Nord Stream subsea tie-ins under way

Offshore staff

ZUG, Switzerland – Preparations have started for welding together two of the three sections of the first 1,224-km (760-mi) Nord Stream gas pipeline in the Baltic Sea.

They will be joined on the seabed in 80 m (262 ft) water depth off the coast of Finland under a process expected to take around two weeks. Technical completion of the first of the twin pipelines should be achieved in June, when the final section is welded onto the pipeline off the Swedish island of Gotland in 110 m (361 ft) of water.

The pipeline will operate without an intermediate compressor station, but with three different design pressures and pipe wall thicknesses to accommodate falling gas pressure during the journey from Russia to the landfall in northern Germany.

Connection of these three sections is being performed offshore where the 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.

Each will be gauged and pressure-tested before being joined via hyperbaric tie-ins and subsequently linked to the landfalls in Russia and Germany.

Technip is managing the hyperbaric tie-ins from its new DSV Skandi Arctic, using equipment supplied by the Pipeline Repair System (PRS) pool administered by Nord Stream partner Statoil.

The procedure takes place on the seabed in a specially created dry zone (underwater welding habitat). Welding operations are controlled remotely from the Skandi Arctic, with divers assisting and monitoring the subsea construction work.

Skandi Arctic transports and operates all equipment needed to move, lift, cut, and weld the pipeline sections together. Pipe handling frames move the pipe ends into tie-in position. They also can shift the pipeline sections sideways to line them up for welding.


Did You Like this Article? Get All the Energy Industry News Delivered to Your Inbox

Subscribe to an email newsletter today at no cost and receive the latest news and information.

 Subscribe Now


Maximizing Operational Excellence

In a recent survey conducted by PennEnergy Research, 70% of surveyed energy industry professional...

Leveraging the Power of Information in the Energy Industry

Information Governance is about more than compliance. It’s about using your information to drive ...

Reduce Engineering Project Complexity

Engineering document management presents unique and complex challenges. A solution based in Enter...

Revolutionizing Asset Management in the Electric Power Industry

With the arrival of the Industrial Internet of Things, data is growing and becoming more accessib...