Nord Stream Begins Underwater Tie-Ins

The Nord Stream consortium has today begun work on the underwater tie-ins of the second pipeline of the project in the Baltic Sea.

The operation, which involves the joining of two of three sections of the second pipeline, is expected to take two weeks. During this time, 80 metres of pipeline will be joined inside a hyperbaric welding habitat on the seabed off the coast of Finland, the consortium says. 

The difficult process will be undertaken at two disparate locations, and the welding itself will take 24 hours on each section. This welding will be remotely controlled from the Skandi Arctic vessel, onboard which a team of 24 trained divers will monitor the process. 

Prior to the welding, three pipe handling frames will be lowered from the Skandi Arctic. These frames will position the overlapping areas of the unjoined pipeline to be welded after these have been cut to size. These ends of pipe will then be bevelled and lifted into place.

Following the welding, the welded sections will be inspected by ultrasound and the welding habitat lifted back onto the Skandi Arctic. The pipes will then be de-watered and dried. 

The consortium expects both the onshore and offshore sections of the pipeline to be completed by autumn of this year, with the second pipe to come online by the final quarter of 2012.