Corrosion-induced failures are common in cast iron pipes used in water supply networks. Over times, cracks may initiate from the corroded pits and grow when subjected to fatigue internal loading. When the particular region of the pipe loses its structural capacity, it will eventually lead to leakage or even pipe burst. Thus, it is important to perform permanent and real-time integrity monitoring on these pipelines. Distributed optical fibre sensors (DOFS) have been proposed to monitor the structural health of water pipelines for the last few decades. Most of the previous studies have shown that DOFS is effective in monitoring the condition of a pipeline subjected to static operating pressure. This paper aims to experimentally demonstrate the ability of distributed optical fibre strain sensor to monitor the fatigue crack growth along the cast iron pipeline subjected to pressure transient. The fatigue test was conducted using a large-scale cyclic internal pressure loading facility. The DOFS was instrumented on the pipe to monitor the condition of the pipe when subjected to internal pressure loading approximation of water pressure loading (operating pressure and pressure transient) experienced in the field. The measured response will show the potential application of DOFS for crack detection, as well as monitoring the fatigue crack growth along the pipe. The results confirmed that DOFS is able to enhance the detection of cracks along the pipe subjected to pressure transient.
- corrosion pitting
- distributed optical fibre sensors
- fatigue damage monitoring
- pressure transient
- structural health monitoring