電磁波伝搬特性を用いた金属管内の欠陥検出法

Abstract

Serious defects may occur in metallic tubes used in factories and power plants owing to long-term usage. Until now, various non-destructive inspection (NDI) methods have been proposed to prevent accidents caused by deformation. However, these conventional methods require longer detection times for very long tubes. Therefore, to overcome this limitation, we propose a new detection method using electromagnetic wave propagation characteristics. In the proposed method, metallic tubes are regarded as waveguides, and we can detect defects based on the propagating electromagnetic waves. To verify this method, we conducted experiments using a vector network analyzer. As a result, we found that the proposed method is effective for detecting defects such as foreign matter and cracks, and for estimating the location and direction of the cracks. Furthermore, the proposed method is effective even if there is a bend or a branch in the metallic tubes.