| 摘要 |
PROBLEM TO BE SOLVED: To achieve a total flaw detection, by arranging a plurality of vibrators at an interval by dimensions smaller than an effective beam width generated by a single vibrator in the axral direction of a cylindrical test object and shifting them by a value exceeding the width of the vibrators in the circumferen tial direction thereof. SOLUTION: The first group of vibrators 11a-11c and the second group of vibrators 12a-12c are arranged at an interval (n) shifted exceeding dimensions equivalent to width dimensions (m) of the vibrators 11a-11c and 12a-12c in the circumferential direction of a steel pipe 5 and at an interval P smaller than an effective beam width X1 in the axral direction of the steel pipe 5. Therefore, the effective beams X1-X3 formed by the vibrators 11a-11c in the axral direction of the steel pipe 5 are closely overlapped. In the automatic flaw detection, the probe and the steel pipe 5 are relatively moved so that the track of the effective beam width of the probe spirally scans the surface of the steel pipe 5. The first group of vibrators 11a-11c and the second group of vibrators 12a-12c may be arranged and shifted in the circumferential direction by the relative spiral movements of the probe 10 and the steel pipe 5. |
