Keeping product moving during a major Canadian pipeline intervention

Across Canada and the wider North American pipeline network, operators are being asked to deliver more from existing assets while preparing infrastructure for a changing energy mix. Large-diameter liquids pipelines remain central to security of supply and economic activity; however, many were built decades ago and now require increasingly complex integrity, modification and valve replacement work. The challenge is not simply technical as maintenance and repair must be completed safely, predictably and within ever shrinking scheduled line maintenance windows, while minimising throughput disruption and reducing venting, drain-up or purging large pipeline volumes.

For major midstream operators, planned interventions and isolation on high-capacity systems can have commercial consequences well beyond project execution costs. Even short, unplanned outages can result in financial penalties for the operator and risk security of supply to customers. This has increased demand for pressurised pipeline isolation, hot tapping, line stopping and bypass services that allow essential repair or replacement activities to proceed while the line remains operational.

STATS Group has seen this trend accelerate across North America. The BISEP® line stopping technology is designed to provide leak-tight double block and bleed isolation through a single hot tap intervention, with an integrated bypass arrangement that can maintain pipeline flow during sectional isolation. The system is DNV type approved, is available for 3” to 56” pipelines and uses an internal hydraulic circuit to activate dual elastomer seals that can be independently tested and monitored before and during the intervention. The dual seals radially expand against the pipe wall and create a leak-tight active seal, compared to passive lip seal technology. The pipeline pressure acting against the BISEP pressure head offers a fail-safe feature, maintaining isolation integrity independent of the hydraulic control circuit.

Lip seal technology relies on pipeline pressure to keep the seal engaged with the pipe and risk pressure fluctuations degrading the seal performance thus increasing the risks of the passive seal becoming disengaged or increasing the already “manageable leak”.

The scope centred on a 48” liquids pipeline forming part of one of the largest pipeline systems in North America. The line, originally constructed in the early 1970s, is a critical high-throughput asset and had seen only limited line stop activity in its operating history. Previous isolations on the pipeline were completed during the mid-2000s at comparatively low pressure using older passive lip seal line stopping equipment.

In 2024, the operator completed its first single BISEP isolation with bypass on the system to complete a 48” valve repair. Building on that experience, the latest intervention required a double BISEP isolation with integrated bypass to facilitate removal of a 48” valve that no longer served its original purpose and replacement with a new pipe section. For the operator’s North American assets, the scope represented the first 48” double isolation with bypass of its type in Canada.

The operating driver was clear: the line needed to continue throughput while the maintenance team completed the valve removal and tie-in work. A complete shutdown, or an extended outage to accommodate traditional isolation methods, would have substantially increased operational complexity, risk and cost. The selected strategy therefore combined hot tapping, leak-tight double block and bleed line stopping with a temporary bypass, giving the operator a controlled isolation envelope while maintaining flow.

From the outset, the project required close coordination between STATS and the operator, with the execution plan developed collaboratively and refined over several months ahead of the final intervention. STATS supplied the split tees, while the operator installed them on the pipeline. STATS then supplied its double block and bleed slab valves, completed the 48” hot taps using the SureTap® ST1530 hot tapping machine, and mobilised the BISEP tools and field technicians for the isolation and bypass operation.

The ability of the BISEP to provide a tested and proven, leak-tight dual seal isolation that can then be monitored was central to the strategy. Traditional line stop technologies can depend on passive sealing arrangements and may require additional barriers to manage uncertainty around seal leakage. In contrast, each BISEP seal can be proved independently against pipeline pressure in the expected direction of differential pressure. Once the isolation is achieved, the annulus between the two seals is bled and monitored, creating a verifiable zero-energy zone between the live pipeline and the worksite.

This provided two important advantages. First, it gave the operator confidence that the isolation envelope was secure before draining up and cutting into the pipeline section between the BISEP tools. Second, it allowed the temporary bypass to be operated maintaining line flow rate and avoiding an interruption to service during the valve removal. During bypass operation, the bypass line was flowing at approximately 4000 m3/hr at around 300 psi.

The project was staged to reduce risk during the final intervention, as well as maximise the resource availability of the maintenance crews assigned to the execution plan. The week before the tie-in, STATS installed the slab valves and completed the hot taps. This enabled the BISEP line stop tools to be prepared and installed ahead of the repair window, while the operator fabricated and assembled the temporary bypass piping between the two 48” BISEP assemblies.

All assets were assembled, the complete bypass system including BISEP tools were pressure tested at line operating pressure. The system was then flooded from the operating line the day before tie-in execution, ensuring that the bypass was ready for service and reducing the number of critical activities required during the main work window.

On the day of execution, with the pipeline still operating, STATS lowered the BISEP tools simultaneously and diverted flow from the normal flow path into the bypass. Once the BISEPs were set and the seal integrity confirmed, STATS issued the Isolation Certificate. The maintenance crew completed drain up on the isolated pipeline section between the two BISEP tools, removed the 48” valve and installed a pretested replacement pipe section.

Following welding and non-destructive examination, the operator flooded the newly installed pipe section and equalised pressure across the isolated area. STATS then unset and retracted the BISEP tools, returning flow from the bypass to the normal flow path. Completion plugs were installed in the split tee completion flanges, allowing the slab valves to be removed and blind flanges bolted onto the 48” split tees.

The full execution period, from isolation to restoration of normal line operation, was completed within the planned 48-hour window. For a critical 48” asset operating at significant flow, the ability to complete the valve removal and replacement without interrupting throughput was a key measure of success and eliminated a potential 96 hour line outage using the traditional methods.

The project demonstrated that the value of high-integrity isolation extends beyond the immediate avoidance of an outage. The dual seal configuration provided a predictable, monitored barrier that gave the operator confidence to reduce reliance on secondary vapour management measures commonly used to compensate for leaking or uncertain isolation seals. By shortening the distance between the BISEPs and allowing the seals to perform as the primary isolation barrier, the operator could reduce the extent of excavation and backfill, simplify site activities and limit the use of temporary barriers that add time and introduce additional operational risks and project costs.

In this case, bringing the split tees closer together helped reduce excavation and backfill requirements by approximately one third compared with alternative isolation approaches. Avoiding traditional mud plug use or eliminating the need to track and receive vapour tool pigs also removed associated cost, schedule and risk from the work scope. The commercial case for the BISEP with integrated bypass was therefore based not only on uninterrupted flow, but also on a more streamlined construction and reinstatement sequence.

Environmental performance was also improved. Hot tapping and line stopping reduce the need to depressurise long pipeline sections, displace large product volumes or vent hydrocarbons during maintenance. On gas systems, avoiding venting can prevent significant greenhouse gas releases; on liquids lines, the benefits include reduced product handling, reduced waste generation and a smaller operational footprint. For operators under pressure to maintain supply while demonstrating responsible asset stewardship, these benefits are increasingly important.

For future work on ageing and high-demand assets, the project points to a broader shift in how operators can approach maintenance. Rather than viewing isolation as a constraint that forces extended shutdowns, high-integrity line stopping and bypass methods can make isolation an enabling technology. They allow repairs, valve repairs or replacements and tie-ins to be planned around safety and asset integrity requirements without automatically sacrificing throughput.

For pipeline owners facing ageing assets, increasing throughput demands and tighter expectations around safety and environmental performance, this approach offers a compelling option. High-integrity isolation is no longer simply a specialist service for exceptional circumstances, it is becoming a core maintenance strategy for operators that need to manage pressure, minimise risk and extend the reliable life of essential pipeline systems.