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Liquefied hydrocarbons (such as liquefied petroleum gas, ethylene, propylene, etc.) are characterized by flammability and explosiveness, as well as the need for low temperatures and high pressures; they are also volatile and spread rapidly. The safety measures for storing them in tanks and transporting them through pipelines must cover the entire process, including design, equipment selection, operation, maintenance, and emergency response, with risk management tailored to their physical and chemical properties. The specific security measures are explained in detail from multiple perspectives below. 1 Design and site selection: Reducing risks at the source. During the design phase, it is necessary to strictly adhere to **standards** (such as the \"Fire Protection Design Standards for Petrochemical Enterprises\" GB50160, and the \"Code for Fire and Explosion Protection Design of LPG Storage Areas\", etc.) in order to establish a basic safety barrier. The location and layout of the tank area should be such that it is far away from densely populated areas (such as residential zones and schools), open flames (such as boiler rooms), and important facilities (such as substations). The fire separation distances must meet the specified requirements (for example, a distance of at least 50 meters from civil buildings, and at least 30 meters from other Class A installations). The tank storage area should be arranged in a centralized manner, with separate fire compartments established; it should be separated from surrounding facilities using fire walls and fire dikes (the height of the fire dikes should be no less than 1.0 meter, and their capacity must be sufficient to contain the maximum amount of liquid that could leak from the tanks). Avoid locating it in low-lying areas (to prevent accumulation in the event of a liquefied hydrocarbon leak); the site must be level and drainage should be directed outside the fire dike to prevent backflow of rainwater. Equipment selection and materials: Spherical tanks are preferred for storage tanks due to their even stress distribution and high volume efficiency. For low-temperature liquefied hydrocarbons (such as ethylene, with a boiling point of -103.7°C), low-temperature storage tanks are required, which have a double-layer vacuum insulation structure with an outer layer that provides thermal insulation; low-temperature steel (such as 09MnNiDR) is used as the material to prevent brittle failure at low temperatures. The pipe material must be suitable for the properties of the medium: seamless steel pipes (such as 20# steel) are used for high-pressure pipelines, while low-temperature alloy steel pipes are used for low-temperature pipelines. For valves, forged valves should be chosen to avoid defects associated with cast products, and the flange sealing surfaces should adopt keyway or male-female designs to improve sealing performance. 2 Equipment and safety accessories: The reliability of the equipment and accessories that ensure operational stability is key to preventing leaks and overpressure; they must be installed in accordance with specifications and regularly calibrated. Safety valves: Each storage tank shall be equipped with at least 1 safety valve (2 valves for tanks with a larger capacity). The setting pressure of these valves should be 1.05–1.1 times the design pressure, and their discharge capacity must be sufficient to meet emergency pressure relief requirements (to prevent overpressure explosions). The outlet of these valves should be connected to a flare system or a safe discharge area (to avoid direct release into the atmosphere, which could cause fires or explosions). Emergency shut-off valves: Pneumatic or hydraulic emergency shut-off valves must be installed on the inlet and outlet pipelines of the storage tank, as well as on the liquid/gas pipelines. These valves should be interlocked with level gauges and pressure transmitters (to shut off automatically in case of excessive liquid level or pressure), and they must also have a remote manual shutdown function (allowing forced closure from the control room). Level gauges: A dual-level gauge system is used (such as a magnetic flap level gauge + radar level gauge) to prevent overfilling due to the failure of a single gauge (the filling volume must not exceed 85% of the tank’s capacity to allow for expansion), and a high-level alarm is installed (with the alarm set at 80% of the capacity). Pressure gauges and thermometers: Their range should be 1.5–3 times that of the normal operating pressure/temperature, with an accuracy of not less than grade 1.6. They need to be calibrated regularly (at least once a year) to ensure real-time monitoring and prevention of overheating or overpressure (for example, a cooling system should be activated when the ambient temperature is too high). · Pipeline safety measures: The pipelines must be equipped with anti-static grounding (with a grounding resistance of ≤10Ω), and jumper wires (copper strips or copper stranded wires) should be used at the flange connections to eliminate potential differences (to prevent static sparks). Long-distance pipelines require compensators (such as bellows compensators) to absorb the thermal expansion and contraction caused by temperature changes (to prevent pipeline stress-induced rupture). Connection points such as valves and flanges require the use of metal-wound gaskets (resistant to high temperatures and pressures), and the wear of the sealing surfaces should be checked regularly (to prevent minor leaks). 3 Operation and maintenance management: Standardized procedures are needed to prevent errors, as improper operations are a major cause of accidents; standardized processes and strict controls are essential to reduce human-related risks. Filling and transfer control: Before filling, it is necessary to check the pressure and liquid level in the storage tank (to ensure no overfilling) as well as the status of the valves (close any unnecessary valves). After the pipes are connected, nitrogen should be used to displace the air (with an oxygen content of ≤2%) in order to prevent the formation of explosive mixtures in the gas space. The filling rate must be controlled (liquid phase pipeline flow velocity ≤ 3 m/s, gas phase ≤ 8 m/s) to prevent static electricity generation due to high-speed flow ； Monitoring must be carried out throughout the filling process; overpressure is strictly prohibited (filling must be stopped when the pressure exceeds 90% of the design value). Pumps should be used preferentially for transportation (to avoid pressurization with compressed air and prevent air from mixing in), and a check valve should be installed at the pump’s outlet (to prevent backflow of the material). For daily monitoring and inspections, a \"four-shifts, three-shift rotation\" system is employed, with inspections carried out every 2 hours. The key aspects checked include whether there are any leaks in the storage tanks/pipelines, whether the pressure/level is within normal ranges, whether there are any signs of valve activation, and whether the grounding systems are in good condition. A DCS system is used to monitor key parameters (pressure, level, temperature) in real time, with interlocks for overpressure, overlevel, and overheating (which automatically shut off feeding and trigger alarms when activated). 4 Maintenance and repair: Potential hazards must be eliminated promptly. Equipment that has been in operation for a long time is prone to defects due to corrosion and fatigue, and regular maintenance is necessary to prevent the escalation of failures. Regular inspection and maintenance: A comprehensive inspection of the storage tank is carried out every 3–6 years (including hydrostatic testing and airtightness testing), while an external inspection (for corrosion, deformation, and the condition of accessories) is performed annually ； Low-temperature storage tanks require inspection of the insulation layer (to prevent corrosion of the outer wall due to condensation). Non-destructive testing of the pipes is carried out every 2 years (using ultrasound or radiography to inspect the welds, with a focus on areas prone to stress concentration such as elbows and tees), and thickness measurement is performed once a year (to monitor the corrosion rate; the pipes are replaced immediately if the wall thickness falls below the minimum allowable value). Safety valves, pressure gauges, and emergency shut-off valves should be calibrated every 6 months to ensure their sensitivity and reliability ； The valve is manually opened and closed once per quarter (to prevent jamming). To protect liquefied hydrocarbons exposed to corrosive media such as hydrogen sulfide, the inner walls of storage tanks must be coated with anti-corrosion coatings (such as epoxy resin) or lined with materials like stainless steel ； Regularly test the hydrogen sulfide content in the medium (it must be removed if it exceeds 100 ppm). External corrosion protection: The outer wall of the storage tank is coated with anti-rust paint and sunproof paint (to prevent temperature rise due to direct sunlight), while underground pipelines are protected against soil corrosion through cathodic protection (sacrificial anodes or external current). 5 Leak monitoring and emergency response: Rapid response to control consequences. After a liquefied hydrocarbon leak, explosive clouds can form; therefore, early detection through real-time monitoring is necessary, along with prompt action to prevent the spread of such clouds. For leak detection and alarm, combustible gas detectors are installed in the tank area and at pipeline flanges (to detect propane, propylene, etc., with a range of 0-100% LEL). An alarm is triggered when the detected concentration reaches 25% LEL (via sound and light alarms plus a notification in the control room), and interlocks are activated at 50% LEL (to shut off feed and start exhaust ventilation). Equipped with portable gas detectors (to be carried by operators during inspections); explosion-proof tools must be used near the leak site to avoid sparks. Leak handling procedure for minor leaks: Immediately close the relevant valves and purge the leak site with nitrogen (to dilute the residual medium); once the concentration drops to a safe level, carry out repairs (by replacing gaskets or valves). Major leakage: Immediately activate the emergency response plan – shut off the feed/exit valves of the storage tank, turn off the main power supply in the area (using explosion-proof switches), and evacuate people downwind (evacuation radius ≥ 500 meters) ； Cover the leakage area with a fire suppression curtain (to reduce concentration); open flames and static electricity are strictly prohibited (the use of non-explosion-proof equipment is forbidden). · Special fire-fighting equipment is provided for emergency response to fires and explosions: dry powder fire extinguishers (type MF/ABC5 or higher), wheeled dry powder fire extinguishing systems, and fire hoses (to cool storage tanks and prevent explosions). It is strictly prohibited to use water to extinguish flames involving liquefied hydrocarbons, as this can cause the fire to spread. During a fire, priority should be given to cooling the storage tanks (by spraying water on their walls to keep the temperature at or below 50°C); once the fire is under control, dry powder extinguishers can be used to put it out ； If the storage tank’s safety valve activates or the tank wall changes color (indicating overheating), evacuation must be carried out immediately (to prevent an explosion). 6 Personnel and Systems: Strengthen training for those responsible for ensuring compliance with requirements, and operators must receive specialized training (on the properties of liquefied hydrocarbons, equipment operation, and emergency response). Only after passing the assessments can they work with a valid certificate (Special Equipment Operator Certificate), and they must undergo retraining once a year. Emergency responders need to be proficient in using air respirators (as oxygen levels can be low in areas with liquefied hydrocarbon leaks), operating explosion-proof tools, and following fire suppression procedures; they must conduct drills once per quarter (simulating leak and fire scenarios). The safety management system includes the formulation of the \"Safety Management Regulations for Liquefied Hydrocarbon Storage Areas,\" which specify the responsibilities for tasks such as inspections, filling, and maintenance (for example, \"the person who operates is responsible, and the person who conducts the inspection signs off\"). Establish a register for identifying potential hazards (addressing these hazards immediately upon discovery; shutting down operations to rectify serious hazards), and conduct regular HAZOP analyses (Hazard and Operability Studies) to identify potential risks and develop corresponding measures. The safety protection of liquefied hydrocarbon storage tanks and pipelines must adhere to the principle of \"prevention first, combined prevention and control.\" By implementing comprehensive management across the entire chain – through compliant design, reliable equipment, proper operation procedures, timely maintenance, and efficient emergency response – the risks of leaks and fires can be minimized. At the same time, it is necessary to adjust measures accordingly based on the characteristics of the medium (such as low temperature, high pressure, and corrosivity), and to keep an eye on updates to relevant regulations and standards (such as GB50160 and TSG 21-2016 \"Safety Technical Regulations for Fixed Pressure Vessels\") to ensure that the safety measures are scientific and effective.