LNG tank semi trailer unloading operation, these safety precautions must be kept in mind

LNG is the abbreviation of Liquefied Natural Gas (Liquefied Natural Gas), is a colorless liquid, the main component is methane, may also contain a small amount of ethane, propane, nitrogen and so on. LNG tanker transport is a way of liquefied natural gas land transport, in recent years, due to not in accordance with the safety regulations for unloading the vehicle caused by personal injury accidents are not a few, so today we will learn: LNG tanker unloading operation what are the safety precautions? 1. The tank truck enters the liquid loading area, carefully checks the scene, and confirms that there is no open flame nearby. The tank truck is parked at the designated safe working place for loading and unloading, the engine is turned off and the main power switch of the car is braked with the hand brake. At the same time, the mask is laid on the bottom of the car, and the ground wire of the filling is connected to the tank car. 2. Carefully check whether all the pipes and joints of the tank truck are secure, and whether the positions of valves and electrical switches are correct. Check that the pressure gauge valve level gauge valve tee is on and other valves are closed. 3. The unloading metal hose of the LNG tanker is connected to the liquid phase pipe interface of the liquid loading point respectively. If the flange is connected, the flange surface should be sealed with a gasket, and the metal hose should be securely connected with an explosion-proof wrench. 4, when unloading liquid, first check whether the tank pressure meets the liquid filling standard. If the pressure is too high, first pull the pressure back to the tank car, and then fill the liquid. 5, in the filling and unloading of liquid, to be particularly careful, do not touch the unloading hose, to prevent frostbite (long into contact with the pipeline is prone to pipe and skin adhesion). 6. During loading and unloading, the operator, driver and escort shall not leave the scene and shall not start the vehicle at will. 7, when filling, shall not exceed the maximum allowed filling amount, it is strictly prohibited to overfill, if there is overfill must be discharged until it meets the "maximum filling weight". 8. When unloading the liquid, the liquid in the container must not be completely drained, there must be a margin of not less than 300KG, and the residual pressure is not less than 0.1Mpa2, the vehicle must comply with the safety parking regulations to prevent unnecessary accidents. 9, after the discharge of liquid, carefully check the emergency cut off valve, gas phase valve, liquid phase valve is normal, and finally open the total vent valve to vent the residual gas phase. In addition, when we encounter problems with the above steps, what should we do to avoid accidents? When the safety valve of the tank truck is activated when the low-temperature LNG unloading sled is unloaded, we should: (1) Immediately close the booster liquid valve of the tank truck, open the gas phase valve of the tank truck pipeline, unload the tank truck pressure into the pipe network, and open the middle discharge valve to speed up the discharge of liquid; (2) After the relief valve of the tank car is discharged and the pressure is returned to the setting pressure, the normal operation can continue. When the hose is broken when the low-temperature LNG tanker is unloaded, we should: (1) Immediately stop loading and unloading operations, open the emergency release valve at the rear of the vehicle, close all valve switches on the vehicle, and close the pipeline inlet valve; (2) Quickly remove the loading and unloading hose; (3) Replace the hose and resume the loading and unloading operation When the hose flange leaks when the low-temperature LNG tanker is unloaded, we should: (1) Immediately stop loading and unloading operations, open the emergency release valve at the rear of the vehicle, close all valve switches on the vehicle, and close the pipeline inlet valve; (2) Quickly remove the loading and unloading hose; (3) Check whether the gasket is broken, such as broken gasket change, and then tighten the screw. If not broken, just tighten the screws diagonally to restore normal operation. When the low-temperature LNG tanker leaks during unloading, we should: (1) Immediately stop loading and unloading operations, open the emergency release valve at the rear of the vehicle, close all valve switches on the vehicle, and close the pipeline inlet valve; (2) Quickly remove the loading and unloading hose (if necessary, it can be urgently pulled off); (3) The fire hose of the filling station is connected to the fire hydrant, and the water gun is sprayed to the top of the tank car, the leak point and the tire to cool down and prevent the explosion caused by the sharp rise of pressure; (4) If the situation permits, the tank truck can be driven from the station area to an open area for processing in a planned way; (5) Immediate efforts should be made to plug the leak to prevent a large flow of liquefied natural gas; (6) If it is not possible to immediately deal with the leak, immediately organize enough manpower and material resources to set up a security cordon, and let it leak and volatilize under the condition that it is not enough to cause danger. When the piston ring of the pump body leaks during the cryogenic pump loading and unloading truck of the cryogenic LNG tank truck, we should: (1) Immediately stop loading and unloading operations, open the emergency release valve at the rear of the vehicle, close all valve switches on the vehicle, and close the pipeline inlet valve; (2) Find the leak point, repair and replace the gasket; Of course, these operations are to ensure their own safety, when endangering their own safety, we should immediately flee the site in an orderly manner, and report to the headquarters of the site situation.