Reliability of pipeline affected by corrosion and third parts

An approach to evaluate the structural safety of pipelines affected by corrosion and third parts is presented. This formulation is applied when the information about the corrosion state of the system is available. This information includes: the total number of detected corrosion defects, depth and length of each measured defect. The probabilistic model considers the detected and undetected corrosion, and generation of new corrosion defects over time. In other words, the model takes into account the corrosion state of the system and the quality of the inspection tool. The failure is defined by a safety margin that is evaluated in terms of pressure stress. The undetected defects and the generation of new defects are modeled by a Poisson process. The contribution of failure by third parts to the failure probability is taken into account in a simplified way. For this case the probability function is obtained from the reported failures. The proposed model is applied to a pipeline segment in which reliability indexes over time are represented in terms of reliability functions that characterize the probability distribution between failures.