Risk-based reliability evaluation of multi-site damage in pipelines

In this paper, a probabilistic procedure is used to conduct local fracture evaluation of pipelines subjected to multiple cracking in service. Mixed-mode fracture mechanics is applied to a multiple cracking case of two non-coplanar parallel cracks in an infinite elastic solid plate under remote tension. A numerical simulation model is then used to determine the relation between the proximity of the cracks interacting tips and the conditions under which they may not coalesce. Based on these results, a Monte Carlo simulation model is then applied to establish a correlation between the existing population of cracks configuration and the reliability of pipelines affected by multi-site damage (MSD). Thus, the relation between failure probibility and pipelines serviceability is investigated. It is concluded that the maintenance strategies used to optimize safety for pipelines could be based on a probabilistic analysis that permits risk assessments associated with the pipelines operating decisions as well as the type and frequency of inspection done to ensure continued safe operation of these lines.