Gas export from Norway to Britain gained a new channel on Monday when the last section in the pipeline between the Sleipner field in the North Sea and Easington was welded into place. Next year the entire 1200 kilometre long pipeline will be complete.
On Monday evening the last weld was verified on the southern section of Langeled, which connects the Sleipner field to Easington. The pipelay vessel Acergy Piper (formerly LB200) laid one pipeline from Sleipner and one from Easington, and on Monday the two end pieces were welded together by divers operating from the diving vessel Toisa Polaris.
The pipeline has been laid with a precision that enabled the two ends to be welded together without the need for a joining piece between the two pipes.
"Now that Langeled has been connected in one piece from Sleipner to Easington, Norwegian gas supplies to Britain can begin when the reception facility in Easington is ready in the autumn," says Anne Strømmen Lycke, Hydro’s asset manager for the Langeled project.
"From October the gas export will commence via Sleipner to Easington through the new export pipeline. This provides enormous market opportunities in Europe’s largest gas market, not least when the northern part of Langeled is complete and the export of gas from the Ormen Lange field begins in October 2007," says Lycke.
Successful welding operation
The welding operation on the southern section of Langeled was begun in April. Twelve divers have worked six hours at a time, spread across four shifts. The welding operation has been carried out at depths of between 72 and 84 metres.
To complete the last join connecting the two pipe ends, divers from ‘Toisa Polaris’ welded five joints on the pipeline at the Sleipner field.
During the welding a special preparedness system was used. A so-called habitat with the designation Pipeline Repair System was placed on the seabed, and after being emptied of seawater, the divers could work in an indoor environment with ordinary working clothes. The habitat system is owned jointly by Hydro, Statoil and Exxon Mobil.
"The welding operation went very well. Before the last joint was welded, we spent 48 hours measuring exactly to ascertain that the welding could be carried out without any joining section between the pipe ends. This is the largest operation we have carried out with this repair system," says Jan Henrik Hatlestad, Statoil’s project manager for the connection of Langeled.
"In spite of challenging operations involving a lot of lifting we have been able to complete the connection with no personal injuries or damage to the environment or equipment. We are pleasantly surprised how robust this system has turned out to be even under such extensive operations as this," says Hatlestad.
Pipe-laying in the North
At the same time as the southern end of Langeled has been welded together, the pipelay vessel ‘Acergy Piper’ is underway with pipe laying at the northern end of Langeled, from Nyhamna in the direction of Sleipner.
"Acergy Piper is on schedule and has laid 140 kilometres of pipeline so far," says Hydro’s Per Harald Hansen, who is design manager of the Langeled project. "Towards the end of the summer the pipelay vessel Solitaire will lay pipes for the last section in to the Sleipner field. In January next year, we can therefore commence a new welding operation, when the northern end of the pipeline is joined to the rest of the pipeline," he says.
Hydro is operator for Ormen Lange/Langeled in the development phase, while Statoil is responsible for the project management of the pipe-laying project. The project organisation is manned with personnel from both companies.