| 摘要 |
PURPOSE:To detect a lateral flaw efficiently and accurately, by a method wherein a plurality of ultrasonic vibrators are arranged in concentric circles so that ultrasonic beam from the vibrators can cover whole circumference of a steel pipe. CONSTITUTION:Vibrator groups 201, 202... each comprising a plurality of vibrators 21, 22... are arranged in concentric circles of a pipe 1, thereby ultrasonic beam 3 can cover whole circumferential directions in outer and inner surfaces of the pipe 1. Since the ultrasonic beam 3 of a plurality of vibrators 21, 22... are oscillated in the pipe axial direction and covers whole circumference of the pipe 1, the pipe 1 or the vibrator need not be scanned in the rotating direction but a flaw of the pipe 1 can be detected during the travelling. The number of vibrators to be arranged is determined by the outer diameter of the pipe 1 and width of the vibrator. Size of the vibrator is determined by the amount of a lateral flaw to be detected and type of the vibrator. |
