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Safety Technical Requirements for Liquefied Petroleum Gas Supply Stations I. Requirements for Key Areas (1) Liquefied Petroleum Gas Unloading Platforms A liquefied petroleum gas storage and supply station is a facility that supplies liquefied petroleum gas both externally and internally to refineries or petrochemical plants; it is responsible for various tasks related to distribution and retail supply. As independent departments and service points dedicated to fuel supply, reserve supply stations cover a wide range of areas, vary in size, and employ diverse storage and supply methods; therefore, it is essential to establish a comprehensive and thorough safety supervision system. Reserve supply stations should identify the key areas for safety supervision based on the nature of their operations. Unloading platforms are areas prone to accidents, and strict supervision and management are necessary. (II) LPG Filling Room The filling room is the place where LPG is unloaded and filled. Due to the varying condition of the LPG cylinders, loading, unloading, and filling operations are carried out frequently; as a result, the LPG remaining in the filling nozzles continuously leaks out, causing the concentration of flammable gases in the environment to fall within the explosive range. This makes it easy for fires and explosions to occur due to open flames or friction sparks ； At high pressure, liquefied gas is released at high flow rates, increasing the risk of static electricity and also making fires and explosions more likely. (III) LPG cylinder storage facilities Storage facilities for replacing LPG cylinders are widely found in cities, industrial and mining enterprises, as well as in areas where employee residences are concentrated in large government agencies and organizations. If the valves of the propane cylinders are not properly sealed or are defective, it can result in the propane cylinder storage area becoming a space filled with explosive gas mixtures. Moreover, with people coming and going for ventilation, there is a high likelihood of the use of open flames, as well as the generation of friction sparks and impact sparks; poor management can easily lead to various accidents. (IV) LPG compressor room and instrument room There are areas prone to fire and explosion, as well as zones with explosive gases, surrounding the compressor room and instrument room. Equipment failures and faulty instrument operations can both lead to serious problems, resulting in various types of accidents. (V) Fire extinguishing facilities Fire extinguishing facilities are crucial for disaster relief operations at liquefied petroleum gas stations; they should be installed in accordance with regulatory requirements and kept in good condition. II. Safety technical requirements for key areas (I) Unloading platforms at storage and supply stations 1. Railway unloading platforms The safety supervision aspects related to railway unloading platforms have been discussed in detail in the section on loading and unloading platforms; this section only provides some necessary supplementary information. Throughout the entire length of the dedicated line, there should be no stray currents entering; rail insulating joints should be installed at the joints. The work line should be straight; if conditions make this difficult, curves with a radius of curvature of at least 500 meters can be used. When the capacity of the tank cars for loading and unloading at a railway terminal used for liquefied petroleum gas exceeds 4, the terminal shall be constructed for loading and unloading in accordance with the relevant specifications ； The capacity to load and unload tank cars is 1–3 units; fixed unloading pipe sets can be installed on the platform, and emergency shut-off valves can be placed at convenient locations along the pipeline that transfers fluid from the platform to the storage tanks. The piping assemblies and unloading equipment shall be tight, secure, and leak-free. Both the dedicated line and the unloading pipe set must be grounded, with no fewer than two sets for static grounding. The work station platform should be equipped with reliable communication facilities connected to the compressor room and tank area, as well as strict fire management procedures. 2. Highway unloading platforms Buffering and crash prevention facilities are installed between the unloading stations and the parking areas; there are parking signs for various types of vehicles, as well as strict regulations regarding fire hazards. When the vehicle enters the work area, a flame arrester should be used, and the engine must be turned off during loading and unloading. Automobile liquefied gas tankers and piping systems are equipped with static grounding devices. The unloading pipe assembly is sturdy and airtight, with no leaks. It is strictly prohibited to start the engine and drive the vehicle until unloading is complete and the unloading valve has been closed, with confirmation from management obtained first. (II) Filling room at the reserve supply station The filling room shall be an open or semi-open building with a fire resistance rating of not less than grade two, and it must have good ventilation. The stopcocks or other air injection valves used for loading and unloading must open and close smoothly, and the pipe assemblies as well as all connections must be tight and leak-free. The floor at the filling station should be paved with a material that does not produce sparks upon impact. The pipe assemblies and scales must have static electricity grounding measures. All cylinders that are filled must have valid pressure vessel inspection certificates, clear markings, and pass visual inspections. Cylinders that do not meet the requirements will not be filled. Residual liquid must not be discharged arbitrarily. The filling station should replace equipment and collect residual liquids in a dedicated area for centralized treatment. The filling level of the gas cylinder and the filling pressure must not exceed the specified values. Gas concentration monitoring and alarm equipment should be installed in the bottling room. Workers must wear anti-static clothing, shoes, and hats, and must not bring any hard metal tools or equipment into the work area. (III) LPG Cylinder Storage Facility LPG cylinder storage facilities should be designed and constructed in accordance with the requirements set out in the current \"Code for Fire Protection Design of Buildings\" for Class A storage facilities, as well as the regulations in the \"Code for Design of Urban Gas Systems\" regarding LPG supply stations. It is advisable to use open or semi-open design for such storage facilities. The total number of bottles stored in a single warehouse should not exceed 360 bottles (based on 15kg bottles). The actual bottles should be placed upright; those with a capacity of 15 kg or more can be stacked in only one layer, while those with a capacity of less than 15 kg can be stacked in two layers. A protective rubber ring should be fitted around the gas cylinder. A dedicated trolley should be used for transportation; dragging is not allowed. When shipping, use padding and secure the items tightly to prevent dangerous collisions and friction. The roof of the warehouse should be covered with lightweight asbestos shingles, and the floor should be paved with a material that does not produce sparks when struck. The doors and windows should open outward, and the glass should be painted white to prevent direct sunlight from entering. The winter temperature should be kept above –35°C to prevent cold crisp cracking of the welds during handling. In summer, the temperature inside the warehouse should not exceed 35°C. The warehouse should be equipped with floor windows or bottom ventilation holes to prevent the accumulation of liquefied petroleum gas. The ground level should be higher than the natural outdoor ground level. Cylinders with poorly sealed angle valves, damaged fittings, loose bases or handles, or unclear markings are not allowed to be stored or transported in or out. III. Introduction to Accident Cases On March 4, 1978, a severe liquefied gas explosion occurred at a fertilizer factory in Jiangsu Province, resulting in 6 deaths, 8 serious injuries, and 47 minor injuries; the economic loss caused by the accident amounted to 760,000 yuan. The cause of the accident was that the driver drove the liquefied petroleum gas tank truck into the garage and connected the hose at the back of the vehicle to the cast-iron check valve of the liquefied petroleum gas storage tank, without carrying out the handover procedure ； The newly assigned driver started the vehicle without conducting any checks, forcibly shutting off the valves; as a result, a large amount of liquefied petroleum gas from the tank escaped, and when it came into contact with the open flame in the boiler, an explosion occurred, leading to the accident. The cause of the accident was the change of driver during transportation without proper handover, with the new driver driving blindly without conducting a check. However, the use of cast-iron valves in LPG storage tanks also poses a significant risk of serious accidents. On April 15, 1988, an explosion occurred at the second filling station of a company in Tianjin. 3,000 liquefied petroleum gas cylinders and a 50m3 horizontal tank for storing liquefied petroleum gas exploded during the filling process. The fire burned for 68 hours, destroying a filling line worth $370,000 as well as 118 tons of liquefied petroleum gas. Seven people were injured in the efforts to extinguish the fire. The cause of the accident was improper operation: the cylinder was overfilled, and the filling tube was removed without closing the cylinder valve, causing liquefied petroleum gas to spill out under pressure. The static electricity generated by the high-speed gas flow triggered a fire and explosion. On January 20, 1989, an explosion occurred in a liquefied petroleum gas cylinder at a testing facility in a certain area of Hubei Province. On that day, during a routine inspection, a steel cylinder already filled with compressed air was about to undergo a gas-tightness test when it suddenly exploded, resulting in 2 deaths and 2 serious injuries. The cause of the accident was the failure to remove residual liquefied petroleum gas and replace it before filling with compressed air. On April 14, 1992, an explosion occurred in a liquefied petroleum gas cylinder at a company in Guangxi Province, resulting in 3 serious injuries and 2 minor injuries. The accident occurred during the process of repairing liquefied petroleum gas cylinders. The illegal instructions given by the factory management and the illegal operations carried out by the workers were the direct causes of the accident. The incorrect practice of filling the cylinder with compressed air without first replacing the liquefied petroleum gas inside it, and then using gas welding to heat the cylinder, caused an explosion of the liquefied petroleum gas within it. March 30, 1993. An explosion occurred in a vehicle-mounted liquefied petroleum gas cylinder at a mine in Inner Mongolia; 102 cylinders and one truck were destroyed, resulting in losses of around 100,000 yuan. On that day, a vehicle carrying 102 cylinders of liquefied petroleum gas leaked gas due to poor securing and rough handling during transportation, which caused the angle valves on some of the cylinders to loosen; the liquefied petroleum gas then caught fire and exploded when exposed to an open flame. The accident shows that design and construction flaws, illegal instructions, failure to follow regulations, and improper operations are the fundamental causes of such accidents.