Nord Stream is an offshore natural gas pipeline from Vyborg in Russia to Greifswald in Germany, owned and operated by Nord Stream AG. The pipeline runs from the Vyborg compressor station at Portovaya Bay along the bottom of the Baltic Sea to Greifswald.
This vast subsea pipeline is 1,222 km, of which 1.5 km lie in the Russian interior, 121.8 km in Russian territorial waters, 1.4 km in the Russian economic zone, 375.3 km in the Finnish economic zone, 506.4 km in the Swedish economic zone, 87.7 km in Danish territorial waters, 49.4 km in the Danish economic zone, 31.2 km in the German economic zone, 49.9 km in German territorial waters and 0.5 km in Germany.
The pipeline has two parallel lines, each with a capacity of 27.5 billion cubic metres (970 billion cubic feet) of natural gas per year. The pipes have a diameter of 1,220 millimetres (48 in), a wall thickness of 38 millimetres (1.50 in) and a working pressure of 220 bars (22 MPa).
Tideway was responsible for the pre-lay and post-lay rock placement for the installation of two 48’’ gas pipelines. Rock was sourced from quarries in Finland and Sweden and installed in four countries: Russia, Sweden, Denmark and Finland.
Large stockpiles were organised in Kotka (Finland) and Oskarshamn (Sweden) to ensure continuous operations.
The total volume eventually installed was 3.5 million tonnes (1.1 million tonnes of pre-lay installation and 2.4 million tonnes of post-lay installation).
The main equipment deployed was the DP Fallpipe Vessels Seahorse and Tideway Rollingstone.