Issues to Consider in Chemical Plant Maintenance

Pay attention to turning off the equipment power, ensuring that cleaning and replacement are done properly, cutting off the pipes or installing blind flanges. All types of maintenance work must be carried out in strict accordance with established procedures. After the maintenance is completed, the work site must be cleaned up thoroughly. A joint inspection by the safety, equipment, and production departments is also required, among other things. That’s roughly it; it may not be detailed enough, so I hope others can provide additional information.

The poster can refer to the \"AQ3026-2008 Safety Specifications for Equipment Maintenance Operations in Chemical Production Units,\" and by earnestly implementing the requirements of the following relevant standards, accidents can be prevented and reduced: AQ3018-2008 General Safety Rules for Operations in Hazardous Chemical Storage Areas, AQ3021-2008 Safety Specifications for Lifting Operations in Chemical Production Units, AQ3022-2008 Safety Specifications for Hot Work in Chemical Production Units, AQ3023-2008 Safety Specifications for Groundwork Operations in Chemical Production Units, AQ3024-2008 Safety Specifications for Circuit Interruption Operations in Chemical Production Units, AQ3025-2008 Safety Specifications for High-Height Operations in Chemical Production Units, AQ3027-2008 Safety Specifications for Blind Flange Installation and Removal Operations in Chemical Production Units, and AQ3028-2008 Safety Specifications for Operations in Confined Spaces in Chemical Production Units. It should also be noted that although these standards and specifications are quite comprehensive and detailed, what truly matters is their proper implementation.

One thing to note is the displacement process: Before carrying out maintenance work involving open flames, it is necessary to displace the flammable and explosive substances inside the container with an inert gas. For example, the presence of hydrogen in chlorine gas, or oxygen in hydrogen gas, increases the risk of explosion. However, if the amount of inert gas in the explosive mixture is increased, the mixture will no longer explode. This is because the inert gas separates the fuel molecules from the oxygen molecules, creating an inert \"barrier\" between them. The correct method of displacement is to replace the flammable gases with nitrogen, and then replace the nitrogen with air, so as to bring the oxygen content in the container to the required level (18%–21%). 2 Steam purging: Depending on the materials stored in the container, over time significant amounts of dirt accumulate on its inner walls, especially at the joints. Flammable and combustible substances get trapped on these deposits on the container’s inner surface. Due to changes in temperature and pressure, these flammable gases are released gradually, which can alter the conditions suitable for performing welding or other thermal operations; therefore, steam purging is necessary as an additional step. During the steam purging process, it is necessary to avoid using too short a time period; although this may result in satisfactory sample results, over time the residues will continue to evaporate, producing flammable vapors that can reach an explosive level. II. Ventilation: To maintain an adequate amount of oxygen inside the container, all manholes and access holes in the container must be opened to allow natural ventilation or mechanical ventilation to be used; however, oxygen cannot be employed as a means of ventilation. Three-system isolation: A container device is often connected to other devices through pipes in multiple places. However, valves that remain open tend to accumulate debris at their openings, or corrosion may prevent them from closing properly, resulting in internal leaks and thus introducing combustible substances back into a container that was originally purged clean. The isolation method generally involves using a blind flange to cut off the inlet and outlet pipelines connected to it, thereby completely isolating it from the production area. It is important to note the following: (1) The blind flange must ensure good sealing properties, with no air leaks; (2) It must have sufficient strength to meet the requirements of the production process; (3) Depending on the properties of the material, it must meet anti-corrosion requirements; (4) The section of pipeline connected to the container needs to be removed. Avoid using the closing of valves as a substitute for isolating from other equipment and pipelines in the production system. For containers equipped with mechanical stirring, it is also necessary to strictly follow the relevant regulations for electrical operations; a \"tagging system\" should be implemented at the control switches to prevent accidents caused by accidental operations. IV. Analysis, detection, and control of combustible material levels – It is crucial to keep the concentration of combustible materials within safe limits; this is key to the successful performance of welding operations in containers. The thoroughness of container treatment should be determined by the quantitative analysis of the gas components

Safety Specifications for Equipment Maintenance Operations in Chemical Production Units (AQ3026-2008) 1 Scope These specifications establish the safety requirements prior to equipment maintenance in chemical production units, the safety requirements during the maintenance operations, and the safety requirements after the maintenance is completed. This standard applies to major, medium, and minor repairs as well as emergency repair work on equipment in chemical manufacturing units. 4 Safety requirements prior to maintenance 4.1 External maintenance contractors must possess the **required appropriate qualifications and carry out maintenance work within the scope permitted by their level of certification. 4.2 When signing a contract for equipment maintenance, a safety management agreement should be signed simultaneously. 4.3 In accordance with the requirements of the equipment maintenance tasks, the maintenance contractor shall prepare a maintenance plan, which must be reviewed by the entity that uses the equipment. The maintenance plan should include safety and technical measures, as well as designate a person responsible for safety regarding the maintenance tasks. The maintenance contractor shall assign a dedicated person to be responsible for the specific safety aspects throughout the entire maintenance process. 4.4 Before the maintenance work begins, the entity that operates the equipment shall provide safety training to the personnel involved in the maintenance tasks. This safety training mainly includes the following contents: 4.4.1 Safety rules and regulations related to maintenance work. 4.4.2 Hazard factors present at the maintenance site and during the maintenance process, potential problems, and corresponding countermeasures. 4.4.3 Usage methods and precautions for personal protective equipment used during maintenance operations. 4.4.4 Relevant accident cases and experiences, lessons learned. 4.5 Appropriate safety signs shall be installed at the maintenance site in accordance with the provisions of GB 2894. 4.6 The person in charge of the maintenance project shall organize the maintenance personnel to go to the site to explain the maintenance plan. 4.7 Before the maintenance work, the construction unit must ensure that the organization for the maintenance is in place, that the personnel responsible for the maintenance are available, and that all safety measures for the maintenance are implemented. 4.8 When equipment maintenance involves tasks such as working at heights, working with open flames, digging, cutting off circuits, lifting, removing or installing blind flanges, or working in confined spaces, it is necessary to follow the relevant safety regulations for such operations. 4.9 Temporary power usage must go through the necessary procedures, and it must be installed and set up in accordance with regulations. 4.10 The equipment user is responsible for isolating, cleaning, and replacing the equipment, and handing it over once it meets the required standards. 4.11 The person in charge of the maintenance project shall, together with the person in charge of the equipment user, conduct inspections to confirm that the equipment and processing methods meet the safety requirements for maintenance. 4.12 Inspect various tools and equipment used in maintenance work, such as scaffolding, lifting machinery, electrical and welding appliances, and hand-held power tools ； Handheld and mobile electrical tools should be equipped with leakage protection devices. Any tools or equipment that do not meet the safety requirements for operation shall not be used. 4.13 Reliable power-off measures should be taken for the electrical power supplies on the equipment under maintenance; after confirming that no power is present, a safety warning sign should be placed at the power switch or it should be locked. 4.14 Special personnel should be assigned to inspect the gas protection equipment, fire-fighting equipment, communication devices, lighting equipment, etc., used in maintenance operations, to ensure they are in good condition. 4.15 Inspect ladders, railings, platforms, grating boards, covers, etc. at the maintenance site to ensure safety. 4.16 Repair areas where corrosive media are present should be equipped with a flushing water source for emergency use by personnel, as well as appropriate protective equipment. 4.17 Effective protective measures shall be taken for pits, wells, ditches, holes, etc. present at the maintenance site that may pose a safety risk, warning signs shall be installed, and red warning lights shall be provided at night. 4.18 Items at the maintenance site that pose a risk to safety during maintenance should be removed. 4.19 The fire exits and access routes at the maintenance site should be inspected and cleared to ensure they remain unobstructed. 4.20 Workplaces that require night-time maintenance should be equipped with lighting fixtures that meet the required standards. 4.21 For the radioactive sources involved in the maintenance site, appropriate measures should be taken in advance to keep them in a safe state. 5 Safety requirements during maintenance work 5.1 Personnel involved in maintenance work shall wear protective equipment correctly as required. 5.2 Maintenance workers shall comply with the safety and technical operating procedures for their specific job. 5.3 Maintenance personnel engaged in special operations must hold a special operations permit. 5.4 When multiple types of work are carried out at different levels simultaneously, coordinated planning is required, along with the implementation of appropriate protective measures. 5.5 When carrying out maintenance work involving radioactive materials, it is necessary to inform the relevant operators and maintenance personnel on site to move away, ensure an appropriate safety distance, place clear warning signs in accordance with **relevant regulations, and assign a dedicated person to supervise the operation. 5.6 For night-time maintenance work and maintenance work in adverse weather conditions, a dedicated person must be assigned to provide safety supervision. 5.7 When abnormal conditions occur in the production facility that may pose a threat to the safety of maintenance personnel, the equipment operator shall immediately inform them to stop working and evacuate the work area promptly. Only after the abnormality has been resolved and safety is confirmed as a result of the treatment can the maintenance personnel resume their work. 6 Safety requirements after maintenance 6.1 Safety devices such as covers, grating plates, handrails, railings, and protective shields that were removed due to maintenance work must be restored to their functional state for safe use. 6.2 Tools and equipment used for maintenance, scaffolding, temporary power supplies, temporary lighting fixtures, etc., should be removed from the site in a timely manner. 6.3 The waste materials, debris, trash, oil stains, etc., remaining after the maintenance work is completed must be cleaned up.

1. Safety training for construction workers. Operators must be familiar with the maintenance tasks and procedures, while maintenance personnel need to be aware of the relevant hazards. If there are outsiders present, it is even more necessary to provide proper safety training and monitor safety during the construction process. 2. The relevant equipment and pipelines must be properly isolated. Clear management systems and records must be in place for the installation of valves and blind flanges, in order to facilitate restoration after maintenance. 3. When carrying out maintenance or work by external technicians, those who issue work orders and related safety permits must have a thorough understanding of the construction activities in order to effectively control hazards. 4. Ensure that all safety equipment and fire-fighting equipment are in good and controllable condition. 5. An individual’s personal protective PPE must be complete. 6. The emergency plan must be detailed, and everyone involved in the operation must be aware of it. 7. The relevant personnel and equipment must be coordinated properly to ensure the efficient progress of maintenance work. 8. Environmental protection must be ensured to prevent materials from polluting the environment. 9. Security departments and relevant personnel should conduct regular on-site safety inspections to prevent all unsafe behaviors. 10. Safety warnings related to the on-site work area must be in place, along with adequate warning signs and directional markers. The above are my personal opinions for reference only.

Abstract: Shutdown and maintenance accidents in chemical plants occur frequently. The main reason for this is that operators fail to conduct adequate hazard identification and risk assessment, which leads to mistakes during operations and results in accidents. This article explores the implementation of safety standardization management during maintenance processes, the establishment of standardized safety procedures, the development of risk assessment mechanisms, and the control of risks in such processes. 　　Keywords: safety standardization, maintenance process, hazard identification, risk control. The shutdown and maintenance phase of chemical plants is a period with a high incidence of accidents. Relevant data show that accidents that occur during chemical plant maintenance account for over 75% of all accidents in the chemical industry. Of these, accidents caused by unsafe behaviors of workers make up approximately 88% of maintenance-related accidents, while accidents resulting from unsafe working conditions account for about 10%. The remaining 2% are caused by other various factors. Ultimately, it was because the workers failed to properly identify hazards and assess risks, which led to certain mistakes at work and resulted in the accident. Therefore, how to standardize and strengthen the management of the maintenance process in order to prevent and reduce accidents has become an issue that safety management professionals must address. Safety standardization management involves establishing standardized work processes and operational standards, as well as introducing risk management mechanisms, so that all levels of personnel at every working level must identify and control risks in a timely manner, operate in accordance with these standards, and effectively avoid management and operational errors. Therefore, implementing safety standardization to control risks during maintenance is an effective approach to safe production management. 　　The maintenance of chemical plants is generally divided into the preparation phase, the plant shutdown phase, the maintenance phase, and the restart phase. Conducting risk assessments in line with the characteristics of work at each stage, and formulating and implementing control measures based on the results of hazard identification and risk assessment, is the foundation and core for ensuring the safety of the maintenance process. Among them, the device shutdown phase, maintenance phase, and startup phase are the key areas for risk control. Based on the maintenance plan, identify the equipment and facilities involved in the maintenance tasks, as well as the working environment and activities involved. Apply different risk analysis methods to these equipment and facilities, working environment, and activities in order to identify hazards and control risks. For each piece of equipment, facility, and working environment, the Safety Checklist Method (SCL) is used for analysis. Based on the results of this analysis, a status verification list is prepared to determine whether the equipment, facilities, and working environments meet the required standards. Regarding the various activities involved in the work process, a list of these activities is first created; for each activity, the Job Hazard Analysis (JHA) method is applied. In conjunction with relevant management regulations and requirements, safety measures are established within the maintenance and construction plan, and a system for managing work permits is put in place. Each major step of the work must be checked and confirmed by the workers involved. As each task is completed, a corresponding work permit is filled out. The process of filling out these permits is essentially a way of implementing the relevant management regulations, as well as a means of creating records. At the same time, to ensure that the actual operators are truly aware of the risks associated with the operation process as well as the corresponding control measures, on-site verification prior to the operation is necessary. The entire management process can be carried out according to the following steps: 1 Management during the preparation phase for maintenance work 1.1 Selection of contractors If a company decides to outsource its maintenance tasks, it must first select appropriate contractors. When selecting a contractor, factors such as the contractor’s qualifications, its safety management systems, past safety record, and construction capabilities should be taken into account based on the risks associated with the project. Strict safety and environmental protection requirements should be imposed on the contractor, and a safety management agreement should be signed to clarify the responsibilities and obligations of both parties. Of course, if a company uses only its own maintenance team, this preparation step can be omitted. 　　1.2 Material Preparation 　　Before the maintenance work begins, qualified suppliers are selected based on the materials required for the project. In strict accordance with the regulations governing material procurement, risks during the purchasing process are controlled to ensure that the available materials meet the requirements of the maintenance work. 　　1.3 Formulation of maintenance plans Enterprises should develop maintenance plans, implementing the \"five fixings\" principle, namely fixing the maintenance plan, the maintenance personnel, the safety measures, the quality standards for maintenance, and the schedule for maintenance. Hazard identification and risk assessment are carried out for maintenance operations, effective risk control measures are established, and emergency plans should also be developed for tasks with higher levels of risk. The specific details are as follows: The SCL method is used for hazard identification and risk assessment in tasks such as confirming the conditions prior to shutdown, verifying the safety conditions before delivering process equipment and facilities for maintenance, checking the implementation of control measures before carrying out maintenance work, inspecting and accepting the process equipment and facilities after maintenance for use in production, and conducting safety inspections prior to restart. Based on the results of these identifications and assessments, corresponding safety inspection checklists are prepared. For the shutdown process, maintenance process, and restart process, the operational activities are broken down according to the workflow to create a list of such activities; the JHA method is then used to identify hazards and assess risks for each activity. Based on the results of these identifications and assessments, shutdown plans (including steps to be taken, potential hazards, risk control measures, etc.), various process confirmation forms, and restart plans (including steps to be taken, potential hazards, risk control measures, etc.) are prepared. 　　1.4 Safety training before maintenance work 　Enterprises should provide safety training to the workers of contractors upon their arrival at the site; those who pass the assessment are issued access permits, and records of this safety training are kept. Before entering the work site, the grassroots unit where the site is located shall provide safety training to the workers of the maintenance and construction units (including those from contractors as well as those from the company itself). Work may only commence after they pass the assessment, and the grassroots unit shall keep records of such safety training. The educational content includes: the safety rules and regulations that maintenance workers must abide by; potential unsafe factors at the maintenance site and during the maintenance process, along with corresponding countermeasures; the proper wearing and use of safety equipment and supplies during maintenance work; as well as the maintenance tasks, projects, plans, and safety measures. 　　2 Management during the plant shutdown phase 　　2.1 Formulation of the shutdown plan 　　Although the process specifications contain specific rules regarding plant shutdowns, different operating conditions, as well as the objects and tasks involved in the shutdown maintenance, result in varying requirements for the shutdown procedures. Therefore, a specific parking plan should be developed before parking. Before formulating the plan, it is necessary to list in detail the operational activities involved in the shutdown process. For each of these activities, the JHA method is used to identify hazards and assess risks. The work steps, hazards, potential or possible consequences, existing safety control measures, and recommended corrective controls are compiled into a Job Hazard Analysis (JHA) sheet. Based on the results of this identification and assessment, a shutdown plan is then prepared, including details such as work steps, potential hazards, risk control measures, and the person responsible for approval. This plan is submitted to the relevant authorities for approval, and once approved, it is implemented according to the planned schedule after appropriate training has been provided. 　　2.2 Verification of parking conditions Each key step in the parking process must be verified by a designated person. Before shutting down the unit, the shutdown conditions are checked and verified using a pre-established safety inspection checklist (SCL); only when all requirements are met can the next step of shutdown be carried out, thereby avoiding the risks associated with attempting a shutdown under inadequate conditions. It should be specifically noted that the inspection criteria should be as specific and actionable as possible. 　　2.3 Inspection and confirmation of the conditions for delivering process equipment and facilities for maintenance Once the entire plant has been shut down, the person in charge of the unit where the maintenance work is to be carried out should organize equipment specialists and process engineers to check and confirm that the treatment of process equipment and the installation/removal of blind flanges meet safety requirements. The person in charge of the maintenance project shall also verify this to ensure that all tasks are completed as required. The SCL method should be used to identify hazards and assess risks associated with the condition of the equipment. The results of these identifications and assessments should be translated into a safety condition confirmation form for handover during maintenance; this form should include items to be checked, standards, actual conditions, recommended corrective control measures, completion deadlines, and the person who confirms the details. Before handing the device over to the maintenance contractor for work, complete the confirmation form and address any issues found promptly. 　　3 Management during the equipment maintenance phase 　　3.1 Verification of safety conditions prior to maintenance work 　　Before starting the work, the maintenance contractor must check and confirm its own preparation status to determine whether the conditions for safe execution of the work are met. The inspection items include the construction plan, safety protection plan, safety training, organizational structure, equipment and tools, provision of personal protective equipment, arrangement in the tool room, vehicles, site environment, fire protection facilities, external workers, and environmental protection. Any issues identified during inspections must be addressed promptly; construction work can only begin once all problems have been resolved. 　　3.2 Formulation and implementation of construction plans 　In light of the specific conditions of a maintenance project, the construction unit responsible for the maintenance work must carry out hazard identification and risk assessment when preparing the construction plan, as well as formulate safety management measures for the project. These measures need to have specific details in order to ensure safety during the construction process, rather than merely including general safety requirements. When formulating safety measures, first compile a list of work activities involving all the operations throughout the construction process. Once the list of work activities is completed, the basic tasks involved in the entire construction process become clear. Subsequently, a JHA is conducted for each work activity, resulting in a Job Hazard Analysis form that should include the work steps, hazards, potential or possible consequences, existing safety control measures, and suggested corrective controls. 　　After conducting hazard identification and risk assessment of all construction activities and equipment involved, a construction plan is formulated based on the analysis results, and it is implemented upon approval by the person in charge of the maintenance and construction unit. To ensure that the actual workers are truly aware of the risks associated with the work process as well as the corresponding control measures, the maintenance and construction units should conduct on-site verification prior to starting the work, in order to reduce risks during the project’s construction. 　　3.3 Safety management during construction During the construction process, the maintenance and construction unit shall inspect and verify the construction materials obtained, and manage the various work stages in accordance with the requirements of the construction plan and various regulatory provisions. For high-risk operational activities such as working at heights, working with fire, lifting operations, and scaffolding construction, a risk analysis must be conducted before each operation. Based on the results of this analysis, various work permits are prepared, which are approved following established procedures. Additionally, operators are required to sign to confirm that the required steps have been completed. The unit where the maintenance work is carried out must provide the maintenance contractors with conditions for safe work, assign dedicated personnel to oversee the construction site, and enhance information communication and coordination. The relevant management departments of the enterprise should conduct continuous inspections and supervision at the maintenance construction site, and correct any issues found promptly. 　　3.4 Inspection and delivery for production acceptance after maintenance 　After the maintenance work is completed, the person in charge of the maintenance project should, together with the relevant maintenance staff, check whether there are any items left unaddressed in the maintenance work, as well as whether any tools or materials remain inside the equipment. Together with the equipment operator and process engineer, they should also check the status of the blind flanges according to the requirements of the production process. All safety facilities should return to normal, and the work area must be left in a state of “finished work, no leftover materials, and clean surroundings”. The maintenance and construction unit, in conjunction with the unit to which the equipment belongs, conducts pressure and leak tests on the equipment, adjusts the safety valves, instruments, and interlock devices, and carries out individual and combined tests on the repaired equipment. After all items have been inspected and confirmed to meet the requirements, the acceptance and handover procedures are carried out, and the unit enters the preparation for commissioning phase. 　　4 Management during operation 　　4.1 Inspection and confirmation of operating conditions 　　Once the equipment maintenance work is completed and the project passes the acceptance inspection, it proceeds to the operation phase. Before starting up the device, a check and analysis of the startup conditions are carried out in a manner similar to that done for shutdown conditions. Based on the results of this analysis, a safety checklist for the startup conditions is prepared to verify those conditions. The confirmation form includes items to be checked, standards, actual conditions, recommended corrective control measures, completion time, and the person who confirms it. 　　4.2 Preparation and implementation of the startup plan The startup process is broken down into the various operational tasks involved, using the Job Hazard Analysis (JHA) method to identify hazards and assess risks for each task; a startup plan is then prepared based on the results of this analysis. The driving plan should include specific operational steps and control measures, as well as a list of potential hazards and possible consequences. Train employees who will operate the equipment, and carry out the operation once the equipment is ready for use. A dedicated person must be responsible for verifying each key step in the startup process; the next step can only be carried out after it has been confirmed that the previous step was fully completed to meet the requirements, thereby avoiding the risks associated with attempting to start the system when the conditions are not met. 　　5 Conclusion In accordance with the requirements of safety standardization management, it is necessary to establish a safety management model that combines preventive measures with effective emergency responses. By introducing a risk assessment mechanism and continuously improving the control of operational processes, systematic hazard identification and risk evaluation can be carried out for the four stages of the entire maintenance process. Practical risk control measures should be formulated, standard safety operation procedures established, and oversight of various operational steps strengthened to regulate the behavior of workers. This approach can effectively ensure the smooth progress of maintenance activities and prevent accidents from occurring.

I agree with the third floor’s view; the focus should be on implementing various safety management systems and following the relevant operating procedures.

This post was last edited by lyhh9024 on 2010-3-9 at 23:25. For chemical plant maintenance, a cleaning plan must be developed in advance to thoroughly clean the production equipment and pipelines. Blind flanges should be installed on the relevant equipment and pipelines depending on the areas where welding will take place, and these flanges need to be recorded. Testing should be conducted 30 minutes before welding begins to ensure that all conditions for welding are met.