【Safety Article】Hazard identification and potential risk assessment techniques

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Potential accident hazards refer to hidden dangers, that is, things or disasters that are concealed and pose a high risk. Potential accident hazards refer generally to unsafe human behaviors, unsafe conditions of equipment and materials, as well as management deficiencies within a production system that can lead to accidents. Potential accident hazards are categorized into 21 major types: fires, explosions, poisoning and asphyxiation, water-related disasters, collapses, landslides, leaks, corrosion, electric shocks, falls, mechanical injuries, coal and gas outbursts, injuries caused by road facilities, injuries caused by road vehicles, injuries caused by railway facilities, injuries caused by railway vehicles, injuries in water transportation, injuries at ports and docks, injuries in air transportation, injuries at airports, and other types of hazards. During enterprise safety inspections, attention should be paid to the following commonly existing accident hazards: First, there are 11 main types of unsafe human behaviors, which are also the primary direct causes of accidents in production. 1. Ignoring safety, ignoring warnings, and making operational errors. 2. Manually causing the safety devices to fail. 3. Use of insecure devices. 4. Use hands instead of tools for operation. 5. Objects are not stored properly. 6. Venturing into dangerous places. 7. Climbing or sitting in unsafe positions. 8. There are behaviors that cause interference and distract attention. 9. Ignoring the use of individual labor protection equipment and tools, or failing to use them correctly. 10. Unsafe attire. 11. Improper handling and processing of hazardous materials such as flammable and explosive substances, etc. II. There are mainly 4 categories of the safety status of objects, which are also the primary direct causes of object-related accidents in production. 1. Devices for protection, insurance, signaling, etc., are missing or defective. 2. The equipment, facilities, tools, and accessories are defective. 3. Lack of or defective personal protective equipment. 4. Poor working environment at the production (construction) site. III. There are mainly 7 categories of management deficiencies, which are also the primary indirect causes related to management in work safety accidents. 1. Defects in technology and design. 2. Insufficient safety production education and training. 3. Unreasonable labor organization. 4. Lack of inspection or incorrect guidance regarding on-site work. 5. There are no safety production management regulations and safety operating procedures, or they are inadequate. 6. There are no accident prevention and emergency response measures, or they are inadequate. 7. Inadequate efforts to address potential accident hazards, with insufficient funding allocated. Identification of hazardous and harmful factors: Hazardous factors refer to those that can cause injury or death to people, or sudden damage to objects ； Harmful factors are those that can affect human health, cause diseases, or result in chronic damage. Normally, the two are not distinguished from each other and are collectively referred to as dangerous and harmful factors. I. Classification of hazardous and harmful factors – Classifying hazardous and harmful factors is the basis for their analysis and identification. There are many methods for classifying dangerous and harmful factors, with the following two being the main ones: 1. Classification based on the direct causes of accidents and occupational hazards. According to the provisions of the \"Classification and Codes for Dangerous and Harmful Factors in Production Processes,\" these factors are divided into the following 6 categories: (1) Physical dangerous and harmful factors: 1) Defects in equipment and facilities such as insufficient strength, poor stiffness, lack of stability, poor sealing, stress concentration, geometric defects, exposed moving parts, brake defects, and other defects in equipment and facilities. 2) Protection defects: lack of protection, defects in protective devices and facilities, inadequate protection, improper support, insufficient protection distance, and other protection defects. 3) Exposure of live electrical parts, electric leakage, lightning, static electricity, electric sparks, and other electrical hazards. 4) Noise: mechanical noise, electromagnetic noise, hydrodynamic noise, other noises. 5) Vibrations: mechanical vibrations, electromagnetic vibrations, hydrodynamic vibrations, other vibrations. 6) Electromagnetic and ionizing radiation: X-rays, gamma rays, alpha particles, beta particles, protons, neutrons, high-energy electron beams, etc ； Non-ionizing radiation: ultraviolet light, lasers, radiofrequency radiation, ultra-high voltage electric fields. 7) Solid projectiles from moving objects, liquid splashes, rebounding objects, soil and rock slippage, pile slippage, air currents, impact-induced ground pressure, and other hazards from moving objects. 8) Open flames 9) High-temperature substances that can cause burns: high-temperature gases, high-temperature solids, high-temperature liquids, and other high-temperature substances. 10) Substances at low temperatures that can cause frostbite: low-temperature gases, low-temperature solids, low-temperature liquids, and other low-temperature substances. 11) Dusts and aerosols do not include explosive and toxic dusts and aerosols. 12) Poor working environment: Messy working environment, foundation settlement, defective safety walkways, poor lighting and illumination, harmful light exposure, inadequate ventilation, oxygen deficiency, poor air quality, poor water supply and drainage, water ingress, forced body postures, excessively high or low temperatures, excessively high or low air pressure, high temperature and humidity, natural disasters, and other poor working conditions. 13) Signal defects include the absence of signal facilities, improper selection of signals, incorrect signal placement, unclear signals, inaccurate signal display, and other signal defects. 14) Marking defects include absence of markings, unclear markings, non-standard markings, inappropriate selection of markings, defects in marking location, and other marking defects. 15) Other physical hazards and harmful factors (2) Chemical hazards and harmful factors 1) Flammable and explosive substances: flammable and explosive gases, flammable and explosive liquids, flammable and explosive solids, flammable and explosive dusts and aerosols, other flammable and explosive substances. 2) Spontaneously combustible substances 3) Toxic substances: toxic gases, toxic liquids, toxic solids, toxic dusts and aerosols, other toxic substances. 4) Corrosive substances: corrosive gases, corrosive liquids, corrosive solids, other corrosive substances. 5) Other chemical hazards and harmful factors (3) Biological hazards and harmful factors 1) Pathogenic microorganisms: bacteria, viruses, and other pathogenic microorganisms. 2) Vectors of infectious diseases 3) Harmful animals 4) Harmful plants 5) Other biological hazards and harmful factors (4) Psychological and physiological hazards and harmful factors 1) Excessive loads: excessive physical load, excessive hearing load, excessive vision load, other types of excessive loads. 2) Abnormal health condition 3) Engaging in prohibited types of work 4) Psychological abnormalities such as abnormal emotions, a tendency for risk-taking, excessive stress, and other psychological issues. 5) Identify perception delays in functional defects, recognition errors, and other functional defect issues. 6) Other psychological and physiological risks and harmful factors (5) Behavioral risks and harmful factors 1) Command errors: mistakes in giving commands, unlawful command issuance, and other command-related errors. 2) Operational errors, improper operations, violations of procedures, and other operational mistakes. 3) Errors in supervision 4) Other errors 5) Other behavioral hazards and harmful factors (6) Other hazards and harmful factors. 2 Classification by accident categories: Referring to the “Classification Standards for Occupational Injuries and Fatalities of Enterprise Employees” (GB6441), and taking into account factors such as causative objects, predisposing causes of accidents, harmful agents, and modes of injury, hazards and harmful factors can be classified into the following 20 categories. (1) Object strike refers to the situation where an object, driven by gravity or other external forces, moves and strikes a person, resulting in injury or death; it does not include object strikes caused by mechanical equipment, vehicles, lifting machinery, collapses, etc. (2) Vehicle-related injuries refer to accidents caused by corporate motor vehicles in operation, such as falls of people and collapses, drops, or crushes of objects, and do not include accidents that occur during the lifting by lifting equipment, when vehicles are being pulled, or when vehicles are stationary. (3) Mechanical injuries refer to injuries such as pinching, collision, shearing, entrapment, twisting, crushing, cutting, and piercing caused by the direct contact between moving (or stationary) parts of mechanical equipment, tools, and workpieces with the human body; these do not include mechanical injuries caused by vehicles or lifting machinery. (4) Lifting injuries refer to crushes, falls, injuries caused by falling objects (such as lifting tools and loads), and electric shocks that occur during various lifting operations (including crane installation, maintenance, and testing). (5) Electric shock includes fatalities and injuries caused by lightning strikes. (6) Drowning includes drowning due to falling from a height, but does not include drowning caused by water ingress in mines or underground areas. (7) Burns refer to burns caused by flames, scalds from hot objects, chemical burns (burns inside and outside the body caused by acids, bases, salts, and organic substances), and physical burns (burns inside and outside the body caused by light or radioactive substances). This does not include electrical burns or burns resulting from fires. (8) Fire (9) Fall from height refers to injury or death accidents caused by falling during work at heights, excluding accidents resulting from electric shock. (10) Collapse refers to an accident that occurs when an object, under the action of external forces or gravity, exceeds its strength limit or experiences a loss of structural stability, such as soil and rock collapse during trenching, scaffold collapse, or the collapse of piled materials. It does not apply to roof and wall collapses in mines, nor to collapses caused by vehicles, lifting machinery, or blasting. (11) Roof and sidewall collapse (12) Water inrush (13) Blasting refers to casualties occurring during blasting operations. (14) **Explosion accidents** refer to those that occur during the production, processing, transportation, and storage of explosives and their derivatives. (15) Gas explosion (16) Boiler explosion (17) Container explosion (18) Other explosions (19) Poisoning and asphyxiation (20) Other injuries II. Methods for identifying hazardous and harmful factors: The choice of identification method depends on the nature and characteristics of the object under analysis, the different stages of its lifespan, as well as the knowledge, experience, and skills of the analysts. The two commonly used identification methods are as follows: 1. Intuitive experience analysis method – This method involves comparing with relevant standards, regulations, or checklists, or relying on the observer’s analytical skills; it utilizes experience and judgment to analyze the hazardous and harmful factors in a company. (2) Analogical method: The analogical method involves using experience from identical or similar engineering systems or working conditions, along with statistical data on occupational safety and health, to infer and analyze the hazardous and harmful factors in a company. 2. System safety analysis methods: System safety analysis methods involve applying certain techniques from system safety engineering evaluation to identify hazards and harmful factors. System safety analysis methods are often used for new systems that are complex and lack accident experience. Common system safety analysis methods include event trees, fault trees, etc. III. Main contents of identifying dangerous and harmful factors 1. The site selection is analyzed from aspects such as engineering geology, topography and landforms, hydrology, natural disasters, surrounding environment, meteorological conditions, transportation facilities, and fire protection support. 2. Plant layout (1) General plan: Zonal arrangement of functions (production, management, auxiliary production, living areas) ； Layout of facilities for high temperatures, hazardous substances, noise, radiation, and flammable and explosive materials ； Process flow layout ； Layout of buildings and structures ； Orientation, wind direction, fire protection distance, safety distance, health protection distance, etc. (2) Transportation routes and docks: factory roads, factory railways, hazardous materials loading/unloading areas, and factory docks. 3. Fire resistance rating, structure, fire protection, explosion protection, safe evacuation, orientation, natural lighting, transportation access, etc. of buildings and structures. 4. Materials used in the production process (toxic, corrosive, flammable, and explosive materials), temperature, pressure, speed, operating and control conditions, accidents, and uncontrolled states, etc. 5. Production equipment and devices
(1) Chemical industry equipment and devices: High temperature, low temperature, corrosion, high pressure, vibration; critical equipment; control, operation, maintenance, as well as emergency abnormal situations occurring during malfunctions or errors. (2) Machinery and equipment: moving parts and workpieces, operating conditions, maintenance operations, improper operation and misoperation. (3) Electrical equipment: power outages, electric shocks, fires, explosions, improper operation and malfunctions, static electricity, lightning. (4) Equipment with relatively high risk, equipment for working at heights. (5) Special monomer equipment and installations: boiler rooms, acetylene stations, oxygen stations, oil depots, hazardous materials warehouses, etc. (6) Hazardous work environments such as dust, toxins, noise, vibration, radiation, high temperatures, and low temperatures. (7) Management facilities, emergency rescue facilities for accidents, and auxiliary production and living hygiene facilities. The classification of the fire hazard of substances is based on the Code for Fire Protection Design of Buildings. The fire hazards associated with the production, use, and storage of substances are divided into 5 categories: Class A, Class B, Class C, Class D, and Class E. The details are as follows: 1. Class A: (1) Liquids with a flash point of <28°C. (2) Gases with an explosion lower limit of <10%, as well as solid substances that, when exposed to water or water vapor in the air, can produce gases with an explosion lower limit of <10%. (3) Substances that can decompose on their own at room temperature or oxidize in air, thereby causing rapid spontaneous ignition or explosion. (4) Substances that, at room temperature and in contact with water or water vapor in the air, can produce flammable gases and cause combustion or explosion. (5) A strong oxidizing agent that is highly prone to causing combustion or explosion when exposed to acids, heat, impact, friction, catalysis, or flammable organic substances and inorganic substances such as sulfur. (6) Substances that can cause combustion or explosion upon impact, friction, or contact with oxidizers or organic substances. (7) Production carried out in enclosed equipment at a temperature equal to or above the substance’s own autoignition point. 2. Category B (1) Liquids with a flash point of ≥28°C and <60°C. (2) Gases with a lower explosion limit of ≥10%. (3) Oxidizers that do not belong to Class A. (4) Chemical flammable hazardous solids that do not belong to Category A. (5) Oxidizing gas (combustion-supporting gas). (6) Suspended dust and fibers that can form explosive mixtures with air, as well as liquid droplets with a flash point of ≥60°C. (7) Items that can slowly oxidize when in contact with air at room temperature, and may catch fire spontaneously due to the accumulation of heat. 3. Class C (1) Liquids with a flash point ≥ 60°C. (2) Combustible solids that do not belong to categories A or B. 4. Class D (1) Production involving the processing of non-combustible materials, which generates intense radiant heat, sparks, or flames under high temperatures or in a molten state. (2) Various types of production that utilize gases, liquids, or solids as fuels, or that involve burning gases and liquids for other purposes. (3) Production of non-flammable materials for use or processing at normal temperatures. (4) Stored flame-retardant items. 5. Class V (1) Production of non-flammable materials used or processed at normal temperatures. (2) Non-combustible items stored. Identification of major hazard sources: Broadly speaking, any equipment, facility, or location that may lead to a major accident can be considered a major hazard source. **The standards “Identification of Major Hazard Sources” and the “Work Safety Law” provide clear regulations regarding major hazard sources. A major hazard source refers to a unit (including sites and facilities) that permanently or temporarily produces, transports, uses, or stores hazardous substances in quantities equal to or exceeding the critical level. II. Criteria for identifying major hazard sources: Currently, internationally, major hazard sources are identified based on the types of hazardous and harmful substances and their allowable limits. The Seveso Directive in the EU lists 180 hazardous and harmful substances along with their limits. Our country has issued the standard for identifying major hazard sources, namely «Identification of Major Hazard Sources» (GB18218). All major hazard sources must undergo safety assessments and inspections, and subject to the requirements resulting from these assessments and inspections, they must be under close monitoring. Main strategies and measures for addressing potential hazards: 1. Adopt mechanized and automated production. Mechanized and automated production is not only an important means for developing production but also the fundamental way to achieve intrinsic safety. Mechanization can reduce the intensity of labor, while automation can decrease the risk of personal injury. Intrinsic safety refers to the property of equipment, facilities, or technical processes that possess built-in functions capable of fundamentally preventing accidents from occurring. Specifically, it includes three aspects: 1. Fool Proof safety function. 2. Fail Safe function. 3. The aforementioned safety functions should be built into the equipment, facilities, or process technologies. II. Installation of safety devices Safety devices include protective devices, safety locks, and warning devices, etc. III. Enhancing mechanical strength: Mechanical equipment, apparatuses, and their main components must possess the necessary mechanical strength and safety factors. IV. Ensuring electrical safety and reliability. Electrical safety measures typically include protection against electric shock, electrical fires and explosions, as well as protection against static electricity. The basic conditions for ensuring electrical safety are: 1. Safety certification. 2. Backup power supply. 3. Protection against electric shock. 4. Electrical fire and explosion prevention. 5. Anti-static measures. V. Maintain and service machinery and equipment as required. Machinery and equipment are the main tools for production; during operation, it is inevitable that some of their components gradually wear out or get damaged prematurely, which can lead to accidents involving the equipment. This not only causes production to come to a halt but may also result in injuries to the operators. Therefore, to keep machinery and equipment in good condition at all times and prevent equipment failures as well as accidents causing injuries or deaths, regular maintenance and scheduled inspections are essential. VI. Maintain a reasonable layout of the workplace. The workplace is the area where workers use machinery, tools, and other auxiliary equipment to process raw materials and semi-finished products. A well-organized structure and rational layout not only facilitate production but are also essential conditions for ensuring safety. Scattered metal scraps, lubricants, emulsions, raw materials, and half-finished products in the workplace, along with uneven floors, can all lead to accidents. VII. The provision of personal protective equipment must be based on the hazards and harmful factors, as well as the type of work, with PPE that offers appropriate protective functions being used as a supplementary measure.