Inline-Inspection for Both Circumferential Cracking and Axial Stress Using EMAT Guided Wave

There is a persistent need to improve the inline inspection (ILI) technology to identify accidents before they occur. Circumferential cracks could be induced by land movement or extensive residual stress. ILI tools that can detect circumferential crack detection and measure bending stress are still lacking in the market due to limited research funding on this topic. PHMSA is preparing regulatory requirements for pipeline operators to detect circumferential cracking. The research and development of such inspection technology will help support this requirement.The main objective of Phase I of the project is to evaluate the performance and feasibility of using EMAT guided waves to inspect circumferential cracking and measure axial stress. Prototype EMATs designed for exciting optimal guided wave modes will be fabricated and tested in a pipe with manufactured defects. The sensitivity to the defects of different sizes will be evaluated. To simulate bending stress, a universal test machine is used to apply loading on a plate sample. The wave speed will be measured on the plate sample for different stress levels. The sensitivity and repeatability of using waves to measure the axial stress will be evaluated. The sensor module will also be conceptually designed based on the findings.