Operating procedures for containers and equipment

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Due to the flammable, explosive, harmful, and toxic nature of chemical production, it is necessary to identify potential hazards based on the operating conditions before entering containers and equipment. It is also important to raise awareness of self-protection, conduct safety assessments in advance, develop measures to prevent accidents, and implement these measures in the construction plans. Today, the editor shares with you eight essential things to know when working with containers and devices – see if you can meet them all! These guidelines can save your life at critical moments! What are containers and equipment? What is referred to here are containers and equipment; in chemical production, various towers, vessels, boxes, cabinets, kettles, tanks, troughs, furnaces, pipes, wells, ditches, pools, hoppers, silos, as well as larger mechanical devices that may enter such spaces, along with other poorly ventilated confined areas, are all collectively termed container equipment. Dangers of working inside containers: 1. There is a risk that harmful and toxic substances from connected containers or pipelines could mix and cause harm, and there is also a possibility that harmful and toxic elements from outside the container could enter it, making it difficult for those working inside to anticipate and avoid such hazards. 2. Poor ventilation within the container prevents harmful substances such as toxins from spreading easily. Moreover, during operation, harmful and toxic residues may gradually be released, increasing the amount of toxic or flammable materials while simultaneously reducing oxygen levels, thereby raising the risk. 3. Poor lighting can lead to accidental operations. 4. The space inside the container is limited, increasing the risk of mechanical injuries and object strike accidents. 5. When performing maintenance in tall containers, the large height difference between components increases the risk of falls ； The combustible components inside the device (such as grills, scaffolding, packaging materials, etc.) are highly flammable and can cause fires quickly. 6. It is difficult to carry out rescue in case of an accident inside the container. 7. The temperature inside the container is high, the operator’s body temperature is elevated, the workload is heavy, respiration and blood circulation speed up, resulting in an increased intake of toxins. It has been determined that the amount of air a human breathes is related to the level of physical activity; the amount of air required when at rest is eight times greater than that needed when running. High temperatures accelerate the evaporation of residues inside the container, increasing the amount of toxins that reach the human body and making it easier to suffer from poisoning. 8. High humidity inside the container. The remaining liquid in the container and sweat from the operators increase the humidity inside it, and as humidity rises, so does the risk. The reason is: it increases the solubility of the toxin in the human body, thereby increasing its absorption. Some chemicals, such as cyanide, produce highly toxic hydrogen cyanide gas when exposed to moisture ； Some substances with low toxicity can become more toxic when exposed to moisture. Higher humidity reduces human resistance, increasing the risk of electric shock. Because in a dry environment, the human body’s resistance can reach 1000–1500 ohms, while in a humid environment it can drop to 600–800 ohms. Therefore, the voltage of portable lights should generally not exceed 36 volts; in humid environments as well as inside metal containers such as towers and tanks, it should not exceed 12 volts. The “eight musts” for working inside containers and equipment: Given the many dangers associated with working inside containers, which greatly increase the likelihood of accidents, it is essential to follow the “eight musts” when entering such containers or equipment to carry out work: First, it is necessary to apply for permission and obtain approval ； II. Safety isolation must be implemented ； III. The power supply must be cut off, and safety lighting must be used ； IV. Replacement and ventilation are necessary ； V. Safety analysis must be conducted within the specified time frame ； VI. Required protective equipment must be worn ； VII. Someone must be outside the device to provide supervision and stay at their post ； VIII. There must be backup measures for emergency rescue. I. It is necessary to apply for a permit and obtain approval. A chemical production plant is a production system composed of various equipment and pipelines. During operation, the equipment and pipelines in such systems are subject to continuous changes, including chemical corrosion, erosion by the medium, stress corrosion and fatigue under alternating loads, wear, deposition, scaling, adhesion of materials to the walls, loosening of internal components, and peeling of linings. Changes in some of the aforementioned items will lead to a deterioration of the control parameters, affecting safe operation and resulting in a decline in production; to a certain extent, it becomes necessary to shut down the system for cleaning, maintenance, or renovation. Due to the dangers associated with working inside equipment and pipelines in chemical production, it is necessary to strengthen the control and management of operations carried out inside containers and equipment. Such operations should be conducted in an organized and supervised manner, with a permit system in place; random entry into containers and equipment is not allowed in order to prevent accidents. When entry is necessary, an application must be submitted by the project leader, who will then review and approve it. Its purpose is to coordinate work schedules, review additional safety measures, and clarify the responsibilities of personnel at all levels and in all categories. Leadership approval and signature are essentially a form of confirmation system that ensures proper management, prevents accidents, and stops cases of failing to obtain necessary permits or acting carelessly. Leadership approval should avoid formalism, and responsibilities must be clearly defined. In daily work involving entry into containers and equipment, there are countless cases in which accidents occur as a result of operators lacking knowledge of safety procedures or being careless, or failing to go through the necessary application, licensing, and approval processes before starting work... Applying for licenses and going through the relevant approvals helps to develop proper safety measures, clarify responsibilities among personnel, and ensure that these measures are actually implemented. Thoroughly handling and approving permits is the first and very important step in strengthening safety measures for work inside containers and equipment. It helps prevent chaos caused by unregulated operations and reduces the occurrence of accidents. Even in cases of emergency repairs, approval procedures must still be followed. In emergency situations involving accident rescue, the on-duty safety officer must ensure that the safety measures for entering the container are properly implemented. II. Safety isolation is necessary. Safety isolation is a critical measure for working inside containers and equipment. It has two meanings: one is to define the scope covered by this task. Work performed inside containers or equipment is regarded in management terms as a separate project, which is organized and carried out by a project leader. The contents and scope of the project must be clearly defined. Isolate the equipment and pipelines outside the scope of this task to create a closed construction system. At the same time, the responsibility area was also defined. Second, it effectively prevents toxic and harmful substances in equipment and pipelines outside the system from intermingling with and causing harm to this system. Therefore, safety isolation must be taken seriously, and the methods must be reliable. First, thoroughly inspect all devices and pipelines outside the system to ensure nothing is overlooked; isolate them all from the system, leaving no even the smallest pipelines unaddressed. Secondly, isolation is achieved by installing blind flanges as per specifications, or by removing a section of pipeline and then blocking it. It is absolutely forbidden to use closing valves and adding water seals as isolation methods, as many accidents have proven that they are unreliable. To ensure the safety and reliability of isolation, a plan can be formulated first, a blind flange diagram drawn up to determine the locations and responsible personnel; the project leader shall oversee the process in accordance with the established sequence and schedule, and no one is allowed to give instructions or carry out operations without authorization. Note: Before adding a blind flange or removing a section of pipe, the pressure must be released and all material drained first. The plug mesh plate should be handled in accordance with safety technical regulations; if it contains highly toxic substances, they must first be replaced before the flanged pipes can be removed. Design Institute Network #Manufacturing##Pressure Vessels# What are the main manufacturing steps for pressure vessels? Video Account 3: It is necessary to cut off the power supply and use safe lighting. Before cleaning or maintaining any power-related equipment, the power source must first be disconnected. Entering containers or equipment results in a confined working space; if there are moving parts, working among these internal components without shutting off the power supply can very easily lead to personal injury accidents. There are many lessons to be learned in this regard, such as being ground to death inside the ball mill after entering it ； Got strangled inside the mixer and binder. The cause of such accidents is that some managers and operators lack a clear understanding of what it means to cut off the power supply, or they are reluctant to go through the extra effort; some mistake the shutdown button for a means to cut off the power. As a result, when there are errors in operation, the machinery starts running again and injures the maintenance staff. Cutting off the power source means turning off the power switch and locking it with a sign, or removing the fuse protection and having it kept by the maintenance personnel. By taking the above measures, even in the event of a mistake, the machine will not start, thereby achieving intrinsical safety. There are also components driven by material flows (such as gases, liquids, etc.), for which not only must the valves be closed, but blind plates (including on the pipes) must also be installed to prevent accidental operations. Since the container is a closed space, even if access hatches are opened, the lighting inside the container is not sufficient to meet the requirements of the work; therefore, lighting equipment is generally necessary when working inside the container. When using lighting fixtures inside a container, it is inevitable that the fixtures may collide with objects inside the container and get damaged; moreover, it is also inevitable that friction and compression may occur when pulling the power cord, thereby damaging its insulation layer. Therefore, when working inside a container, the likelihood of electric shock when using lighting fixtures is much higher than outside the container. To prevent electric shock accidents, safe lighting must be used for working inside containers. When wires are inserted into a container, measures must be taken from the opening of the container to ensure no friction occurs and that they do not come into contact with sharp objects or materials, thereby preventing damage. The safe voltage for lighting fixtures inside metal containers is 12 volts. Explosion-proof fixtures should be used when there are flammable materials inside the container; if necessary, the fixtures can be placed outside the container and used to illuminate its interior. Do not, for the sake of convenience, use other lamps in situations where safety lamps should be used; this is very dangerous. IV. Purging and ventilation are mandatory. When personnel need to enter containers or equipment to perform work, purging must be carried out from the perspective of preventing fires, explosions, or poisoning. Only after sampling and analysis confirm that the conditions are safe is entry permitted. Given that chemical production involves numerous flammable, explosive, toxic, and highly corrosive materials, and the process gases are complex, working inside equipment or containers without proper purging and ventilation can easily lead to fires, explosions, poisoning, and personal injuries. To ensure the safety of personnel entering containers and equipment, ventilation must be carried out prior to entry, and ventilation should also be provided once inside. Replacement involves using a safe medium to substitute the flammable or toxic and harmful substances inside a container, thereby ensuring that the container and equipment meet safety requirements. How to substitute? The medium used for substitution should be determined based on the properties of the substance being substituted; no adverse reactions should occur when the two are mixed. If flammable gases are present inside the container, they must first be replaced with non-flammable substances such as water, steam, nitrogen, carbon dioxide, or flue gas. Only after meeting safety requirements can air be used to replace these substances before entry is permitted. If there are residues in the container that are difficult to remove by conventional methods, an appropriate cleaning solution should be used, or steam, hot water, or purging should be applied to decompose them. To ensure thorough displacement without any dead corners, a displacement plan should be developed before the process begins, and a flowchart of the displacement procedure should be created. It is particularly important to note that, due to process requirements, certain equipment designs may create dead corners; in such cases, gas displacement should be used for the final displacement step, as in the case of bubble columns and shell-and-tube heat exchangers. Under the operating pressure of the equipment and within the safe oxygen content range, the staged pressurization displacement method can be used. The outlet selected for displacement must not only ensure thorough displacement but also avoid creating an unsafe working environment around the outlet. The selection of replacement media and methods must ensure safety and reliability as well as economic Rationality; neither aspect should be neglected. Working inside containers and equipment involves poor air circulation, limited space, and crowded conditions. To prevent accidents, proper ventilation is necessary when working inside the device; mechanical ventilation can be used if required. But remember not to use oxygen or oxygen-enriched gases for displacement and ventilation, as this can easily lead to accidents. Replacement and ventilation are important measures to ensure safe operations inside containers and equipment. It is essential to attach great importance to this in terms of mindset and to implement it properly in operations; under no circumstances should there be any violations of regulations or reckless actions. Image 5: Safety analysis must be conducted in accordance with the specified time requirements. (1) Standards for analysis: 1. The analysis of the concentration of flammable gases in the air shall comply with the provisions of Article 106 of the \"Safety Management System for Chemical Enterprises\" as well as the requirements regarding gas analysis set out in the \"Six Prohibitions\" for hot work. 2. The oxygen level is 19–22%. 3. The content of toxic substances shall comply with the provisions of Article 32 of TJ36—39, \"Hygienic Standards for the Design of Chemical Enterprises\". When multiple poisons are present in a container, attention must be paid to their synergistic effects. When carbon monoxide is present together with hydrogen sulfide or carbon monoxide together with nitrogen oxides, an additive and a multiplicative effect occurs. The standard for the combined sampling analysis of multiple toxins follows the relationship: C1/M1 + C2/M2 + …… Cn/Mn ≤ 1. Here, C1, C2, …… Cn represent the actual concentrations of each substance (in mg/m3), while M1, M2, …… Mn represent the maximum allowable concentrations for each substance (in mg/m3). For example, the maximum allowable concentration of carbon monoxide is 30 mg/m3 ； The maximum allowable concentration of hydrogen sulfide is 10 mg/m3. And in actual measurements inside the container, the carbon monoxide level was 20 mg/m3 ； Hydrogen sulfide 6mg/m3. Calculating 20/30 + 6/10 gives 0.67 + 0.6 = 1.27. This shows that although CO and H2S are each within acceptable limits, their combined effect after mixing exceeds the permissible threshold. The safety conditions for working inside the container are not met. When taking samples for analysis, pay attention to representativeness to reflect the highest concentration of toxic substances inside the container. The sampler and project supervisor must go to the site in person to take samples from the most representative locations, based on the specific conditions inside the equipment and the properties of the medium. When sampling inside a container, gas samples should generally be taken from the upper, middle, and lower sections. For gases that are lighter than air, the sampling location should be at the upper and top parts of the container ； For gases that are heavier than air, the sampling location should be at the lower part or bottom of the container. (II) Timing and requirements for analysis: 1. After the container has been cleaned and purged, sampling and analysis must be carried out immediately. Only once the safety requirements are met can work be done inside the container; such work should be completed within 30 minutes. If this time limit is exceeded, sampling and analysis must be repeated. 2. Even after the container has been cleaned, replaced, and found to meet the requirements through analysis, during operation, toxic substances may continue to be released from deposits inside the container and adherences on its walls due to temperature changes and activities such as removing rust, which could render what were originally qualified conditions non-compliant. Therefore, during the operation, tests should be conducted at least every 30 minutes, with a maximum interval of 2 hours; if the limits are exceeded, the operation must be stopped immediately and personnel evacuated promptly. At this point, it is necessary to actively identify the causes and eliminate potential hazards; only after re-analysis confirms that everything is satisfactory can work be resumed inside the container. 3. Where conditions permit, reliable and calibrated gas detectors, explosion detectors, and alarm devices can be used to monitor the working environment inside the containers at any time, allowing for prompt action in case of any changes. Analysis is a step that must be carried out before entering a container; it is an important means of verifying whether the conditions for safe operation are met inside the container. Working inside a container without conducting analysis, or without analyzing it as required or within the specified time frame, is highly arbitrary and dangerous; facts have shown that this approach is not advisable. Relying on unscientific methods such as simply sniffing is unreliable and should be abolished. VI. It is necessary to wear the required protective equipment. Protective equipment represents the final line of defense that must be employed when safety measures related to processes, equipment, and the working environment are in place, yet it still cannot guarantee 100% protection for workers from harm. As a precaution, appropriate protective equipment or tools must be worn for all general labor tasks. It is particularly important to wear protective equipment in containers and equipment where the working space is limited, the conditions are complex, there are many risk factors, and situations change frequently. This is because objects inside the container can cause accidents such as impact injuries, mechanical injuries, falls from heights, chemical burns, and poisoning. At the same time, there are also issues such as dead corners, deposits, and attachments that make it impossible to eliminate them 100%, as well as human negligence and unforeseeable factors. Therefore, workers entering the container must wear the prescribed protective equipment to prevent accidents. How to wear protective equipment? Based on the working conditions inside the container and the potential hazards, protective equipment such as safety helmets, gloves, masks (gas masks, air (oxygen) respirators), eye protection, protective work clothing, safety belts, and explosion-proof tools should be selected to safeguard the physical safety of workers. In actual work, there are many cases of accidents occurring due to the failure to wear protective equipment as required. It is evident that wearing protective equipment is an essential safety measure for workers. VII. Someone must be stationed outside the equipment for supervision and to remain at their post. Working inside containers or equipment involves many risk factors, complex and changing conditions, a high likelihood of accidents, difficulties in entering and exiting the equipment, poor communication between the inside and outside, difficulty in detecting accidents once they occur, and challenges in providing rescue. Assign a dedicated person to monitor the operations inside the equipment from outside, so as to promptly detect unsafe conditions and provide rapid assistance. Appointing a supervisor is an important organizational measure to prevent accidents during operations in containers and equipment and to carry out emergency rescue. Guardians are required to have extensive practical experience and a strong physique, and must earnestly fulfill the following responsibilities: 1. Before starting work, guardians shall carry out the following inspections. Is there a permit for entering containers and equipment for work, which has been applied for and approved? Check whether the safety measures specified on the certificate are complete and have been properly implemented. Check whether the personnel entering the container are sick or have a weak constitution, and prevent those under supervision from entering the container to work while sick. Find out whether the personnel entering the container are clear about their tasks and have a well-defined division of responsibilities, especially the project leader and the contacts inside and outside the container. Check whether the protective equipment used in the inspection area is complete and meets the requirements, and whether safety facilities such as scaffolds, ladders, platform railings, and inspection instruments are up to standard. 2. After conducting an inspection, the guardian shall submit suggestions for improvement regarding hazardous operations for which safety measures have not been implemented or are inadequate. If no improvement is seen despite such requests, the person should be denied participation in guardianship duties, and the matter should be reported to the department head. 3. The guardian and the person under guardianship should agree on contact methods and signals. Otherwise, entry into the container for work is not permitted. 4. The guardian has the right to supervise the ward’s compliance with safety measure requirements. If any illegal operations are detected, they must be ordered to stop working immediately. 5. Guardians must be aware that it is strictly prohibited to use electrical equipment such as cranes and winches as tools for lifting workers. Because when a power outage occurs, the workers are unable to evacuate from the container. 6. The guardian must pay attention to their own safety, and the environment at the supervision location must meet safety requirements. At the same time, preparations for handling accidents must be made; personnel must not participate in construction operations, nor perform any tasks that could interfere with supervision. They must absolutely not leave their supervisory posts. 7. When working inside the container for an extended period, both the workers and supervisors should work in shifts, with strict handover procedures in place. Entering containers or equipment to work, without a supervisor present or with a supervisor who fails to stay at their post, has claimed many workers’ lives. During the course of carrying out their duties, some supervisors encounter urgent matters or are called away to handle other tasks, which results in delayed rescue efforts for those inside the device, or causes equipment damage due to improper operations. The absence of a guardian, the guardian’s failure to fulfill their responsibilities, or the guardian’s departure to attend to other matters can all lead to workplace accidents inside the equipment, delay rescue efforts, increase the severity of the accidents, and render it impossible to prevent accidents that could have been avoided or to recover losses that could have been saved. Image 8: Backup measures for emergency response are necessary. Having ready backup measures for emergency response involves the material and organizational preparations needed to carry out urgent rescue operations in the event of an accident while working inside containers or equipment. Now, when workers inside a container are in danger, supervisors and those around them will actively participate in the rescue efforts. However, due to the lack of proper backup measures for such rescues, actions are taken recklessly, leading to chaos at the accident site. Rescue workers may enter the container in violation of safety rules, which can result in tragic outcomes such as one person being poisoned and multiple others dying. Accidents often escalate because the supervisors are at a loss when faced with certain situations. Whenever anyone takes on the task of external monitoring, they must clearly anticipate potential dangers and determine the appropriate rescue methods as well as the necessary supplies. First of all, one needs to have a set of protective equipment that allows entry into the container for rescue purposes, such as gas masks or masks with long air supply tubes, as well as oxygen respirators. Secondly, determine how to rescue the people inside the container in case of danger: should they be rescued from above or below? In cases where rescue is performed from above, regardless of whether there is any danger or not, a safety harness must be worn; the rope should be held by a supervisor. There must also be a metal ladder extending from the working surface to the container opening ； If rescue is facilitated using such devices, and the methods vary, then the preparation work will also differ. Furthermore, the rescue methods for poisoning and fires are clearly different, as are the preparations required. In the event of danger, the methods for guardians to report and the rescue measures must be predetermined in advance; this is the organizational preparation for carrying out rescues. Emergency backup measures for working inside containers and equipment are often overlooked; there have been too many lessons learned in this regard... Therefore, supervisors and project leaders must pay close attention to this issue. While assigning someone to oversee the work, it is also necessary to implement appropriate rescue methods and measures so that in the event of an accident, help can be provided promptly to minimize losses.