Invalid ultrasonic testing report on a newbuilding deck seam
At a newbuilding yard you are surveying the upper deck buttweld seams of a 62,000 DWT bulk carrier. The deck is 32 mm thick EH36. The yard's NDT subcontractor reports that 100% ultrasonic testing of the No. 4 seam is acceptable. The report is signed by a technician whose ISO 9712 Level II certificate expired three months ago. Your own visual examination of the same seam finds 1.5 mm undercut along 300 mm, a grinding mark over a repaired area, and a weld toe that has been painted over without your seeing the surface. The yard's quality manager says the technician has 20 years' experience and that the certificate is 'a formality'; the yard offers to re-issue the report under a certified supervisor's signature without repeating the test. The vessel's delivery is in 10 days. The repair procedure for the area proposes local grinding of any indication and re-testing by magnetic particle testing only.
1. Can you accept the ultrasonic testing report? Give your reasoning.
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No. The UT report is only acceptable if the procedure, the equipment and the personnel are qualified. A technician whose ISO 9712 Level II certificate expired three months ago is not currently certified for the method and level, so the report is not valid evidence of acceptability. My visual findings of undercut, a painted-over repair and a ground area also mean the surface has not been properly presented for examination.
The yard's offer to re-issue the report under a supervisor's signature without repeating the test would be a paper exercise, not an examination. I would reject the report and require the seam to be cleaned and re-tested by a currently certified Level II or III under a qualified procedure, with records traceable to the technician and equipment.
2. What repair and re-examination do you require?
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Because the concern is a possible planar defect in a 32 mm full-penetration buttweld, magnetic particle testing alone is not sufficient: MT finds surface and near-surface defects, not lack of fusion at depth. I would require excavation of the suspect area to sound metal, re-welding with a qualified WPS and qualified welders, and re-examination by UT, supplemented by MT or PT at the repaired surface.
The extent should not be limited to the one indication: the same welder and the same seam should be sampled over a longer length, and adjacent seams welded under the same conditions should be included, in line with the class rule's extended examination requirements. Final acceptance should be by UT after repair, not by visual appearance.
3. How do you handle the yard's proposal and the delivery pressure?
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I would tell the yard that the delivery date is not a factor in the acceptance decision, put the rejection and the reason in writing, and copy the class or recognized organization and the flag administration if the yard proposes to proceed. The nonconformity, the rejected report and the expired certificate should be in the survey file, with the date and the names of those present.
If the yard replaces the technician and repeats the test properly, the seam can be accepted on the new evidence; if it tries to close the report without re-testing, I cannot sign the certificate. I would also raise the NDT subcontractor's competence with the yard's quality manager, because the problem may affect other blocks.