Design and development of a robotic crawler to inspect pipelines using Electromagnetic Acoustic Transducer (EMAT)

In this paper, we propose the usage of Shear Horizontal (SH) guided waves for internal pipe inspections, offering the possibility of rapid inline scanning. The design and development of an Electromagnetic-Acoustic Transducer (EMAT) probe integrated with a robotic crawler are discussed in detail. The present work embraces mounting, excitation/reception and data analysis of the EMAT probe. The present work reports a pipeline inspection system consisting of SH-guided waves probes attached to the crawler‘s linkage arm, which expands with the help of a linear actuator, allowing minimal contact with the inner periphery of the pipeline. The EMAT probe transmits and receives axially polarised SH-guided waves propagating in the circumferential direction; simultaneously, the crawler onto which the probes are installed, moves axially into the pipeline. Each round-trip signal’s time of flight, in the form of SH-guided waves, is measured and monitored at every point of scanning, which assists in locating the flaws circumferentially inside the pipeline. The axial location of the defect is then identified using an independent wheel on the robotic crawler coupled with an encoder. The experiment demonstrates the proposed approach is presented in detail with analysis in the present article.