Experimental Investigation on Characteristics of Leak Noise in Gas Pipeline Systems

Pipelines are essential elements in the daily operation of modern cities, but significant economic loss and environmental damage commonly occur because of pipeline leakage. The acoustic method has proven to be effective for leak detection and location in gas pipelines. However, very little is currently known about the characteristics of leak noise generated by different leak shapes, sizes, and pressures. Moreover, the feasibility of the acoustic method in the presence of complexities has not been closely examined. This study attempted to address these research gaps through an experimental investigation. A pipeline test bed with a length of approximately 100 m and an internal diameter of 150 mm was established, and was structured to permit different leak shapes (circle and rectangle), sizes ($\phi 1$, $\phi 3$, and $\phi 5$ for circular leaks; $2\times 1$, $2\times 3$, and $2\times 10\mathrm{mm}$ for rectangular leaks) and pressures (0.1 and 0.3 MPa). The cross-correlation method was used to locate the leakage. The results suggest that leak noise is mainly concentrated at low frequencies and was capable of being transmitted into the branch and across bends. It is likely to be the leak area that affects leak noise and the effect of leak shapes can be neglected. The leak was accurately detected and located with a sensor distance of up to 70.15 m when the bandpass filter was appropriately selected. The feasibility of the acoustic method to detect and locate leakages in complex pipelines was demonstrated.