Nord+Stream%3A+the+world%E2%80%99s+longest+offshore+pipeline

A milestone of the energy partnership between the European Union and Russia, Nord Stream is a twin pipeline system through the Baltic Sea transporting natural gas from Russia to Europe.

“DNV’s strong reputation adds as much to our project as DNV’s highly skilled professionals and their independent assessments. One main step for the success of the Nord Stream project was the selection of an independent certification organisation in an early phase. With DNV we found a very competent and experienced partner.” Henning Kothe, Project Director at Nord Stream AG
The Nord Stream pipeline from Russia to Germany.

Natural gas plays a key role in the European Union’s energy mix and is expected to gain importance as back-up fuel for variable electricity generation in the years to come.

The Nord Stream pipeline, a “project of European interest” according to the European Union’s TEN-E (Trans-European Energy Networks) guidelines, represents a key element in the development of the EU’s internal energy market, reinforcing economic growth and the creation of employment. The project is a substantial step forward in achieving the EU’s energy supply goals, such as the diversification of the energy mix and increase of import capacity with additional supply routes.

Nord Stream consists of 48-inch twin pipelines which transport natural gas over a distance of 1,224km through the Baltic Sea. It has been planned and built by a consortium consisting of the majority shareholder Gazprom together with Wintershall, E.ON Ruhrgas, Nederlandse Gasunie and GDF Suez to enhance long-term energy security and help achieve climate change goals in Europe. The two pipelines link vast gas reserves in Russia to the energy markets in the European Union and are capable of transporting 55 billion cubic metres of gas annually – enough to supply 26 million households in Europe.

Pipeline certificate by DNV
DNV started supporting the project at an early stage – when it involved Nord Stream’s predecessor North European Gas Pipeline in the late 1990s. During the conceptual phase in 2005, DNV verified the Nord Stream conceptual/FEED study for Gazprom. Since 2007, DNV has been hired by Nord Stream AG to verify that the design, fabrication and installation meet the governing standard DNV-OS-F101: Submarine Pipeline Systems. Adherence to this internationally accepted standard of safety for submarine pipeline systems safeguards the integrity of offshore pipeline projects, helping ensure public safety and environmental protection.

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From left to right, first row: French Prime Minister Francois Fillon; German Chancellor Angela Merkel; Dutch Prime Minister Mark Rutte; Russian President Dmitry Medvedev; and European Union Energy Commissioner Günther Oettinger turn a wheel to symbolically start the flow of gas through Line 1 of the Nord Stream twin pipeline system this Spring.

Henning Kothe, Project Director at Nord Stream AG, confirms: “One main step for the success of the Nord Stream Project was the selection of an independent Certification Organisation in an early phase. With DNV we found a very competent and experienced partner for our requirements, with a high level of reputation in the offshore industry. This gave us a strong support during all project phases in talks with suppliers, shareholders, banks and the media – they all know DNV and have a high regard for the company and its independent assessments.”

DNV’s expertise and experience, which stem from the development of the standard since it was first issued in 1976 and the independent verification of most major offshore trunkline projects, have been important for confidently ensuring quality and integrity at all stages of a project that is pushing limits in terms of pipeline length and diameter. Nord Stream utilised DNV’s full range of multidisciplinary technical competences and provision of comprehensive and independent technical quality assurance to manage all the high-risk elements. Risk-based verification according to DNV-OSS-301: Certification and Verification of Pipelines has involved state-of-the-art methods and tools at each stage, from design verification to manufacture control and independent construction inspection.

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Many challenges
The project’s challenges included the development of the heaviest ball and gate valves ever produced as well as risks specific to the Baltic Sea environment, such as corrosion control in brackish waters, pipelaying on an irregular seabed with soft soils, and interference with fishing activities and ship traffic – the Baltic Sea has some of the world’s busiest shipping routes with around 2,000 sizeable ships sailing on it at any time. The size of the fishing equipment compared to the pipeline diameter is very different to the neighbouring North Sea, and fishing in the vicinity of a subsea pipeline is a new experience for local fishermen. In addition, the fact that the Baltic Sea contains obstacles such as sea mines from the First and Second World Wars and shipwrecks posed installation risks.

For DNV a project of this size comes with peculiar challenges; altogether more than 7,000 were reviewed, and there were days when more than 20 documents arrived for review by specialists in different disciplines; a well-attuned, committed team is required to handle this amount of information consistently, reliably and on time. From a geographic point of view, DNV’s strong global presence was a great advantage: for example in the fabrication subproject alone, verification work took place at four plate fabrication sites, three pipe mills, two concrete coating yards and the production sites for valves, anodes, buckle arrestors, bends, pig traps, anchor flanges and bends, in many countries ranging from the US to Japan, Russia, Italy, the UK and many others. Having stations with experienced surveyors all working to the same global standards allowed DNV to mobilise personnel at short notice too, ensuring that verification work had no impact on the overall project schedule.

Not finishedyet
Gunn Stirling, DNV’s project manager, says: “When the first of the Nord Stream pipelines became operational last year, it was an important milestone and many expected the project to start approaching the end. However, final verification completion is not reached until both pipelines are fully commissioned. The project team must see that all elements are properly closed and documented, and that the 50-year operations are also planned so as to keep the integrity intact. Therefore, the DNV experts cannot be fully released until we have provided Nord Stream AG with the final Pipeline Certificates for Line 1 and Line 2. We are also looking into extending our cooperation with regard to verifying the integrity for the operational phase too, but that will be a separate DNV project.”

Text: Maud Hanitzsch

Nord Stream facts

Length: 1,224km (two parallel lines)
Maximum water depth: 210m
Pipeline joints per pipeline: 101,000
Pressure segmented design: Three pressure sections (220, 200 and 177.5 bar) and pipe wall thicknesses (34.4, 30.9 and 26.8 mm respectively)
Amount of raw materials used in the concrete-weight-coating plants: 1,5 million tonnes of iron ore, 500,000 tonnes of aggregate, 430,000 tonnes of cement, 43,000 tonnes of wire
Amount of steel used: 2,424,000 tonnes
Weight of four gate valves at the landfall locations:
102 tonnes each
Capacity: 55 billion cubic metres per year
(27.5 bcm per line)
Nominal diameter: 1,220 millimetres (48 inches)
Shareholders: OAO Gazprom (Russia, 51%), E.ON Ruhrgas AG (Germany, 15.5%), BASF SE/Wintershall Holding GmbH (Germany, 15.5%), N.V. Nederlandse Gasunie (Netherlands, 9%), GDF SUEZ S.A. (France, 9%)
Total investment: 7.4 billion euros
Start of gas transportation (line 1): November 2011; Pipelaying completed (line 2): April 2012
Environmental monitoring programme: appr. 1,000 survey locations – 16 parameters
DNV’s key deliverable: Pipeline Certificates for Line 1 and Line 2 based on verification of design, manufacture and construction.

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