The effect of complex corrosion profiles on remaining wall thickness quantification using shear horizontal guided waves

Corrosion of plate and pipe structures is a major concern to many key industries, including power, maritime, and oil and gas. When there is a need to inspect large areas quickly or when access to the structure is limited, guided wave testing is often preferred over bulk wave measurements. In this work, shear horizontal guided waves are employed for wall thickness quantification. Specifically, the interaction of modes SH1 and SH0 with complex corrosion defects is investigated. The guided wave mode are selectively generated using a phased array-based approach. A pair of identical phased array probes are positioned before and after the simulated corrosion profile, to monitor the reflected and transmitted waves. The targeted mode is excited selectively using a 32-element 3 mm pitch array and guided wave modes are decomposed after a 2DFFT is performed. The cut-off frequency technique using mode SH1 is shown to be adequate when smooth wall thinning defects are considered. When sharp pits are present, mode SH0 proved sufficient to determine the pits depth.