Fabrication, Welding Procedure and Welder Qualification
Domain 4: Fabrication, welding procedure and welder qualification
This domain tests the qualification chain and the responsibilities attached to it: preliminary WPS, procedure qualification record, WPS, welder qualification and production control.
The qualification chain
ISO 15614-1 is a common route for procedure qualification of steels: a pWPS is used to make a test piece, which is tested to produce a WPQR; the WPS is then written from the qualified range. Essential variables include process, base-metal group, thickness range, consumable classification, joint design, position, preheat, post-weld heat treatment and impact testing. A change outside the qualified range requires requalification or a new WPQR.
Personnel and coordination
ISO 9606-1 covers welder qualification. The test piece, process, position and thickness set the range of approval; a plate test does not qualify pipe, and a PA test does not qualify vertical-up. ISO 14731 defines welding coordination tasks, and ISO 3834 sets quality requirements for fusion welding from part 2 (comprehensive) to part 4 (elementary).
Worked example
A WPQR exists for GMAW, 10 mm S355, no impact testing. A contract asks for 25 mm S355 with Charpy testing at −20 °C. The thickness range is an essential variable, and impact testing changes the qualification basis. A new WPQR with impact specimens is needed; increasing preheat or adding a second pass does not extend the existing range. The correct answer is to qualify, not to adjust the WPS informally.
Traps
Treating WPQR and WPS as the same document. Assuming a welder qualified for one position covers all positions. Forgetting that consumable classification and shielding gas can be essential variables. Using an expired or unconfirmed welder certificate.