Ettrick Field - North Sea
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T.D. Williamson SA, a leading supplier of pipeline services and equipment, has performed a successful "hot tap" operation for Acergy. This subsea operation was carried out on a gas pipeline in the North Sea to facilitate tie-in of the Ettrick Field gas export pipeline operated by Nexen Petroleum U.K. Limited, in order that gas can be exported to the onshore gas plant north of Aberdeen, UK.
What makes this hot tap project particularly impressive is that throughout the operation a prevailing pipeline operating pressure of 117 BarG was maintained, and that it was undertaken at approximately 94 meters (311 ft.) sea depth.
The entire hot tap operation was carried out safely, with no production downtime. While the offshore hot tap operation was completed in very little time, the planning and preparation contributed by T.D. Williamson to the project was extensive.
Testing and Offshore Supervision Contribute to Hot Tap Success
As primary contractor for the project, Acergy was responsible for providing engineering, procurement, installation and pre-commissioning of the hot tap assembly, and the temporary and permanent subsea structures.
Acergy awarded T.D. Williamson a contract to supply a comprehensive range of services to support the program. With its in-depth experience in hot tapping, T.D. Williamson was retained to engineer and supply all bespoke hot tap equipment. As part of the equipment development program, the custom-built equipment would be subjected to rigorous endurance testing as part of the factory-based trials phase. Working together with Acergy divers and support personnel during this phase, the team would build upon both parties' extensive knowledge of -- and experience in -- the hot tapping process. The company would also be responsible for overseeing the onshore System Integration Test (SIT). Finally, T.D. Williamson was to provide 24 hour on-site supervision of the divers throughout the offshore hot tap operation.
Offshore Supervision Provides Safety Cushion
T.D. Williamson provided invaluable on-site supervision of the dive team throughout the offshore hot tap operation. Working from the dedicated divers' support vessel, a team of experienced T.D. Williamson operatives were on-hand around-the-clock to offer guidance and monitor the divers’ progress to ensure that the operation was carried out in accordance with written procedures.
"I am pleased to report that every aspect of T.D. Williamson's work scope was performed efficiently and effectively, thanks to the expertise and dedication exhibited by the Hot Tap Project team," said Rutger Schouten, General Manager - Europe & Caspian Region for T.D. Williamson SA. "Working with Acergy to ensure that this challenging operation would be carried out safely required a great deal of care and attention to detail. The Acergy team's commitment to making the operation an outstanding success was evident, as they tackled this very precise and demanding process. The fact that the program was completed within the requisite timeframe for Acergy makes it that much more impressive. We are proud to have contributed to the success of this operation, and look forward to working with Acergy on future hot tap operations."