Reliability Evaluation of Corroding Pipelines Considering Multiple Failure Modes and Time-Dependent Internal Pressure

A methodology is developed to evaluate the annual failure probabilities of a pressurized pipeline at an active metal-loss corrosion defect. The methodology takes into account three different failure modes at the defect (i.e., small leak, large leak, and rupture) and the time dependency of the pipe’s internal pressure by modeling the pressure as a simple stochastic process consisting of a sequence of independent and identically distributed random variables, each occupying a period of one year. The impact of periodic maintenance actions on the failure probabilities is incorporated in the methodology. Two numerical examples are used to illustrate the methodology. The sensitivity of the calculated failure probabilities with respect to the time dependency of the internal pressure is also investigated.