Study on In-Pipe Corrosion Diagnosis System (Corrosion Estimation on Screw Parts Using a Surface SH Probe)

In diagnosing air-conditioning pipe deterioration, it is especially important to inspect screwed parts because their original thickness is thinner than that of straight parts and it is comparatively easy for leakage to occur if there is local internal corrosion. We examined a method of applying an ultrasonic test for the inspection, and proposed a method for detecting internal local corrosions of screwed parts and estimating the size and the position of corrosion with angle probe of surface SH waves. In this paper, we describe results of experimental analysis on the echo from screwed parts of pipes, and we show the method to detect the internal local corrosion and estimate the size and position by using the pipe-end echo. Finally, we describe the results of tests on artificial corrosion pipes and the limitations of this method.