Detection of internal crack growth in polyethylene pipe using guided wave ultrasonic testing

Despite the success of guided wave ultrasonic inspection for internal defect detection in steel pipes, its application on polyethylene (PE) pipe remains relatively unexplored. The growth of internal cracks in PE pipe severely affects its pressure-holding capacity, hence the early detection of internal cracks is crucial for effective pipeline maintenance strategies. This study extends the scope of guided wave-based ultrasonic testing to detect the growth of internal cracks in a natural gas distribution PE pipe. Laboratory experiments and a finite element model were planned to study the wave-crack interaction at different stages of axially oriented internal crack growth with a piezoceramic transducer-based setup arranged in a pitch-catch configuration. Mode dispersion analysis supplemented with preliminary experiments was performed to isolate the optimal inspection frequency, leading to the selection of the T(0,1) mode at 50-kHz for the investigation. A transmission index based on the energy of the T(0,1) mode was developed to trace the extent of simulated crack growth. The findings revealed an inverse linear correlation between the transmission index and the crack depth for crack growth beyond 20% crack depth.