PURPOSE: To improve the property of close contact with a surface to be inspected and to improve the accuracy in detection of a defect of an inner peripheral curved part of a pressure vessel nozzle by holding an ultrasonic probe rotatably around the axis of rotation intersecting a contact surface perpendicularly, with a bearing interposed.
CONSTITUTION: After permanent magnet wheels 13a and 13b are set on a horizontal part A of a nozzle 2 and permanent magnet wheels 14a and 14b on a slant B, an angle of rotation of a support arm 21 is regulated so that an ultrasonic probe 23 can apply an ultrasonic beam to an inside curved part 4. In this state, the ultrasonic probe 23 is pressed on a radius part 5 by a cylinder 26, while the angle of rotation of the arm 21, the position in the direction of the nozzle axis of a flaw detector elevator stage 17 in relation to a frame 11 and the positions in the radial direction of an elevation part 20 and a joint box 30 in relation to the elevator stage 17 are controlled, with water supplied in the meantime. A running truck 10 is made to move round on the nozzle 2 with the ultrasonic beam applied to the inside curved part 4 from the probe 23, the position of the truck 10 is determined by each encoder and the position and degree of a defect are specified by using the data on the position of the truck.
HOSHIYAMA MUTSUO
KOBAYASHI KOJI
NARIMATSU AKITADA
