Acoustic emission detection of underground pipeline leakage was studied. Several methodsof locating the leakage sources, based on attenuation and waveform analysis, weredeveloped and tested in site. The ability of extracting leakage signal from variousbackground situations was also evaluated and tested. The flowing mediums of the pipelineinvestigated are air, water, and industrial gases. Different size holes were drilled onthe over 100 m length research pipeline for artificial leakage sources. The real sourcesof industrial pipeline leakage are studied too. The differences between undergroundpipeline and above pipeline are compared such as acoustic influences by coating ofanticorrosion and earth. The waveforms of the leakage signals are studied to get betterunderstanding of the generation of the acoustic emission signal caused by the leakageand the influence of the signal propagation. FFT, Wavelet and neural network patternrecognition are employed to study the leakage signals and background noise. The locationprecision and the sensitivity of the acoustic emission detection are estimated by boththeory and experiment. The diameter, materials, thickness and the coating of thepipeline have different influence on leakage signal propagation. The sensitivity isstrongly depended on the pressure of the working medium and the size of the leakage. Forsome steel pipeline a leakage with 1mm diameter hole could be detected by a sensorplaced over 100m away from the leakage source. The error of the location can be betterthan 10% of the distance of two sensors. The results of theory analysis and experimentsshow the positive conclusion on the ability of acoustic emission detection ofunderground pipeline leakage.
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