When designing a cold storage racking system, we first need to distinguish the cold rooms. In high temperature cold storage, the temperature needs to be controlled between 0℃ ~ 6℃.There are many types of storage products: vegetables, fruits, fresh milk, and cold meat. In low temperature cold storage, the temperature needs to be controlled between -18℃ ~ -20℃. There are many types of storage products: frozen meat, frozen pastry, ice cream and frozen dumplings. In the real case, -18℃ cold room is in common.
1. Choose the right racking steel material
Low temperature environment has specific requirements for the application of steel. It should have good low temperature toughness and ductility to avoid brittle fracture. Commonly used in the racking of ordinary carbon structural steel Q235, there are Q235A, Q235B, Q235C, Q235D, Q235E different grades, mainly because of the impact of different temperatures. A means no impact, B is above 20℃, C is above 0℃, D is above -20℃, E is over -40℃, A to E is different, and their respective properties are different in impact temperature.
Due to the microelement is different in A/B/C/D, the quality grade is increasingly higher, and its performance in low temperature is better. In general, Q235D will be used as the main material of cold storage racking.
Fasteners are fabricated by high nickel chromium (e.g., Cr18Ni9), alloy steel, or non-ferrous metals (such as copper and aluminum), which exhibit almost no low temperature brittleness. The thermal expansion coefficient of the steel is 1.2*10-5/℃. The thermal expansion coefficient of the concrete is about 0.7*10-5/℃. Both of them are close and can be effectively connected when the temperature difference is within 40℃.