How do you put the roof on a 900 tonne tank? With air pressure!

Ethane tank roof installed with air pressure

At Project ONE, the ethane tank roof was installed in a unique way. The roof sections were brought to the site and welded together like pizza slices to form a round structure. This was done inside the tank, after which the entire roof was lifted using air pressure until it was in place.

The tank has a radius of 46.50 metres and the roof was ‘blown up’ at a rate of 20 to 30 centimetres per minute. And you can take that blowing quite literally. The roof was installed using compressed air, at a surprisingly low pressure: 0.013 bar at the start and 0.014 bar for the rest of the operation. By comparison, a car tyre has a pressure of around 2 bar.

During the operation, the 900-tonne steel roof was held in place by 30 cables to prevent it from tipping over. Once the roof was in place, it was secured and then welded. A concrete finish will be applied to the roof dome later.

The project is being carried out by TGE and Martifer on behalf of INEOS Project ONE. There is also a lot of work to be done inside the tank: insulation and finishing work on the outer and inner tanks. The Project ONE ethane tank will be ready for testing from July 2026.

Would you also like to see how the floor slab and walls of the ethane tank were built?