Abstract: Pipe inspection is an important issue from the perspective of power plant thermal equipment safety. It is difficult to inspect pipe with the conventional non-destructive methods, because of a high temperature and a limited accessibility in the region. The fundamental torsional guided wave is very effective for long range crack of pipe inspection, because of its non-dispersive characteristics. In order to generate non-contact T(0,1) mode, array of fundamental torsional mode electromagnetic acoustic transducers(EMATs) is designed and developed. Using the transducer, T(0,1) mode is generated and detected in the thick-wall pipe with small diameter. By optimizing the element connections of array of EMATs, when the elements are connected in parallel, the generated signal energy not only can be improved, but also other modes can be inhibited. Meanwhile, the frequency response characteristic is tested and the artificial defect along the circumferential direction of the sample pipe is detected. The transducer can achieve identification and accurate location of crack in the circumferential direction of the sample pipe. This proposed method provides a certain foundation for generation and detection T(0,1) mode and non-contact detection of cracks in the pipe.

Key words: array of EMATs, guided wave, pipe inspection, T(0,1) mode