Advancement in understanding ultrasonic wave propagation in metallic pipes by simulation and experimental validation

Ultrasonic gauging and defect detection of metallic pipes is a multi-disciplinary task, as it has to be performed in situ and involves several difficulties due to their curvature, limited access and corroded/eroded surface roughness due to harsh operating conditions. This research paper focuses on the investigation of employing a focused piezoelectric transducer in an immersion pulse-echo (PE) mode to measure the wall thickness (WT) from the inner side of the metallic pipes and to detect defects in the pipes. This paper also provides advances for understanding ultrasonic wave propagation in metallic pipes by simulation study using modern finite element technology and validating the results experimentally using battery-operated, water-immersible, IP67-grade stand-alone two-channel ultrasonic instrumentation that can move inside the pipe under test in flowing liquids such as water or oil. A simulation model has been established for time-of-flight (TOF) measurements for metallic pipes with various wall thicknesses, detection of standard defects and wall-thinning by inspecting the inner diameter (ID) surface of pipes and the pipe filled with water. The simulated results for the metallic pipes are in good agreement with the experimental data, providing an accurate and quantitative assessment of WT in the presence or absence of defects.