essential variables differ from non-essential and supplementary essential variables. Know that a change in an essential variable requires requalification, and that welder qualification is specific to process, position, thickness, and joint type. Understand test coupon requirements, bend and tensile testing, and the role of the responsible inspector in verifying records and traceability.
Traps in questions
- Confusing PQR (procedure qualification record) with WPS (welding procedure specification).
- Assuming a qualified welder is qualified for all processes and positions.
- Treating a non-essential variable change as requiring requalification.
- Overlooking supplementary essential variables when toughness is required.
- Accepting expired or undocumented qualification records.
Worked example
A welder qualified in the vertical-up position on 10 mm plate with one process applies to weld 8 mm plate in that position with that process, but not to a different process or to a thickness beyond the qualified range stated in the governing standard. Rule of thumb: qualification follows the essential variables listed in the code; anything outside them needs new testing.
Inspection link
Audit the paper trail before production: WPS, PQR, welder certificates, consumable certificates, and calibration records.