Probabilistic and Deterministic Approach to the Setting of In-Line Inspection Intervals

Abstract

All pipelines are susceptible to the possibility of corrosion damage. Corrosion is a time dependent process that leads to localised gradual thinning of the pipeline wall and if allowed to continue will eventually cause failure of the pipewall. Due to the progressive nature of corrosion the likelihood of failure increases with time. One means of mitigating the likelihood of such failures is to perform an in-line inspection using a metal loss detection tool. The frequency of inspection is an important parameter to operators since if it is too high, excessive costs will be incurred and if it is too low, failure involving loss of supply, threats to safety and the environment may follow. Operators therefore seek the optimum frequency. This paper describes a robust method for optimizing inspection intervals based on the use of structural reliability analysis.