Fault detection in small diameter pipes using ultrasonic guided wave technology

Ultrasonic guided wave technology is one of the more recent developments in the field of non-destructive evaluation. In contrast to conventional ultrasonic, this technology requires exposing only the areas where the transducers will be placed, hence requiring minimal insulation removal and excavation for buried pipes. This paper discusses how this technology can be used to detect defects in pipes under different conditions. Here the experiments were performed on small diameter pipes (<5 cm diameter); which were bare pipe, buried pipe and bitumen coated pipe. The results were gathered to see the effectiveness of this technology in detecting defects. Experiments were conducted using two dry coupled piezoelectric transducers, where one of them transmitted guided waves along the pipe and the other received them. The transducers produced tangential displacement, thereby generating the fundamental torsional mode T(0,1). In order to assess whether having multiple transducers has any effect on the resultant waveform, the receiving transducer was rotated around the circumference of the pipe.