Non-contact detection of leak-derived energy loss for an in-service pipeline system using digital image correlation

This study presents a novel method for no-contact detection of water leakage in pressurized pipelines using digital image correlation (DIC). This method focuses on pipe deformation caused by water hammers including leakage information, which combines the idea of transient test-based techniques (TTBTs) and non-destructive testing (NDT). Water leakage induces the hydraulic energy loss in pipelines and the damping of both water hammers and strain energy stored in pipe. We focus on detecting the leak-derived damping of this strain energy using DIC. In experiment, we measured pipe deformation due to water hammers with water leakage using DIC for an in-service agricultural pipeline system. Experimental cases included the conditions of no leak, one leak at downstream and one leak at upstream. As a result, DIC can detect the hoop and axial strain changes due to the water pressure changes in the in-service pipeline. Based on these DIC strain changes, we determine the strain energy of this pipe. The further downstream a leak location is, the greater the damping of the strain energy is. This study provides the non-contact method for detecting water leakage in the pipeline system, which enables us remotely and safely to inspect in-service pipelines that are difficult to access.