- For a new LNG plant in Russia Linde is building a storage tank at record speed.
- The cold Russian winter and the short construction period pose tough challenges.
- To fulfil the task within time Linde combines sophisticated construction technologies of specialised companies with the use of new building standards.
On a small peninsula in Russia’s northwest edge, building workers, engineers and welders are chasing records. As part of a new LNG plant, Linde’s Engineering Division is building the related full-containment LNG storage tank in record speed: Thanks to fast-track engineering and procurement, sophisticated construction technologies an optimised time schedule is achieved. The 42,000-cubic-metre tank is scheduled to be realised within only 22 months – despite the challenging Russian winter.
Just two hours from metropolitan Saint Petersburg, heading northwest along route E18 towards the Finnish border, one of the last exits leads to a site of birch woodlands tinged with salty sea air. This is the site of Portovaya, where a complex for liquefied natural gas (LNG) production, storage and shipment is being erected. The plant will have a yearly capacity of around 1.5 million tonnes of LNG, classifying it as mid-scale.
The Portovaya plant will use Linde's LIMUM® technology, a multi-stage mixed refrigerant process achieving best-in-class energy efficiency, applying its proprietary coil-wound heat exchangers. Linde is performing basic and detail engineering for the process plant while also supplying the equipment and related bulk material.
Raising the walls within 15 days
One key element of the new LNG plant will be the storage tank, with its design based on European standards, in particular new EN 14620. Another of the project’s key elements is execution speed: In the search for an Engineering, Procurement and Construction (EPC) contractor, one of the plant owner’s priorities was to build the tank within the shortest possible time. This required the use of special construction technologies. The outer tank, for example, which is 60 centimetres thick, was erected by sliding of the concrete wall. The construction formwork climbed continuously higher, thus heightening the wall by two metres per day. Thanks to this engineering artistry, the concrete outer tank was mounted within only 15 days.
Still another remarkable element about the construction of this LNG tank is the technology used to build the roof. The roof itself was assembled inside of the concrete walls. Instead of using a crane, the 216-tonne structure was lifted by air pressure. The roof hovered at a speed of 16 centimetres per minute. Within only 2 hours and 14 minutes, the roof reached its final position. This unique roof air raising technique has advantages of lowering the costs, shorting the schedule, and reducing hazards from avoiding working at height. This successful air raising operation took place only 11 months after construction started and indeed marks a milestone in the successful execution of the project.
Storage tanks at the Hammerfest LNG plant in Norway.
The construction site that never sleeps
To make use of these sophisticated construction technologies, specialised partners are needed. Construction was conducted by Renaissance Heavy Industries. For Engineering and Procurement, Linde teamed up with SPG Steiner as a subcontractor. Country-specific adaption of the design also required the involvement of Russian design institutes.
The collaboration of multiple companies and teams also requires ideally aligned timetables. Project management and close contact with all subcontractors are enormously important to meet such an ambitious deadline. Temporarily, 200 people were working at the construction site, partly during nightshifts.
Winter is coming
With a dome height of 37.2 metres, the storage tank is the highest building in the complex, surmounting the trees to offer a magnificent view at the Gulf of Finland, the easternmost arm of the Baltic. When the roof was lifted in February 2018, the Gulf was frozen and covered by a thick layer of snow.
Since the area’s winter temperatures can drop down to minus 38 degrees Celsius, ‘winterisation’ of construction plans is required, which includes the use of tents and radiators. Filling the tank for hydrotesting during the upcoming winter period will be one further challenge.
Assembling onion walls layer by layer
Before engineers start to flood the tank, several wall layers must be completed. Starting with the outermost layer, the concrete shell, the storage tank consists of six different layers with a decreasing radius – similar to an onion.
Within the concrete wall, the outer tank liner is made of carbon steel. The third layer does not cover the whole height of the tank but only the lowest segment. This foam glass element is called thermal corner protection. A double layer of perlite and mineral wool thermally insulates the liquefied natural gas, which has a temperature of minus 163 degrees Celsius.
Full containment tank with a capacity of 25.000 m³ (Nynäsham,LNG)
Curved inner tank design
By the end of 2018, the inner tank will be welded to completion. This assembly process can be compared to putting together a massive 3D puzzle. In total, the inner tank shell consists of 400 plates of different sizes. To be transported to the construction site, the plates must fit inside of an ordinary truck and in the construction openings of the tank. This task, alone, is quite a challenge – for example, one of the biggest plates is 12 metres wide and 2.4 metres high.
Due to the cylindric form of the tank, the plates are curved. As the height increases, they become thinner. The plates themselves are made of a special steel alloy that contains nine percent nickel. This percentage is necessary due to the extremely low temperatures of minus 163 degrees Celsius that LNG is kept at.
Linde Engineering is optimistic that it will hand over the LNG storage tank in time. To achieve this, the project's ambitious technological and logistical processes have engaged like meshing gears. Thanks to sophisticated construction technologies and optimised time tables, the time needed to complete similar projects could be shortened significantly. With this great success, the bar is raised for future projects – no matter the schedule or wintery skies.