| 摘要 |
PURPOSE:To detect the vertical seam welded part of piping and other flaw with high accuracy by transmitting ultrasonic waves in a direction of a specific angle with respect to the advance direction of a pig by an ultrasonic probe. CONSTITUTION:The transmission direction of ultrasonic waves is set to + or -45 deg. or + or -135 deg. with respect to the advance direction of a pig. The ultrasonic waves transmitted from probes 10a, 10b, 10c,... transmit through the pipe wall or surface of piping or helically propage therethrough and the flaw detection of the whole surfaces of a matrix, a vertical seam welded part and a circumferential welded part is substantially performed accompanied by the advance of the pig and the detected flaw is measured by a measuring device and the state and position of the flaw are stored in a memory device. During a change period from a state I to a state II, the flaw 36 of the matrix is detected by the probe 10b and, in the state II, the flaw 37 in the vertical seam welded part is detected by the probe 10a. The flaw 38 of the circumferential welded part is detected by the probe 10a by the further advance of the pig. |
