Study on inspection capability of ultrasonic testing for fatigue crack in piping

Ultrasonic testing (UT) technique is widely used as an in-service inspection (ISI) method, to assure the integrity of nuclear safety power plant components. It is understood that detection and sizing are the key roles of inspections, because evaluation of the components necessitates such data as flaw size and distribution of flaws.Therefore, reliability or accuracy of the inspection is most important. However, data on inspection capability in terms of detection and sizing had not been necessarily sufficient.In Japan, comprehensive research program has been carried out, in order to verify UT performance on both detection and sizing since 1995. In this program, various types of specimens with realistic flaws were manufactured to be used in UT trial for detection and sizing with multiple inspection teams. They were eventually destructed for flaws to be investigated, and detectability and sizing accuracy of UT were evaluated.In this paper, results of UT verification test regarding to carbon steel pipes specimens with fatigue cracks are presented. The results of the tests, it was verified that UT had relatively high performance on flaw detection and sizing for fatigue cracks. (author)