Modelling and measurement of guided wave propagation in denso tape coated pipes

Ultrasonic guided waves are widely used for defect detection in pipelines. The procedure normally works in a pulse-echo principle where the shape and duration of the incident pulse is carefully controlled. However, the maximum sound output from existing long range ultrasonic transducers is limited, and this limitation of sound power output limits the inspection length in coated and/or buried pipes where sound energy is either absorbed by the coating or radiates into the surrounding material. Therefore, it is desirable to investigate and select a wave mode capable of propagating longer distances in a coated pipe thus reducing inspection time and costs. In this paper, acoustic properties of a Denso tape coated pipe are investigated. A set of experiments are carried out to measure the attenuation ratios of T(0,1) and L(0,2) wave modes in a wide frequency range. Theoretical predictions are also made through a semi-Analytical finite element (SAFE) method. The theoretical predictions are compared to the experimental data and good agreement is observed.