The mechanical integrity of industrial plants is evaluated based on fracture mechanics, and therefore flaw sizing must be performed as accurately as possible. Several techniques based on the ultrasonic testing method such as the tip echo technique, time of flight diffraction technique and so on, have commonly been used to estimate flaw height. However, they are not always applied to test objects easily and most of the results depend on personnel proficiency. In this study, a flaw sizing technology based on a B-scan image using a creeping wave probe was investigated.After availability of the technology was demonstrated experimentally, a handy scanner and evaluation software for practical use were developed, and the flaw sizing procedure for field application was proposed. Finally, some austenitic stainless steel welds with SCCs were examined in accordance with the procedure. As a result, a highly accurate estimate within an RMS error of 1mm was obtained and it is clear that misjudgment and/or measuring error due to personnel ability can be reduced.

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