Composite Concrete Cryogenic Walls

Wall/Slab Connection Detail

Efficient High-Performance with Sliding Concrete Walls and Integrated Liner

Composite concrete cryogenic (C3T) walls are constructed of prestressed concrete panels that are vertically prestressed and circumferentially wrapped with prestress wires encased in shotcrete. A non-structural carbon steel liner, whose sole function is to provide a liquid and vapor barrier, lies between precast, prestressed panels and the shotcrete layer. The liner is under biaxial compression and not in direct contact with the LNG, which makes it less susceptible to thermal shock.

Robust Concrete Roof Dome

The precast wall connects to the roof via a cast-in-place ring beam. The roof consists of a robust concrete dome with a carbon steel liner and a suspended ceiling for the roof insulation. Roof detailing is similar to that for conventional tanks.

Established Technologies for Insulation and Mechanical Equipment

The insulation, equipment support structures, and mechanical equipment are the same as for a conventional 9% nickel (Ni) steel tank with a long track record of reliable performance. Tank commissioning, such as hydrostatic testing, pressure and vacuum testing, purging and drying, and cooldown, follows well-defined procedures similar to those used for conventional 9% Ni tanks.

The robust concrete wall of the primary containment tank can take out-of-plane bending loads and is not susceptible to buckling, such as elephant-foot buckling, that steel inner tanks face. Once the wall panels are fully integrated by wire wrapping, the concrete wall can sustain the full wind load without bracing. No resilient blanket is needed to protect the concrete wall from buckling under the pressure of the settling perlite insulation in the annular space.

The bottom of the walls can move radially and, thus, avoid building up constraining forces at the wall/foundation joint. This is in contrast to conventional cast-in-place secondary tank walls that are monolithically connected with the base slab and need to be designed for large constraining loads during a spill. As a result, conventional monolithic wall connections need a thermal corner protection (TCP) to control cracking in this area. A precast concrete wall with sliding support does not need TCP. Resistance to circumferential shear and wall uplift is provided by a combination of shear lugs and restraining cables that allow the wall to slide radially, but constrain it in vertical and circumferential direction.

The shotcrete layer on the tank exterior provides a durable concrete surface. The outer shotcrete layer may be reinforced with fibers or provided with an additional insulation layer to improve the wall's resistance to external fire and missile impact.

Why Choose C3T