Pipe inspection system by guide wave using a long distance waveguide

Abstract

Nondestructive inspection of a high-temperature structure is required to guarantee its safety. However, there are no useful sensors for high-temperature structures. Some of them cannot work at temperatures over 50°C. Another concern is that it is too expensive to use. Therefore, a sensing system, which can transmit and receive an ultrasonic wave and travel a long distance using a long waveguide, has been studied. This means that an ultrasonic sensor could be driven at atmospheric temperature. Especially, the work was focused in applying the developed technique to a pipe which is used in a nuclear power plant. Therefore, the best rectangle-shaped wave-guide was studied and tried to wound the waveguide around a pipe to drive as an acoustic source of a guide wave. Finally, L (0,2) and T (0,1)-mode guide wave were detected successfully by devising the shape of the opposite edge of the rectangle shaped waveguide and could detect the reflected signal from an artificial defect machined into a test pipe.