Bend Test Failures on an Otherwise Sound Weld
A 10 mm butt test piece in material group 1, process 111 (covered electrode), welded in the vertical-up position (PF), passes visual examination with no relevant imperfections. Radiography shows no unacceptable indications. However, on bend testing, two of the four bend specimens (two root bend, two face bend) show open defects exceeding the permitted size on the tension surface of the root bends. The welder argues the weld is sound because the radiograph was clean and the face bends passed. The examiner must decide the outcome and what it means for the qualification.
1. What is the correct evaluation of the test piece, and why does a clean radiograph not save it?
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The test piece fails. Each test method in EN ISO 9606-1 has its own acceptance criteria, and all required tests must be satisfactory. Bend specimens are evaluated on the tension surface; open defects exceeding the permitted size on the root bends are a failure regardless of the radiographic result. Radiography and bend testing detect different things: a planar root defect (e.g. lack of root penetration or root concavity cracking) can be missed or judged acceptable radiographically yet open up on bending. A clean radiograph is necessary but not sufficient.
The welder's argument that 'the face bends passed' is also wrong: the required set of bend specimens must all meet the criteria; partial success does not qualify.
2. What should the examiner do next, and can any part of the qualification be salvaged?
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Record the failure and the defect type/location, and do not issue a qualification for that test. The welder may be re-tested, but the re-test must address the cause - here a root-side defect in the PF position suggests a root fusion/penetration problem in vertical-up welding, so the re-test should use the same essential variables to demonstrate the problem is corrected. No partial credit is given: the qualification is all-or-nothing for the scope tested.
If the welder already holds other valid qualifications, those are unaffected; only the scope covered by this failed test is withheld.
3. The production manager asks whether the welder can nonetheless be put on the PF butt work 'because the radiograph was clean'. How do you answer?
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No. The qualification test is the evidence of competence; a failed test means there is no qualification for that scope, and production welding in that scope would be outside the welder's qualified range. A clean radiograph on a test piece is not a substitute for a passed qualification test, and it says nothing about the welder's consistency in production.
The correct route is re-test (or, if the employer has other qualified welders, reassign the work). Document the decision so the traceability of the qualification status is clear.