GB/T 20368-2021Production，storage and handling of liquefied natural gas (LNG) (English PDF)

3.1 General

3.1.1 Liquefied natural gas; LNG

A cryogenic liquid fluid whose primary component is methane and may contain small amounts of ethane, propane, nitrogen, or other components commonly found in natural gas.

3.2 Gasification facilities

3.2.1 Vaporizer

A device that introduces heat in a controlled manner to convert a liquid into a vapor or gaseous state.

3.2.2 Ambient vaporizer

The main heat source of the vaporizer is not separated from the actual gasification heat exchanger. The main heat source is the environment, sea water or geothermal water, etc.

NOTE: It includes air-temperature vaporizer.

3.3 Storage facilities

3.3.1 Tank system

Low-pressure (operating pressure less than 100 kPa) field-assembled, vertical, cylindrical, and flat-bottomed equipment used to store liquefied natural gas or other hazardous liquids.

3.3.6 Full containment tank

A storage tank composed of a liquid-tight and air-tight secondary container and a primary container built into the secondary container. The secondary container is an independent self-supporting closed structure with a vault. [Source: GB/T 8423.3-2018, 5.2.28]

3.3.7 Membrane tank

A composite structure capable of storing cryogenic liquids consisting of a thin steel main container (i.e., membrane), insulation layer and prestressed concrete tank. [Source: GB/T 8423.3-2018, 5.2.31]

3.3.8 Liquefied natural gas pressure container

LNG pressure container A factory-made steel vessel used for the storage of liquefied natural gas and operating at a pressure greater than or equal to 100 kPa.

4.1 Soil protection for cryogenic facilities

When designing and constructing the foundations of LNG storage tanks, cold boxes, pipes and pipe racks, and other low-temperature facilities, measures shall be taken to prevent the destructive forces caused by soil freezing or frost heaving.

4.4 Control room

4.4.1 The LNG plant shall be equipped with a control room. The setting of the control room shall be determined according to the scale and characteristics of the plant, as well as the different requirements of the management and production modes. The control room mainly has functions such as production operations, process control, safety protection, and instrument maintenance.

4.4.2 The setting of the control room shall comply with the following requirements.

5.1 Site selection

5.1.1 Plant site selection shall be based on the region's topography, geology, hydrology, meteorology, transportation, fire protection, water supply and drainage, power supply, communications, available land and social life conditions.

5.1.4 Plants shall have all-weather evacuation conditions.

5.1.5 The plant shall be located on the upwind side of the lowest frequency wind direction in the adjacent town or residential area throughout the year.

5.1.6 Highways, regional overhead power lines, and regional oil (gas) piping shall not cross the plant site.

5.1.9 Plants shall not be located in the following areas and sections.

5.1.10 The plant shall not be built in a Category IV site area with a seismic fortification intensity of 8 degrees.

5.2 Floor plan

5.2.1 The layout of devices and equipment shall comply with the requirements for operation and inspection and maintenance access of the plant.

5.2.2 The layout of installations and equipment shall take into account prevailing wind directions and sources of ignition.

5.2.3 The layout of devices and equipment shall comply with emergency escape requirements for personnel.

5.3 Tank spacing

5.3.3 Double containment tanks, full containment tanks and membrane tanks shall be separated from the impounding areas of adjacent single and double containment tanks.

Avoid damage to storage tanks caused by fire or leakage in adjacent storage facilities.

5.3.4 If there are no fire protection measures, the concrete outer tank shall be designed to prevent external fire. Conduct thermal analysis to determine temperature distribution and fire action time.

5.3.5 Multiple tank shut-off valves shall have at least 0.9 m of operating space.

5.3.6 LNG storage tanks larger than 0.5 m³ shall not be built indoors.

5.3.7 Flammable liquid and flammable refrigerant storage tanks shall not be arranged in the LNG storage tank impounding area specified in Chapter 12.

5.4 Vaporizer spacing

5.4.1 In addition to the provisions of 5.4.5, the distance between the vaporizer and the plant fence shall not be less than 30 m.

5.6 Loading-unloading equipment spacing

5.6.1 Piers or berths used for piping transportation of LNG shall be such that any vessel being loaded or unloaded shall be no less than 30 m from any bridge spanning a navigable waterway.

5.7 Construct buildings

5.7.1 Structures not covered in 9.4~9.6 shall be installed in appropriate locations or other provisions shall be made to reduce the entry of flammable gases or evaporative gases.

5.7.2 The distance between structures not covered in 9.4~9.6 and the connection points of storage tanks, ships or equipment containing LNG and other hazardous liquids shall not be less than 15 m.

6.1 General requirements

6.1.1 The installation of process equipment for LNG and other hazardous medium shall meet the following requirements. 6.3.12~6.3.16.

6.1.2 Welding and brazing of process equipment shall meet the following requirements.

6.1.3 Dangerous goods storage containers and equipment other than LNG shall comply with the provisions of Annex A.

6.1.4 Process equipment shall be marked with the maximum allowable working pressure.

6.1.11 Evaporative gas shall be discharged to a closed system or an atmospherically safe location to avoid harm to personnel, equipment or surrounding facilities.

6.1.12 Process equipment, piping, cold boxes or other equipment that may form a vacuum shall be designed to withstand vacuum conditions or take measures to prevent vacuum. If air supplementary measures are used, the formation of flammable mixtures in the system shall be prevented.

6.2 Pumps and compressors

6.2.1 The material selection of pumps and compressors shall comply with the design temperature and design pressure regulations.

6.2.2 Valves shall be provided so that each pump or compressor can be isolated for maintenance.

6.3 Vaporization facilities

6.3.1 If the temperature of the natural heat source of an ambient heat source vaporizer exceeds 100°C, the vaporizer shall be considered a remote heated vaporizer.

6.3.2 If the natural heat source of an ambient heat source vaporizer is separated from the actual vaporizer, and a controlled heat transfer medium circulation is used between the heat source and the vaporizer, the vaporizer shall be considered a remote heated vaporizer and shall comply with the regulations for the heated vaporizer.

6.3.3 The design, construction and inspection of vaporizers that meet the definition of pressure vessels shall comply with the requirements of TSG 21.

6.3.7 For unattended LNG plants, or vaporizers installed within 15 m of heat sources or flammable liquid containers, if an automatic shut-off valve is installed within a 3 m radius of the vaporizer or vaporizer system, the setting of automatic shut-off valve shall comply with the provisions of 11.1.7.2.

6.3.8 In manned LNG plants where the vaporizer is installed beyond 15 m from a heat source or flammable liquid container, an automatic or manual shut-off valve shall be installed at least 15 m from the vaporizer, vaporization system or vaporizer building.

7.1 General requirements

7.1.1 LNG membrane tanks, LNG metal storage tanks and LNG concrete storage tanks shall comply with the provisions of 7.4.

7.2 Design requirements

7.2.1 All materials in the LNG storage tank system that come into contact with LNG or low-temperature LNG vapor (temperature below -20°C) shall be adapted to their corresponding operating temperatures.

7.3 Inspection

7.3.1 The LNG storage tank system shall be inspected before being put into use to ensure that the engineering design, materials, manufacturing, installation and testing comply with the provisions of this document.

7.4 Liquefied natural gas storage tank system

7.4.2 Tank insulation

7.4.2.1 The external insulation layer shall be made of non-combustible, water-free, resistant to fire water erosion and moisture-proof materials. Its outer shell shall be constructed of steel or reinforced concrete. The flame spread index of the outer protective layer shall not be greater than 25.

7.4.3 Bleed device

7.4.3.1 Storage tanks shall be equipped with safety valves and vacuum safety valves.

7.4.3.2 The pressure and vacuum relief devices shall be directly connected to the atmosphere when in use.

7.4.3.3 When the storage tank may experience negative pressure and exceed its design pressure, a vacuum relief device shall be installed.

7.4.9 Other requirements for membrane tanks

7.4.9.1 The hot corner protection system of membrane tanks shall be functionally equivalent to the hot corner protection system of full containment concrete outer tanks.

7.4.9.2 The hot corner protection system shall protect the entire bottom of the outer tank and at least 5 m below the tank wall. Maintain necessary temperature isolation from cryogenic liquids. Ensure the liquid tightness of the integral connection or hinged connection between the tank wall and the bottom plate.

8.1 General requirements

8.1.1 Piping

8.1.1.1 The internal and external process piping systems and pipe fittings of the storage tank are part of the LNG storage tank and shall comply with the provisions of GB/T 150 (all parts), GB/T 20801 (all parts) or GB 50316. The remaining process piping shall comply with the regulations of GB/T 20801 (all parts) or GB 50316.

8.1.3 Stress requirements

8.1.3.1 The design of piping systems and components shall consider the fatigue effects caused by the hot and cold cycles to which the system is subjected.

8.1.3.2 The hot and cold compensation of piping and their connections shall comply with the provisions of Chapter 9 of GB 50316-2000 (Edition 2008).

8.1.4 Material selection

8.1.4.4 In addition to complying with the provisions of 14.2, thermal insulation materials used in fire environments shall also comply with the provisions of GB 50264 or SY/T 7419.

8.2 Piping system materials

8.2.3.2 Cast iron, malleable iron and ductile iron valves shall not be used.

8.2.2 Pipe fitting material

8.2.2.1 The grade of threaded joints shall not be lower than Sch 80.

8.2.2.2 Cast iron, malleable iron and ductile iron pipe fittings shall not be used for hazardous medium.

9.1 Design classification

Buildings, equipment and piping systems shall be classified according to the following requirements.

9.2 Factory facilities

9.2.1 The design of buildings, equipment and piping shall be able to withstand the earthquake, wind load and snow load specified in this document. The wind load and snow load shall not be less than the values specified in GB 50009.

9.5 Fire and explosion control

If LNG and flammable liquids are produced and stored in the building or adjacent buildings, the building shall be designed for fire protection and explosion venting in accordance with GB 50016.

9.7 Combustible gas or boil-off gas control

Buildings or enclosures other than buildings (structures) used to produce, store and ship LNG, flammable refrigerants and flammable gases shall take measures to reduce the entry of flammable gases or evaporation gases.