Low-Temperature Stainless Steel Spherical Tank: Adapting to Cryogenic Environments, Ensuring Storage of Liquid Nitrogen and Liquefied Natural Gas

Low-temperature stainless steel spherical tanks, with their special adaptability to cryogenic environments, have become core equipment for storing low-temperature media such as liquid nitrogen and liquefied natural gas (LNG). In extreme low-temperature environments ranging from -196°C (boiling point of liquid nitrogen) to -162°C (boiling point of LNG), they build an efficient and reliable low-temperature storage system with material stability and structural safety, providing guarantees for cryogenic needs in the energy and industrial fields.

The core of cryogenic adaptability lies in the low-temperature toughness of materials. Spherical tanks made of 304L ultra-low carbon stainless steel (carbon content ≤ 0.03%) still maintain an impact energy (AKV) of over 60J at -196°C, which is 8 times that of ordinary carbon steel, avoiding the risk of "cold brittle" fracture at low temperatures. For the special needs of LNG storage, some spherical tanks use 9% nickel steel, whose yield strength at -196°C reaches 680MPa, and the linear expansion coefficient is only 11×10⁻⁶/°C, which can reduce the tank stress caused by temperature changes. The actual measurement of an LNG storage tank shows that when the daily temperature difference is 15°C, the stress change of the tank wall is controlled within 120MPa, far below the yield limit of the material.

The structural design enhances the tightness and safety in cryogenic environments. The tank body adopts a double-jacket structure, with the inner layer storing low-temperature media and the outer layer filled with perlite (thermal conductivity ≤ 0.025W/(m·K)) and vacuumized (vacuum degree ≤ 5Pa), forming an efficient thermal insulation barrier. This design controls the daily evaporation rate of low-temperature media in the tank below 0.05%, and the annual loss of LNG during storage is 60% less than that of single-containment tanks. The connection between the nozzle and the tank body uses a bellows compensator, which can absorb the 100mm displacement caused by low-temperature shrinkage, avoiding seal failure due to rigid connection. The sealing surface is made of copper-plated nickel material, which still maintains good elasticity in deep cold, ensuring that the leakage rate of flange connections is ≤ 1×10⁻⁶Pa·m³/s.

In practical applications, these characteristics are transformed into full-cycle storage safety. Liquid nitrogen storage tanks are protected by dual safeguards of safety valves and rupture discs on the top (set pressure is 1.1 times the design pressure), which can cope with sudden pressure rises caused by unexpected temperature increases. LNG spherical tanks are equipped with low-temperature submersible pumps, which directly transport through the in-tank pumps, avoiding cold loss during medium export (temperature rise during transportation ≤ 2°C). Data from an energy station shows that a 500m³ low-temperature stainless steel spherical tank storing LNG has no excessive cold loss for 3 consecutive years of operation, while traditional storage tanks need to replace the thermal insulation layer twice a year on average, with maintenance costs 3 times higher.

From liquid nitrogen reserves in the medical field to LNG storage and transportation in the energy industry, low-temperature stainless steel spherical tanks resist cryogenic challenges with material toughness, reduce medium loss with thermal insulation design, and build a "low-loss, high-safety" storage barrier in extreme low-temperature environments, becoming a key support for the application of cryogenic technology.