Pipeline thickness measurement for in-line inspection using wholly stepped electromagnetic acoustic transducers

Pipelines are critical components in various industrial applications, responsible for the safe and efficient transportation of fluids and gases. However, over time, these structures experience a reduction in wall thickness due to prolonged service, which can significantly compromise their structural integrity. To address this issue, a rapid and non-contact method for measuring pipe thickness is proposed. This method utilises the angular velocity invariance of circumferential SH1 (CSH1) guided waves, generated by a wholly stepped electromagnetic acoustic transducer (EMAT), which is specifically designed for effective in-line inspection. The novel EMAT improves the excitation efficiency of the CSH1 mode, allowing the dispersive CSH1 mode to effectively collect information from both circumferential directions of the pipeline. Finite element simulations and experimental validation on a defective aluminium pipe demonstrated the method’s accuracy, achieving a relative error of less than 0.5%. This technique offers a contactless, reliable baseline for pipeline condition assessment, unaffected by lift-off, and significantly improves defect detection and real-time condition monitoring, making it suitable for potential robotic inspection applications.