Non-Contact Detection of Water Leakage in Service Pipeline by Digital Image Correlation Method with Damping Coefficients

Abstract

In-service pipeline for a long time has accumulated damage, which is leading to water leakage accidents. It is necessary to detect the water leakage phenomena by non-destructive and non-contact method. In this study, we aim to detect the water leakage phenomena based on generated water hammer in service pipeline, which is monitored by non-contact image analysis. The experimental conditions are set to three cases, which is composed of non-leakage, the leakage 0.07 km away from the variable constant flow valve and the leakage 11.6 km away from the variable constant flow valve. In experiments, water pressure and pipe material deformation were monitored in exposed line. The deformation parameters are detected by the Digital Image Correlation (DIC) method, which is applied to lowpass filter. Subsequently, it is evaluated by damping coefficients. As results, the cyclicity in circumferential strain is correlated with the cyclicity due to water hammer. Damping coefficients are determined to increase in the following order: non-leakage, leakage 11.6 km away from the valve, and leakage 0.07 km away from the valve. Thus, the attenuation of circumferential strain is greater with leakage phenomena than non leak condition. This phenomenon can be described by the law of energy conservation within pipeline system.