Gulf of Mexico gas pipeline valve upgrade complete 24 November 2014

Pipeline services specialist TD Williamson (TDW) is reporting the successful upgrade of valve systems at an unnamed operator's gas export pipeline offshore New Orleans in the Gulf of Mexico.

Working with this operator, TDW provides pipeline pressure isolation services under a global services contract entered into in 2012, using its remote-controlled SmartPlug tool to isolate pressure in pipelines and risers so that repairs or interventions can be carried out safely.

Bjørn-Olav Gilje, project manager for TDW, explains that, initially, TDW was required to isolate a 16-inch gas riser connected to "a major subsea gas pipeline network" to replace a valve.

He says TDW carried out engineering work, assembled the pressure isolation tool, and completed factory acceptance testing in mid-2012.

But plans changed when the operator decided to postpone replacement of the single valve so that three additional valves could be installed, and a launcher extension added to facilitate inline inspection tool runs.

In the event that the original valve did not meet the regulatory function requirements, TDW shipped the SmartPlug tool and the factory acceptance testing rig to Houston where they remained on stand-by for a rapid response during this interim period.

Gilje says that early this year it was advised that the planned isolation would commence in May, so the firm re-verified the project engineering, performed additional communication and pull tests, and executed a new in-depth factory acceptance test.

Working with the operator's team, 3,500 hours were invested in preparing for the isolation so that when the teams mobilised to the platform, they were fully prepared to execute the isolation.

With only essential personnel working on the platform, the SmartPlug tool was pigged for 18.28m into the riser toward its set location, with TDW using its remote-controlled SmartTrack system to track the tool's progress.

Upon reaching its set location, the tool was set into position. By 1 pm that night, the isolation was confirmed and certified. The riser was securely isolated against a pressure of 118 bar for 79 days.

During this 11-week period, the three valves were replaced and the launcher extension installed, to ease future inline inspections of the line.

"Because we worked in such close cooperation with this strategic partner, we developed an extremely high level of communication and understanding, which was essential to making the isolation a first-time run success," comments Gilje.

"As a result, the complex valve upgrade project and launcher extension installation were completed with minimal downtime, without disrupting production or supply to millions living on the Gulf Coast," he continues.

"The fact that it was achieved safely, without affecting the surrounding environment in any way makes it all the more satisfying," he adds.

Brian Tinham

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