Acoustical characteristics and the detection method of leak sounds due to a damage in an underground gas pipeline

摘要

By examinations of acoustical characteristics of the leak sounds doe to a damage in an underground gas pipeline, detection methods of the leak position were studied. Frequency characteristics of the leak sounds out of the pipeline were shown as well as the frequency spectrums due to changes of diameters of the pinholes. Though the leak location in the pipeline could identify by sound intensity measurement on the ground surface, the detectability extensively depended on the depth of the underground pipeline from the surface. From measuring and analyzing frequency spectrums of the leak sounds propagating inside the pipeline, the existence of the damages as well as the situation of those such as pinholes or looseness of the joint between the pipes could be detected. It was shown that the cross correlation method using the time delay of the leak sounds measured at two distant points would be effective to detect location of the damage by analyzing sound attenuation in distance of the leak sounds in the pipeline.