Detectability of single and plural flaws by ultrasonic testing

An outline and up-to-date test results of an eight year project of proving tests on the effectiveness of in-service inspection is described in the first part of the present paper. Effects on the detectability of such testing parameters as refraction angle, thickness of stainless steel cladding, inspectors, standard flaws in reference specimens, stress state subjected to defects are discussed. This is followed by a discussion of detection reproducibility, resolution and accuracy of inspected size of a defects. The latter part of the paper deals with up-to-date results of tests on resolution and shape determination of propagating adjacent and co-linear fatigue cracks by ultrasonic examination. It was found that real lengths of fatigue crack and EDM surface notch will be roughly estimated by 12 dB and 8 dB down methods, respectively. It is also concluded that the 10 dB down method is available for estimation of the inside distance of two co-linear surface cracks