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Offshore construction of TurkStream pipeline gets under way

Thu 15 Jun 2017

Offshore construction of TurkStream pipeline gets under way
Audacia is responsible for the shallow water sections of TurkStream; another Allseas vessel, Pioneering Spirit will lay the deepwater sections

Construction of the technically challenging TurkStream gas pipeline got underway in the Black Sea early in May 2017

Having been awarded the contract to install the first line for the TurkStream gas pipeline in December 2016 and a contract for the second line in February 2017, contractor Allseas began work on the first string offshore the Russian coast using the pipelay vessel Audacia. The vessel will also be used for pipe pulling through microtunnels. Construction work in deep water will be undertaken by another Allseas vessel, the single-lift/pipelay vessel Pioneering Spirit, which only recently set a world lifting record with the safe and successful removal of Shell UK’s 24,000 tonne Brent Delta topsides from the North Sea.

“Today, we started the practical implementation of the TurkStream gas pipeline project, laying the offshore section. By late 2019, our Turkish and European consumers will have a new, reliable source of Russian gas imports,” said Alexey Miller, chairman of Gazprom’s management committee.

As of June 2017, Pioneering Spirit had also commenced installation work in the Black Sea, installing the deepwater sections of the 900 km long pipelines on the seabed in water depths of up to 2,200 m.

The TurkStream gas pipeline will consist of two parallel gas pipelines stretching for a total of 930 km across the Black Sea, each with a diameter of 32 in (81 cm) and an annual throughput of 15.75 billion cubic metres.

TurkStream is noteworthy for a number of reasons, not least because it is the first pipeline of its size to be installed at such great depths. One of the pipelines will cater for the Turkish market, and the other will stretch to the Turkish-Greek border to ensure reliable deliveries of Russian gas to the European markets. In line with the schedule, first gas is expected to flow through TurkStream by late 2019.

Each of the offshore pipelines is made up of thousands of individual pipe joints 12 m in length. The pipes are produced in specialised mills and shipped to construction yards. The walls of the pipeline are made from 39 mm thick carbon manganese steel. Pipes laid closer to the shore are coated with concrete for additional stability and protection of the pipeline.

Pipe is transported by ship to the pipelaying vessels. On board the pipelayers, the pipe joints are welded onto the main string. Afterwards, the weld is tested and then coated before the pipe string is lowered into the water. Slowly but surely, the pipelaying vessel will traverse the Black Sea adding new sections to the pipe string as it moves. Operating around the clock, vessels typically lay as much as 3 km of pipeline each day.

The pipelines will start near Anapa, on the Russian coast, and come ashore on the Turkish coast some 100 km west of Istanbul, near the village of Kiyiköy. The project is being implemented by South Stream Transport BV, an Amsterdam-based subsidiary of Gazprom.

Nord Stream awards pipeline inspection contract to MMT

MMT Sweden has been awarded a three-year contract by Nord Stream AG to inspect both lines of the Nord Stream gas pipeline running through the Baltic from Russia to Germany. External inspection of the pipeline will be executed by the joint venture between MMT Sweden and Reach Subsea.

The scope of work, involving approximately 150 days for 2017, includes visual and instrumental inspection of the pipelines with remotely operated vehicles over the entire length of the route. The trenched sections and cable crossings of the pipeline will also be inspected. The survey will mainly be conducted from the vessel Stril Explorer.

The purpose of the surveys is to acquire data on the condition of both pipeline strings and associated installations. This information is used in the continued assessment of the pipelines’ integrity and will complement the data generated in earlier inspection campaigns.

 

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