How should emergency shut-off valves be installed in hazardous chemical storage tank areas?

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According to Article 5 of the \"Criteria for Identifying Major Potential Hazards in Production and Operation of Chemicals and Hazardous Chemicals (Trial)\\", Document No. An Jian Zong Guan San [2017] 121: Hazardous chemical storage areas that constitute level 1 or level 2 major hazard sources do not have an emergency shutdown function in place； The hazardous chemical storage areas that constitute Class I and Class II major hazard sources involving toxic gases, liquefied gases, and highly toxic liquids are not equipped with independent safety instrument systems. Failure to meet the above requirements is considered a major hazard. So, how exactly should the emergency shut-off valve be installed? 1. Requirements regarding the installation of emergency shut-off valves for storage tanks in tank farms as specified in relevant standards and codes: (1) Article 7.2.15 of the \"Code for Fire Protection Design of Petrochemical Enterprises\" GB50160-2008 (2018 edition) stipulates that for equipment handling liquefied hydrocarbons or flammable liquids with an operating temperature equal to or higher than their auto-ignition point, a shut-off valve should be installed on the pipeline leading from the equipment to the pump, near the base of the equipment. When the volume of the equipment exceeds 40 m3 and the distance between it and the pump is less than 15 m, such a shut-off valve must be a remotely operated valve with a manual function; the control button for this remotely operated valve should be located at a distance of no less than 15 m from the pump. (2) In Table 3 of the \"Guidelines for Safety Risk Assessment of Old Equipment in Enterprises Producing and Using Hazardous Chemicals (Trial Version)\\", under the section on safety inspections of process operations: Article 3: 1) For towers and containers with a volume greater than 40 m3, an emergency isolation valve must be installed on the main pipe at the suction inlet of the high-temperature oil pump, using an electric or pneumatic actuator ； 2) For inlet and outlet valves of high-temperature oil pumps with a diameter of ≥ DN300, electric or pneumatic gate valves should be selected ； 3) Fire prevention measures should be taken for facilities such as cable trays above the high-temperature oil pump. (3) “Regulations on Further Strengthening the Safety Design Management of Hazardous Chemicals Construction Projects” (Safety Supervision General Administration Document No. San [2013] 76), Item 22: Emergency shutoff devices that can be operated automatically or manually via remote control should be installed on the pipelines for feeding and discharging materials from toxic material storage tanks, cryogenic storage tanks, and pressure spheres. (4) \"Code for Fire Protection Design of Petrochemical Enterprises\" GB50160-2008 (2018 edition), 6.4.2: When there are no buffer tanks in the station, an emergency shut-off valve that is easy to operate should be installed on the loading and unloading pipelines at a distance of more than 10 m from the loading and unloading cranes. (5) \"Code for Safe Design of Spherical Storage Tanks for Liquefied Hydrocarbons\" SH3136-2003: 6.1 Emergency shut-off valves should be installed at the inlet and outlet of the liquid phase in spherical storage tanks for liquefied petroleum, and these valves should be located near the spherical tank. (6) Article 13 of the Interim Provisions on the Supervision and Management of Major Hazard Sources of Hazardous Chemicals stipulates that emergency shut-off devices shall be installed for key facilities within major hazard sources, such as toxic gases, highly toxic liquids, and flammable gases. (7) \"Specifications for the Installation and Use of Emergency Shutoff Valves in Hazardous Chemical Enterprises\" T/CCSAS023-2022 5.5 Requirements for the installation of shutoff valves in hazardous chemical storage tanks: 5.5.1 Class III emergency shutoff valves shall be installed at the inlets and outlets of tanks that store toxic substances or large-scale liquid hazardous chemicals, near the base of the tanks; the local operation buttons for these emergency shutoff valves shall be located outside the fire dike surrounding the tank cluster. 5.5.2 Class III emergency shut-off valves shall be installed on the inlet and outlet pipes of pressure storage tanks for liquid hazardous chemicals. The emergency shut-off valve should be installed near the storage tank, and its local control button should be placed outside the fire dike of the tank cluster. The emergency shut-off valve must be capable of withstanding the lowest temperatures that can occur due to potential leaks within the tank cluster or leaks from adjacent storage tanks. 5.5.3 When storage tanks or tank groups for flammable liquids or combustible liquids constitute a major hazard of Class I or II, each tank within such groups shall be equipped with a Class III emergency shut-off valve at the location of the inlet and outlet pipes near the base of the tank. The local operation button for the emergency shut-off valve shall be placed outside the fire dike of the tank group. 5.5.4 When the inlet and outlet pipes of the storage tank are equipped with flexible connections, the emergency shut-off valve shall be installed between the storage tank and the flexible connections. 2. Criteria for identifying major hazards: (1) In chemical storage areas that constitute level 1 or level 2 major hazard sources, emergency shut-off valves must be installed at the inlets and outlets of each storage tank; otherwise, it is considered a major hazard. (2) In chemical storage areas that constitute major hazard sources of level 1 or 2, a main emergency shut-off valve is installed on the main inlet and outlet pipelines of the area; if no such valves are installed at each individual storage tank, it is considered a serious safety hazard. (3) For chemical storage tank areas that constitute major hazard sources of level 1 or 2, if an emergency switching mechanism is installed between tanks of the same purpose to prevent situations such as excessive liquid levels or overpressure in the tanks, they are not considered to be major safety hazards. (4) In chemical storage areas that constitute major hazard sources of level 1 or 2, if the storage tanks do not have an emergency shutdown function, but the enterprise has conducted HAZOP analyses and SIL assessments and the results show that safety requirements are met, such areas may not be deemed to represent significant hazards. (5) Storage areas for hazardous chemicals that constitute major hazard sources of level 1 or 2 and involve toxic gases, liquefied gases, or highly toxic liquids, which are not equipped with an independent safety instrumented system, are considered to represent major safety hazards.