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To further strengthen safety management in the vinyl chloride production process and improve the intrinsic safety level of enterprises engaged in its production, the Ministry of Emergency Management organized the revision of the mandatory standard \"Safety Technical Specifications for Vinyl Chloride Production by the Acetylene Method\" (GB 14544—2025), which was released on October 5. It will come into effect on September 1, 2026, replacing the \"Safety Technical Regulations for Vinyl Chloride Production by the Calcium Carbide-Acetylene Method\" (GB 14544—2008). The production process of vinyl chloride involves various flammable, explosive, toxic, and harmful chemicals such as acetylene, hydrogen chloride, and dichloroethane; the process is complex, and safety risks are significant. In this revision of the standard, drawing on the lessons learned from vinyl chloride-related accidents at home and abroad in recent years, as well as incorporating practical experience in ensuring safe production of vinyl chloride via the acetylene method, clear and specific safety technical requirements have been established in various areas such as equipment and facility construction, basic safety management, control of key production parameters, installation of interlock devices, specifications for material storage, and emergency response procedures. This enhances the standard’s applicability and practicality. The implementation of this standard will provide scientific safety and technical guidance for enterprises that produce vinyl chloride using the acetylene method, helping to improve the overall level of intrinsic safety across the industry and to effectively prevent and curb the occurrence of serious accidents. Key changes between the old and new standards: 1. Standard name – It has been changed from \"Safety Technical Regulations for the Production of Vinyl Chloride by the Calcium Carbide-Acetylene Method\" to \"Safety Technical Specifications for the Production of Vinyl Chloride by the Acetylene Method\". II. Scope of application of the standards: Applicable to units that produce vinyl chloride and vinyl chloride polymers using the calcium carbide-acetylene method, in new construction, renovation, and expansion projects. Departments related to PVC production should also refer to it. ”Changed to “Applicable to the production, storage, and emergency response of enterprises producing vinyl chloride via the acetylene method”. III. Terminology Definitions: The terms “hot work” and “vessel cleaning work” along with their definitions have been removed. IV. Improvement of basic requirements (I) Strengthening the requirements for basic safety management 1. It is stipulated that when the supply of liquid vinyl chloride is stopped, the pipelines should not be sealed; safety pressure relief measures must be in place. 2. It requires that at least one minor repair of the gas holder be carried out each year, at least one medium repair every 3 years, and at least one major repair every 5 years, with corresponding repair tasks specified. 3. During normal operation, no more than 2 process operators shall enter the same vinyl chloride production facility or storage area ； The number of personnel for tasks such as catalyst replacement shall not exceed 6. The number of workers at the sites where vinyl chloride and high-boiling-point distillation residues are stored should not exceed 2. (II) Requirements were put forward regarding the location and layout of the plant facilities: 1. Vinyl chloride gas cabinets and storage tanks should not be located adjacent to, or on a higher level than, the process units, key plant facilities, and areas where people gather. 2. Buildings where people gather, such as control rooms, shift change rooms, laboratories, and offices, should be located outside the facility, and it should be determined based on explosion risk assessment whether blast resistance design is necessary. (III) Regarding structures under construction, it is stipulated that trenches shall not be installed in vinyl chloride production facilities. (IV) Requirements for equipment and pipelines: 1. Metal universal piping filling systems should be used for loading and unloading ethylene and high-boiling-point distillation products. 2. Centrifugal pumps with single-face mechanical seals or packing seals should not be used to transport vinyl chloride. (5) Requirements regarding electrical instruments and intelligent management have been added. 1. It is stipulated that the power load for instruments and control systems should be classified as a particularly important load within the first category of loads. The power consumption for stirring in the polymerization reactor, the pump used for adding terminators, and the pump for sealing water should be classified as first-class load. 2. Personnel positioning systems should be developed and applied. It is required that key equipment and facilities such as gas cabinets, vinyl chloride storage tanks, mixers, and compressors have functions for monitoring their operating status and providing early warnings of failures. Achieve unmanned inspection. Full-process video surveillance of special operations in areas such as gas holders, storage tank areas, and polymerization reactors. V. Additional safety technical requirements for vinyl chloride production (I) Mixing and dehydration: 1. Flow monitoring should be in place for acetylene and hydrogen chloride before they enter the mixer, with automatic adjustment of the mixing ratio. 2. Emergency shut-off valves should be installed separately for acetylene and hydrogen chloride before they enter the mixer; an high-temperature alarm in the mixer should trigger the interlocked closure of the acetylene emergency shut-off valve. 3. In the case of mixed dehydration using freeze-drying technology, an online water content analyzer should be installed on the main pipe of the mixed gas prior to entering the converter. 4. Remote-controlled nitrogen filling facilities are installed before the switch valve of the acetylene inlet pipeline in front of the mixer, as well as behind the switch valves of the main acetylene outlet pipelines. (II) Synthesis of vinyl chloride: For new, renovated, or expanded vinyl chloride production projects, low-low alarms for the hot water flow rate in each converter, as well as high-high alarms for the temperature of the reaction bed, should trigger the interlock to shut off the gas feed valve for that respective converter. 2. Pressure transmitters should be installed on the inlet and outlet manifolds of the converter’s gas phase. (III) Compressor and distillation system: 1. Low-pressure alarm interlock shutdown for the inlet main pipe of the vinyl chloride compressor or the inlet and outlet main pipes of the gas holder. 2. The recovery of vinyl chloride should be carried out through a distillation column with three towers; high-boiling-point storage tanks should not be used directly for the heating and recovery of vinyl chloride. (IV) Safety requirements for gas cylinders 1. Multiple gas cylinders are not allowed for vinyl chloride gas cylinders; new, renovated, or expanded vinyl chloride gas cylinders should not have a capacity exceeding 2500 m3, while individual acetylene gas cylinders should not exceed 5000 m3 in capacity. 2. It is explicitly required that the oxygen content in vinyl chloride entering the vinyl chloride gas tank should not exceed 1% (by volume) ； The oxygen content in the acetylene entering the acetylene tank should not exceed 1% (by volume). 3. The gas tank should be equipped with a volume indicator; the utilization volume for vinyl chloride gas tanks is 20%–75%, while that for acetylene gas tanks is 20%–80%. In weather conditions such as thunderstorms or winds of force 6 or higher, the utilization volume should be less than 60%. 4. Pressure transmitters and emergency shut-off valves should be installed on the main inlet and outlet pipes of the gas holder, and sealed drainage measures should be employed at the lowest points of these pipes. 5. The maximum rising or falling speed of the gas holder bell cover shall not exceed 1.0 m/min. (5) Safety requirements for vinyl chloride polymerization reactors: 1. An alarm for feeding volume deviation should be installed between the equipment used to feed monomers and initiators into the reactor; an overfeeding alarm as well as an interlock system to stop the sequential control process of the reactor should be in place for monomer feeding. 2. In case of a high pressure alarm in the polymerization reactor or an alarm indicating failed stirring, an inhibitor is added as part of the interlock mechanism. VI. Additional requirements have been added regarding the safe storage of vinyl chloride. 1. For new, renovated, or expanded projects, the capacity of each vinyl chloride storage tank shall not exceed 2000 m³, and the total capacity of all storage tanks in the storage area shall not exceed 4000 m³. 2. The filling level of the vinyl chloride storage tank shall not exceed 85% of its total volume ； Emergency shut-off valves should be installed on the inlet and outlet pipelines of the storage tank ； Chloroethylene storage tanks larger than 100 m³ are equipped with water injection facilities. VII. Requirements for emergency response have been modified. In the event of a fire in the acetylene system, the fire source should not be extinguished directly; instead, the acetylene system must be kept under positive pressure, with this pressure not exceeding 100 kPa, and then nitrogen should be used to put out the fire.