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This post was last edited by Yu Qin on 2020-6-19 21:07. Liquefied petroleum gas, or LPG, refers to petroleum gas that has been liquefied under high pressure or low temperature; it is also simply called liquefied gas. Its composition includes propane, n-butane, isobutane, along with small amounts of ethane, organic compounds with more than 5 carbon atoms, and unsaturated hydrocarbons. Thanks to its high calorific value, absence of smoke and ash, and ease of use, it has been widely adopted in people’s daily lives. Therefore, the safety of storing and transporting liquefied petroleum gas is receiving increasing attention. Although accidents related to the storage and transportation of liquefied petroleum gas occur from time to time, as long as safety regulations are strictly followed and relevant safety standards are implemented during these processes, the safety level of such storage and transportation will **improve**. 01 LPG storage and transportation methods 1. LPG storage The storage of LPG is an important part of the LPG supply system. The storage method and the amount of storage to be kept should be determined through comprehensive consideration of various factors such as gas supply availability and users’ gas consumption patterns. Storage methods can be classified according to the state of liquefied petroleum gas being stored into storage at normal temperature and high pressure in liquid form, storage at low temperature and normal pressure in liquid form, and solid-state storage ； Based on spatial relative location, there are storage in strata caves, storage in underground metal tanks, and storage in above-ground metal tanks. Among these, liquid storage at normal temperature and high pressure is often used for the transportation and storage of liquefied petroleum gas since no insulation is required ； Liquid storage at low temperature and normal pressure is used in tankers for the maritime transport of liquefied petroleum gas, as the gas storage facilities operate at normal pressure and only require insulation ； Solid-state storage is convenient to carry and use, and is suitable for use in special situations such as hiking and camping. Regarding the choice of spatial location, geological cavern storage offers advantages such as large storage capacity, low metal consumption, and reduced investment, but it is necessary to find suitable storage strata ； Underground metal tank storage is divided into two types: full-pressure storage and full-freezing storage. Full-pressure storage is generally used when ground conditions prevent the installation of surface tanks, whereas full-freezing storage requires the use of insulation devices ； Above-ground metal tanks have advantages such as simple structure, easy construction, a wide variety of tank types, and ease of selection. However, they are greatly affected by temperature changes; in areas with high temperatures, cooling measures must be taken during the summer. 2. The methods of transporting liquefied petroleum gas from its source sites to supply centers include pipeline transportation, railway tank car transportation, road truck tank car transportation, and waterway tank ship transportation. The choice of transportation method should be based on the scale of the supply base, the transportation distance, and traffic conditions; when necessary, a technical and economic comparison of various options should also be conducted. 2.1 Pipeline transportation: The characteristics of pipeline transportation include large transport capacity, safe and reliable system operation, and low operating costs. However, this method requires a large one-time investment, and it consumes a lot of pipes and metal. When the volume of transport is small and the distance is short, pipeline transportation can be used. 2.2 Railway Transport: Railway transport generally uses train tank cars as the means of transportation. Railway transportation is characterized by large loading capacities, low transportation costs, and relative flexibility; however, its operation and scheduling are more complex than those of pipeline and road transportation, and it is subject to constraints such as railway connections and the construction of dedicated railway lines. This mode of transportation is suitable for situations with long distances and large volumes of cargo to be transported. 2.3 Road Transport Road transport generally uses tank trucks as the means of transportation. Its advantage is flexible transportation, with the capacity for timely adjustment, which facilitates scheduling; however, the transportation cost is high. Truck-mounted tanks are mainly used for transportation at medium and small supply stations; they can also serve as auxiliary transportation tools at large supply bases. When necessary, such tanks can be used as mobile storage tanks as well. Currently, there are mainly three types of liquefied petroleum gas tankers used in China, namely fixed tankers, semi-trailer tankers, and mobile tankers. The selection, design, manufacturing, inspection, and operational management of road tankers must all comply with relevant **requirements. 2.4 Water transport: In areas where water transportation is convenient, using tankers equipped with liquefied petroleum gas storage tanks to transport liquefied petroleum gas is also one of the available options. Currently, water transport is divided into two categories: sea transport and river transport. Sea transport is widely used in the international trade of liquefied petroleum gas. LPG tankers used for maritime transport are mostly low-temperature and atmospheric-pressure tankers, with capacities of tens of thousands of tons ； Trough ship transportation technology is mature, with well-equipped facilities and comprehensive safety measures. LPG tankers used for offshore and river transport are generally normal-temperature, pressure-type tankers. These trough ships have a relatively small capacity, usually in the range of hundreds or thousands of tons. In areas with suitable navigational conditions, developing river or offshore transportation for liquefied petroleum gas can reduce its transportation costs. 02 Hazard analysis of LPG storage and transportation: LPG is a flammable and explosive substance, and accidents involving it are often characterized by sudden ignition and explosion, leaving no sufficient time for firefighting. If a tank truck has an accident in an area with high population density, the tank may collide and leak, causing liquefied petroleum gas to reach its explosive limit; upon encountering an open flame, an explosion will occur, with extremely serious consequences. 1. Tankers, storage tanks, cylinders used for transporting liquefied petroleum gas in environments where fire hazards exist, as well as gas transmission pipelines, may experience gas leaks due to improper operation or performance degradation and malfunctions resulting from a lack of maintenance over time. As it spreads, the leaked liquefied petroleum gas comes into contact with various sources of fire such as open flames, electrical sparks, static electricity sparks, and sparks emitted from the exhaust pipes of motor vehicles. It poses a fire hazard. 2. Explosion hazard: At normal temperatures, liquefied petroleum gas is in a gas-liquid equilibrium state inside the container; the gas pressure in a properly filled container can reach over 980 kPa. Our country has a vast territory, and temperatures vary from place to place; road transportation is not very developed, and vehicle accidents occur from time to time. Therefore, vehicles used for long-distance transportation of liquefied petroleum gas are sometimes exposed to heat, intense vibrations, and impacts, posing a risk of explosion. Furthermore, liquefied petroleum gas that leaks from tank cars, cylinders, and pipelines can reach its explosive limit in the air, and there is a risk of explosion if it comes into contact with a fire source. 03 Fire safety measures for the storage and transportation of liquefied petroleum gas 1. Fire safety measures for the storage of liquefied petroleum gas The location of liquefied petroleum gas storage and distribution stations should be chosen on the outskirts of the city, downwind or to the side of residential areas, as well as areas where open flames or sparks may occur. Solid walls made of non-combustible materials, with a height of not less than 2 meters, should be constructed around the area. The tank storage area, compressor rooms, hydrocarbon pump rooms, auxiliary gas cylinder storage areas, tank truck loading/unloading platforms, and trestles should be located in the production area; buildings such as repair shops, power distribution rooms, offices, and control rooms should be situated in the auxiliary area. The layout of structures, buildings, and equipment within the station shall comply with the requirements of safety technical specifications. The compressor room, the hydrocarbon pump room, and the auxiliary gas cylinder storage area should be located separately, with a fire separation distance of not less than 13 meters between them. Fire dikes should be installed near the tank area, and the tanks must be regularly inspected and maintained to ensure safety, as well as reliability and efficiency. 2. Fire safety measures for pipeline transportation: Pipeline systems for the long-distance transport of liquefied petroleum gas consist of a starting storage tank, a starting pump station, a metering station, intermediate pump stations, pipelines, and an ending storage tank; their installation must comply with relevant safety regulations. Seamless steel pipes are preferred for pipelines. For the convenience of maintenance, pipe connections should primarily be made by welding, with flange connections used as a supplement. Pipelines are usually laid underground. Pipeline systems for transporting liquefied petroleum gas shall not pass through buildings or structures that house liquefied petroleum gas facilities, nor shall they pass through areas containing flammable and explosive materials or corrosive liquids. The distance between such pipelines and other pipelines, buildings, and structures must comply with relevant regulations. The burial depth of liquefied petroleum gas transmission pipelines should not be less than 0.6 meters. When pipelines intersect railways or roads, they should pass beneath the railway, and protective sleeves should be installed for the sections passing through. When pipes cross railways, roads, and pedestrian paths, they should have a sufficient safety height. When pipelines intersect rivers and lakes, they can be crossed by an overhead structure or passed beneath the riverbed. To meet the requirements for the installation, operation, maintenance, and fire safety of liquefied petroleum gas transmission pipelines, valves should generally be installed at the entrances and exits of stations, at the points where branch pipes diverge as backup lines, along major railway and highway routes, and on both sides of important rivers. Regular inspections of the pipeline system are necessary; liquefied petroleum gas delivery pipelines should be maintained on a periodic basis, so that any leaks in the pipes, valves, and other components can be detected and repaired promptly. The use of open flames is prohibited when checking for and fixing air leaks. Fire safety measures must be implemented for hot work maintenance. 3. Fire safety measures for railway tank car transportation: The design, manufacture, use, maintenance, and operation of liquefied petroleum gas railway tank cars must comply with relevant regulations issued by the ** as well as departments such as those responsible for labor, railways, and chemicals. The tank should be marked with a prominent red sign stating “No Smoking or Open Flames,” and necessary fire-fighting equipment should be installed in appropriate locations. Before filling a liquefied petroleum gas railway tank car with liquefied petroleum gas, it is necessary to carefully check the condition of safety accessories such as pressure, liquid level, and emergency shut-off devices, and to verify the name of the medium to be filled into the tank car. When loading and unloading liquefied petroleum gas, safety operating procedures must be strictly followed to prevent leaks of the liquid or gas, thereby avoiding the accumulation of liquefied petroleum gas at the loading and unloading site and the resulting fire hazard. Loading and unloading operations should be halted in case of thunderstorms, or when there are factors that threaten safety during loading and unloading such as abnormal hydraulic pressure in tanks, gas leaks, or fires near the loading and unloading areas. Railway tank car escorts for liquefied petroleum gas must not only be familiar with the properties of liquefied petroleum gas, understand the structure and performance of the tank cars as well as the safety regulations for transporting hazardous goods by rail, but also possess necessary knowledge of fire prevention and suppression so as to handle incidents such as leaks or fires that may occur during transportation properly. When liquefied petroleum gas railway tank cars are arranged in a train, they should be separated by at least 4 other vehicles from the steam locomotives pulling them, as well as from passenger cars and vehicles carrying explosive materials. They should also be separated by at least 1 other vehicle from diesel or electric locomotives, vehicles equipped with furnaces, vehicles carrying goods other than explosive materials, and vehicles carrying flammable and explosive substances. Railway tank cars carrying liquefied petroleum gas shall not stop for long at any stations along the route; upon reaching the final railway station, a locomotive should be used to push the tank car to the liquefied petroleum gas station as soon as possible. In the event of a major leak during transportation, the escort personnel must promptly inform the train supervisor, issue danger signals, stop the train to seal the leak urgently, and immediately report to the local authorities as well as the police and fire departments. A safety zone should be established, and safe evacuation procedures should be organized. 4. Fire safety measures for the transport of liquids by tank trucks (1) The design and manufacture of liquefied gas tank trucks must comply with the relevant regulations set by ** and the labor authorities. Safety accessories such as pressure relief valves, emergency shut-off valves, and anti-static grounding chains on liquefied gas transport vehicles must be complete and meet safety technical requirements; they should also be regularly inspected during transportation to ensure they remain functional and reliable. A reliable spark arrester must be installed on the engine exhaust pipe. Furthermore, in order to be able to extinguish incipient fires that occur during transportation promptly, tank trucks should also be equipped with two dry powder fire extinguishers of 5 kilograms or more, or 1211 fire extinguishers of 3 kilograms or more. Before transporting liquefied petroleum gas, road tankers must be thoroughly inspected for their condition, and they are not allowed to carry any other flammable or explosive materials. Along the way, when passing through overpasses, culverts, tunnels and other important road transportation facilities, one must pay attention to the elevation levels, drive at the prescribed speed limits, and avoid stopping. When entering the urban suburbs, one should drive at the speed limits and along the routes specified by the local public security authorities, and must not pass through important public places or busy areas. During transportation, the temporary parking location should be well-ventilated and located away from government offices, schools, bridges, factories, warehouses, and areas with heavy foot traffic. During stopovers, the driver or escort must remain with the vehicle to supervise it, and open flames or any tools that may generate fire must not be used for repairs. During night rest, tank trucks must not be parked in public parking lots, warehouses storing flammable and explosive materials, or near ordinary vehicles. When parking in summer, avoid exposure to direct sunlight. Before carrying out loading and unloading operations, the tank truck must be stopped and its engine turned off; a ground wire should be connected, the pipe connections secured, and any air inside the tank removed. When performing loading and unloading operations, the vehicle must not be started, nor should fluids be drained or air released; additionally, tools that may cause fires must not be used. In case of thunderstorms, hydraulic abnormalities, fires in the vicinity, or other factors that pose a threat to the safety of loading and unloading, tank trucks should cease such operations. After unloading the liquid, the vehicle should be parked in a dedicated vehicle tank garage; it must not be parked randomly in other locations. With the development of society and the improvement of productivity, liquefied petroleum gas has become widely used in our production and daily life. As a fuel that is highly prone to explosion when exposed to open flames and can cause accidents, we must pay special attention to the safety of its storage and transportation.