Seamless gas segregation

STATS Group was contracted to perform hot tapping and line stopping operations for OQ Gas Networks (OQGN) on its 48 in. gas pipeline in Sur, Sultanate of Oman. This complex project involved deploying dual STATS BISEP® line stop tools to achieve a leak-tight double block and bleed isolation of a 150 m pipeline section, ensuring the safe and efficient integration of a new extension of Sur gas supply station. Gas flow was maintained continuously through an integrated bypass operating at 75 bar, the operation eliminated the need to shutdown and purge the entire 65 km pipeline, significantly reducing greenhouse gas emissions by preventing large-scale venting and flaring.

The integration of the extended gas supply station into the existing 48 in. pipeline was successfully completed without disrupting service to OQGN customers. By isolating the pipeline section and employing advanced hot tap and BISEP isolation technologies, the project team enabled safe, controlled modifications on a live system – ensuring uninterrupted gas supply and maintaining consistent pressure throughout the operation.

To support the project, STATS provided two 48 in. BISEPs each with a slab valve, split tee fitting and completion plug, rated to class 600. In addition, STATS supplied SureTap® hot tap machines and personnel for 48 in. and 2 in. tapping operations. 

STATS BISEP technology provides operators with pioneering hot tap installed line stopping capabilities to enable the safe and effective repair and modification of pressurised pipeline infrastructure. The patented BISEP provides a fail-safe double block and bleed isolation deployed through a single full bore hot tap intervention and is the only DNV Type Approved line stop tool. This verifies that the design criteria satisfy the requirements for Pipeline Isolation Plugs to provide dual seal and isolation in accordance with; DNV-OS-F101 (Submarine Pipeline Systems) and recommended Practices; DNV-RP-F113 (Subsea Pipeline Repair) and in compliance with code ASME BPVC Section VIII, Division 2. 

Prior to mobilisation to the worksite, all STATS supplied equipment undertook a client witnessed Factory Acceptance Test (FAT) at STATS operational facility in Abu Dhabi. All equipment was tested at maximum isolation pressure to meet operational requirements and ensure full compliance with safety and operational standards.

The work scope began with the excavation of a 150 m straight pipe section on the 48 in. pipeline, parallel to the new extension of Sur gas supply station. Once the excavation was completed, two split tee fittings were welded onto the 48 in. pipeline, one at each tie-in location and hydrotested to verify the integrity of the welded joints. Following successful testing of the fittings, STATS 48 in. slab valves and SureTap hot tap machine were installed. Hot tapping was performed at each location and the pipe coupon recovered, allowing the hot tap machine to be removed providing full bore access for the BISEP isolation tool. With access points created the 48 in. BISEPs were installed to the slab valves and a 50 m temporary bypass line was constructed and attached to the BISEP deployment launcher, ensuring continued gas flow once the BISEPs were deployed into the flowing pipeline. 

The BISEPs were hydraulically deployed into the pipeline and activated, each plugging head features dual elastomer seals that are compressed to radially expand against the inside of the pipe wall. Hydraulic activation allows for high integrity sealing, even in pipelines with internal corrosion, pitting or ovality issues. 

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Read the article online at: https://www.worldpipelines.com/special-reports/22052025/seamless-gas-segregation/