Can pressure relief manholes be installed on atmospheric storage tanks for highly toxic liquids?

The storage of highly toxic liquids must strictly comply with relevant safety and environmental protection regulations. Generally speaking, highly toxic liquid storage tanks should not be equipped with pressure relief manholes that discharge liquid into the air, as this can cause severe environmental pollution and pose a threat to human health. Benzene is a highly toxic and volatile chemical; its vapors can enter the human body through breathing, causing poisoning, and long-term exposure may lead to serious health problems such as leukemia. Therefore, when designing and using tanks that contain highly toxic liquids such as benzene, the following measures are generally taken to ensure safety: 1. Closed system: The tank should be designed as a closed system to prevent the leakage of toxic gases. 2. Safety valves and pressure relief systems: Safety valves and pressure relief devices can be installed; these devices open automatically when the pressure exceeds the designed limit, thereby releasing pressure. The gas released after pressure relief must be purified through specially designed treatment equipment to ensure that the gas emitted into the atmosphere meets environmental standards. 3. Piping and filtration systems: The pipes that connect the storage tanks to the outside world are usually equipped with filtration or absorption systems to capture and remove harmful chemicals. 4. Detection and alarm system: A toxic gas detection and alarm system should be installed in the tank area to enable timely action in the event of a leak. 5. Emergency response plan: Appropriate emergency response plans must be developed and put into practice to deal with potential accidental leaks. Therefore, the design and operation of high-toxicity liquid storage tanks must undergo professional evaluation, and effective measures must be taken to ensure environmental safety and human health; the pressure-release gases cannot be released directly into the air. If you are responsible for the design or management of such storage tanks, be sure to consult professional experts in chemical safety and environmental protection to ensure that all operations comply with local safety and environmental regulations. .

If it is a new installation, highly toxic substances are no longer allowed to be stored in atmospheric-pressure tanks, so this problem does not exist

Which specification requires that highly volatile liquids cannot be stored in tanks at atmospheric pressure?

This post was last edited by qldch2306 on 2025-4-14 14:34. I. Can highly toxic liquids be stored in atmospheric-pressure tanks? It can be stored, but strict safety conditions must be met. Storage feasibility: According to , highly toxic liquids such as 1,2-dichloroethane and toluene can be stored in single-containment tanks at atmospheric pressure. However, it must meet the requirements of the \"Design Code for Tank Areas in Petrochemical Storage and Transportation Systems\" (SH/T 3007-2014), such as the installation of nitrogen sealing systems, vent valves, pressure monitoring, and alarm devices, in order to control the gas phase pressure in the storage tanks and reduce the risk of leaks. . Leak risk control: The storage of highly toxic liquids requires the use of dikes, leak collection systems, toxic gas detection and alarm systems, etc., to prevent the spread of leaks. For example, it is emphasized that failures in the tank level monitoring devices or overfilling can lead to leaks, and therefore real-time monitoring through an automatic control system is necessary. II. Can an emergency pressure relief manhole be installed? Setting is allowed, but it must comply with design specifications. Functional necessity: When a storage tank experiences overpressure due to issues with the vent valve, sudden changes in ambient temperature, or a fire, the emergency pressure relief manhole allows for rapid pressure release, thereby preventing the tank from rupturing. For example, it is specified that emergency pressure relief manholes (DN450 or larger) must be installed at the top of the storage tank, with an opening pressure that is higher than that of the breathing valve but lower than the designed positive pressure of the tank (such as +1.90 kPa). . Design requirements: Material and sealing: Corrosion-resistant materials (such as 304/316L stainless steel) must be used, along with a flame-retardant layer to ensure sealing (such as PTFE gaskets). Installation specifications: According to relevant standards, the diameter of manholes is usually 600 mm; they must maintain a safe distance from the oil inlet and outlet pipelines, and multiple vent valves should be installed to enhance redundancy. Pressure relief capacity: The flow area should be 1.5–2 times greater than the rated venting capacity of the tank, and its pressure relief capability must be much higher than that of a breather valve. III. Is direct emission into the atmosphere illegal? Direct discharge of highly toxic substances is considered a violation of regulations. Regulations explicitly prohibit this: in accordance with the \"Pressure Vessels\" standard (GB 150.1-2011) and the \"Safety Technical Inspection Regulations for Fixed Pressure Vessels\" (TSG 21-2016), for media with an extreme, high, or moderate level of toxicity, the discharge devices must be connected to conduits that lead to safe locations for handling; direct discharge into the atmosphere is strictly forbidden. For example, highly toxic substances such as acraldehyde must be treated in an harmless manner through an exhaust gas collection system. . Special handling for emergency venting: In extreme situations such as fires, if the emergency pressure relief hatch is opened due to a fire, flame arrestors and fireproof design measures (such as the CNC121/122 series from MTP) must be employed; however, pollution still needs to be controlled through an exhaust gas treatment system after venting. Selection of accident relief equipment: It is indicated that the accident relief equipment can lead directly to the atmosphere, but this provision applies only to inert gas sealing systems or non-toxic media. For highly toxic liquids, they still need to be conveyed through conduits to treatment facilities. IV. Conclusions and Recommendations. Storage feasibility: Highly toxic liquids can be stored in atmospheric-pressure tanks, but nitrogen sealing, vent valves, pressure monitoring, and leak prevention systems are required. . Installation of emergency pressure relief manholes: It is permitted, but the material, dimensions, operating pressure, and other specifications must be met, and a fire arrestor layer must be provided. . Emission compliance: The release of highly toxic liquids must go through an exhaust gas collection and treatment system; direct discharge into the atmosphere violates **standards and must be strictly prohibited. Implementation suggestions: During the design phase, standards such as SH/T 3007-2014 and GB 50160-2008 should be referenced to ensure that the storage tanks and pressure relief facilities meet the required specifications. Regularly maintain the breathing valve and pressure relief manhole, and engage a third-party testing agency to conduct annual inspections if required. Remote pressure monitoring and alarm functions are implemented in conjunction with the DCS system to enhance emergency response capabilities. 1. Purpose of installing emergency pressure relief manholes in atmospheric-pressure storage tanks. China Chemical Safety Association. 2. Introduction to PDF safety assessment methods. 3. Technical specifications of emergency relief manholes for petrochemical storage tanks. Shanghai Shenhong Valve Co., Ltd. 4. PDF Product introduction: Emergency pressure relief manhole covers for large-capacity liquid storage tanks. Motherwell Tank Protection (MTP). 5. PDF Exploration of safety facility design for liquid waste storage areas in hazardous waste disposal plants. Zhou Liang (Shanghai Conglin Environmental Protection Technology Co., Ltd.). 6. Analysis of the technical specifications of emergency relief manholes for petrochemical storage tanks. 7. PDF Environmental impact assessment report for an integrated project related to the comprehensive utilization of alkane resources. Ministry of Ecology and Environment of the People’s Republic of China. 8. Design and selection of emergency pressure relief manholes for chemical storage tanks. Shanghai Shenhong Valve Co., Ltd. 9. Principles and structure of pressure relief manholes. 10. PDF Project for the annual production of 100 kg of bromfenac sodium, 60 kg of dibazol, and 100 tons of ferrous protein succinate active pharmaceutical ingredients. Hubei Duoxilu Pharmaceutical Co., Ltd. 11. PDF Chemical safety – Abstracts from the China Chemical Safety Association. China Chemical Safety Association. 12. PDF Construction project for Jiangxi Shengwei Technology Co., Ltd. to produce 460 tons of flavors and fragrances along with by-products per year. Nanchang Xiongmai Environmental Protection Technology Co., Ltd. 13. Expert answers! Questions and Answers on Safety Risk Identification in Storage Tanks and Remediation of Potential Hazards in Various Scenarios (Part 2). Chemical 365. 14. PDF. Guidelines on Environment, Health, and Safety in the Manufacturing of Bulk Petrochemical Organic Products. World Bank Group. 15. PDF. Fire Protection Standards for the Design of Petrochemical Enterprises. People’s Republic of China. 16. PDF. Environmental Impact Assessment Report for a Project to Expand the Production Capacity of Admixtures by 100,000 tons per year. Yueyang Dongfang YuHong Waterproofing Technology Co., Ltd. 17. Regulations on the Management of Atmospheric and Low-Pressure Storage Tanks. 18. Safety Management and Design Specifications for Nitrogen-Sealed Storage Tanks in Petrochemical Storage and Transportation Systems. 19. Fire Protection Standards for the Design of Petrochemical Enterprises GB50160-2008 (2018 Edition). Jianbiao Ku. 20. It is essential to understand the risks associated with highly hazardous process units in chemical enterprises. I asked AI for an answer, and this is what it came up with. Ugh. . .