1. Inner tank wall

The inner tank wall is the main component of low temperature storage tank, which is welded by steel plate with good low temperature resistance and mechanical properties. Generally, special steel such as a5372 grade, A516 gr.60, gr18ni9, ASME 304, etc. are selected. For example, 16 mm thick A537 Cl2 steel plate can be used as the bottom plate and ring plate of a tank, and 6.35 mm thick A537 CL1 steel plate can be used as the other plates.

2. Cold insulation layer

Cold storage of tank wall

Polyurethane foam is sprayed inside the lining plate of the outer tank. Generally speaking, the thermal conductivity of polyurethane foam is less than 0.03 W/ (M. K), the density is 40~60 kg/m3, and the thickness is about 150 mm.

Cold storage at top of tank

The inner tank top adopts suspended rock wool cold insulation layer. For example, four layers of glass fiber cold insulation layer are set on the tank top, each layer is 100 m m thick, the density of glass fiber cotton is 16 kg / m3, and the thermal conductivity is 0.04 w / (m · K).

Cold storage at bottom of tank

Cold storage at the bottom of the tank is more complicated. Besides waterproofing polyurethane foam under the steel plate, waterproof structure should also be designed. The following figure shows the cold insulation structure of a tank bottom, including 65 mm thick cushion, 60 mm thick dense concrete, 2 mm thick waterproof felt, 2 layers of 100 mm thick foam glass respectively, and finally covered with 70 mm thick concrete to protect the outer tank concrete from low temperature.

3. Concrete outer tank

The concrete outer tank wall and the outer tank top are composed of prestressed reinforced concrete and low temperature resistant steel lining plate. The concrete strength shall be ≥ 25 MPa. The external tank top and tank wall shall be able to withstand the internal pressure caused by accidental gas leakage, so the reinforced concrete shall have sufficient tensile strength.

For large-scale storage tank, in order to make the prestressed concrete tank wall evenly stressed, the design method of equal strength and unequal thickness or equal thickness and unequal strength can be adopted.