Magnetic Particle Indication in a Seal Area
A supplier is performing magnetic particle examination on 25 API 6A valve bodies. The inspector observes a linear indication approximately 3 mm long in a sealing surface area on one body. The supplier's Level II examiner says the indication is acceptable because it is below the 4 mm recording threshold in the written procedure. The purchase order requires conformance to the applicable product specification and the supplier's approved procedure. The inspector notices that the examiner's certification card expired two weeks earlier. The body has not yet been machined to final dimensions in that area.
1. Should the indication be accepted as presented? Explain the reasoning, including the effect of the examiner certification.
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It should not be accepted as presented. The examiner's certification expired two weeks before the examination, so the examination cannot be attributed to a currently qualified examiner under the supplier's quality system. Separately, the 4 mm recording threshold is not necessarily an acceptance threshold; an indication below the recording size can still be relevant if it is in a critical sealing area and the applicable acceptance criteria address that area. The inspector should require re-examination by a currently certified examiner using the approved procedure, and should verify the technique, magnetization direction, and surface condition. Acceptance should be based on the applicable acceptance criteria for the seal area, not on the recording threshold alone.
2. If the indication is confirmed and exceeds acceptance criteria, what disposition path is appropriate?
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The body should be identified and segregated as nonconforming. The supplier should raise a nonconformance report and propose disposition under its approved quality system. Because the area is not yet at final dimensions, machining may remove the indication, but only if the approved repair or rework procedure permits it, the minimum wall or seal dimension is maintained, and the area is re-examined after machining. Weld repair, if used, must be qualified and approved for the material and application, followed by heat treatment if required and re-examination. The inspector should not allow a local grind-and-blend without confirming dimensional acceptance and re-test coverage.
3. What additional examination or documentation would you require before releasing the remaining 24 bodies?
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The inspector should confirm that all 25 bodies were examined by a certified examiner with current certification, using calibrated equipment and the approved procedure. If the certification issue affects the whole shift or lot, the examinations should be repeated or otherwise validated. The inspector should review the examination reports for technique, equipment identification, calibration status, and acceptance results, and should verify that any indications recorded were dispositioned. For the remaining bodies, a sample re-examination may be justified if process control is in question, but the primary requirement is that the original examination be valid. The release package should contain the corrected examination reports and the nonconformance disposition for the affected body.