1. Before the first use, the lng storage tank must be purged and precooled with nitrogen. The purging pressure shall be equal to or lower than 50% of the working pressure.

2. Precautions for first filling:

(1) Open the upper and lower liquid inlet valves, and fill the top and bottom at the same time. At the same time, open the liquid filling overflow port valve to discharge the gas in the tank. When there is lng gas discharged, close the filling overflow port valve immediately;

(2) When flushing to more than 50% of the volume of the lng storage tank, the lower liquid inlet valve shall be closed;

(3) When filling to 85% of the volume of the lng storage tank, close the upper liquid inlet valve and stop filling for 3 minutes to calm the liquid level in the tank, then open the upper liquid inlet valve to continue filling until liquid flows out of the filling overflow port valve, immediately close the filling overflow port valve, stop filling and close the upper liquid inlet valve;

(4) At the beginning of liquid filling, loosen the connectors at both ends of the liquid level gauge, fully open the liquid phase valve and gas phase valve for liquid level display, and check whether the air flow discharged contains water. If there is water, continue to discharge until there is no water. Tighten the connectors at both ends of the level gauge and close the balance valve to make the level gauge work normally.

3. Refill procedure:

(1) After the first filling of the lng storage tank, the gas phase pressure in the tank shall be reduced as much as possible when refilling;

(2) Fill up and down at the same time. When the liquid level gauge shows about 50% full, close the lower liquid inlet valve. When the liquid level reaches 85%, close the upper liquid inlet valve and stop filling for 3 minutes to calm the liquid level in the tank. Then open the upper liquid inlet valve to continue filling until liquid is discharged from the overflow valve, close the overflow valve to stop filling, and close the upper liquid inlet valve at the same time;

(3) During the filling process, observe the pressure gauge and liquid level gauge, and try to keep the pressure difference of 0.2 MPa. (If the pressure rises to higher than the filling and delivery pressure or close to the relief pressure of the safety valve, the gas discharge valve must be opened to discharge the gas phase in the lng tank in an appropriate amount)

Precautions when using natural gas storage tanks are jacketed vacuum powder insulated pressure vessels used to store and supply low-temperature liquefied gases. It has been widely used in industrial production.