Shear circumferential guided waves in coated gas pipeline

Shear circumferential guide waves propagating in the gas pipeline have been widely explored in recent years. Radial cracks in gas pipeline are susceptible to shear circumferential guide waves because there are no waves conversion when ultrasonic guided waves are reflected and scattered by such defects. The development of Electromagnetic Acoustic Technique (EMAT) now can easily excite different mode of shear circumferential guide wave for crack detection. Previous investigations of guided wave propagation in the gas pipeline have led to the development of pipelines inspection for bare pipes. However, most pipes in industrial are wrapped in coatings and the existence of the coatings will bring impacts to guided waves propagation. This paper focuses on the influence of the coating on the shear circumferential guide waves in gas pipeline. Dispersion curves and distribution of energy (displacement) along the radial direction of different wave modes are discussed. The work is crucial for optimizing the parameters of EMAT transducer.