12" Remote Tecno Plug, Onshore Production Station, New Zealand

At an onshore production station in New Zealand, STATS was contracted by OSD Pty Limited, on behalf of a national energy company, to avoid both.

The task was double block and bleed isolation of a 12 inch gas pipeline at an operating pressure of 72 barG, to allow the safe replacement of an ESD valve without shutting the pipeline down or clearing it of hydrocarbons.

STATS proposed a remotely operated Tecno Plug rather than a conventional repair, which would have required flaring the gas and nitrogen-purging the entire length of pipeline to make it safe to work on - adding significant time, cost and environmental impact. STATS' piggable isolation tools are non-invasive: unlike hot tap and line stop technology, they require no welding or cutting into the live line and leave no residual fittings or holes in the pipeline.

A STATS isolation technician visited the production station ahead of the workscope to carry out a site survey, gather critical information, complete a noise survey and help select the right tool configuration. The Tecno Plug was configured in a four-module arrangement, and before deployment it underwent a full Factory Acceptance Test in a purpose-built test fixture fabricated to simulate the client's pipeline - witnessed throughout by an independent verification body.

Once onsite, a team of four isolation technicians deployed the Tecno Plug and pigged it to its set location with MEG, passing through three ball valves and the production tee before reaching the 5D bend. The tool was set in position using through-wall communication, tracked and accurately positioned by an extremely low frequency (ELF) radio control system.

At location, the Tecno Plug was hydraulically set to activate its locks and dual seals. The seals were independently tested with full pipeline pressure in the correct direction to confirm leak-tight isolation, allowing the pipeline to be bled down to ambient from the platform launcher to the rear of the tool. The annulus between the seals was then vented to ambient to create a zero-energy zone, held through a 24 hour isolation stability period before the Isolation Certificate was issued.

With double block and bleed isolation verified, the valve replacement workscope went ahead safely. The Tecno Plug was constantly monitored and remained stable for the full seven day isolation period. A reinstatement leak test was then conducted against the new valve, the pipeline pressure was equalised, and the tool was unset and pigged back to the launcher for demobilisation.

STATS has a long-established track record delivering high pressure isolation services for major operators worldwide, and demand for that work is growing across the Asia Pacific region. This workscope is one of a number of safety-critical isolation projects STATS has recently completed there.