Session: 07-04-01 Crack Management

Paper Number: 87372

87372 - Framework for Pipeline Stress Corrosion Cracking Susceptibility Using Inspection & Mitigation Results: A Bayesian Approach 

Stress Corrosion Cracking (SCC) is a form of cracking that occurs in pipelines caused by interaction of a susceptible material, tensile stress, and a suitable environment. Considering recent SCC failures in pipelines coupled with increasingly stringent regulatory requirements, it is imperative for a pipeline operator to have a robust and efficient SCC integrity management program. To accomplish this, it is essential for the program to not only integrate multiple interacting factors that influence the occurrence of SCC, but also cohesively incorporate field evidence from direct assessment, in-line inspection, hydrostatic testing, and opportunistic digs. This paper presents a framework based on Bayesian updating approach to incorporate multiple lines of evidence to estimate a more representative failure rate. Knowledge gathered from industry SCC management best practices and SCC susceptibility models  are used in conjunction with expert knowledge and in-line inspection findings to develop the framework proposed in this paper. The framework consists of three components; first, the SCC susceptibility component is established to quantify the SCC occurrence rate on a pipeline segment and to estimate the SCC failure rate due to this occurrence. This output can be used to develop a susceptibility/risk-based inspection plan by estimating the total number of SCC features and the expected number of excavations needed to address these features. Second, location specific field evidence is incorporated into the framework using Bayesian updating to refine the estimates of segment specific susceptibility. Third, expert knowledge is coupled with results from historical SCC excavations and estimated SCC occurrence rate to support risk-informed decisions in post in-line inspection excavations. Considering the potential of high number of false positives, the proposed framework would facilitate better utilization of the program resources by reducing unnecessary excavations. The approach provides a significant flexibility to easily update the susceptibility model at any maturity level of the program as additional data becomes available.

Presenting Author: Oleg Shabarchin Enbridge

Presenting Author Biography: Oleg Shabarchin is Integrity Reliability Specialist at Enbridge Gas Transmission & Midstream based in Houston, Texas. Oleg is a Professional Engineer, and he holds a Master’s of Science degree in Civil Engineering from the University of British Columbia (UBC). Oleg has more than 12 years of diverse experience in the Oil & Gas industry. His expertise is in pipeline & facility integrity assessment with application of probabilistic risk & reliability methods. His recent work is focused on predictive model development for corrosion and stress corrosion cracking to support informed decision making of Integrity Management Programs.