Procedure Qualification Stretched to a Thicker, Impact-Tested Shell

Matching P-numbers is necessary but not sufficient. Procedure qualification is bounded by essential and supplementary essential variables, and here at least three are not addressed by the existing PQR.

• Thickness. The qualified base metal thickness range is set by the essential variable covering thickness and the thickness tables; a 3/8 in. coupon does not qualify 1.0 in. plate. The shop's assumption that P-number equivalence overrides thickness is wrong.
• Notch toughness. Once the construction requires impact testing of the weld, impact testing becomes a supplementary essential variable. A PQR made without impact testing cannot be extended to impact-required work; the procedure must be qualified with Charpy testing of the weld metal and heat-affected zone per the applicable code requirements.
• Condition. The PQR is as-welded. If production requires post-weld heat treatment, or if the preheat and interpass practice differs from the production joint, the PQR does not cover it.

Conclusion: the WPS is not qualified for these seams, and the existing production welds were made to an unqualified procedure - a nonconformance, not merely a paperwork gap.

A production test coupon has legitimate uses where the code provides for production weld toughness verification, and it can demonstrate that a particular seam met the acceptance criteria. It does not convert an unqualified procedure into a qualified one. Procedure qualification must be established before production and must address every essential and supplementary essential variable, including thickness, position, consumable, preheat, and post-weld heat treatment.

What I would require:

1. Withdraw the WPS from service and issue a nonconformance covering the completed seams.
2. Qualify a new procedure on a coupon representative of production thickness (1.0 in.), in the production condition, with impact testing of weld metal and heat-affected zone and acceptance per the code's toughness criteria.
3. Re-qualify welders on test coupons that satisfy performance qualification thickness limits and notch-toughness requirements.
4. Propose a disposition for the existing seams to the client: additional volumetric examination, surface examination at weld toes and nozzle connections, and evaluation of whether the toughness of those welds is demonstrable. A production coupon cut from a seam can support that evaluation, but it does not cure the qualification deficiency.

Welder performance qualification carries its own thickness limits, separate from procedure limits. A welder qualified on 3/8 in. plate is qualified to deposit up to a defined maximum thickness, not to the full 1.0 in. production joint, so the welders are likely not qualified for these seams on thickness grounds alone.

In addition, when notch toughness is required by the construction, performance qualification test coupons must themselves be impact tested unless a specific exemption applies. The shop's welders qualified without any impact testing, so they do not hold toughness-qualified performance certification for this work.

The determination is governed by the performance qualification variables and thickness tables in the welding standard, not by the procedure qualification. Both must be satisfied independently: a qualified welder using an unqualified procedure is nonconforming, and a qualified procedure applied by an unqualified welder is equally nonconforming.

Action: treat the welders as unqualified for this joint until re-tested, and record the deficiency against the specific welders and seams affected so the traceability of the nonconformance is preserved.