Compliance without compromise

As urban expansion brings growing populations closer to historically remote pipeline corridors, legacy infrastructure must be reassessed, not only to maintain reliability, but also to comply with strengthened federal safety standards. In 2024, the US Department of Transportation’s Pipeline and Hazardous Materials Safety Administration (PHMSA) advanced this shift with significant revisions to the Federal Pipeline Safety Regulations. These amendments, responding to congressional mandates, National Transportation Safety Board recommendations, and extensive public input, introduced new integrity management requirements and tightened expectations for material traceability, periodic assessments, and reconfirmation of maximum allowable operating pressure (MAOP) for older, previously untested pipelines.

For one of North America’s major energy companies, these regulatory changes intersected with a rapidly transforming landscape. Decades of residential and commercial growth near two parallel 36 in. natural gas transmission lines (A and B) originally constructed in 1961 triggered new class location designations and, with them, a mandate to remediate the pipeline. To ensure compliance and uphold the company’s long-standing commitment to safe, reliable and affordable energy supply, the operator undertook a complex replacement project of line B involving 2 miles of new pipeline being laid and tied in. While line A was subject to a MAOP hydrotest, all activities were conducted while gas flow was maintained, ensuring a safe and reliable source of daily fuel to communities for cooking, heating, air conditioning, and other daily essentials.

Phase 1: pipeline replacement

The operator required two sections (North and South) of pipeline B to be safely isolated, allowing breaking of containment and a new section of pipeline, totalling 2 miles, to be installed comply with US Department of Transportation’s PHMSA’s requirement for class location changes. To enable this STATS deployed two 36 in. BISEP double block and bleed line stop tools at each location with an integral 30 in. bypass line to maintain product flow during remediation works (Figure 1).

To enable the BISEPs to be deployed, the operator excavated the pipelines and two 36 in. hot tap fittings were welded at each location, North and South. STATS installed their double block and bleed slab valves to the fittings and using their proprietary SureTap® hot tap drilling machines, cut access points into the pressurised pipeline at each location, recovering and removing the cut pipe (coupon). The slab valves were closed, allowing the hot tap machines to be depressurised and removed, with full bore access now provided, four BISEPs were installed (two at each location). The client then installed a 30 in. temporary bypass between the BISEPs at each location and the slab vales were opened allowing gas to flow through the bypass. While the pipeline was flowing (18 - 25 mph) and pressure at 882 psi, each of the four BISEPs were deployed into the pipeline and hydraulically set.

The simple hydraulic deployment of the BISEP ensures controlled setting of the dual elastomer seals and ensures leak-tight isolation even in pitted or corroded pipelines, ideally suited to ageing pipelines. During isolation barrier proving, each seal was tested independently with full pipeline pressure in the direction of the expected pressure differential, proving both seals of the double block isolation are leak-tight. A 2 in. hot tap was then conducted between the BISEPs in the isolate section, allowing the trapped gas to be vented and purged. Following successful seal proving, the seal annulus void is vented, closed and monitored confirming isolation integrity throughout the isolation period.

With isolation certificates issued for the North and South locations, the sections of pipe between the BISEP were cut and removed, allowing the newly constructed pipeline B to be tied-in and leak-tested (Figure 2).

Once the new line B was connected, packing, purging, filling, and equalisation activities were completed to commission the new pipeline. At this stage the BISEPs at each location were unset and recovered into the launchers, allowing gas flow to continue through the new line B. The slab valves were closed, allowing the launchers and temporary bypasses and old pipeline section to be vented and purged.

Read the article online at: https://www.worldpipelines.com/equipment-and-safety/04012026/compliance-without-compromise/