Customized Processing of Liquefied Natural Gas Storage Tanks

Liquefied Natural Gas (LNG) storage tanks are specialized equipment used to store cryogenic liquefied natural gas (-162°C). Their steel structure design and construction must meet high strength, low-temperature resistance, leak-proof, and safety requirements. The following is information and key points regarding the steel structure of LNG storage tanks:

Steel Structure Types of LNG Storage Tanks

LNG storage tanks typically use special steel and composite structures to cope with low-temperature environments and high-pressure requirements. Common types include:

1. Single-Wall Steel Tank (Single Containment Tank)
   • Structure: Made of a single steel wall (usually 9% nickel steel or low-temperature steel), with an outer layer of insulation material (such as perlite or glass wool).
   • Use: Suitable for small LNG receiving stations or gas stations.
   • Features:
     • The inner wall thickness is generally 10-20mm, depending on the capacity.
     • Requires an external concrete protective wall or earthen embankment to enhance safety.
   • Advantages: Simple structure, low cost.
   • Disadvantages: Lower safety than multi-wall tanks, limited leakage protection.
2. Double-Wall Steel Tank (Double Containment Tank)
   • Structure:
     • Inner tank: 9% nickel steel or low-temperature stainless steel (such as 304L/316L), stores LNG, wall thickness 10-30mm.
     • Outer tank: Carbon steel or low-temperature steel, protects the inner tank and prevents external environmental influences, wall thickness 8-15mm.
     • Interlayer: Filled with insulation material (such as expanded perlite) or evacuated to reduce heat conduction.
   • Use: Widely used in medium and large LNG storage tanks (such as integrated refueling and gas stations).
   • Features:
     • The inner tank bears the cryogenic liquid, and the outer tank resists external loads and environmental corrosion.
     • The interlayer can be equipped with a leakage monitoring system.
   • Advantages: High safety, in accordance with the "Technical Specification for Liquefied Natural Gas (LNG) Production, Storage and Transportation" (GB/T 20368).
   • Application: CNOOC and Sinopec LNG storage tanks mostly use this structure.
3. Full Containment Tank
   • Structure:
     • Both the inner and outer tanks are made of 9% nickel steel or low-temperature steel, with thicker walls than double-wall tanks (inner tank 15-40mm, outer tank 10-20mm).
     • The outer tank can completely contain the LNG leaking from the inner tank, providing the highest level of safety.
   • Use: Large LNG receiving stations or strategic reserve stations.
   • Features: Complex design, need to consider earthquakes, wind loads, and low-temperature shrinkage.
   • Advantages: Strong disaster resistance, suitable for high-risk areas.
   • Disadvantages: High cost, long construction period.
4. Support Structure and Foundation
   • Type:
     • Steel Support: Saddle or ring support made of H-shaped steel or steel plates, used to fix the storage tank.
     • Concrete Foundation: Reinforced concrete base plate or pile foundation, 1-2m thick, to prevent settlement.
   • Features: Need to consider anti-buoyancy (groundwater buoyancy) and seismic design.
   • Use: Ensure the stability of the storage tank, disperse weight and low-temperature stress.