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Nordstream AG finishes first underwater gas pipeline, and completes Russian section of second pipe

World Pipelines,


All three sections of the first of Nord Stream's twin 1224 kilometre natural gas pipelines have now been joined together underwater by hyperbaric tie-ins. The completed pipeline through the Baltic Sea will now be prepared for connection to the landfalls in Russia and Germany later in the summer.

The connection by hyperbaric tie-in of these three pipeline sections was successfully carried out at the two offshore locations. The connection of the Gulf of Finland and central sections took place off the coast of Finland at a sea depth of approximately 80 metres, and the connection of the central and south western sections off the Swedish island of Gotland at a depth of approximately 110 m. Each of the two "tie-ins" was carried out in an underwater welding habitat and was remotely controlled from a diving support vessel, the Technip Skandi Arctic. The specialised subsea equipment used to perform the tie-ins was provided by the PRS (Pipeline Repair System) pool, a pool of pipeline operators administrated by Statoil. The construction work was supported by teams of divers, who were present at all times to ensure that the equipment was correctly positioned and operated subsea.

Nord Stream's twin pipelines each consist of 101,000 12 m long 48 in. diameter concrete-weight coated steel pipes each weighing about 23 tonnes. The pipes of the first line were welded together on board special pipelay vessels and laid on the seabed along a precisely defined route which had been agreed with the authorities of the five countries through whose waters the pipeline passes: Russia, Finland, Sweden, Denmark and Germany.

The company has also completed the construction of Line 2 of the Nord Stream Pipeline in Russian waters and has resumed pipe laying in Finnish waters. Over 230 km of Line 2 have now been laid in the Baltic Sea, 124 kilometres of which are in Russian waters. Simultaneously, Saipem’s Castoro Sei is laying pipes in the Gulf of Finland as well. Line 1 has been completed and will be put into operation in the fourth quarter 2011.

On the Russian shore in Portovaya Bay near Vyborg, construction of landfall facilities for both pipelines and pressure tests have been completed in June. Herewith, the main scope of work on Nord Stream’s Russian section consisting of the 1.5 km dry part and 124 km offshore part has been finalised.

When both lines are fully operational by the end of 2012, the Nord Stream Pipeline will be capable of transporting 55 billion m3 of gas a year to Europe. No other major new pipeline with a capacity over 10 billion m3 is expected to come on-stream before 2015.

Read the article online at: https://www.worldpipelines.com/business-news/22062011/nordstream_ag_finishes_first_underwater_gas_pipeline_and_completes_russian_section_of_second_pipe/

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