Estimating the diameter/thickness of a pipe using the primary wave velocity of a hollow cylindrical guided wave

A method for measuring the diameter/thickness (d∕t) of a pipe using a characteristic of a hollow cylindrical guided wave (HCGW) is presented. The HCGW is an ultrasonic guided wave propagating along a pipe. In the first part of this letter, we briefly show that the primary wave (first-arriving wave packet from an impulse source) of the HCGW achieves a faster group velocity for a larger d∕t. Experimental verifications were carried out for aluminum pipes (several different d∕t’s) using a laser ultrasonic method to generate the HCGW. The experimental results are in fairly good agreement with the theoretical prediction described.