Leak location identification of water pipes using elastic waves

Leak noise is a good source to identify the exact location of a leak point of underground water pipelines. The necessity of long-range detection of leak location makes to identify low-frequency acoustic waves. Acoustic wave propagation coupled with surrounding boundaries including cast iron pipes is theoretically analyzed and the wave velocity was confirmed with experiment. An experimental water pipeline, which is about 120 m, was installed. The leak locations were identified both by the acoustic emission (AE) method and the cross-correlation method. In a short-range distance, both the AE method and cross-correlation method are effective to detect leak position. However, the detection for a long-range distance required a lower frequency range accelerometers only because higher frequency waves were attenuated very quickly with the increase of propagation paths. Two algorithms for the cross-correlation function were suggested, and a long-range detection has been achieved at real underground water pipelines longer than 300 m.