THICKNESS MEASURING METHOD BY ULTRASONIC WAVE, AND INSTRUMENT THEREFOR

PROBLEM TO BE SOLVED: To provide a thickness measuring method by an ultrasonic wave capable of measuring easily and precisely a thickness of a material without removing a heterolayer, using an attenuation difference of the ultrasonic wave between the heterolayer such as a coating layer and the material, and an instrument therefor. SOLUTION: In this method of measuring the thickness of a steel pipe 21 having the coating layer 22 on a surface by the ultrasonic wave, echoes (multiple echoes) generated multiple reflection on the steel pipe 21 are selected out of reception signals obtained by transmitting an ultrasonic pulse into the steel pipe 21, and the thickness of the steel pipe 21 is found based on intervals thereof. COPYRIGHT: (C)2007,JPO&INPIT