Development on microwave nondestructive testing of a wall thinning inside a pipe by optimizing microwave probe and analyzing wall thinning profile

Sasaki, Kota*; Liu, L.*; Yusa, Noritaka*; Wakai, Takashi ; Hashizume, Hidetoshi*

This study reports the development of a new microwave probe for the NDT of wall thinning inside a pipe so that a microwave nondestructive testing method is applicable to pipes with a large inner diameter. Three-dimensional finite element simulations for the conventional flat-plate profile, the round chamfer one and the semi-elliptic one are carried out to optimize the profile of the microwave probe. The numerical simulation results show that a probe with an elliptic profile enables smaller reflection at the probes as well as much better single-mode propagation inside the pipe than conventional and round chamfer ones. Experimental verifications are carried out using specimens simulating pipe wall thinnings with various profiles, whose results demonstrate that the microwave probe with an elliptic profile provides better signal-to-noise ratio.