Study on simulation of non-destructive testing for pipeline defects by ultrasonic guided waves

The detection of defects in pipes is of very importance to the oil, chemistry, gas industry etc. The guided wave method that detects refection waves from defects is developed and proves to be effective. The disadvantages such as low speed and high cost in current non-destructive testing for defects in pipes, the influences of varying exciting frequency on the detection of defects are numerically simulated and analyzed both in straight and curved pipes. And the results suggest that, under the condition of certain wall thickness of pipes, the testing sensitivity increases at first as the exciting frequency increases along, and then it begins to decrease when the frequency arrives at a specific value. It is also concluded that the error in determining the defect locations increases too as the exciting frequency increases. These results have instructive significance on realizing long distance and rapid non-destructive testing for longitudinal ultrasonic guided waves in pipes. At last, the structure of ring transducer that can excite guided waves is also presented in the paper.