Safety design in chemical engineering design

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Focusing on the hazard factors present in petrochemical plants, this article discusses design methods and measures to ensure the safety of such plants from various aspects, including the selection of process routes and engineering design (covering process system design, instrumentation and automatic control design, equipment design, plant layout design, piping design, civil engineering design, water supply and drainage design, ventilation design, and fire protection design), thereby emphasizing the importance of safety design. Petrochemical plants primarily use petroleum, natural gas, coal, and their derivatives as raw materials for processing, in order to produce a variety of products for society. The raw materials and products used in the facility are mostly flammable, explosive, and toxic substances; therefore, there are inherent risks of fire, explosion, and poisoning. This is due not only to the characteristics of petrochemical plants such as more complex processes, harsher conditions, numerous constraints, and concentrated equipment, but also to social, economic, and managerial factors. Reasons for safety hazards: (1) Emphasis on economic scale, leading to increasingly larger factories (plants) ； (2) Reduced land for construction leads to crowded equipment layout and increased asset density ； (3) To eliminate bottlenecks, increase capacity and efficiency, save energy, and improve the environment, add equipment or facilities to the existing installations ； (4) Increased production man-days; prolonged operation cycles result in inadequate timely maintenance and updating of equipment ； (5) A reduction in staff, with high turnover among operational managers. Additionally, whether technology, equipment, and training are provided in a timely manner is also one of the reasons. How to achieve safe design, how to identify various potential hazards in petrochemical processes, how to estimate deviations from normal process conditions, and how to take measures at the fundamental stage of project development (design) to prevent problems before they occur, are all topics of widespread concern. A commonly adopted practice abroad is to implement Hazard and Operability Studies (HAZOP) in project design, in addition to emphasizing inherently safe design. These studies involve analyzing process deviations in order to systematically and qualitatively identify process hazards and potential consequences, thereby allowing for the implementation of appropriate measures. In project management, the (Health and Safety Executive) procedures are implemented to review and verify safety, health, and environmental protection aspects at various stages of the project. In addition, a safety assessment of the project can also be conducted at the owner’s request. At present, there is no complete safety analysis method or management system for the design of petrochemical plants in China. Requirements related to safety, hygiene, and environmental protection are often scattered across various **regulations and standards at different levels, which makes implementation and management quite difficult. Moreover, many requirements related to safety, hygiene, and environmental protection are not covered by existing standards or cannot be incorporated into them during the design process. In project management, emphasis is placed only on the “preliminary” review, while the “post-implementation” phase is neglected, often resulting in half the effort yielding half the results. To ensure the safety of device design, it is first necessary to strictly and correctly implement **regulations and standard requirements (especially mandatory standards).** What else should designers do? 1 Hazard factors of installations There are many types of petrochemical installations. Due to differences in technical routes, raw materials, products, and process conditions, the existing hazard factors vary accordingly. They can be broadly summarized as follows. 1.1 Risk of poisoning: In the petrochemical production process, workers are exposed to toxic substances in the form of raw materials, finished products, semi-finished products, intermediates, reaction by-products, and impurities. During operations, these substances can enter the body through the mouth, nose, and skin, causing pathological changes in the body’s physiological functions and normal structures. In mild cases, this can disrupt the body’s normal responses and reduce a person’s ability to make correct judgments and take appropriate actions during production; in severe cases, it can even lead to death. 1.2 Fire and explosion hazards: Mixtures of combustible gases, oil and gas, and dust with air, when their concentration reaches the explosive limit, can cause fires and explosions if ignited. The radiant heat from the fire and the shock waves generated by the explosion can cause damage to people, equipment, and buildings. In particular, explosions of vapor clouds formed by the leakage of large amounts of flammable gases or oil and gas are often devastating. There are many such examples, such as the explosion of the ethylene air separation unit at Fushun Petrochemical Company in 2001, the explosion of the high-pressure polyethylene unit at Beijing Yanshan Petrochemical in 2000, and the hydrogen explosion at the high-pressure hydrogenation unit of Daqing Petrochemical Company in 1967; the losses resulting from these incidents were extremely severe. 1.3 Reactive hazards Chemical reaction processes are divided into endothermic and exothermic types. Generally, exothermic reactions are more dangerous than endothermic reactions, especially oxidation reactions that involve strong oxidizers ； The halogenation reaction, which involves the introduction of halogen atoms into organic molecules. 1.4 Negative-pressure operation
Negative-pressure operation can easily allow air and moisture to enter the system. This may result in the formation of explosive gas mixtures, or the oxygen and water vapor in the air may trigger hazardous reactions involving materials sensitive to oxygen and water—as is the case in the vacuum distillation tower systems used in atmospheric and vacuum distillation units in oil refineries. 1.5 High-temperature operation: Operating flammable liquids at temperatures above their flash point or boiling point can result in the formation of explosive vapor clouds in the event of a leak ； The operating temperature of flammable liquids is equal to or above their autoignition point; once they leak, they can ignite spontaneously or serve as a source of ignition ； A hot surface is also a source of ignition; flammable liquids splashing onto it can cause a fire. For example, in 2001, the Maoming coking plant experienced a major fire and severe casualties due to the use of incorrect pipeline materials, which allowed high-temperature residue oil to leak out. 1.6 Low-temperature operation: Not designed for low-temperature conditions; the intrusion of low-temperature media leads to low-temperature brittle failure of equipment and pipelines. Such as damage to the low-temperature equipment in air separation, and low-temperature brittle fracture at -195°C in the low-temperature methanol washing process of large-scale fertilizer slag gasification. 1.7 Corrosion Corrosion is a common cause of equipment and pipeline damage, leading to fires. The importance of a material’s corrosion resistance, in terms of optimizing its performance, is second only to its mechanical properties. Its corrosion resistance is often determined through experience and testing, with no established standards available (there are however existing standards for selecting materials used in Sinopec’s facilities for processing high-sulfur oil). Furthermore, the diversity of corrosion types and the influence of ever-changing environmental conditions add an element of unpredictability to the risk of corrosion. For example: fires in the oil kettles at Tianjin Petrochemical, corrosion caused by high-temperature sulfur, and corrosion caused by low-temperature sulfur. 1.8 Leakage Leakage is an important pathway for hazardous substances in equipment pipelines to be released into the atmosphere. The static and dynamic seals of equipment pipelines fail; in particular, periodic changes in temperature and pressure, as well as the presence of corrosive media, can easily lead to seal failure. Weak points in equipment piping, such as failures of bellows expansion joints, glass level gauges, and dynamic seals of rotating equipment, can lead to serious accidents once they are damaged. A major fire caused by a mechanical seal leak in the hydrogenation unit of Zhenhai Refining & Chemical Company. Incidents such as the pipeline leak involving high-temperature and high-pressure threaded locking rings in the hydrocracking unit in 1996. 1.9 Open flames: An arc or spark 0.5 mm long is sufficient to ignite hydrogen. The open-flame heating equipment (heating furnaces) in the device, as well as high-temperature surfaces, and potential arcs, static sparks, friction sparks, and flying embers from chimneys, all have sufficient energy to ignite explosive mixtures. For example, during the construction of the new power plant at Zhenhai Refining & Chemical Company in 2001, a fire broke out in the turbine building. 2 Safety considerations in the selection of the process route. The safety of the process method is the foundation for the safe design of the facility; therefore, during the project initiation and feasibility study phases, due attention should be paid to the safety aspects of the process route. 2.1 Try to use materials with low risk. To obtain a certain end product, the raw materials or auxiliary materials are not always unique. Where possible, materials that are free from danger or have low risk should be given priority. 2.2 Try to ease the severity of process conditions. The severity of process conditions can indeed be changed. For example, catalysts or better catalysts can be used, as well as dilution and the use of gas-phase feed instead of liquid-phase feed, in order to reduce the intensity of the reaction. 2.3 Simplify by eliminating complexities to avoid interference and ensure intrinsic safety. The probability of process accidents is related to influencing factors; the more parameters there are, the greater the interference. In cases where a single device performs multiple functions, it is possible to use multiple devices, each responsible for one function, in order to enhance production reliability. Improve the reliability and intrinsically safe level of equipment, automation, and electrical systems. 2.4 Minimize the amount of hazardous materials stored. The greater the quantity of hazardous materials stored, the greater the losses and scope of impact in the event of an accident. For example, using membrane distillation in place of distillation columns, continuous reactions instead of batch reactions, flash drying instead of tray dryers, and centrifugal extraction instead of extraction columns. 2.5 Reducing production waste: Whether raw materials, additives, solvents, carriers, catalysts, etc. used in the process are necessary, and whether their use can be reduced ； Can it be recycled and reused? ； It is possible to make comprehensive use of waste, carry out harmless treatment of it, reduce production waste, make the most of available resources, and thereby minimize environmental pollution. 3 Safety in Engineering Design 3.1 Safety Principles in Engineering Design >>>> Description of Material Hazards Material hazards can typically be described using material safety data sheets, which include the following key information: general fire hazard characteristics such as flash point, ignition temperature, explosion limits, relative density, boiling point, melting point, and water solubility. Classification of fire hazards (see GB50160/GBJ16); hazards to health: maximum permissible concentrations of harmful substances in the workplace (see TJ36), acute toxicity (LC50 or LD50) and associated symptoms, conditions and consequences of chronic poisoning, and carcinogenicity. Classification of toxicity hazard levels (see GB5044). Reactivity hazards: stability under environmental conditions, intensity of reaction with water, sensitivity to heat or mechanical shock. Reactivity hazard class (refer to NPPA704) – storage and transportation requirements. Methods for extinguishing accidents, emergency measures. >>>> Process conditions: The essence of a normal production process is the relative balance of various process parameters. Any change in a parameter beyond its allowable range disrupts the balance, potentially leading to accidents. How to control and adjust process conditions, and what emergency measures to take in case of loss of control in order to minimize and avoid losses. Various reactions, including the main reactions and side reactions, as well as possible harmful reactions and measures to prevent their occurrence. Optimization software is used to control and adjust the production process. >>>> Coordination between combined operation units: Petrochemical plants are essentially combinations of various process operation units. How to achieve secure connection between units and avoid mutual interference ； When a certain unit encounters an accident or failure, how to isolate it, how the other units should continue to operate, and how to achieve a smooth shutdown. A combined unit is a combination of several original conceptual units, resulting in a relatively higher asset density; it is particularly important to ensure proper coordination in the design of the process system. >>>>Sealing and sealing systems: Production systems that continuously emit flammable, toxic gases, dust, or acid mists should be designed to be closed, with provisions for mist removal, dust removal, or absorption. For low-boiling flammable liquids, toxic liquids, or those that can undergo oxidation, decomposition, autopolymerization, or deterioration in reaction with oxygen and water in the air, inert gas sealing should be employed, along with anti-corrosion measures. >>>> Reduce the entry of hazardous substances into the fire scene. While ensuring stable production, minimize the residence time of materials within the equipment, and use distillation equipment with a small liquid storage capacity. Emergency isolation valves should be considered for the bottom of large-scale equipment, high-displacement pumps, the pump inlets at high temperatures (≥ flash point, ≥ auto-ignition point), the inlets of liquefied hydrocarbon pumps with a discharge rate greater than 8 m3/h, and the outlets of liquefied hydrocarbon tanks, in order to cut off flow in case of an accident and thereby reduce the amount of material that could leak out. The best way to extinguish a gas fire is to cut off the gas supply. Therefore, accident isolation valves should be installed on the combustible gas pipes at the boundary of the gas processing unit. >>>> Overpressure protection for equipment: Both GB150 and the Safety Technical Supervision Regulations for Pressure Vessels require that pressure vessels be equipped with overpressure protection ； Positive-displacement pumps and equipment requiring overpressure protection must be equipped with safety pressure relief devices. When medium corrosion, coking, or blockage causes the safety valve to fail, it is advisable to consider using a combination of a safety valve and a rupture disc, or to provide steam shielding and steam (or electric) tracing. For equipment subject to sudden overpressure or where the thermal pressure rises rapidly, automatic pressure relief or a combination of detonation tubes and rupture discs should also be installed. >>>>Pressure relief and venting: The pressure relief from safety valves for flammable media should be directed to the flare system. Since the relieved substances contain liquid, a liquid separator tank must be installed in the facility ； The flare main should be capable of handling the maximum discharge volume in any single incident. Accidents in the emissions from the vent flares of petrochemical plants. The venting of liquefied hydrocarbon equipment and pipelines should go into the flare system. The harmless treatment shall be carried out for the release of toxic and corrosive media. Drainage from equipment and pipelines shall be collected in a closed manner. >>>> Purging and displacement: Purging and displacing equipment and pipelines within the startup/shutdown units create conditions for safe startup, shutdown, and maintenance. Incomplete purging, an imperfect purging system, or unsuitable purging media can create conditions for fires. The fixed purge system should have measures to prevent the backflow of hazardous media. >>>> Isolation from the system: Shut-off valves should be installed at the boundaries for any hazardous materials entering or leaving the device, and \"8\"-shaped blind plates should be placed on the device side to prevent interference in case of a fire or maintenance work on the device. For equipment handling flammable and toxic media, when it is necessary to shut down the unit during operation for maintenance and cleaning, double valves or valves equipped with blind plates should be installed. >>>> Utility supply: In the event of a water supply interruption, the cooling system must be able to maintain normal cooling for at least 10 minutes. For other items such as fuel and instrument air, accident supply sources or emergency reserves should be considered. >>>> Handling of extreme operating conditions: Fires and other accidents can easily occur during the startup, shutdown, or emergency shutdown of the equipment. The process system should not only provide normal operating procedures but also outline procedures for starting up and shutting down, as well as steps to take in cases of water or power outages, ensuring that the entire production process proceeds in an orderly manner. Such as the accident response plans for large petrochemical facilities. 3.2 Instrumentation and Automatic Control Design: Instruments serve as the operator’s eyes, while the automatic control system acts as the hub for regulating and controlling the equipment. >>>> The power system should be equipped with emergency power and gas supplies to ensure sufficient time for dealing with accidents. >>>> For the selection of instruments and controllers, fail-safe types should be used to ensure that the production system remains safe in the event of a failure. After automatic stop, the instrument circuit should be prevented from automatically returning to normal operation without confirmation and reset. Avoid using multi-functional instruments that may lead to misjudgments. >>>> Interlocking and shutdown systems: Important operational stages should be equipped with alarm, interlocking, and emergency shutdown systems. When an (ESD) emergency shutdown could have a significant impact on production, the signaling system should be equipped with a 3-out-of-2 voting system. When control system failures could lead to serious accidents, a n:1 or even 1:1 redundant control system should be installed. During production operation, the instruments and shutdown circuits should be detectable. >>>> Field instruments: Instruments, analysis devices, and controllers in areas prone to explosions must be equipped with appropriate explosion-proof designs. >>>> Advanced monitoring of harmful gases: In locations where harmful gases or vapors are released, monitoring and alarm systems should be installed. >>>> Instrument cables: In areas at risk of fire and explosion, instrument cables should be made of non-flammable materials or flame-retardant materials. 3.3 Equipment Design Process equipment is the core element for carrying out a process; all individual operational steps are carried out through specific equipment. Therefore, the reliability of this equipment is crucial for the safe operation of the facility. The main aspects of equipment design include manufacturing materials, mechanical design, manufacturing processes, and process control systems. >>>> Material selection requires a thorough understanding of the manufacturing process, external environment, failure modes, and the processing properties of the materials. Corrosion is a significant factor leading to equipment damage and fires; therefore, corrosion-resistant materials and appropriate corrosion margins should be selected carefully. >>>> Mechanical design should be able to meet the stress requirements imposed on the equipment under severe temperature and pressure conditions. Pay special attention to the vibration loads generated by the power units on the container, as well as the alternating loads resulting from periodic changes in temperature and pressure. Stress analysis of high-temperature and high-pressure hot-wall reactors. The piping for large reciprocating compressors follows API618. Section 3.3) specifies the acoustic simulation calculations and analysis of pressure pulsations, as well as the use of fault diagnosis techniques. >>>> In equipment manufacturing and design, it is most important to assess the quality control procedures for the equipment materials as well as the quality procedures in the manufacturing process, to verify that the production meets the design requirements. The following safety issues should be considered in the design. (1) Pressure vessels shall strictly comply with the \"Regulations on Safety Supervision of Pressure Vessels\", and facilities for cleaning and ventilation of the vessels shall be installed ； Install erosion and anti-static protection facilities ； The internal components should prevent the accumulation of liquid ； Dead zones in the flow should be avoided inside the container ； The support structure of vertical containers should be provided with fire protection. (2) Rotating equipment: Rotating equipment used to handle flammable and toxic media should employ double-end sealing or a sealing system with better performance ； Cast iron materials and components that can react with the medium (and/or lubricant) must not be used ； The inlets of each stage of the compressor should be equipped with liquid separation facilities ； Large pumps and compressors should be equipped with vibration suppression devices. Advanced dry gas seal technology and floating ring seal technology are employed. (3) Open-flame equipment: The furnace chamber shall have air, nitrogen, or steam purge ports ； Gas stoves should be equipped with a constant-light source ； Large open-flame heating equipment should be equipped with flame monitors. 3.4 Electrical Design: Electricity is the main power source for equipment production, and a continuous and reliable power supply is an essential guarantee for the safe operation of such equipment. (1) For critical continuous production processes, dual power supply should be used ； (2) Critical equipment that could cause explosions, fires, poisoning, and casualties in the event of a sudden power outage must be equipped with a backup power supply. (3) When starting high-power motors, it is necessary to ensure that the starting current does not exceed the peak current allowed by the power supply system, or soft-start devices should be used. (Voltage conversion technology). (4) The structure, classification, and grouping of electrical equipment in explosive hazardous environments shall comply with GB50058. (5) Cables and cable assemblies installed overhead in fire-hazardous environments shall be of flame-retardant type. (6) Buildings and equipment shall have possible lightning protection and grounding measures ； Equipment and pipelines that may generate static electricity should have measures to prevent the accumulation of static charge. (7) Safety facilities such as fire alarms, emergency lighting, and evacuation lighting should be equipped with a backup power supply. 3.5 Equipment Layout Design The equipment layout includes the arrangement of machinery, structures, and passages, ensuring the smooth progress of processes, compliance with safety spacing requirements, facilitating operation, maintenance, and firefighting activities, as well as enabling easy evacuation of personnel. >>>> The equipment layout shall meet the requirements imposed by the process on equipment arrangement (such as pump filling heads, elevation differences between equipment rooms) ； The fire separation distances between equipment rooms, as well as between equipment and buildings, shall comply with the provisions of GB50160 ； Continuous ignition sources (open-flame heating equipment) and hazardous release sources should be avoided from being placed in close proximity to each other ； High-risk equipment and ordinary risk equipment should be arranged separately as much as possible ； The equipment should be arranged in an open or semi-open area as much as possible, in order to minimize the size of the area at risk of explosion ； Unless required by the process, when the equipment is arranged in multiple layers, it should not exceed three layers ； Air coolers are generally not installed above equipment where the operating temperature is equal to or greater than the auto-ignition temperature of the medium ； Safety spray and eye wash stations should be installed near medium and equipment that may cause accidental injury to humans. Such as methanol plants. >>>> Layout of buildings and structures: Buildings that may generate sparks or use open flames (such as control rooms, power distribution rooms, laboratories and maintenance areas, office buildings) should be located in non-explosive zones; if they are situated in Zone 2, they should be raised 0.6 m above the outdoor ground level ； The vertical arrangement of the facility should facilitate the discharge of leaks and fire-fighting fluids, thereby reducing their residence time in the facility area. Such as the explosion-proof facilities in foreign control rooms. >>>> Channel setup: An annular channel should be provided around the device ； The fire access routes of the facility should run through the facility area, with no fewer than two intersections connecting to the surrounding roads ； The areas separated by roads for the installation should ensure that there are no dead zones in firefighting operations ； The distance between the equipment joint platform and the adjacent evacuation passage of the framework should not exceed 50 m. 3.6 Pipeline Design Pipeline design consists of three parts: pipeline layout, pipeline fittings, and pipeline machinery. Poor design and mistakes can pose risks to safe production and even lead to disasters. >>>> Pipe layout: Apart from the necessary flange connections, welding should be used as much as possible for pipe connections ； Small-diameter branch pipes on the pipeline should be connected to the main pipe using reinforced pipe fittings ； Pipelines transporting liquefied hydrocarbons or corrosive media on pipe bridges should be arranged in the lower layer ； Oxygen pipelines should be arranged away from oil pipelines. For pipes carrying hazardous media that cross roads, in addition to the required clear height, no valves, flanges, or bellows shall be installed above them ； Various valves used for handling accidents, such as emergency venting, accident isolation, fire suppression steam, and fire suppression risers, should be located in safe, visible, and easily accessible locations. >>>> Pipeline fittings: The pipeline fittings used should be capable of withstanding the forces generated under the most severe temperature and pressure conditions during operation ； The use of piping fittings shall not exceed the limits permitted by the specifications, and materials not allowed by those specifications must not be used ； For pipelines carrying corrosive media, careful selection of corrosion-resistant materials and appropriate corrosion margins is necessary ； For the connection of pipes of different grades, flange connections should be used as much as possible to avoid welding of dissimilar steels ； For pipelines carrying hazardous media, it is advisable to avoid using bellows expansion joints in order to ensure the flexibility of the pipelines ； For valves used in pipelines carrying highly toxic and liquefied hydrocarbons, valves with threaded valve caps must not be used; high-pressure valves should employ a pressure-sealing structure or an even better sealing mechanism. When a soft seal is used for the accident isolation valve, it should be fire-resistant ； The pipeline sealing (flange temperature and pressure rating, connection type, seal surface type, gasket material and structure type, bolt and nut materials) should be selected appropriately ； The adoption of new equipment should be subject to evaluation by **or in conjunction with industry authoritative technical departments. >>>> Piping machinery must ensure that the pipes have sufficient flexibility under design conditions. In particular, for pipelines connecting high-temperature, thick-walled, large-diameter pipes to sensitive equipment (such as pumps, compressors, turbines, air coolers, etc.), the forces and moments acting on the equipment nozzles must meet the requirements of the equipment manufacturer ； In addition to considering flexibility, the connections of reciprocating compressors should also undergo pulse vibration analysis ； When two or more devices serve as backups for each other or undergo switching operations, the effects of different operating conditions on stress analysis and vibration analysis should be considered ； Cold tightening can reduce the force exerted by the pipes on the fixing points of the equipment during operation, but pipes connecting rotating equipment must not be tightened in this manner ； The pipe support structure should be reliable and reasonable. Vibrating pipeline supports should not be anchored to the plant building or equipment. For two-phase flow pipelines and other pipelines subject to impact loads, the supports should take the effect of impact forces into account ； The openings in the pipes should be reinforced. 3.7 Civil engineering design: The fire resistance ratings of control rooms, power distribution rooms, and production workshops shall meet the requirements of GBJ16. The control room, facing the side of the equipment containing hazardous materials, should be a solid wall made of non-combustible material without any doors or windows ； For Class A and B factories with explosion hazards, lightweight structures should be used, and the pressure relief area must meet the requirements of GBJ16 ； The safe evacuation routes in buildings and frameworks shall comply with the regulations ； When flammable liquid equipment is installed in multi-story buildings, facilities should be in place to prevent such liquids from leaking to the lower floors ； For large power foundations, vibration isolation measures should be adopted to consider the impact on the plant building ； In fire hazard areas, load-bearing steel structures and prestressed reinforced concrete structures shall be provided with fire protection measures, and their fire resistance limit shall not be less than 1.5 hours ； **In fortified areas, building design must also comply with seismic code requirements ； When the foundation of a low-temperature cold storage tank comes into contact with the soil, measures should be taken to prevent the 0°C temperature line from passing through the soil layer. 3.8 Water supply and drainage design: The wastewater system in production facilities is particularly prone to fires. Plant-wide production wastewater shall not pass through the process unit boundaries ； The combustible liquid separation tank for production wastewater in the plant equipment area must be equipped with a cover made of non-combustible material ； The manhole covers for wastewater from Class A and Class B facilities must be sealed. 3.9 Ventilation design: Facilities for ventilation should be provided in workshops where harmful gases or vapors are released, and the number of air changes per hour must meet the requirements specified in TJ36 regarding the maximum allowable concentrations of harmful substances in workshop air ； The intake openings for mechanical ventilation must ensure that the concentration of harmful gases or dust in the air being exhausted does not exceed 30% of the maximum allowable level of such substances in the workshop air ； Facilities where a large amount of harmful gases or vapors may be generated suddenly should be equipped with an emergency ventilation system. 3.10 Fire protection design: The main elements of the fire protection design for facilities are various fixed installations; however, the roads surrounding these facilities, as well as the fire access routes and fire hydrants along the roads, will facilitate the entry and exit of fire vehicles and the retrieval of water ； The fire water pipes of the installation should be arranged in a circular pattern; there should be no fewer than two inlet pipes, and the circular piping system should also be divided into several pipe sections using valves. Large-scale equipment installations should be protected by high-pressure water cannons. When the framework platform for Class A and Class B equipment is higher than 15 cm, a vertical fire water supply pipe must be installed. Equipment that is prone to serious accidents if it cannot be cooled in a timely manner after catching fire should be equipped with a water spray or mist system. For pump rooms for flammable liquids and compressor rooms for Class A gases with a volume of less than 500 cubic meters, fixed sprinkler systems using perforated pipes should be installed. Fixed steam fire extinguishing systems shall be installed in the furnace chamber of the heating furnace and in the elbow boxes with plugs. The flange connections of equipment whose operating temperature is equal to or greater than the auto-ignition point of the medium shall be protected by annular steam strainer tubes. Dry powder or foam fire extinguishers should be installed in the equipment production area, while gas fire extinguishers should be available in the control room. Fire alarm buttons should be installed around Class A and Class B plant areas. Alarm panels for temperature, smoke, flame, etc. are installed in the control room, which should also be equipped with a dedicated telephone for fire alarms ； When the plant control room is built together with other buildings, a separate fire compartment shall be provided, along with an automatic fire alarm system.