Reviewing the old to gain new insights: Safety knowledge for equipment maintenance in petrochemical enterprises

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This post was last edited by yinkuilin6868 on 2016-2-24 08:57. In petrochemical enterprises, equipment maintenance involves frequent emergency repairs, is complex, requires high technical skills, and carries a high level of risk. The equipment in such enterprises is arranged in a concentrated manner, and the maintenance areas are relatively small; operations often take place in complex, multi-layered settings, both inside and outside the equipment, as well as at heights or underground. During maintenance tasks, activities such as hot work, working at heights, working inside tanks, lifting operations, electrical work, and disassembly/assembly are frequently carried out. If organization is poor, planning is inadequate, or carelessness exists, accidents are likely to occur. According to statistics, more than 66% of the accidents involving explosions, poisoning, suffocation, falls, electric shocks, and other injuries in petrochemical enterprises across the country occur during maintenance activities. Therefore, it is particularly important to implement effective safety measures during equipment maintenance. Risk factors
1. Main manifestations of the risks associated with hot work
(1) Inadequate system safety measures. Issues such as incomplete cleaning, the presence of dead corners inside containers, improper use of blind flanges, unseparated connected pipelines, and valve leaks can lead to fires and explosions during hot work.
(2) Flammable and explosive substances trapped in the internal surfaces of equipment and pipes or in the insulation materials on their outer surfaces may be released during hot work if not properly removed, resulting in fires and explosions.
(3) The areas around and below hot work sites in petrochemical plants may contain flammable and explosive materials; if these are not cleared away, fires and explosions can occur.
(4) Failure to obtain the necessary hot work permits or to follow the safety measures specified in those permits can also lead to fires and explosions.

2. Main manifestations of the risks associated with working inside equipment
(1) Toxic and harmful gases that have not been properly cleaned, displaced, or analyzed may cause poisoning.
(2) An oxygen level within the container that is not within the required range can lead to suffocation.
(3) Prolonged working periods combined with poor ventilation in the container increase the risk of suffocation.
(4) The use of lighting fixtures or electric tools powered by unsafe voltages, or damaged power cords, can result in electric shock accidents.
(5) Entering toxic areas without wearing appropriate protective gear, having defective protective equipment when working inside equipment, insufficient oxygen supply, or ineffective protective agents can all lead to poisoning incidents.
(6) Working inside deep containers without adequate safety measures can result in injuries from falling objects.

3. Main manifestations of the risks associated with working at heights
(1) Improperly constructed scaffolding with poor stability can lead to falls from heights.
(2) Sudden releases of toxic gases due to changes in the surrounding environment can cause poisoning and falls from heights.
(3) Failure to follow safety procedures such as not obtaining a permit for working at heights, not wearing safety belts, or not using helmets can result in falls from heights and injuries from falling objects.
(4) Falling can occur if appropriate measures are not taken after removing barriers or floor panels during maintenance work.

In addition, workers may also face the risk of burns and scalds during maintenance activities ； Or colliding and falling in confined spaces, resulting in bruises and injuries ； Or being caught in operating machinery and equipment, resulting in limb injuries; accidents occurring due to construction cranes, winches, and hand-held grinders that have not been inspected – all of these require close attention. II. Causes of accidents during chemical plant maintenance work 1. Inadequate coordination of maintenance activities The most fundamental requirement for safe maintenance work is the existence of safe conditions for the equipment itself. For hot work, the equipment involved must be isolated, cleaned, purged, and analyzed to ensure compliance before any work can proceed ； Work involving entry into towers or tanks also requires isolation, decontamination, displacement, purging, and analysis of oxygen content and toxicity levels; operations may only proceed after all tests yield satisfactory results. In actual operations, due to the frequent concurrent tasks during maintenance work, poor coordination can undermine the safety measures of the equipment and lead to accidents. The following is an example of poor coordination: During maintenance work at a factory, the workshop scheduled a team of maintenance workers to enter the shift converter at 8 a.m., with the task set to be completed at 10 a.m ； At 10 a.m., three teams of maintenance workers began restoring the connecting pipelines of the shift converter. During the operation, due to the high difficulty of the task, Team 1 of maintenance workers failed to complete the maintenance work within the specified time. Meanwhile, Team 2 started the reset process at 10 o’clock, which caused nitrogen to be introduced into the converter that was originally in a safe condition; as a result, three workers inside the converter suffered severe suffocation. 2. Inspectors lack knowledge of safety procedures and have low skills in safety technology, resulting in frequent occurrences of \"three violations.\" The \"three violations\" refer to giving orders in violation of regulations, carrying out operations in violation of regulations, and violating labor discipline. Accident investigations have shown that over 85% of accidents are caused by violations of safety rules. A low level of safety knowledge is the direct cause of accidents. The quality of safety production directly influences the behavior of maintenance supervisors and workers. For specific maintenance operations, starting from supervisors to workers, it is necessary to first understand the physical and chemical properties of the medium, and then understand the hazards associated with the equipment. Only then can appropriate countermeasures be devised based on these properties. Only in this way can the safe execution of the renovation be ensured, guaranteeing absolute safety. 3. Lack of protective equipment or improper use 　Protective equipment serves as a barrier to prevent accidents and is an important element in avoiding such incidents. In practical work, some organizations, in an effort to reduce production costs, eliminate or reduce the personal protective equipment that should be provided, or replace it with items intended for welfare purposes. This allows the dangerous and harmful factors associated with chemical maintenance tasks to directly affect the human body and cause injuries. Furthermore, some maintenance personnel often neglect to learn the basic knowledge regarding the use and storage of protective equipment and personal protective gear; as a result, accidents can occur due to improper use during maintenance work. For example, when a company was performing maintenance on a desulfurization tower, workers used long-tube protective masks; no one was monitoring the end of those long tubes, and debris blocked them, forcing the workers to remove their masks – which led to poisoning immediately. When existing protective equipment is used or stored improperly, resulting in damage or moisture absorption, it may perform poorly or become unusable when put into use, which can also lead to accidents. 4. Poor quality of maintenance supervisors can also lead to accidents; sometimes, enterprise production supervisors do this in order to save time. If production is increased, there will be a tendency to take risks by ignoring safety measures during maintenance, which can lead to accidents on a large scale with wide-ranging impacts. For example, in most enterprises, there is a shortage of maintenance workers during repairs, and the supervisors in some organizations assign unqualified personnel to carry out the work. On one hand, improper handling by these unqualified individuals can lead to accidents during the operations. On the other hand, it is difficult to ensure the quality of the work, and this may lead to other accidents during the production of the equipment being repaired. Accident prevention during maintenance 1. Make proper preparations for maintenance 　　(1) Organizational preparation. First, it is necessary to establish a sound organizational structure for equipment maintenance as well as clear safety responsibilities at all levels ； Secondly, the maintenance organization must be well-structured, with clear roles assigned for the person in charge of maintenance, the safety officer, and the workers; it is essential to have clear tasks and a clear understanding of what needs to be done. (2) Preparation of measures: Ensure that the maintenance tasks and construction activities are properly planned ； Formulation of construction plans and start/stop plans, as well as planning of the schedule ； For major maintenance projects and large-scale, complex lifting operations, a lifting plan and safety technical measures must be developed. The construction team is responsible for implementing these safety measures. Safety rules for entering the construction site must be clearly defined, and personnel should be assigned to oversee the promotion, inspection, and enforcement of these rules. (3) Material preparation: Based on the scope, content, and requirements of the maintenance work, the materials, accessories, and equipment needed for the task must be prepared in advance. A prior safety inspection of lifting equipment, welding equipment, power tools, rigging, and lifting devices is also necessary ； Check safety warning signs, do-not-operate signs, no-closing signs, blind flange signs, and grounding wires to ensure that there is a complete variety of items, sufficient quantities, acceptable quality, and that they are used properly. (4) Personnel preparation. It is necessary to designate a safety supervisor for the maintenance work, establish a safety leadership group, and define the responsibilities of safety supervisors at all levels as well as the procedures for coordination and communication among them ； Comprehensive safety training should be provided to all personnel involved in the maintenance work, explaining the safety issues that need to be addressed in each item and at each stage of the safety-based maintenance plan. Each person in charge of a specific maintenance task must carry out the “five clarifications” before starting work: clarifying the tasks to be performed, the safety measures to be taken, the methods for safe work, the safety precautions to observe, and the relevant regulations to be followed. Personnel working in specialized roles should receive safety training focused on the safety techniques specific to their job as well as the safety rules related to maintenance, so that they can perform their duties effectively.

2. Strictly implement all measures related to maintenance
(1) Eliminate hazardous factors associated with the equipment. Equipment that is in operation must go through a series of procedures such as shutting down, releasing pressure, draining fluids, cooling down, removing blind flanges, replacing substances, purging, cleaning, conducting safety analyses, and cutting off power supplies, before it can be maintained in a safe condition.
(2) Strictly follow the procedures for obtaining permits for safe maintenance work. Every maintenance task requires a task order, which serves as a document that outlines the tasks to be carried out, the safety measures to be implemented, records of the maintenance work, and details for inspection and approval. It is an essential measure to ensure the quality and safety of the maintenance work. Once the hazards associated with the equipment have been eliminated, the person who hands over the equipment must sign the task order, confirming that all safety measures have been taken, after which the maintenance workers can proceed with their work. For various types of operations, corresponding safety permits must be obtained in accordance with regulations.
① Any welding or cutting operations carried out in areas where fires are prohibited, or any temporary operations that may generate flames, sparks, or hot surfaces, such as those using blowtorches, electric drills, or grinders in flammable or explosive environments, require a “Fire Safety Permit.” Only after this permit has been approved and signed can work begin within the specified time frame ； 　　②Any work carried out in various towers, spheres, reactors, tanks, vats, furnaces, boilers, pipelines, containers, as well as in basements, manholes, pits, sewers, or other enclosed areas within petrochemical production zones requires a \"Permit to Enter Equipment and Containers.\" All power sources connected to the equipment must be properly disconnected. To isolate pipelines safely, blind flanges can be used or a section of the pipeline can be removed; water seals or valves cannot be used in place of blind flanges or removed sections of pipeline. Blind flanges cannot be replaced with iron sheets or asbestos pads, and the thickness of the steel plate must be at least equal to that of the pipeline wall. To ensure proper disconnection of power, measures such as removing the fuse or turning off the power switch and locking it in place should be taken, along with the installation of warning signs. In environments with low oxygen levels or toxic substances, isolating gas masks must be worn. In flammable and explosive environments, explosion-proof low-voltage lighting fixtures and tools that do not generate sparks must be used, and the wearing of synthetic fabrics is prohibited. The lighting voltage inside equipment should be 36V or less; in wet or confined spaces, it should be 12V or less ； 　　③Any work carried out at heights of 2 meters or more above the reference level from which a fall could occur requires a \"High-Height Safety Work Permit\". The person responsible for approving high-altitude work must inspect the site to ensure that all safety measures are in place before granting permission for such work ； Persons working at heights must receive safety training and be familiar with the site conditions as well as the safety requirements for such work. Those who suffer from occupational contraindications, or are elderly, weak, overfatigued, have poor eyesight, or are under the influence of alcohol, are not allowed to work at heights ； 　　④The installation of temporary power sources must comply with safety regulations; they should not be connected or set up arbitrarily. Equipment installed outdoors must have measures to protect it from rain and moisture, and electrical work must be carried out in strict accordance with the work order system. Other types of work, such as lifting operations and groundwork, also require corresponding work permits, which must be obtained before such work can proceed. (3) Appropriate fire protection measures must be in place. During maintenance, it is necessary to ensure that the factory’s fire roads are unobstructed, that there is sufficient water pressure for firefighting, and that all necessary fire-fighting equipment is available and functional. In principle, no welding or other flammable activities are allowed within the area where the fire water supply has been shut off; if such activities are indeed necessary, fire prevention and emergency response measures must be in place. 3. Supervise and inspect safety management at the work site. Safety managers at all levels and project supervisors must be responsible for specific areas, conducting regular inspections and oversight within their respective jurisdictions. Special attention should be paid to the compliance with rules and regulations, the proper use of various permits, adherence to organizational discipline, the readiness and condition of safety facilities, the proper installation and use of temporary electrical circuits, and the availability and proper use of tools and equipment needed for maintenance. Efforts should be made to address any violations in these areas. To strengthen safety controls, a “violations exposure board” can be set up at the maintenance site to publicly identify those units and individuals who fail to follow safety regulations, give illegal instructions, or carry out illegal activities during maintenance. The work site should be cleaned regularly during maintenance, with materials and tools stored properly. Safety signs or barriers should be placed in dangerous areas, and red lights should be used at night. 4. Ensure proper acceptance of completed maintenance work. After maintenance is finished, the workers must clean up the site, removing all oil stains, trash, and waste materials ； All safety facilities such as railings, protective covers, equipment lids, grounding systems, and neutral connection systems must be restored to their original state. Before handing over the work, it is necessary to check whether there are any maintenance tasks that have been overlooked, to ensure that all blind flanges that need to be removed have indeed been removed (one by one, with no omissions), and to verify that the safety devices are functioning properly. Equipment such as pressure vessels and storage tanks must undergo pressure testing, leak testing, and airtightness tests in accordance with regulations, and finally, the equipment or system must be tested in operation to confirm its functionality