While the WPS qualifies the procedure, the WPQ qualifies the welder. It is a demonstration that a welder has the skill and manual dexterity to produce a sound weld using a specific, already-qualified WPS. The welder performs a test on a qualification coupon, which is then examined (often visually and through bend tests or radiography). If the test coupon meets the acceptance criteria, the welder is considered qualified to use that WPS within the limits defined by the essential variables for welder performance.
The ASME B31 series and Section VIII are the primary construction codes that mandate the use of ASME Section IX for welding:
In high-pressure manufacturing, safety and structural integrity are non-negotiable. Whether constructing a nuclear reactor, a cross-country oil pipeline, or a brewery bioreactor, the components must withstand immense thermal and mechanical stress. The American Society of Mechanical Engineers (ASME) provides the global benchmark for ensuring these fabrications do not fail. welding standard asme
Rules for Construction of Pressure Vessels. ASME Section I: Rules for Construction of Power Boilers.
Unlike the WPS, which lists allowable ranges, the PQR records the exact measurements taken during the test. While the WPS qualifies the procedure, the WPQ
A PQR is proof that the recipe in the WPS actually works. To make a PQR, a shop makes a test weld using the WPS rules. Then, experts test that weld to see if it is strong. They bend it, pull it, and look inside it. If the weld passes the tests, the PQR is approved. 3. Welder Performance Qualification (WPQ)
Section IX is a "service code," meaning it is rarely used in isolation. It is called upon by "construction codes" across the ASME ecosystem to handle welding requirements. Construction Code Focus Area Role of Welding / Section IX Power Boilers If the test coupon meets the acceptance criteria,
of the Boiler and Pressure Vessel Code (BPVC), which serves as the global benchmark for qualifying welding procedures and personnel [20, 22]. Unlike safety-specific standards like ANSI Z49.1 [26, 28], ASME focuses on the structural integrity reproducibility of welds in pressurized systems [20, 21]. Core Pillars of ASME Welding (Section IX)
The Quality Manager must sign and date the completed PQRs and WPSs, taking organizational legal responsibility for their accuracy.