Guided wave inspection penetration power in viscoelastic coated pipes

Ultrasonic guided waves have been widely studied for over a century. Applications in inspection, however, are recently receiving attention. Various ultrasonic guided wave techniques have been applied to pipe inspection. Greater penetration power of guided waves in pipeline is always desired for purposes of both non-destructive evaluation (NDE) and structural health monitoring (SHM). However, penetration power in coated pipe is dramatically reduced because of the viscoelastic characteristics of coating materials. In order to study the penetration power in coated pipe, the finite element method (FEM) is used in theoretical work. As very significant input data for FEM modelling, the viscoelastic coating properties are determined by both experimental tests and the theoretically driven fitting method. FEM models of different coating materials are presented. Various coating thicknesses of Bitumastic 50 coating are also simulated in ABAQUS®. A comparison of the theoretical calculations and FEM simulations is provided, producing excellent results and similarity. The differences in theoretical and experimental results are below 10% for various coating materials. For Bitumastic 50 material, the thickness influence is critical when the coating is thicker than 1 mm.