7 LNG Storage Tanks
7.1 General Provisions
7.1.1 Selection of Liquefied Natural Gas (LNG) Storage Tanks shall comply with the following specifications:
Conduct risk assessments for LNG tank design to determine the impact on surrounding environment, personnel, and property safety.
Choose the tank type shown in Appendix B of this specification for liquefied natural gas storage tanks.
In areas with dense entry points or facilities, it is advisable to choose double-walled tanks, full capacity tanks, or film tanks.
Under conditions where the required safety spacing is met, a single-container option can be selected.
7.1.2 The design of the liquefied natural gas storage tank shall comply with the following regulations:
During and after the OBE period, the tank system should continue to operate.
During and after the SSE, the storage capacity of the tanks should remain unchanged and they should be capable of being isolated and maintained.
The liquefied natural gas (LNG) storage tanks should undergo seismic calculations under OBE and SSE conditions, ensuring safe shutdown of the LNG storage tanks under SSE conditions. The prestressed concrete outer shell of the fully contained tanks should be subjected to ultimate bearing capacity calculations under ALE conditions.
7.1.3 The pipe openings of the liquefied natural gas storage tank should be located at the top of the tank.
7.1.4 The response spectra for OBE, SSE, and ALE should be determined according to the following requirements:
OBE should represent seismic ground motion with a probability of exceedance of 10% within 50 years (return period of 475 years) and a damping ratio of 5%, and its response spectrum should not be less than the corresponding value for seismic fortification design for the region as specified in the current national standard "Code for Seismic Design of Buildings" GB 50011.
SSE should represent seismic ground motion with a 2% probability of exceedance within 50 years (return period of 2475 years) and a damping ratio of 5%, and its response spectrum should not be less than the value corresponding to rare earthquakes in the region as specified by the current national standard for seismic design of buildings, GB 50011.
The acceleration value of the ALE response spectrum should be half of the SSE response spectrum acceleration value.
4 When the vertical seismic response spectrum is not available, the vertical seismic influence coefficient should not be less than 65% of the maximum value of the corresponding horizontal seismic influence coefficient.
7.1.5 The auxiliary structures of the liquefied natural gas tanks should be designed in accordance with OBE.
7.1.6 During seismic action, the damping ratios for each component of the liquefied natural gas storage tank design should be selected according to the specifications in Table 7.1.6.
Table 7.1.6: Yarn Counts for Various Design Components
7.1.7 The permanent loads and variable loads of the liquefied natural gas storage tank shall comply with the specifications of Table 7.1.7.
Table 7.1.7: Permanent and Variable Loads for Liquefied Natural Gas Tanks
Note: 1 a), b) Refer to Appendix B of this specification, where "√" indicates consideration and "—" indicates non-consideration.
2 "√*" indicates it applies only to the steel tank top at room temperature for the outer steel container of low-temperature steel.
7.1.8 The seismic and accidental loads of the liquefied natural gas storage tanks shall comply with the specifications in Table 7.1.8.
Table 7.1.8 Seismic and Accidental Loads on Liquefied Natural Gas Storage Tanks
Note: a), b) Refer to Appendix B of this specification. "√" indicates consideration, while "—" indicates non-consideration.
7.1.9 The liquefied natural gas receiving station site should undergo seismic and geological disaster assessment.
Liquefied Natural Gas (LNG) storage tanks are specialized products for storing LNG, classified as special equipment and type III pressure vessels. They are made of 06Ni9DR material, and undergo non-destructive testing, hydrostatic and pneumatic testing, as well as on-site inspection by the Technical Supervision Bureau, resulting in a pressure vessel inspection certificate. The manufacturing process also includes external rust removal and painting. The LNG storage tanks undergo rigorous quality assessment for the material of the pressure components, appearance dimensions, weld quality, operational quality, installation quality, internal equipment, and safety accessories.
Routine physical and chemical tests for the cylinder material, such as mechanical properties and chemical composition.
The welding joints, welds, head closures of the tanks, and the mutual geometric positions of all pressure elements are rigorously inspected through X-ray non-destructive testing and magnetic particle inspection. Tests are conducted on the product's sealing, pressure resistance, and all technical indicators that could affect the safe operation of the product.
Chinese Name: Liquefied Natural Gas Storage Tank Category: Product Common Structure: Vertical LNG Storage Tank, Horizontal LNG Storage Tank Atmospheric Storage Tank Atmospheric LNG Storage Tank and Extra Large Atmospheric LNG Storage Tank
Table of Contents
1 Common Structure
2 Cautionary Notes
Common Structures Editing
Common structures of LNG tanks include: vertical LNG tanks, horizontal LNG tanks, vertical mother-child tanks, and atmospheric storage tanks.
Vertical LNG Storage Tank
Volume options include 50, 100, 150, and 200 cubic units.
Horizontal LNG Storage Tank
Volume options include 60 cubic and 100 cubic.
Vertical mother and son drum
A mother tank refers to an inner tank composed of multiple interconnected child tanks to meet large storage capacity requirements. These child tanks are assembled side by side within a large outer tank. The number of child tanks ranges from 3 to 7, generally not exceeding 12. Each child tank should not have an excessively large volume, typically between 100 to 150 cubic meters, with the maximum reaching 250 cubic meters. Common sizes include 1000 cubic meters, 1750 cubic meters, and 2000 cubic meters.
Atmospheric Storage Tank:
We offer medium to large-sized atmospheric LNG storage tanks, as well as extra-large atmospheric LNG storage tanks.
Cautionary Notes
1. Cylinders must be stored in well-ventilated areas, with a minimum distance of 1.5 meters from any fire or heat source. Cylinders are strictly prohibited from being heated with fire, boiled, or left in direct sunlight. Regular inspections should be conducted for the gas tightness of cylinder valves and pipeline joints, ensuring no leakage. Leaks can be checked using soap water, and it is strictly forbidden to test for leaks with an open flame.
2. When lighting, ignite the igniter first, followed by opening the gas; do not reverse the order. There should be a person supervising during use, do not leave, to prevent boiling water from spilling and extinguishing the flame, which could cause the liquefied gas to escape and lead to an explosion. After using the gas cylinder, the valve must be tightly closed to prevent gas leakage.
3. Do not completely deplete the liquefied gas inside the cylinder; a certain residual pressure should be maintained. The residual pressure should generally be greater than 49.03 kPa (i.e., 0.5 kg/cm², gauge pressure) to prevent air from entering the cylinder. After the liquefied petroleum gas is used up, the remaining residue inside the cylinder is also a flammable substance and should not be disposed of arbitrarily to avoid fires caused by the residue's flow and evaporation.
4. LPG cylinders are pressurized containers that require proper maintenance and regular inspection. Prevent the cylinders from falling or being struck during handling and use. Do not use metal tools to敲击 open the valve, and protect them from direct sunlight and prolonged exposure to rain. Cylinders should be inspected every 2 years.
5. Although the explosive range of liquefied petroleum gas (LPG) is not very wide, its lower limit is small, making it easily ignitable upon leakage. Additionally, as LPG is heavier than air, it tends to flow downward in the air and accumulate in low-lying areas, posing a hidden danger of gas explosions. Therefore, areas prone to gas leakage require more than just window ventilation; attention must be given to lower-level ventilation as well.
6. Upon discovering a liquefied gas leak indoors, promptly open windows and doors for ventilation, allowing it to disperse in the direction away from any open flame. Strictly prohibit any fire nearby until the fault is resolved and the distinctive odor has dissipated before reusing. For any leaked waste liquid on the ground, cover it with sand and soil before removing it to a safe location. In case of a gas cylinder fire, immediately close the valve, move it to an open area outdoors, and extinguish the fire using dry powder extinguishers, CO2 extinguishers, or by covering it with a wet sack.
7. Educate children not to tamper with gas cylinders at will, and users must understand the safety knowledge of using gas cylinders.
