| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect a planar defect existing within a welded part of a steel pipe with a probe. SOLUTION: An ultrasonic flaw detector performs the ultrasonic flaw detection of a planar defect 4 in the weld part 3 of a welded steel pipe 1 by using an oblique probe 5 attached to the outer peripheral surface of the steel pipe. The ultrasonic flaw detector is provided with a flaw detection refraction angle calculating means 11 for calculating the flaw detection refraction angleθof ultrasonic wave made incident on the steel pipe from the oblique probe based on ratio (t/D) of the wall thickness to the outside diameter in the steel pipe, a distance calculating means 14 for calculating a distance PWD between the planar defect 4 in the welded part and the oblique probe 5 by the flaw detection refraction angle and the outer diameter calculated by the flaw detection refraction angle calculating means, and supporting mechanisms 15, 17 supporting the oblique probe to the position which is calculated by the distance calculating means on the outer peripheral surface of the steel pipe and corresponds to the distance. COPYRIGHT: (C)2003,JPO
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