Pipelay Vessel Castoro Sei Takes Over Laying Nord Stream Pipeline in German Waters
Pipe Laying Ahead of Schedule
Sept. 26, 2010 | Zug/Rügen | The Castoro Sei pipelay vessel reached German waters off the island of Rügen today to continue laying the Nord Stream Pipeline. The Castoro Dieci, a second, smaller vessel specially designed to lay pipes in shallow waters, has laid 27 kilometres of the pipeline in the Bay of Greifswald. The Castoro Sei will recover this pipeline string and continue laying the pipeline towards Bornholm, Denmark. “The construction of both lines in German waters is progressing faster than initially planned,” said Dr Georg Nowack, Nord Stream AG Project Manager for Germany. “We are almost four weeks ahead of schedule.”
The laying-sequence requires the pipeline to be laid down and picked up again at several places. This operation is called “Abandonment and Recovery” (A&R). On September 19, the Castoro Dieci had sealed the pipeline with a so-called A&R-head and lowered it down on the seabed. The Castoro Sei now pulls the pipeline back up into the vessel’s main production line. The A&R-head is then removed and additional pipe segments are welded to the pipeline string. The Castoro Sei can lay up to 2.5 kilometres of the pipeline every day. By the second half of October, the Castoro Sei will have laid the remaining 55 kilometres of the 82 kilometres section in German waters.
The Castoro Sei started laying the pipeline in April this year in Swedish waters. Up to 330 people aboard the 150 metre long vessel work around the clock. During pipelay operations, the Castoro Sei uses a mooring system to position itself. A total of 12 anchors are placed by anchor handling tugs and taken in by high-powered winches. To avoid interference with ship traffic during anchor handling operations, a 3 kilometre safety zone is implemented around the Castoro Sei.
The second parallel string of the pipeline is currently being laid by the Castoro Dieci. The pipelay vessel will conclude its work on the Nord Stream project after abandoning the second string east of Rügen. The Castoro Sei will pick up this string in September 2011 and continue laying the second line. When both strings are completed in 2012, each will be 1.224 kilometres long. The Nord Stream Pipeline will then transport 55 billion cubic metres (bcm) of natural gas per year – enough to meet the needs of more than 26 million European households.
