WPS Document Control Gap
During an internal audit, a welding coordinator finds that three WPSs used on a pressure-vessel job reference a PQR number that was superseded eight months ago. The current PQR has revised heat input limits and a different preheat minimum. Welders have been welding with the old WPS, which specifies 100 C preheat instead of the current 150 C. The job involves 22 mm carbon steel with a 0.45 CE. No weld failures have been reported, but the vessel is 60 percent complete. The QA manager asks whether the completed welds must be rejected and what corrective action is needed.
1. Assess the technical risk of the completed welds and determine whether they must be rejected.
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The welds were made with a preheat of 100 C instead of the qualified 150 C on 22 mm steel with 0.45 CE. This is a deviation from the qualified procedure, but rejection is not automatic - it depends on whether the deviation affected mechanical properties.
Risk factors:
- Hydrogen cracking susceptibility: 0.45 CE and 22 mm section thickness make the joint susceptible to hydrogen-assisted cracking. The 50 C reduction in preheat increases the risk of delayed cracking, particularly in the heat-affected zone.
- No reported failures is not proof of soundness; hydrogen cracking can be delayed.
Recommended actions:
- NDE the completed welds - at minimum, surface NDE (MT or PT) after a suitable delay, and volumetric NDE (UT or RT) on a sampling basis or 100 percent depending on criticality.
- Evaluate fitness-for-service if NDE finds indications; do not simply reject without assessment.
- Do not continue welding under the old WPS.
Conclusion: Rejection is premature. NDE and engineering assessment should determine acceptability. If NDE is clean and the deviation is documented, the welds may be accepted with a concession; if indications are found, repair or rejection follows.
2. Describe the corrective action plan to close the document-control gap.
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The root cause is a document-control failure: superseded WPSs remained in use after the PQR revision. Corrective action should address both the specific job and the system:
- Immediate containment: Withdraw all copies of the superseded WPSs from the shop floor, weld stations, and planning packages. Issue the current WPS revision with the 150 C preheat.
- Verify current documents: Confirm that all WPSs on the job reference current PQRs and that welders have been briefed on the change.
- Retrospective review: Identify all welds made under the superseded WPS, document the deviation, and route them through NDE and engineering disposition.
- Document-control fix: Implement a master register with revision status, controlled distribution, and a recall process for superseded documents. Add a check at the pre-job planning stage that WPS and PQR numbers match current revisions.
- Training and audit: Retrain welding coordination staff on document control and add a periodic audit of WPS/PQR cross-references.
- Record the nonconformance and verify effectiveness at the next audit.
Closure criteria: No superseded documents in use, all affected welds dispositioned, and the register verified.