Reliability based failure assessment of deteriorated cast iron pipes lined with polymeric liners

Abstract

Defects may appear or further develop in cast iron pipes lined with polymeric liners in the form of surface corrosion pits/patches, through-wall holes, gaps, longitudinal cracks, circumferential cracks and/or failed joints etc. This paper examines the performance of deteriorated cast iron pipes lined with polymeric liners using probabilistic analysis. The deterioration of lined cast iron pipes includes corrosion of cast iron pipes together with creep and creep rupture of polymeric liners. Various potential failure modes of lined pipes and the uncertainties of key physical parameters, including geometries, deterioration models and material properties of the pipe and liner, dimensions of the defects in the pipe and loading conditions etc., in probabilistic failure assessment of lined pipes are considered. The probability of failure of each lined pipe is calculated over its lifetime and a sensitivity analysis is also conducted to identify the most influential parameters on the failure probability of the lined pipe. It is found that the coefficients for the rupture strength and the creep retention factors of the liners are most influential on the probability of failure of the lined pipes.