engleski

Accreditation of Ultrasonic Thickness Measurement Methods – Practical Aspects

Basic requirement in accreditation of laboratories that perform ultrasonic thickness measurement is to provide evidence that method is performed according approved procedure. The most relevant general prerequisites are that NDT personnel have adequate certificates while instruments and equipment have to be traceable. In the process of accreditation these two unavoidable prerequisites could be tested by assessors in a very administrative way. Some remarks on assessment procedure will be presented in this paper. The comments are regarding to inspection bodies that prove implementation of the method and particularly about demands considering ultrasonic thickness measurement uncertainty. Given examples are mainly based on practice from Croatian shipyards and from process and petrochemical plants in which manual ultrasonic thickness measurement method is frequently and regularly utilized. Review on the extent of requests and criteria applied by assessors will be given, particularly concerning required certificates, referent standards, performance demonstration and measurement uncertainty. Final approval solely relies on assessors' (inspectors') technical competence and knowledge whereas NDT competence is not enough involved in procedure. Experience from practice shows that measurements are performed according to the procedure with reliable results but out of possible technical achievement. The results could be frozen by measurement capabilities depending on the assessors' competence. It will be evidently presented that professionals in the field are crucial in accreditation process and should be the part of the assessment team.

Accreditation; Ultrasonic; Measurement

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