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During the maintenance of chemical production facilities, due to various factors, if workers fail to conduct proper risk identification and safety assessments and fail to implement adequate preventive measures, it is very likely that mistakes will occur during the work, leading to accidents. Data show that among the accidents that occur during the production and maintenance processes in chemical enterprises, those caused by unsafe behaviors of workers account for approximately 88% of the total number of accidents, while those resulting from unsafe working conditions account for about 10% of the total; the remaining 2% are caused by a combination of various factors. It can be seen that, under the same working conditions, unsafe behaviors of workers are the main cause of accidents. The well-known iceberg safety theory states that among all accidents, fatalities, serious injuries (leading to disability), workday losses, minor injuries, and unsafe behaviors account for approximately 1:30:300:3000:30000 of the total number of accidents. Starting with the highest level of accident, namely “fatal accidents,” they are arranged in descending order in proportion, and their combined shape resembles a pyramid. Thus, the iceberg safety theory is also known as the “pyramid theory”. The theory also states that when the base of the “pyramid” is contracted inward, the “pyramid” will shrink as a result. When the peak of the new “pyramid” is below the line representing “serious injury (disability) incidents” in the original “pyramid”, the new “pyramid” contains only “lost workday incidents, minor injury incidents, and unsafe behavior incidents”. In other words, when the number of unsafe behaviors at work is reduced to a certain level, the likelihood of accidents of the severity level of \"serious injuries (disabilities)\\" or higher approaches zero. The safety management theory put forward by the American company DuPont, which states that \"all safety accidents can be avoided,\" shares similarities with the iceberg safety theory. DuPont has developed a comprehensive system for risk identification and safety assessment, which has enabled it to effectively control the unsafe behaviors of its workers; as a result, no accidents of the severity level of \"serious injury (disability)\\" or higher have occurred at its 135 production and processing facilities around the world over a period of 100 years. Therefore, in practical work, effective risk identification and safety assessment are essential, and it is considered that implementing preventive measures to eliminate unsafe behaviors among workers is the fundamental guarantee for safe production and maintenance. Here, a comprehensive analysis and classification are conducted on the risks associated with six typical maintenance tasks in the chemical production plant area, as well as the corresponding safety measures. 1 Maintenance work in corrosive media 1.1 Job risks Leaking corrosive liquids and gases can cause varying degrees of damage to the workers’ limbs, clothing, and tools, as well as pollute the environment. 1.2 Safety Measures (1) Before carrying out maintenance work, it is necessary to contact the process engineers to drain out any corrosive liquids or gases, replace them with appropriate substances, and rinse the area; after analysis confirms that everything is satisfactory, an \"Operation Permit\" must be obtained. (2) Operators shall wear protective equipment as required, be familiar with the work tasks, especially the opinions issued by the relevant departments. (3) Perform maintenance in low-lying areas; there should be no accumulated corrosive liquids on the site to prevent slips and injuries during work. (4) The working surface where corrosive liquids are handled should be below waist level; otherwise, relevant personnel should be contacted to set up scaffolding to prevent residual liquids from splashing and damaging the body or clothing. Temporary supports such as iron drums shall not be used for this purpose. (5) During work, wear appropriate personal protective equipment such as rubber gloves, protective face masks, and rubber shoes, depending on the specific circumstances. (6) When removing, the connection surfaces can be rinsed with clean water to reduce the erosion caused by corrosive liquids and gaseous media. (7) Limbs, clothing, tools, etc. that have come into contact with corrosive substances should be cleaned promptly ； If any discomfort occurs, it should be treated promptly. (8) After the work is completed, ensure that all tools and materials are removed and the site is cleaned to maintain good hygiene. 2 Maintenance work on rotating equipment (including valves and motors) 2.1 Job risks During the maintenance of rotating equipment, incorrect operation of electrical or steam supplies may cause unintended rotation, thereby threatening the life and property safety of the maintenance personnel ； When the equipment (or spare parts) is large (heavy) and safety measures are inadequate, mechanical injuries can occur. 2.2 Safety Measures (1) Before carrying out maintenance work, it is necessary to contact the process engineers to effectively isolate the system, remove all flammable, explosive, toxic, and harmful substances from the equipment and pipelines that will be used for welding or maintenance, flush them, and conduct proper analyses; thereafter, a \"Work Permit\" must be obtained. (2) When repairing live (steam) equipment, it is necessary to contact the relevant personnel and teams, cut off the power (steam) supply, and hang a sign on the switch box that reads “Do not close – work in progress”. (3) The person in charge of the task shall implement all safety measures for that task, as well as obtain the necessary work permits and carry out the relevant approvals ； For tasks with extremely high risks, a safety assessment should be conducted together with the person in charge of safety at the work site, in order to develop a safe working plan. (4) Workers shall wear protective equipment as required ； Be familiar with the work requirements, especially the opinions issued by the relevant departments, and strictly follow them both before and during the operation. (5) The removed parts and components should be placed in designated areas and properly protected; special personnel should be assigned to monitor important parts or components. (6) When using pneumatic, electric, hydraulic, or other types of tools, it is necessary to operate them in accordance with the \"Safety Operation Instructions\" to ensure safe construction. (7) When the equipment (or spare parts) are large (heavy) and require coordinated work by multiple teams, unified command is essential, with strict adherence to orders. (8) Strengthen the management of oil-based substances; all waste oil should be poured into recycling bins. (9) After the work is completed, ensure that all tools and materials are removed and the site is cleaned to maintain good hygiene. 3 High-altitude maintenance work 3.1 Work risks The working location being at a higher height than the normal working level increases the risk of people and objects falling, leading to accidents. 3.2 Safety Measures (1) The person in charge of the work task shall arrange for the issuance of the \"Work Permit\" and the \"High-Height Work Permit\", with approval granted based on the working height ； The head of the production department where the task is carried out signs the departmental opinion. (2) The person in charge of the task shall check and ensure that the scaffolding (ladders, hoists), safety belts, ropes, and other equipment used for work at heights are safe, and shall assign a supervisor to the work site ； When work requires it, a warning line should be set up. (3) Operators shall wear protective equipment as required and be familiar with the work tasks, especially the opinions issued by the relevant departments ； When working with a safety belt, follow the \"Regulations on the Use of Safety Belts\" ； When using a ladder at work, follow the \"Ladder Safety Management Regulations\" ； When using scaffolding, follow the \"Safety Management Regulations for the Use of Scaffolding\" ； When working inside a basket or hanger, comply with the \"Regulations on Safety Management of Lifting Equipment\". (4) When working at heights, vertical operations should not be carried out simultaneously upwards and downwards. In special cases where vertical work must be carried out simultaneously, approval from the unit’s management is required, and a dedicated protective canopy should be installed or other isolation measures taken. (5) Avoid working at heights at night. When high-altitude work must be carried out at night, approval from the relevant authorities is required; the person in charge of the work must conduct a risk assessment, establish safety measures, and ensure adequate lighting. (6) High-altitude work is not permitted in conditions of severe weather such as winds of force 6 or above, thunderstorms, heavy rain, or dense fog that impair vision and hearing, or when personal safety cannot be ensured. (7) During high-altitude work, the safety supervisor must maintain regular contact with the workers at height; they shall not engage in any other tasks, nor shall they leave their post without permission ； When an abnormal situation occurs in the production system, immediately notify the workers working at heights to stop working and evacuate the site ； When there are significant changes in the working conditions or environment, a new High-Altitude Work Permit must be obtained. (8) After the work is completed, ensure that all tools and materials are removed and the site is cleaned to maintain good hygiene. 4 Hot Work Maintenance Operations 4.1 Operational Risks Heating, falling slag, and spitting sparks can cause burns to people, as well as fires and explosions; arc radiation and electric shock can also pose hazards to human health. 4.2 Safety Measures (1) Before carrying out maintenance work, contact the process engineers to effectively isolate the system, and remove, flush, and replace any flammable or explosive substances present in the equipment and pipelines. (2) After passing the analysis, proceed with the hierarchical approval for the \"Work Permit\" and \"Hot Work Permit\" ； Once the sampling analysis shows satisfactory results, no one shall change the process conditions ； During hot work, if there is an interruption of more than half an hour, sampling and analysis must be repeated. (3) The Hot Work Permit must be carried by the person performing the hot work at all times. All workers must be clear about the work requirements, especially the opinions issued by the relevant departments. (4) Operators must wear protective equipment as required and hold the appropriate qualification certificates ； Before carrying out welding or cutting operations, it is necessary to remove any flammable materials from the surrounding area, set up warning barriers, and hang clear signs; the area where welding or cutting takes place must not be expanded without permission. (5) A supervisor should be assigned for hot work, and fire extinguishers must be available ； During operations, unauthorized personnel are prohibited from entering the area where welding is being performed. When carrying out construction work in a Class A no-fire area, the project supervisor must, as required, notify professional firefighters in advance to be on site to assist with supervision. (6) When performing welding work, check that the joints and wiring are in good condition to prevent accidents caused by electric leakage. (7) During gas welding operations, the distance between the oxygen cylinder and the acetylene cylinder should be maintained at over 5 meters, and the distance between these two cylinders and the point where welding is taking place should be kept at over 10 meters. It is also necessary to check that the gas pipes are in good condition. (8) When performing welding or cutting tasks at heights, a fire tray must be placed to prevent sparks from falling ； At the same time, all combustible materials below must be removed, and sewers, manholes, cables, etc. need to be covered. (9) When performing hot work on combustible gases under pressure without displacement, a work plan must be prepared and safety measures must be implemented. At the same time, the pressure inside the device must not be less than 0.98 kPa, nor exceed 1.5691 MPa, to ensure that no negative pressure is created ； The oxygen content inside the equipment must not exceed 0.5%. Otherwise, hot work shall not be carried out. (10) When the workers leave the area where welding is being carried out, they should promptly cut off the power supply used for the work and extinguish any remaining sources of fire, so as to avoid leaving any potential hazards. (11) After the work is completed, ensure that all tools and materials are removed and the site is cleaned to maintain good hygiene. 5 Inspections in Confined Spaces 5.1 Job Risks Confined spaces present hazards such as low oxygen levels, high temperatures, toxic and harmful substances, as well as flammable and explosive gases. If safety measures are not adequate, fires and explosions can occur, leading to accidents that result in injuries or deaths. 5.2 Safety Measures (1) Contact the process engineers to cut off the power supply connecting the equipment to the outside world, apply locking measures, and hang warning signs ； Effectively isolate all equipment and pipelines connected to confined spaces or containers. (2) After the confined space has been drained, isolated (by installing blind flanges), cleaned, purged, and ventilated, and sampling analysis shows satisfactory results, the workers shall obtain the \"Work Permit\" and the \"Permit for Working in Confined Spaces\", which are subject to hierarchical approval. Once the sampling analysis shows satisfactory results, no one shall change the process conditions. (3) Before starting the work, prepare emergency rescue supplies, including safety belts, safety ropes, long-tube masks, lighting with a safety voltage of no more than 24V, electric shock (leakage) protection devices, as well as communication equipment. (4) Supervisors shall wear protective equipment as required and select an appropriate location for safety supervision ； During the supervision process, regular communication is necessary; any abnormalities should be reported immediately to the workers so that they can stop working and evacuate the dangerous area ； At the same time, it is necessary to pay attention to self-protection. (5) Workers shall wear protective equipment as required. When entering a confined space for the first time, it is necessary to wear a gas mask (long-tube type or air respirator), as well as safety belts and ropes ； Be familiar with the work content, especially the opinions issued by the relevant departments ； Workers working in confined spaces operate on a shift system, changing shifts on time and moving outside to rest promptly. (6) After removing the cover from a confined space, barriers, fences, lighting, etc. must be installed to prevent accidents. (7) When working in confined spaces, online analysis is necessary; if any abnormalities are detected, evacuation should be carried out promptly. (8) After the work is completed, ensure that all tools and materials are removed and the site is cleaned to maintain good hygiene. 6 Electrical Maintenance Work 6.1 Work Risks During electrical maintenance work, there is a risk of electric shock, hazards from arcs, or accidents caused by sparks resulting from short circuits. These can lead to injuries such as electric shock, burns caused by arcs, and injuries due to the explosive forces generated by arcs. Furthermore, electrical accidents can also pose dangers such as fires, explosions, and power outages of the equipment. 6.2 Safety Measures (1) Before carrying out maintenance work, contact the operators to cut off the power supply connected to the equipment, and apply locking measures; hang a prominent sign on the switch box or main circuit breaker that reads “Do not close – work in progress”. (2) All personnel working on or near live equipment must obtain an \"Operation Permit\" and follow the \"Permit Management Procedure\". (3) Operators shall wear protective equipment as required (in accordance with the \"Requirements for Personal Protective Equipment during Substation Work\"), and be familiar with the work tasks, especially the comments provided by the operators in charge. (4) Electrical work must be carried out only by qualified personnel holding relevant certificates, and at least two people should be involved in the work, one of whom shall act as a supervisor. (5) Electrical supervisors must receive professional training, obtain a qualification certificate to work in this role, and be authorized to cut off the power supply to the equipment as well as activate alarm signals ； Prevent unauthorized persons from entering dangerous areas during operations ； No other work tasks shall be carried out. (6) During maintenance, repairs, and fault handling, no one shall arbitrarily change or adjust the set values of protective and automatic devices. (7) Analysis and prevention of arc hazards: For devices with an energy level greater than 5.016 J/m2, an arc hazard analysis must be conducted to ensure safe and effective operation. (8) For processes or systems where static electricity is likely to be generated during maintenance, an electrostatic hazard analysis should be conducted, and appropriate measures and procedures should be established to prevent such hazards. (9) Metal ladders, chairs, stools, etc. must not be used in electrical work areas. 7. Conclusion: When carrying out production activities, it is essential to firmly uphold the principle of \"safety first, prevention foremost.\" The survival and development of a company depend on the efforts and creativity of all its employees. Value life, protect the environment ； Full participation, full control throughout the process. Only by carefully identifying risks and conducting safety assessments in actual work, as well as implementing preventive measures, can safe production and safe maintenance be ensured. This post was last edited by JLH on 2008-1-16 18:52.]