Enbridge T-South Expansion Crossovers

Full-Flow Crossovers for Line Redundancy

In GTM Mainland, British Columbia, Lauren partnered with Enbridge to engineer the T-South Expansion Crossovers, a critical brownfield enhancement installing three full-flow crossover sites on the NPS 36/NPS 30 GTM lines (4BL1/4BL2 and 6AL1/6AL2) to enable seamless operational flexibility and redundancy in the Westcoast natural gas network. Providing multidisciplinary engineering, detailed design, and procurement support from 2018 through 2021, our team conducted vibration assessments, stress analyses, and site optimizations to integrate 762 OD crossovers between 762 OD and 914 OD mainlines, ensuring compliance with CSA Z662 and Energy Institute guidelines while minimizing disruptions in a high-stakes transmission corridor.

Integrating full-flow crossovers for enhanced mainline interconnectivity

This brownfield project delivered three strategically placed 762 OD full-flow crossover facilities linking Enbridge’s 30-inch and 36-inch mainlines, bolstering the T-South Expansion’s capacity and reliability through automated switching capabilities. Lauren’s structural engineering encompassed civil foundations, large-bore piping designs, and electrical/instrumentation for automation, complemented by comprehensive site plan reviews, hydraulics studies, flow-induced vibration analyses, control valve dynamic behavior modeling (DBM), and design guidelines. Additional scopes included AC mitigation studies, stopple/bypass investigations, operating procedures, field pressure test witnessing, and commissioning support, all engineered to facilitate efficient gas flows without compromising pipeline integrity.

Mitigating vibration and stress risks for compliant, high-performance operations

The T-South Crossovers navigated the intricacies of live brownfield integrations in a dynamic gas transmission environment, where Lauren applied rigorous Energy Institute vibration guidelines and CSA Z662 stress analyses to validate designs against fatigue and flow-induced failures. Addressing challenges like precise hydraulics for dual-line balancing and AC interference required iterative modeling and multidisciplinary coordination to optimize foundations and automation without outages. Our proactive approach—encompassing procurement packages and on-site witnessing—ensured seamless executions, reducing risks from high-velocity flows and delivering resilient infrastructure that upholds Enbridge’s safety standards and operational uptime.

What we delivered

Completed between 2018 and 2021 in GTM Mainland, British Columbia, this project demonstrates Lauren’s precision in brownfield pipeline enhancements for reliable gas delivery.

Infrastructure: Three 762 OD full-flow crossover sites with large-bore piping, civil structural foundations, electrical/instrumentation automation, and integrated hydraulics for NPS 30/36 mainlines.

End-to-End Expertise: Multidisciplinary engineering including site reviews, vibration/stress analyses, AC mitigation, stopple/bypass studies, and commissioning support.

Compliance and Optimization Focus: Validated designs per EI guidelines and CSA Z662, with DBM modeling and operating procedures ensuring vibration-free, redundant operations.

• Multi-discipline engineering
• Detailed design
• Procurement support
• Vibration analysis
• Stress analysis