Precision under pressure

Pipeline isolation during maintenance or modification activities remains among the most critical operations in the oil and gas sector. Conventional methods such as full depressurisation and venting, while reliable, have drawbacks including significant downtime, environmental emissions from flaring or venting hydrocarbons, and the potential formation of hydrates in subsea systems. In addition, operators often encounter difficulties isolating sections of their pipeline to facilitate essential maintenance activities when appropriate valves are absent from the line or not functioning adequately.

As an alternative, inline isolation plugs that provide double block and bleed (DBB) capabilities offer a safe and efficient approach by providing two independent sealing barriers separated by a zero-energy zone. This approach ensures the safe breaking of containment on pressurised systems in compliance with the highest industry standards. Achieving DBB in operational high-pressure pipelines without depressurising the system or section of pipeline requires specialised isolation tools.

The Tecno Plug^® inline isolation tool, developed by STATS Group, addresses this challenge by providing DNV Type Approved double block and bleed isolation through a combination of mechanical fail-safes, hydraulic actuation, and energised seal technology.

56 in. valve replacement without shutdown

A recent isolation project completed on a 56 in. crude oil pipeline in Saudi Arabia highlights the advantages that inline isolation tools can provide, enabling the safe replacement of a 56 in. scraper trap valve while production was maintained throughout the entire operation.

STATS was approached by a major client in Saudi Arabia requiring the replacement of a 56 in. scraper trap valve, with the critical condition that the work be completed without shutting down, draining, purging, and flushing the entire pipeline.

Following a detailed site survey and comprehensive engineering study, STATS proposed a custom-designed 56 in. Tethered Tecno Plug, tailored specifically for this application and designed to overcome challenges associated with non- standard scraper trap features.

Mark Gault, Vice President, Middle East at STATS Group, said: “This is the largest Tecno Plug in the history of STATS, highlighting a remarkable milestone in our capability to deliver safe, innovative, and large-scale isolation solutions for critical pipeline infrastructure. This successful project provided a safe and cost-effective double block isolation, resulting in no interruption to production and preventing a costly shutdown. The safe and efficient workscope was the result of advanced planning, dedication, and teamwork between STATS and client personnel.”

Tethered Tecno Plug isolation system

STATS Tethered Tecno Plug isolation system features two integrated isolation modules, both designed to deliver a fail- safe double block and bleed isolation. The first module is the Tecno Plug isolation tool, which features dual seals and taper locks. This plug is pushed with stem bars to the exact isolation location, in this case, the short pipe spool between the scraper trap valve to be replaced and the production tee.

The second module, known as the Door Plug, also features dual seals and taper locks. However, this plug replaces the scraper trap door and includes a bore through the centre of the plug that allows the stem bar to travel. Dual seals in the centre of the Door Plug maintain leak-tight isolation of the scraper trap while allowing the stem bar to travel forward and backward, moving the isolation Tecno Plug through the pipeline.

Each isolation plug (Tecno Plug and Door Plug) features dual elastomer seals separated by an annulus ring and a set of taper locks. The annulus void between the seals is used to independently test the seals with full pipeline pressure to verify that both are leak-tight before STATS issues an Isolation Certificate allowing safe breaking of containment. The annulus is also used to monitor the isolation and ensure the seals remain leak-tight throughout the duration of the work. The locks, which embed into the inner pipe wall, provide the grip required to secure the tool in place.

Read the latest issue of World Pipelines magazine for pipeline news, project stories, industry insight and technical articles.

World Pipelines’ December 2025 issue

The December 2025 issue of World Pipelines explores how the global pipeline sector is adapting to the energy transition, with a strong focus on CCS readiness, digital transformation, integrity management, and operational resilience. Articles span Asia’s CCS pipeline build-out, energy market dynamics, high-precision repair and integrity solutions, repurposing existing pipelines for CO2 service, cybersecurity, autonomous operations, and the shift from traditional to cloud-based training and competency frameworks.

Read the article online at: https://www.worldpipelines.com/special-reports/12122025/precision-under-pressure/