Protection of Underground Gas Pipelines From the Third Party Damage by On-Line Monitoring Using Piezoelectric Accelerometer

Abstract

While it is difficult to detect target signals, on-line monitoring remains the most reliable method to protect underground pipelines from the third party damage. To distinguish signals from a variety of white noises during remote pipelines monitoring, it is necessary to filter signals from unanticipated noise and to find co-relation among signals. In this paper, an on-line monitoring system based on local area network (LAN) is developed not only to detect a damage occurrence but also to find its location along the pipelines. For this purpose, an acoustic wave propagation model is generated along the gas pipelines, and signals based on the model are compared with experimental data. In modeling the wave propagation, auto power spectral density (APSD) and cross power spectral density (CPSD) processing methods are applied to distinguish damage signals from noises. To locate the damage point on the pipelines, signals from three different piezoelectric accelerometers are monitored, and compared with those from the proposed model. From the experiments, the number of sensors should be determined in accordance with the attenuation coefficient of signal. Also, the proposed scheme which combines APSD and CPSD processing methods is proved to be powerful in practical applications.