Estimation of Leak Phenomena in Service Steel Pipeline System by Using Pressure Wave Propagation Field in Non-Steady Water Flow Conditions

This study proposes a novel method for pipeline leak detection by integrating Non-Destructive Testing (NDT) and Transient Test-Based Techniques (TTBT) using Digital Image Correlation (DIC). Pipe deformation induced by water hammers is measured remotely, and the strain energy stored in the pipe is determined from DIC-measured hoop strain changes. Water leakage causes energy loss and damping of water hammer-induced strain energy. Experiments conducted on an agricultural pipeline with three conditions—no leak, one downstream leak, and one upstream leak—demonstrated the effectiveness of this approach. Results show that DIC accurately detects hoop and axial strain changes due to pressure variations. Strain energy damping ratios were found to increase with downstream leak location, enabling precise leak detection. This remote and safe method is especially valuable for inspecting pipelines in inaccessible or disaster-prone areas, offering a significant advancement in leak detection technology.