Development of Guided Wave Testing Technique for STPG370 Piping Using Cylindrical Electromagnets

Abstract

　We are developing a non-contact magnetostrictive guided wave transceive technology using ultrasonic guided waves for the inspection of long pipes. Our main target is a STPG370 pipe, which is often used inside insulation materials. In this study, we investigated a technique for transmitting and receiving longitudinal guided waves by magnetizing entire circumference of the pipe uniformly in axial direction using cylindrical electromagnets. Burst excitation field parallel to the pipe axis was applied to the magnetized part in the pipe to generate the longitudinal guided waves. A differential induction coil was used to receive magnetic signal due to the guided wave, and signal distribution around the circumference of the pipe was measured. As a result, it was confirmed that the longitudinal guided wave was uniformly distributed around the circumference of the pipe. Defect detection was also successfully demonstrated.