TECHNICAL OVERVIEW
The inner chambers consist of 409 reinforced concrete piles one metre in diameter and 10 metres long driven into the bedrock 7 metres deep on backfilled land reclaimed from the sea. On these piles rests a reinforced concrete foundation slab that supports the inner steel-and-nickel chamber. To prevent ground-freezing and the appearance of ice pockets that would damage the structure of the storage tanks, the foundation slab is isolated from the chamber by a double layer of foamed glass insulation and a perlite concrete ring that acts as a support structure for the skirt of the inner chamber. The foundation slab supports a prestressed concrete skirt whose carbon steel inner lining seals in methane vapour.
The one-metre gap between the shell and metal chamber is filled with perlite, a heat-insulation material. The bottom 5 metres of the skirt and the tank are protected by a second insulating barrier designed, in the event of a leak in the inner chamber, to prevent LNG from reaching the junction of the lining and the foundation slab. The steel lining in the skirt, which is in contact with LNG, consists of nickel-enhanced cryogenic steel designed to retain its ductility even in the event of a gas leak and a dramatic temperature drop.
The shell is designed to ensure airtightness and withstand the effects of inner overpressure and decompression. The storage tanks are located on the seashore in a hot, humid, and saline environment that is particularly harsh. To ensure a long useful life in such an environment, the concrete used in this project contains silica fume, which reduces its porosity. The foundation piles, which are partly embedded below the water table, are shielded against corrosion by a cathodic protection system. A plastic film was installed below the foundation slab to protect the tank from rising saltwater. Finally, the walls and roof were covered in acrylic paint to protect them from atmospheric humidity.
