Acoustic injection method based on weak echo signals for leak detection and localization in gas pipelines

Underground gas pipelines are facing health and safety issues due to the material corrosion and equipment aging. Conventional acoustic methods may fail to detect and localize leaks in low and medium pressure gas pipelines because the sound of gas escaping from a leak source is usually too weak to be detected. In this paper, an active acoustic injection method is presented to stimulate specific frequency sound waves into the pipeline for leak detection based on weak echoes from the leak location. Further analysis is conducted on the relationships between the reflection coefficient and the size of the leak hole, the pipe diameter, the wall thickness of the pipe and the sound frequency. A signal reconstruction method is subsequently proposed to effectively detect and localize the echo signals. Finally, some experiments are carried out in a specially constructed gas pipe. Field test results indicate that a leak localization accuracy of 0.1 m can be achieved by the proposed method, which may be beneficial to practical leakage detection in gas pipelines.