Rejected Root Fusion, Expired Qualification, and Repair Limit
After final radiography of 24 welds on a 316L pipe spool, three butt welds show incomplete fusion at the root. The RT film and weld map are clear. The welder’s qualification record shows his GTAW pipe test was completed 7 months ago, and he has not welded that process since. The shop WPS is revision B, but the drawing and the welder’s log refer to revision A, which had a higher current range. The repair log shows one of the rejected welds has already been repaired twice. The client specification allows a maximum of two repairs per weld and requires radiography of each repair. Production wants to cut out the three welds and re-weld them tonight using the same welder because the hydrotest is tomorrow.
1. State your disposition for the three welds and the welder. Justify each decision.
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Disposition:
- Stop production and segregate the spool. Raise a nonconformance report and place the three welds on hold.
- Do not let the same welder re-weld tonight without requalification. His GTAW pipe qualification is 7 months old with no welding in that process since the test. Under common code continuity rules such as ASME IX QW-322, qualification expires after 6 months without welding with that process. He must be requalified, or a currently qualified welder must be assigned.
- Verify the WPS. The drawing and log refer to revision A, but the shop WPS is revision B. Determine which revision is qualified and approved. Do not weld to an obsolete revision just because the log says so.
- Apply the repair limit. The weld already repaired twice has reached the client’s maximum of two repairs. It cannot receive a third repair; cut it out and replace it, or obtain an approved engineering disposition.
- The other two welds may be repaired once, but only under the correct WPS, by a qualified welder, with RT after repair.
2. What root causes would you investigate for the incomplete fusion, and what evidence would you collect?
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Root causes to investigate:
- Actual welding parameters versus the WPS - current, voltage, travel speed, gas flow, and purge quality. The revision A/B confusion may mean the welder used an unqualified current range.
- Joint fit-up - root gap, land, misalignment, and bevel condition. A tight or misaligned root can prevent fusion even at the correct current.
- Cleaning and shielding - oxide, oil, moisture, or inadequate purge can interfere with root fusion.
- Welder technique - torch angle, arc length, travel consistency, and whether the root was deposited with sufficient heat.
- Machine calibration - verify the ammeter and voltmeter readings against a calibrated meter.
Evidence to collect: the WPS revisions A and B, PQRs, welder qualification records, machine calibration records, filler certificates and lot numbers, purge logs, fit-up inspection sheets, RT films and reports, welder’s parameter log, and photographs of the joint preparation. Compare the actual heat input with the qualified range. Do not assume “higher current” means the cause was too much heat; lack of fusion can also come from too little heat, fast travel, or poor fit-up.
3. Describe the documentation and reporting package you would issue after the repairs, including traceability requirements.
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Package contents:
- Nonconformance report with weld IDs, RT report numbers, defect type and location, root cause, disposition, and corrective action.
- Approved repair procedure or WPS revision, with the qualified welder’s ID and current qualification record.
- Repair map showing which welds were repaired, how many times, and which weld was cut out and replaced.
- RT reports for every repair, with film traceability and interpretation results.
- Material traceability - heat numbers, filler lot numbers, and certificates for replacement pipe or fittings.
- Parameter records for the repair, including current, voltage, travel speed, heat input, purge oxygen, and gas flow.
- Final inspection release and, if required, a certificate of compliance.
The report must be signed by the inspector and reviewed against the client specification. The repair count must be visible in the final dossier so the two-repair limit can be audited. Hydrotest should not proceed until the repaired welds have passed RT and the documentation is accepted.