Installation of the Nord Stream gas pipelines in the Baltic Sea is making good progress, with the first of the two lines reaching the landfall point on the Russian shore.
Saipem’s pipelay vessel Castoro Sei, moored 1 km (0.6 mi) from the coast, pulled the pipeline string ashore, and will tackle the second string next week. Construction continues of the 1.5-km (0.9-mi) onshore stretch of the pipeline, along with work on the landfall facilities.
The offshore program involves welding together 12-m (39-ft) long pipes each weighing around 24 metric tons (26.4 tons) into double joints to form a pipeline string, which is pulled ashore by means of an onshore anchored winch and a 121-mm (4.7-in.) diameter pull-in wire.
The pipeline string is laid in a trench, which will be backfilled up to the initial seabed level. This is to protect the pipeline from external impacts, including ice, currents, and waves. To safeguard the excavation and limit the spread of sediment, a temporary causeway has been erected on both sides of the pipeline route in the landfall surf zone.
Portovaya Bay near Vyborg is the starting point of the Nord Stream pipeline through the Baltic Sea. Here the line will be connected to Russia’s gas transportation system via the new onshore Gryazovets-Vyborg trunkline. Gas will be transmitted into Nord Stream from the Portovaya compressor station, 3 km (1.9 mi) inland. Gazprom is building both this and the onshore trunkline.
Before arriving in Portovaya Bay, Castoro Sei had laid around 230 km (143 mi) of the pipeline in the waters off Sweden and Finland. Once it has completed the current shore pull and laying of 7.5 km (4.6 mi) of pipe in Russian waters, the vessel will return for further duty in Finnish waters, with Allseas’ Solitaire taking over pipelay in Russian waters.
The Castoro Sei completed the shore pull at the German landfall on July 16.
