Pipeline Construction Constructing an underwater pipeline is a major undertaking. Approximately 200,000 pipes have been produced to create Nord Stream 2. Pipelaying began in the late summer 2018. Through a carefully planned and tightly managed process, individual lay vessels can construct the pipeline at a rate of about 3 km per day. The Nord Stream 2 twin pipeline will internally to reduce friction, and Pipe Carrier Vessel Pipes weighing up to 24 tonnes each stretch over 1,230 km from Russia’s externally to reduce corrosion, increase are shipped to the pipelay vessel from Baltic coast, through the Baltic Sea, protection and add weight, making the a number of logistics hubs strategically Crane reaching landfall at Germany’s coast pipeline more stable on the seabed. located along the route. Pipes are unloaded by crane from the carrier vessel to the pipelay vessel. near Greifswald. Once fully operational, Helipad the pipeline will have the capacity to Nord Stream 2 will use several pipelay Personnel are transferred to and transport 55 bcm of natural gas per vessels to install the pipelines. A number from the vessel via helicopter. year – enough to satisfy the needs of measures will be taken to minimise of 26 million European households. disturbance to the sensitive Baltic Sea Nord Stream 2 will largely run in environment, which has dense shipping parallel to the Nord Stream system traffic and historic munitions. Pre-Pipelaying Survey in operation. Though the seabed is surveyed during Each pipelay vessel is a floating factory the route planning phase, a pre-lay survey performed before pipeline installation confirms Nord Stream 2 will work with some of where the pipes are received from that no significant changes have occurred the world’s leading suppliers to lay the carrier vessels, welded together into along the route since the previous survey. pipeline through the Baltic Sea. Safety a pipeline in the firing line, and finally and environmental protection are installed on the seabed. The completed foremost considerations throughout the pipeline will undergo rigorous testing pipeline’s construction. The individual and assessment by an independent 12m pipes have been produced at certification body. Once the safety of plants in Germany and Russia, and the pipeline is assured, gas will be able ROV Stinger have a constant internal diameter of to flow directly from the world’s largest The stinger provides support to the 1,153 mm and a wall thickness of up natural gas reserves into the EU’s pipeline as it is progressively lowered to 41 mm. The pipes are then coated internal energy market. to its designated place on the seabed. Pipelaying Process Post-Lay Survey As it touches down on the seabed, the pipeline is monitored to ensure that it is correctly positioned. Edge bevel Pipe Cross section Weld Ultrasonic rays S-Curve As the pipeline is lowered to the seabed, The pipes are unloaded from the To prepare the pipes for welding, Here, 12-metre pipe joints are The double-joint is moved to a it forms an “S” shape, which prevents it 1 pipe carrier vessels and stacked 2 the ends are bevelled to make 3 aligned and welded together 4 non-destructive testing station from being damaged during installation. on each side of the laybarge. Pipe them exactly the right shape to be to create a double-joint segment where every millimetre of the weld deliveries occur regularly to ensure fitted together. The inside of the pipe measuring 24 metres. These sections undergoes automatic ultrasonic testing ROV that there is always an adequate is then cleaned using compressed air will later be connected to the main (AUT) to detect any unacceptable ROV linepipe buffer on board to maintain before it is conveyed to the double- pipe string. flaws. If required, the defect will be A remotely operated vehicle (ROV) fitted with sensors and instruments including the 24-hour pipelay schedule. joint welding station. removed and the weld rescanned to cameras transmits information from the ensure it meets international standards. seabed directly to the survey vessel. Pipe cross-section Polyurethane Weld Concrete weight coating 60 – 110 mm Heat foam Corrosion protection 4.2 mm Ultrasonic rays Former Rock Placement Pipe steel 27 – 41 mm Following AUT, the double-joint The double-joint is now joined Following welding, the weld Once the weld is confirmed The strategic placement of coarse is moved in a pipe elevator to to the end of the pipeline using between the double-joint acceptable, a corrosion gravel is necessary in some locations 5 6 7 8 along the route to create a stable base the central assembly line. There, the a semi-automatic welding process. and the main pipeline undergoes resistant, heat-shrink sleeve is applied on which the pipeline can rest. Antifriction coating insides are checked for debris and the Qualified welding inspectors oversee automatic ultrasonic testing (AUT). over the circumferential girth weld. double joint is aligned with the main each of the steps to ensure that Any unacceptable flaws will be Then, polyurethane foam is poured pipe string in preparation for welding. welding is performed in accordance removed, and the weld rescanned to into a former surrounding the weld with Nord Stream 2’s and authority ensure it meets international standards. area. This foam hardens, providing Pipes shown in yellow for clarity. Pipelay vessel design is for illustration only. approved welding procedures. further protection. Solid Foundations A Strong Team from Solitaire Coast to Coast Allseas’ Solitaire will install a 374-kilometre long section FINLAND of the pipeline in the Finnish Exclusive Economic Zone Nord Stream 2 is working with three pipelay contractors (EEZ), moving towards Russia. to build its twin pipeline through the Baltic Sea. Of these, Allseas is the main contractor with its three vessels that Narva Bay As one of the world’s largest pipelay Key figures NORWAY will be working for the project. vessels, it has laid numerous offshore > Length: 300 metres ESTONIA pipelines, including the twin 48-inch > Width: 41 metres SWEDEN Nord Stream pipelines. Its long length > Maximum speed: 13.5 knots Allseas Group MRTS JSC and ship shape make it particularly > Installed power: 51.5 megawatts RUSSIA Allseas is a global contractor for pipeline MRTS is one of the largest Russian workable, and full dynamic positioning > Dynamic positioning and propulsion: installation, heavy lift and subsea companies operating in the field of sub- allows the vessel to manoeuvre precisely 10 azimuth thrusters construction. The group operates a sea pipeline construction. The company and safely in areas with historic mine > Accommodation: 420 people fleet of state-of-the-art ships. To date, is installing the starting section of the lines and congestion in the Baltic Sea. > Work stations: 2 double-joint factories Allseas has already laid more than twin pipeline in the shallow waters off the Using a vessel working without anchors, with 3 welding stations each, 5 welding LITHUANIA 21,500 kilometres of pipeline in offshore Russian coast, including the two above- only the pipeline touches the seabed stations for double joints, 1 NDT station, projects. As the chief pipelay partner, the water tie-ins close to the Russian landfall. along the pipeline route. This helps to 4 coating stations RUSSIA company is responsible for installing over minimise the impact on the environment BELARUS 96 percent of the two pipeline strings. Saipem and marine traffic. It is using three of its vessels – Solitaire, Saipem, headquartered in Milan, Italy is a GERMANY POLAND Pioneering Spirit and Audacia – to lay a global company that provides onshore and total of about 2,300 kilometres of 48-inch offshore services to the oil and gas sector. pipeline. While the first two ships are Saipem will pull ashore the final section of dynamically positioned, Audacia is being the pipeline and connect it to the landfall Design, construction and operation of to bury the pipelines for their stability, Sea Baltic the through converted into an anchored vessel for its of the Nord Stream 2 Pipeline in Germany. the new twin pipeline system draw on protection and the security of marine work in German waters. It will also perform a number of above Nord Stream experience. However, thorough traffic and fishing activities. To ensure safe Pipeline Twin the Constructing water tie-ins in German waters. preparation is key: 55,000 line kilometres of installation and operation of the pipeline, seabed surveys were carried out to define potential munitions from the World Wars 2 Stream Nord the optimum route for the twin pipeline. are avoided where possible, and cleared The varying topography of the Baltic seabed where necessary. After pipelaying has means that in certain places, preparatory begun, post-lay surveys are performed works had to be performed before pipe- to determine where additional support, laying began. To avoid excessive freespans stabilisation or protection is needed once in the two pipeline strings, among others, the pipelines rest on the seabed. As much rocks between 60 and 100 millimetres in as 90 percent of all rock placement will size are placed on the seabed at dedicated take place post-lay, using only new, clean locations to create supporting berms. In and crushed granite. At some locations the shallow waters near the Russian and along the route where this is deemed German landfalls, dredging must take place impractical, post-lay ploughing is carried over 3.5 and 50 kilometres respectively out to stabilise the pipelines. What does it take to install Facts and Figures Pioneering Spirit Audacia an Offshore Pipeline? The largest construction and pipelay vessel in To build the shallow water section of the pipeline in Germany, the world will also be deployed on the project.