（Mechanical Science And Engineering College, Da Qing Petroleum Institute, Daqing, 163318）
Abstract：An experimental system is set up in a laboratory which is based on ultrasonic-acoustic emission inspection. Propagation characteristics of ultrasonic waves are studied under several defect conditions. The signals from the testing are analyzed with STFT and wavelet analysis methods. The result shows that the defects detected by AET can be located exactly with ultrasonic method, and that with UT we can get more defect information, which set up the basis for engineering application.
Keywords：Pipe，Acoustic emission，Ultrasonic，Wavelet analysis