What are the requirements for transporting liquefied natural gas?

What mode of transportation? Pipes? Tank truck? Ship? Train?

The process of transporting liquefied gas from its source to storage and distribution (supply) stations involves three stages: loading, transportation, and unloading. Since liquefied petroleum gas is usually transported using railway tank cars, road tank trucks, vehicles equipped with cylinders, and pipeline transportation, its transport is generally divided into four methods: transportation by railway tank cars, transportation by road tank trucks, transportation by vehicles with cylinders, and pipeline transportation. I. The dangers associated with transporting liquefied petroleum gas: Due to its flammability, explosiveness, and tendency to generate static electricity, transporting liquefied petroleum gas involves significant risks. 1. There is a risk of fire: LPG storage tanks, cylinders, and pipelines used for transporting liquefied petroleum gas may leak gas due to improper operation, or as a result of long-term use combined with a lack of maintenance that leads to performance degradation and malfunctions. The leaked liquefied petroleum gas encounters various sources of ignition as it spreads, 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. Explosive hazard: At normal temperatures, liquefied petroleum gas is in a gas-liquid two-phase equilibrium state inside the container, and 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 well-developed, and vehicle accidents occur from time to time. Therefore, vehicles used for transporting liquefied petroleum gas over long distances are sometimes exposed to heat, intense vibrations, and impacts, posing a risk of explosion. Furthermore, liquefied petroleum gas that leaks from tank trucks, cylinders, and gas 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. 3. Common causes of fire and explosion accidents: (1) Illegal operations: Illegal operations are not only a major cause of other accidents but also a significant factor in fires and explosions that occur during the transportation of liquefied petroleum gas. (2) Traffic accidents: After a serious accident involving a liquefied gas transport vehicle, the liquefied petroleum gas often leaks, leading to explosions and fires. (3) Damage or failure of safety equipment on liquefied gas tankers and gas transmission pipelines: When the safety equipment and accessories on tankers and gas transmission pipelines are damaged or fail, two consequences often arise ； First, when the pressure in the tanks and pipelines rises to the safe pressure release level, safe pressure release is not possible, leading to an explosion ； Second, leaked or emitted gases can cause explosions and fires. (4) Emitted gases: LPG transport vehicles and pipelines should generally not emit any gases; emergency venting is only permitted in cases where an explosion might occur. The LPG that is released in such emergencies can explode and catch fire when it comes into contact with a source of ignition, which is also a major cause of accidents involving the transportation of LPG. (5) Thermal explosion of the transport container: The liquefied gas tanks in transport tankers, if overfilled and exposed to the sun for an extended period, can sometimes leak gas and catch fire ； If cooling is not carried out promptly after a fire breaks out. Explosions can also occur. II. Fire Safety Measures 1. Transport by tank vehicles (1) The design and manufacture of liquefied gas tank vehicles must comply with the relevant regulations set by ** and the labor authorities. Safety accessories such as pressure safety 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. To prevent fires, tank vehicles used for transporting liquefied petroleum gas must be equipped with explosion-proof electrical devices as required, and the tanks should be marked with prominent red signs stating “No Smoking.” The engine exhaust pipes must be fitted with reliable spark arrestors. 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. (2) The transportation of liquefied petroleum gas by road tankers must comply with **national** and **local** regulations regarding the management and transportation of chemically flammable and explosive substances, as well as traffic safety regulations. Before transportation, the condition of the vehicle should be carefully checked; a prominent “Hazardous Materials” sign should be hung at the front of the vehicle. It is not allowed to tow trailers, nor to carry any other flammable or explosive items. On the way, pass through overpasses, culverts, tunnels and other important road traffic facilities; pay attention to the elevation limits, drive at the prescribed speed, and do not stop ； When entering the urban suburbs, one must 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. The escort must stay with the vehicle and must not leave it at any point. Smoking is prohibited in the vehicle, and no other passengers are allowed. For long-distance transportation in summer, shading measures should be taken, and the liquid phase temperature and gas phase pressure inside the tank should be monitored regularly. When the liquid phase temperature reaches 40 degrees, cooling measures such as spraying water outside the tank should be applied. Long-distance transportation is not advisable when roads are frozen in winter. Otherwise, anti-slip chains should be attached to the tires, and driving at a reduced speed is required. (3) During transportation, the temporary parking location should have good ventilation and be located away from government offices, schools, bridges, factories, warehouses, and areas with heavy pedestrian traffic. A safety distance of over 25 meters must be maintained from important public buildings and facilities, while a safety distance of over 40 meters should be kept from areas with open flames or sparks. During stops, the driver or escort must remain with the vehicle to supervise it, and open flames or any tools that can 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. (4) When liquefied petroleum gas is transported to a liquefied petroleum gas station using road tankers, a loading and unloading platform for such tankers must be installed at the station. Otherwise, steam trough loading/unloading nozzles should be provided in the bottling room or compressor room. The fire separation distance between the vehicle loading/unloading platform and other buildings shall be no less than 15 meters, and the fire separation distance from liquefied petroleum gas storage tanks shall be no less than 30 meters. Near the loading/unloading platform or nozzles, grounding posts with a grounding resistance of not less than 10 ohms per centimeter should be installed for static electricity grounding prior to loading and unloading operations. To ensure the timely evacuation of tank trucks in case of a fire and to facilitate firefighting efforts, a turning area of at least 15 meters * 15 meters should be provided in front of the tank truck loading/unloading platform or nozzles, equipped with two dry powder fire extinguishers weighing over 8 kilograms each. (6) Before carrying out loading and unloading operations, the road tanker should be stopped and its engine turned off; a ground wire should be connected, the pipe connections secured, and the 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; in addition, tools that can cause fires must not be used. In case of thunderstorms, hydraulic problems, fires in the vicinity, or other factors that pose a threat to the safety of loading and unloading, tank trucks should cease such operations. When filling tank trucks with liquefied petroleum gas, careful measurement must be taken to ensure that overfilling does not occur. After a liquefied petroleum gas tank truck arrives at the station, it should be left to stand for 30 minutes first, after which the liquid should be unloaded promptly. The tank truck must not be used as a temporary storage tank, nor should gas be filled into cylinders directly from the tank truck. After the liquid is unloaded from the tank truck, a residual pressure of over 49 kPa should remain in the tank to prevent air from entering and posing a risk of explosion. (7) After unloading its contents, the tank truck should be parked in a dedicated tank truck garage; it must not be parked randomly in other locations. The tank truck garage should be a building with fire resistance ratings of grade 1 or 2. The fire separation distance from civil buildings should be no less than 30 meters, and the fire separation distance from factories and warehouses should be no less than 12 meters. The warehouse should be well-ventilated; electrical equipment such as lighting systems must meet explosion-proof requirements, and it should be equipped with at least two 8-kilogram dry powder fire extinguishers. Basements and trenches are prohibited in the warehouse, vehicle repairs are forbidden, and the storage of other flammable and explosive materials is prohibited. 2. Railway tank car transportation: (1) The design, manufacture, use, maintenance, and operation of railway tank cars for liquefied petroleum gas shall comply with ** as well as the relevant regulations issued by departments such as 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. (2) 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 verify the name of the medium to be filled in the tank car. Filling is prohibited for safety accessories that are incomplete or of poor performance; railway tank cars used for transporting liquefied gases such as liquid chlorine shall not be used to transport liquefied petroleum gas. When loading and unloading liquefied petroleum gas in tank trucks, 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. LPG stations that use railway tank cars to transport LPG should have loading and unloading trestles for these tank cars in their production areas. The centerline of the dedicated lines used for loading and unloading should be at least 20 meters away from the fire protection distance of the LPG storage tanks. At a distance of 30 meters from the tanks, signs indicating the \"locomotive parking position\" should be installed on those dedicated lines, with the approval of the relevant railway authority. Open flames and smoking are strictly prohibited within 30 meters of the loading and unloading area. To enable prompt extinguishment of any incipient fires that may occur during loading and unloading operations, an 8-kilogram dry powder fire extinguisher should be installed on the loading and unloading quay every 10–15 meters in length; in total, no fewer than 2 such fire extinguishers should be available on the entire quay. (3) The escorts of liquefied petroleum gas railway tank cars 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 the necessary knowledge of fire prevention and extinguishment so as to handle properly any incidents such as leaks or fires that may occur during transportation. For railway tank cars that have not undergone pre-filling inspections as required, have been overfilled, or whose sealing status is unknown, the escort may refuse to provide escort services. (4) When liquefied petroleum gas railway tank cars are arranged in a train, they should be separated from the pulling steam locomotives, passenger vehicles, and vehicles carrying detonation equipment by at least 4 other vehicles; they should also be separated from pulling diesel or electric locomotives, vehicles equipped with furnaces, vehicles carrying goods other than detonation equipment, as well as vehicles carrying flammable and explosive materials, by at least 1 other vehicle. (5) 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 promptly. In the event of a major leak during transportation, the escort personnel must immediately inform the train supervisor, issue danger signals, stop the train to seal the leak urgently, and promptly report to the local authorities as well as the police and fire departments, establishing a safety zone and organizing safe evacuations. In the event that a railway tank car leaks gas and catches fire during transport, immediate action must be taken, and the local fire department should be alerted promptly to organize rescue and disaster relief efforts. 3. Pipeline transportation (1) The pipeline system for long-distance transportation of liquefied petroleum gas consists of a starting storage tank, a starting pump station, a metering station, intermediate pump stations, pipelines, and an ending storage tank; its installation must comply with relevant safety regulations. Seamless steel pipes are recommended for pipelines. For ease of maintenance, pipe connections should primarily be made by welding, with flange connections used as a supplement. Pipelines are usually laid underground. (2) 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 substances or corrosive liquids. The distance between such pipelines and other pipelines, buildings, and structures must comply with relevant regulations. (3) The burial depth of liquefied petroleum gas transmission pipelines shall not be less than 0.6 meters. When pipelines intersect railways or roads, they should pass beneath the railways, and protective sleeves should be installed for the sections passing through. The protective sleeve should have sufficient strength; a certain gap should be maintained between its inner wall and the outer wall of the pipe, and the ends should be sealed with soft materials. When a pipeline passes under a railway, the depth from the bottom of the rail tracks to the top of the pipeline should not be less than 1.4 meters. Each end of the crossing sleeve should extend 3 meters beyond the railway track. When a pipeline passes through a road, the depth from the road surface to the top of the pipeline should be no less than 1 meter, and both ends of the casing extending through the road should protrude by 1 meter each. When pipelines cross railways, roads, and pedestrian walkways, 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. (4) 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. To facilitate accident control and maintenance, a section valve should be installed every 10--20 kilometers along the pipeline. The pressure resistance of the valve shall not be lower than the design pressure of the pipeline, and must not be less than 2450 kPa. The valves of buried pipelines are generally located in valve chambers, which should be situated in areas with open terrain, at a higher elevation, with good access for transportation, and where inspection is easy. Valve chambers should be installed on both sides of important rivers. The valve chamber equipped with a vent pipe should be located in a place that facilitates safe venting. During emission, there must be no open flames or sparks within 30 meters around. (5) To discharge the static electricity generated by the flow of liquefied petroleum gas in the pipeline and its friction against the pipe walls, the pipeline must be fully grounded, with a grounding electrode installed every 80 meters. Flanges connecting pipes should be bridged with copper or aluminum sheets. When performing gas transfer operations, the liquid phase flow rate of liquefied petroleum gas in the pipeline should be controlled. The allowable flow rate in a liquid phase is generally 0.8 to 2.5 meters per second, with a maximum of 3 meters per second. (6) Conduct regular inspections and maintenance of liquefied petroleum gas delivery pipelines, in order to promptly identify and eliminate leaks in the pipelines, valves, and other components. Open flames are prohibited when checking for and fixing air leaks. Fire safety measures must be implemented for hot work maintenance. 4. Transporting cylinders by vehicle (1) It is not advisable to use vehicles to transport liquefied petroleum gas over long distances with cylinders on board. Vehicles transporting liquefied petroleum gas cylinders should display a \"Hazardous Materials\" flag and be equipped with two or more 8-kilogram dry powder fire extinguishers. The engine exhaust pipe should be equipped with a reliable spark arrester. (2) Open flames and smoking are strictly prohibited in areas where liquefied petroleum gas cylinders are loaded and unloaded. When loading and unloading gas cylinders, handle them gently; do not roll or collide them. Gas cylinders should be stacked vertically in a single layer inside the carriage. Cylinders with a weight of 15 kilograms or less shall not be stacked in more than two layers, and measures must be taken to ensure a stable stack, in order to prevent the cylinders and their corner valves from being damaged due to vibrations from vehicles, which could lead to gas leakage. Vehicles transporting liquefied petroleum gas cylinders shall not carry passengers or goods. Cylinders that are overweight, leaking, or lack rubber gaskets must not be loaded for transport. (3) Vehicles transporting liquefied petroleum gas cylinders shall be equipped with escorts. Drivers and escorts should receive safety training to learn safety knowledge such as fire prevention and fire extinguishing. Fire safety measures for transportation and stops en route can be referred to those used for transporting liquefied petroleum gas in tank trucks. (4) In the event of a leak of liquefied petroleum gas during transportation, it is necessary to carefully locate the cylinder with the leak and determine the cause of the leak. The angle valve should be closed to stop the leak; if the angle valve is damaged or sealing the leak is ineffective, the leaking cylinder should be moved to a safe location where it can be monitored safely, allowing the leaked gas to disperse naturally while any nearby flames are extinguished. To seal leaks and evacuate cylinders leaking gas, tools that can cause fires must not be used. When a cylinder is leaking gas and on fire, the personnel in charge must take emergency measures and immediately alert the local fire department.

What was mentioned upstairs is LPG (liquefied petroleum gas), while the original poster is asking about LNG (liquefied natural gas); there is a big difference between the two. Due to the special nature of its loading and unloading processes, safety control for liquefied natural gas is particularly important. In the case of LNG transport by sea, it is required that LNG carriers maintain a safety distance of over 150 meters from other ships while in operation.