Ultrasonic Indication Disposition Without a Written Acceptance Criteria
A shop is performing ultrasonic testing on a completed butt weld in 20 mm carbon steel. The examiner records an indication that is 12 mm long and located near the fusion line. The project specification references a general acceptance standard but does not include a project-specific acceptance table. The examiner believes the indication exceeds the reference level but is unsure whether it is rejectable. Production wants the weld accepted so the unit can ship, and the client's inspector is unavailable until the next day. The examiner is asked to sign off on acceptance based on 'engineering judgment.'
1. Evaluate whether the examiner can accept the weld on engineering judgment alone.
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The examiner cannot accept the weld on engineering judgment alone when a written acceptance standard applies. Acceptance criteria for ultrasonic testing are defined by the referenced standard, which specifies how indications are sized, compared to reference levels, and classified. The examiner's role is to apply those criteria, not to substitute personal judgment for them.
If the project specification references a general standard without a project-specific table, the examiner must obtain and apply the referenced standard's acceptance criteria. If the standard's criteria are ambiguous for this indication, the correct step is to escalate to the responsible engineering authority or the client's inspector, not to sign off.
The indication's length and location near the fusion line are relevant to classification, but they do not resolve the question without the applicable criteria. Signing off to meet a shipping date would be a serious integrity and documentation failure.
2. Describe the correct disposition path and the documentation required.
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The examiner should record the indication with its length, location, amplitude relative to the reference level, and the technique used. The weld should be held pending disposition rather than accepted. The examiner should obtain the referenced standard's acceptance criteria and apply them; if the indication is rejectable, the weld is marked for repair or further evaluation according to the procedure.
If the criteria cannot be resolved without the client's inspector, the coordinator should escalate and document the hold. The client's inspector should review the indication record and the applicable criteria before any acceptance decision.
Documentation should include the examination report, the indication record, the standard and revision applied, the disposition decision and its basis, the identity of the person making the decision, and any repair or re-examination results. If the weld is repaired, the repair should be re-examined with the same technique and the results appended to the record.