Serviceability assessment and sensitivity analysis of cast iron water pipes under time-dependent deterioration using stochastic approaches

Determination of the depth of the corrosion pit is essential to predict the serviceability of corrosion affected pipes and to instigate maintenance and repairs for the pipeline system. In this paper, a reliability-based methodology for serviceability assessment of corrosion affected pipes is presented. The depth of corrosion pit is considered as the critical parameter that causes serviceability failure when it is greater than the wall thickness of the pipe. A stochastic model for corrosion depth of cast iron pipes is developed and a time-dependent method is employed to quantify the probability of serviceability failure so that the time for the pipeline to be unserviceable and hence requiring repairs can be determined. A sensitivity analysis is also undertaken to identify the factors that affect the failure due to corrosion. The methodology presented in this study can be used as a tool for infrastructure managers in different industries such as water distribution systems, oil and gas pipelines, sewer networks, etc. The methodology can help pipeline engineers and asset managers in making decisions with regard to the serviceability of corrosion affected pipelines both for assessment of existing systems and for designing new pipelines.