Dispersion Calculation and Defect Detection of Guided Waves in Pipes

There is an urgent need for a convenient and fast defect inspection for aeronautical pipes and oil pipes. This paper investigated the flaw detection method for pipe-like structure in terms of guided wave technology. The dispersion curves were obtained by solving the dispersion equations in Matlab software. According to these curves, the optimal excitation modes and the corresponding frequency for experiment were determined. Combined with the data process and the defects-locating approach, a set of pipe defects detecting methods were given. Experimental results showed that the L(0,2) mode guided waves could detect the defects of a  2 mm through-hole in  25 mm stainless steel pipe, and the maximal detecting distance could reach up to 70 m; in addition, the corrosion in oil pipes could be found as well by adopting the T(0,1) mode guided waves.