Session: 03-62 Pipeline Technology Integrity

Submission Number: 185931

Implementation of Probabilistic Assessment Method for Pressure Management 

Metal-loss Corrosion and stress corrosion cracking (SCC) remain two of the most critical time-dependent threats to the structural integrity of oil and gas pipelines. Among available strategies for managing such integrity threats, in-line inspection (ILI)-based integrity management program has proven to be the most effective approach for mitigating these risks. This ILI-based integrity management program primarily hinges on two key decisions:

Feature assessment for dig prioritization – determining excavation timelines based on ILI-reported defect sizing considering the growth.

Pressure management for safe operation – establishing self-imposed pressure restrictions (SIPR) when mitigation cannot be completed on schedule and defining safe excavation pressure (SEP) to ensure safety during excavations.

Both decisions are inherently uncertain due to variables such as ILI sizing error, defect growth rates, material properties, and burst model assumptions. The traditional deterministic assessment approaches cannot account for these uncertainties explicitly and therefore produce outcomes that represent a proxy of reality. To address these challenges, TC Energy has advanced reliability-based (probabilistic) methods over the past two decades, integrating them into corrosion and SCC management programs across Canada and U.S. assets, where the regulations allow. These methods explicitly account for uncertainty while ensuring a consistent and regulation-compliant safety level. In 2022, TC Energy published a probabilistic approach for determining SIPR (IPC 2022-87252), demonstrating its advantages over traditional deterministic methods.

This paper presents the implementation of probabilistic methods for pressure management and validates proposed thresholds for SIPR and SEP through extensive analysis of full-scale testing and field dig data. Results confirm that these criteria maintain operational and excavation safety while delivering a unified safety standard across the integrity management program—from feature assessment to pressure management. By establishing a data-driven, reliability-based framework, this approach sets a new benchmark for pipeline integrity management, offering the industry a scalable solution to enhance safety, optimize resources, and strengthen regulatory compliance.

Presenting Author: Shenwei Zhang, TC Energy

Presenting Author Biography: Shenwei Zhang obtained his PhD degree in Structural Engineering from the University of Western Ontario in Canada before joining TransCanada in 2014. Currently he is a senior pipeline integrity engineer particularly focusing on the technology development associated with pipeline integrity and risk assessment. He developed advanced integrity decision optimization tools for corrosion, crack, dent and surface loading stress analysis used by TC Energy. He is one of the primary inventors of Psqr corrosion assessment model and won 2021 Global Pipeline Award. Psqr model has been adopted by the 2023 version of ASME B31G and CSA Z662. He has published more than 60 peer reviewed technical papers in the area of pipeline integrity.

Authors:

Shenwei Zhang TC Energy
Elvis Sanjuan Riverol TC Energy
Hannah Huang TC Energy
Jason Yan TC Energy