| 摘要 |
PURPOSE:To perform the flaw detection of a minute defect with good accuracy, by a method wherein a vertical flaw detection probe and an oblique angle flaw detection probe are provided to the outer circumference of a steel specials so as to form a predetermined angle on the basis on the center of siad pipe therebetween on a same plane and the defect of the rib of said pipe is detected by the vertical flaw detection probe while the defect of the matrix material part other than the rib is detected by the oblique angle flaw detection probe. CONSTITUTION:A vertical flaw detection probe 3 and an oblique angle flaw detection probe 4 are arranged to the outer circumference of the titled specials 2 so as to form an angle 4 on the basis of the center of said specials therebetween on a same plane and both probes 3, 4 are rotated at a same speed, for example, to a clockwise direction. During this time, a rib 1(1a-1d) is detected by the change in the flaw detection signal from the probe 3 is detected and the monitor gate circuit of the flaw detection signal from the probe 4 is closed after a predetermined time when the succeeding probe 4 approaches the rib 1 to prevent the interposition of the reflected wave from the rib 1. By this method, the oblique angle flaw detection of only the matrix material except the rib 1 can be performed with good accuracy. |
