Study On Pipeline Corrosion And Leak Detection Based On Acoustic Emission

Pipeline transportation is playing a more and more important part in national economy and modern enterprise, which is one of the five chief transporting industries with others like highway, railway, air-ferry and water carriage. And advanced non-destructive inspection technology is the key to insure safe and reliable operation of pipeline, as well as avoid environmental pollution. This dissertation mainly researched on acoustic emission corrosions and leakage detection technology for pressure pipeline.The present technology of acoustic emission detection is been studied. Based on the mechanism of AE generation and basic principle of acoustic emission, formation mechanism, waveform and spectrum features of AE crack and leak signals were analyzed according to the differences between sudden-signal and continuous signal. Simulated by Nielsen-Hsu lead broken, the AE crack signal of pipeline was researched. According to the phenomena and data acquired in real detection, AE crack signal attenuation during transmission process and the impact factors cased by time-difference measurement were analyzed, and compensation methods, such as changing the time parameters, measuring the actual velocity, and drawing the attenuation curve and so on, were put forward and certificated.The pipeline leakage was judged qualitatively and quantificationally from the pipeline leakage characteristics. The rule of pipeline leak AE parameters varying with size of the leaking point, pressure in pipeline, and propagating distance was studied in detail. The leak location error was analyzed, and correlation analysis method was used to acquire the leak position. Further more, wavelet analysis method was raised to wipe off noise, and was proved to be more effective.