ZUG, Switzerland – The second of the parallel Nord Stream gas pipelines in the Baltic Sea has been completed, ahead of schedule.
Following pre-commissioning and commissioning, Line 2 should start transporting gas to markets in Europe toward the end of the year, as part of a fully automated twin-pipeline system capable of delivering 55 bcm/yr.
The last of the 99,953 steel pipes for Line 2 was fabricated by Europipe in Germany, concrete-weight-coated by Eupec in Mukran, shipped to the Slite yard on the island of Gotland offshore Sweden, and transported to Saipem’s Castoro Sei laybarge.
There it was welded onto the pipeline and lowered to the seabed on April 18. This action also marked completion of the logistics program for the project.
The two completed pipelines comprise a total of 199,755, 12-m (39-ft) long concrete-weight-coated steel pipes each weighing around 24 metric tons (26 tons).
They were laid by Saipem’s Castoro Sei and Castoro Dieci, and Allseas’ Solitaire. Castoro Sei performed close to 138,850 welds for both lines since starting work on the project in April 2010.
Both lines were laid in three sections. The Nord Stream partners designed the lines to operate without an intermediate compressor station: they have been developed with three different design pressures and pipe wall thicknesses as the gas pressure declines during the journey from Russia to landfall in Germany.
Pre-commissioning is already under way for Line 2. Each of its three sections will be flooded with seawater, cleaned and gauged, and pressure tested.
On completion of the pressure tests, these three sections will be connected by underwater hyperbaric tie-ins in May and June off the coasts of Finland and Sweden where design pressure changes from 220 to 200 bar (3,191-2,900 psi) and from 200 to 177.5 bar (2,900-2,574 psi) respectively.
Following de-watering and drying, the completed pipeline will be linked to the landfalls in Russia and Germany and put into operation toward year-end. Line 1 started transporting gas last November.