Nondestructive evaluation of corrosion in pipes with composite coating with the finite element simulation of guided wave propagation

This study aimed to propose an NDE method based on the guided wave propagation for assessing the thickness loss (corrosion) in the metal pipes coated with composites. First, the finite element model of a steel pipe with the thickness of 4 mm and diameter of 200 mm coated with a layered composite material was developed, in which the composite coating constituted by the chopped strand glass fiber mat and woven roving glass fiber cloth layers. Then, the fundamental antisymmetric guided wave mode with the frequency of 100 kHz was propagated in the longitudinal direction of the structure and the phase velocity of the propagated wave was measured in specimens with different corrosion extent in the steel pipe. In the first step, a uniform corrosion was induced throughout the pipe, and in the next step, it was induced in a part of the pipe with a specific length and circumferential angles of 90, 180 and 360 degrees. It was shown that the reduction in the wave phase velocity in the corroded regions compared with the intact regions was between 9% to 33% for different corrosion extents. Besides, the detection of the corrosion in the steel pipe and its location and extent was properly performed using the guided wave propagation method. It was concluded that the simulated guided wave propagation method can be used as a virtual lab for the development of methods for nondestructive evaluation of pipes coated with composites and detection of the location and extent of corrosion in them.