Guided wave-based inspection technique for evaluating the structural integrity of Bitumen-coated pipelines

In ultrasonic testing of pipes by longitudinal ultrasonic guided waves, the insulation layer that covers the pipe largely affects the propagation of guided waves resulting in the loss of wave energy. Therefore, it is more convenient if the tests are done in pitch-catch configuration such that the transmitting probes are different from the receiving ones. In this paper, the possibility of detection of defects in insulated pipes using longitudinal guided waves is experimentally inves-tigated in a pitch-catch configuration. An angle-beam ultrasonic probe generates the L(0,1) guided wave mode in the insulated pipe and a similar probe picks up the signal at a distance of 2.5 m away from the transmitter. The two probes are moved together around the periphery of the pipe and the signals are collected at certain intervals. The test results are then shown as both A-scan signals and B-scan images. Presence of a defect in the pipe significantly affects the ampli-tude of the received signal and is easily detected in both A-scan signals and B-scan images.

کلیدواژه ها:

Ultrasonic testing ، guided wave ، coated pipeline ، longitudinal mode