NORTH YORKSHIRE, UK -- Pipeline Engineering (PE) has designed and manufactured a series of 42-in. (107-cm) and 44-in. (112-cm) Solo Sealing Tools used on the Langeled pipeline, which is the world's longest large diameter underwater gas pipeline. The 1,166-km (725-mi), 44-in. (112-cm) pipeline has capacity to move up to 70 MMcf/d of gas from the Ormen Lange field in Norway to the UK.
The Solo Sealing Tool is a special pig developed to seal the ends of pipe subsea for in-situ pipe welding or pipe tie-ins. Both straight inflation and angled inflation methods were used on the pigs, as well as burst discs to equalize pressure across the pig. Other features of the tools used on Langeled included a high-strength steel body and Omnithane polyurethane inflatable sealing tyres.
For the subsea tie-ins, the Solo Sealing Tools were inserted into the ends of the pipe. The two ends of pipe were laid together so that they could be welded without using a joining piece. Pipe joining was carried out by lowering a "habitat" to the seabed. This habitat was then emptied of water and the pipe welding operation completed. The habitat system is owned by Norsk Hydro, Statoil, and ExxonMobil.
Where pipe spools needed to be joined together, they were first linked in drydock with the Solo Sealing Tools positioned at the end of the spool with an end cap. The pipe spools were then transported and positioned subsea. The habitat was deployed and the welding operation carried out.
PE supplied 25 Solo Sealing Tools. Once welding operations were completed, the tools were pigged from the pipeline, with some travelling in excess of 600 km (372 mi). The Langeled pipeline required the welding of 96,600 individually shaped sections of pipe. A majority were carried out offshore.
PE also supplied pigs for de-watering the pipelines from Ormen Lange. Prior to pipeline commissioning, water needed to be removed from the 240-km (149-mi) subsea loop. PE delivered two four-train articulated pigs and four singular pigs to complete the de-watering operation.