Condition assessment of water pipelines using a modified layer-peeling method

© 2018 American Society of Civil Engineers. Pipe wall condition assessment is critical for targeted maintenance and failure prevention in water distribution systems. This paper proposes a novel approach for condition assessment of water pipelines by adapting the layer-peeling method. This method was previously developed for, and applied to, tubular musical instruments. In the proposed approach, the impulse response function (IRF) of a pipeline is obtained using measured pressure traces resulting from transient events. The original layer-peeling method is further developed for application to water transmission pipelines by (1) modifying the end boundary from being an acoustic source tube to a closed valve; (2) incorporating the effects of unsteady friction and pipe wall viscoelasticity into the layer-peeling algorithm; and (3) incorporating frequency-dependent wave reflections and transmissions. Using the IRF and the modified layer-peeling method, the impedance of a pipeline can be estimated section by section from downstream (the dead end) to upstream of the pipeline. The distribution of wave speeds and wall thickness can then be determined. In this study, numerical verifications were conducted using the pipeline pressure responses simulated by the method of characteristics (MOC). The deteriorated pipe sections (sections with changes in impedance) were accurately detected using the new approach. Experimental verification of the result was conducted on a laboratory copper pipeline. A short section of pipe with a thinner wall thickness was successfully detected.