What You Need to Know About Working in Confined Spaces [Extremely comprehensive]

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What You Need to Know About Working in Confined Spaces. Reproduced from Process Safety Management. On September 29, 2014, the **State Administration of Work Safety issued the ‘Five Provisions on Safe Operations in Confined Spaces’ (Order No. 69), which came into effect as of the date of issuance. 2. “Five Provisions on Safe Operations in Confined Spaces” (Order No. 69): The “Five Musts and Five Prohibitions” are as follows: First, it is mandatory to strictly implement the work approval system; unauthorized entry into confined spaces for work is strictly prohibited ； Second, it is essential to follow the procedure of “ventilate first, then conduct testing, and finally carry out operations”; operations are strictly prohibited if ventilation or testing does not meet the requirements ； Third, personal protective equipment against poisoning and asphyxiation must be provided, safety warning signs must be posted, and operations without proper protective measures are strictly prohibited ； Fourth, safety training must be provided to the workers; it is strictly prohibited for those who have not passed the training to start working ； Fifth, emergency measures must be established, emergency equipment must be available on site, and blind attempts at rescue are strictly prohibited. 3. Site supervisors, monitors, emergency rescue personnel, and workers involved in or performing work in confined spaces (collectively referred to as “the four types of personnel for confined space work”) must undergo specialized safety training related to confined spaces. Special safety training for confined spaces should have dedicated training records, which must be signed by the participants. Persons who have not received specialized safety training and passed the assessment shall not be engaged in confined space management or operations. 4. Teams engaged in work in confined spaces involving flammable and explosive substances, toxic and harmful gases, and low-oxygen environments should conduct a risk awareness training session for such work on a quarterly basis, and promptly improve the relevant work standards. 5. A confined space refers to a space that is enclosed or partially enclosed, isolated from the outside world, has narrow entrances and exits, does not allow workers to remain inside for long periods of time, has poor natural ventilation, and is prone to the accumulation of toxic, harmful, flammable, or explosive substances or to insufficient oxygen levels. Work activities carried out inside confined spaces are referred to as confined space operations. 6. Confined spaces are mainly divided into three categories: enclosed and semi-enclosed equipment, underground structures, and above-ground structures. Facilities that are not used for a long time or areas with poor ventilation, mines, dikes in special situations, and excavation work are considered confined spaces. 7. The “three types of confined spaces” that require special attention refer to those involving flammable and explosive substances ； Confined spaces involving toxic, harmful, or asphyxiating gases or oxygen-deficient environments ； Confined spaces with a risk of drowning or entombment. 8. When using ducted air supply, the forced ventilation intake area should be located away from areas where toxic and harmful gases might be released abnormally. Before supplying air, the medium inside the ducts as well as the air source must be analyzed and verified to ensure that the air source is safe and reliable ； In any confined space requiring ventilation, where no online ventilation equipment is available, dedicated ventilation facilities such as fans and ducts should be installed. 9. When it is necessary to work in a confined space with low oxygen levels, the provisions of the \"Safety Regulations for Work in Low-Oxygen Hazardous Environments\" (GB8958) must be followed, and mechanical ventilation should be employed during such work. 10. To safely isolate a pipeline, a blind flange can be inserted or a section of the pipeline can be removed; water seals or valve closures cannot be used as substitutes for blind flanges or removed pipeline sections. In other words, there are only two ways to achieve a reliable cut-off: one is by installing a blind flange, and the other is by removing a section of pipe. Methods other than this, such as closing valves and using water seals, do not constitute reliable means of isolation. 11. A hypoxic environment refers to an air condition in which the volume percentage of oxygen is below 19.5%. An oxygen-rich environment refers to an air condition in which the volume percentage of oxygen is higher than 23.5%. The maximum allowable concentration of hydrogen sulfide under normal conditions is 10 mg/m3, with a residence time of 8 hours. Operation can continue for an extended period when the CO content does not exceed 24 ppm (30 mg/m3). 12. When working in confined spaces with low oxygen levels or toxic and harmful gases, isolating respiratory protection devices such as air respirators or hose masks should be provided and used. The use of filtering masks is strictly prohibited; when necessary, workers should be equipped with life ropes. 13. When wearing a long-tube respirator, carefully check its airtightness and prevent the ventilation tube from being compressed. The air intake should be placed on the upwind side of fresh air, and a dedicated person should supervise its use. 14. When working in flammable and explosive confined spaces, anti-static work clothing and shoes should be worn, as well as explosion-proof low-voltage lighting fixtures and tools that do not generate sparks. When working in confined spaces where there are corrosive substances such as acids and alkalis, one must wear protective gear including acid-alkali resistant work clothes, work shoes, and gloves. 15. When entering confined spaces containing rotating equipment, it is necessary to proceed with power shutdown procedures, cut off the power supply, and attach warning signs to the switches such as “Personnel are working inside – do not close the switch” and “Start-up prohibited”. Pits, depressions, ditches, or holes in confined spaces, as well as the entrances and exits of passages, should be equipped with protective fences, covers, and warning signs; red warning lights should also be installed at night. 16. Personnel entering confined spaces that are vertical, tubular, cylindrical, or otherwise difficult to rescue, as well as those carrying out inspection and maintenance tasks inside such spaces, must all be equipped with a reliable and secure \"safety rope\" (lifesaving rope), the end of which must be fixed at the entrance to the confined space. This “safety rope” (life rope) shall not replace a safety belt for preventing falls from heights. The supervisor should communicate by using a safety rope tied to the worker. 17. When performing electric welding inside metal equipment or in particularly humid work environments, the level of electrical insulation protection must be enhanced (e.g., by wearing electrically insulating boots and laying down insulating mats). When changing electrodes, one must not lean against conductive objects. Electrical installations used in confined spaces, including power tools, ventilation, lighting equipment, etc., shall be equipped with leakage protection devices. 18. When the confined space was originally a container for storing explosive liquids, gases, or other such substances, an explosion-proof flashlight or an explosion-proof safety lamp with a voltage of no more than 12V should be used; the lamp’s transformer must not be placed inside or on the container. 19. The lighting voltage in confined spaces should be 36V or less. Portable work lights must have insulated handles and metal shields. When working inside metal containers, in humid environments, in narrow containers, or in locations where there is a risk of explosion, the voltage should be 12V or less. 20. Hydrogen sulfide poisoning: Hydrogen sulfide (H2S) is a colorless gas with an odor similar to that of rotten eggs, and it is highly soluble in water ； It is an asphyxiating **gas, and a potent neurotoxin. It is denser than air and tends to accumulate in low-lying areas such as poorly ventilated urban sewage pipes, manholes, septic tanks, and sewage ponds. 21. CO poisoning: CO is a colorless, odorless, non-irritating gas that is flammable, explosive, and toxic. When mixed with air, it forms an explosive mixture, and exposure to open flames or high temperatures can trigger combustion and explosion. Carbon monoxide readily binds to hemoglobin in the blood (rather than oxygen), resulting in tissue hypoxia. 22. Nitrogen is, under normal conditions, a colorless, odorless, and tasteless gas that is generally non-toxic. The excessive amount of nitrogen in the air causes oxygen deficiency and suffocation. When the concentration of inhaled nitrogen is not too high, patients initially experience chest tightness, shortness of breath, and weakness ； Exposure to high concentrations can cause the patient to lose consciousness rapidly and die due to the cessation of breathing and heartbeat. When the oxygen concentration in the air of the workplace is below 19.5%, an air respirator or a long-tube mask must be worn. 23. For confined spaces that are temporarily created due to equipment maintenance or construction work (such as pipes, dikes, pits, etc., that require entry through manholes), a “Notice Board on Hazardous Factors in Confined Spaces” should be installed at the site prior to starting work. This board should clearly indicate the potential hazardous factors in such confined spaces, the safety control measures, as well as the emergency rescue measures (including the emergency rescue equipment and facilities that need to be prepared, as well as the emergency contact numbers). 24. The main hazardous factors in confined spaces include: asphyxiating gases, toxic and harmful gases, oxygen deficiency, flammable and explosive substances, liquids, materials, electric shock, falls, rotating equipment, high/low temperatures, and other hazardous factors. 25. There are 8 aspects to identifying hazards in confined spaces: one is the risk of poisoning or asphyxiation caused by toxic and harmful gases, or oxygen-deficient environments ； Second, there is a risk of fires or explosions caused by flammable gases, liquids, solids, and other combustible and explosive substances ； Third is the risk of drowning caused by an increase in the liquid level or a drop into the liquid storage facility ； Fourth, there is a risk of burial or suffocation caused by the collapse of solids ； Fifth is the risk of entanglement caused by the movement of equipment and facilities ； Sixth is the risk of electric shock caused by humid environments ； Seventh is the risk of falling from a height or being struck by objects falling from above ； Eighth are other hazards such as temperature, noise, and corrosive chemicals. 26. There are three hazardous characteristics of work in confined spaces: First, the working environment is complex ； Second, it poses a high level of danger, and accidents can lead to severe consequences ； Third, it is easy for blind attempts at rescue to lead to an increase in casualties. The main reason for the increase in casualties during work in confined spaces is improper rescue efforts; 50% of those who died in such accidents were rescuers. 27. The toxic and harmful, asphyxiating, and flammable and explosive gases that may be involved in work in confined spaces are as follows: Toxic and harmful, flammable and explosive gases: gas (with the main toxic component being CO), hydrogen sulfide (H2S), methane (biogas, H4C), sulfur dioxide (SO2), ammonia (NH3), hydrogen (H2), oxygen (O2), etc.; Asphyxiating gases: nitrogen (N2), argon (Ar), carbon dioxide (CO2), etc. 28. Based on the potential hazards in confined spaces and the severity of the possible consequences, such spaces should be classified into Grades A, B, C, and D in order to implement hierarchical control and approval processes. (1) Level A: Confined space operations that may result in multiple injuries or deaths of workers ； Approved by the factory leader in charge of production, equipment, and engineering at the unit ； (II) Class B: Confined space operations that may result in the death or serious injury of workers, or relatively major or more severe near-miss accidents ； Operations in confined spaces involving flammable and explosive substances, toxic and harmful gases, asphyxiant gases, or oxygen-deficient environments must be approved by the heads of the units’ production, equipment, and engineering departments; approval for other types of confined space operations may be granted by the supervisors of the respective work areas ； (III) Class C: Confined space work that may cause minor injuries to workers or lead to minor accidents ； Where job standards already exist, they must be strictly followed ； In the absence of operational standards, approval shall be given by the supervisor of the work area where the confined space is located ； (IV) Grade D: The potential hazardous factors in the confined space have been fully identified and effectively controlled. Without any of the following four conditions being met, it is not necessary to subject such areas to confined space management; however, comprehensive and reliable operating standards must be established prior to carrying out the work. 1. Presence of, or potential generation of, toxic and harmful gases ； 2. Presence of or generation of materials that may bury the entrant ； 3. The internal structure may trap entrants inside ； 4. Identified health and safety risks exist. 29. The “Permit for Safe Work in Confined Spaces” shall not be altered; if modification is indeed necessary, it must be approved by the issuer at the place of modification. Each section should be filled out by the respective responsible person; no one else may sign on their behalf. The departments responsible for issuing permits for work in confined spaces, as well as the personnel authorized to approve such permits, shall be identified after being reviewed by the unit’s top management, and then made public for implementation. 30. No one shall enter a confined space for work without proper ventilation and successful testing. The inspection must not be conducted earlier than 30 minutes before the start of the operation. If the work is interrupted for more than 30 minutes, before the workers enter the confined space again to continue working, the area must be ventilated once more, and tests must show satisfactory results before entry is permitted. 31. If it is detected that the ventilation equipment has stopped working, that the oxygen concentration in the confined space is below 19.5% or above 23.5%, or that the concentration of toxic and harmful gases exceeds the **standard values or the limits specified by industry standards, work in the confined space must be stopped immediately. The workers present must be evacuated and counted, and the entrances and exits to the work site should be temporarily sealed off until the ventilation equipment resumes normal operation. 32. The “Four Regulations” for gas detection: First, detect all possible hazardous gases ； Second, insert the detection probe through the ventilation hole ； Third, inspect all areas (top, bottom, irregular shapes) ； Fourth, if dangerous gases or vapors are detected, ventilation and cleaning should be carried out, followed by another test. 33. The test record shall include 10 items: date of measurement, time of measurement, location of measurement, measurement method, measuring instrument, on-site conditions at the time of measurement, number of measurements, measurement results, person who conducted the measurement, and person who recorded it, and it shall be filed after being signed by the tester. 34. The safe displacement of confined spaces containing flammable and explosive gases shall comply with the following requirements: First, inert gases such as nitrogen and carbon dioxide, as well as steam, should be used for cleaning ； Second, before personnel enter or approach the area, it is necessary to ventilate it with fresh air again and continuously monitor the oxygen level in that space. 35. In operations where oxygen levels may change, necessary measurement frequencies or continuous monitoring should be maintained, with monitoring carried out at least every 2 hours. If there are significant changes in the monitoring and analysis results, the monitoring frequency should be increased. 36. Personnel such as on-site supervisors, guardians, workers, and emergency rescue personnel who work in “Category 3” confined spaces must meet the following 3 conditions: First, they must pass an assessment on confined space safety knowledge ； Second, one must be able to use emergency rescue equipment ； Third, it must have on-site emergency rescue capabilities. 37. When working in confined spaces involving flammable and explosive substances, toxic and harmful gases, and oxygen-deficient environments, it is essential to strictly adhere to the principle of \"ventilate first, then test, and finally work\" (the 9-word guideline for working in confined spaces). The monitoring parameters include three concentrations: oxygen concentration, concentration of flammable and explosive substances (flammable gases, explosive dusts), and concentration of toxic and harmful gases. The testing shall comply with the relevant **standards or industry standards. 38. 9-step safety management approach for work in confined spaces: hazard identification before work, safe access, safety isolation, safe ventilation, safety testing, safety protection, safety supervision, safe operation, and safety verification. 39. Before working in a confined space, it is necessary to develop appropriate emergency measures based on safety analysis and assessments of potential emergencies in such spaces. These measures include escape routes and rescue methods for workers in emergency situations, as well as life-saving equipment and fire-fighting devices that should be available on site. 40. Before carrying out work in a confined space, the site supervisor shall organize the safety supervisors, emergency rescue personnel, and workers to refer to the \"Information Board on Hazardous Factors in Confined Spaces\" or the relevant records kept for confined space safety management. They should identify and confirm once again the potential hazardous factors associated with the specific task, work content, and procedures, improve the plan for working in confined spaces, and propose organizational, technical, engineering, and emergency measures to eliminate or control these hazards. 41. Before working in a confined space, it is necessary to clarify the emergency rescue personnel and their responsibilities, as well as the methods for emergency response and information communication, and inform all persons entering the confined space about this. 42. Before entering a confined space for work, inert gases such as nitrogen should be used for displacement, steam should be employed for cleaning, and forced ventilation should be applied in order to eliminate or reduce toxic and harmful gases present in the confined space ； The use of pure oxygen for ventilation is prohibited, as is the introduction of oxygen or oxygen-enriched air into confined spaces. Oxygen poisoning and combustion explosions can occur in an oxygen-rich environment. 43. The work plan must be approved in accordance with established procedures; the person in charge of the site, supervisors, emergency response personnel, and workers must be identified. The workers should be informed about the plan for working in confined spaces, as well as any potential dangerous or harmful factors present at the work site and the measures taken to address them. The on-site supervisor shall ensure that the workers prepare for the work in accordance with the plan. 44. For all work in confined spaces, dedicated (or part-time) safety supervisors must be assigned; for Class A and Class B confined space operations, dedicated supervisors are required ； The supervisor should be an experienced person who is familiar with the environment and processes in the work area, aware of the potential hazards and their impact on the workers, and knowledgeable in first aid. Have received specialized safety training for confined spaces and passed the assessment. 45. During work in confined spaces, the safety supervisor must not leave the work site and must maintain continuous contact with the workers. Before workers enter confined spaces and during the operation, the supervisor conducts inspections and supervision regarding aspects such as the compliance of work permit procedures, the implementation of safety measures, the testing for toxic and harmful gases as well as oxygen levels, the procedures for turning equipment on and off and the installation of warning signs, the proper isolation or shutdown of pipelines carrying energy sources, power supplies, or toxic and harmful gases leading to the work site, the safety of the surrounding environment and ventilation conditions, the identification and correction of violations and potential hazards, as well as the availability of emergency rescue facilities. 46. When working in confined spaces, reliable separation measures must be taken to isolate the facilities and equipment that could pose a threat to safety, as well as the areas containing toxic or harmful substances, from the work area. 47. For the “Category 3” confined spaces that are temporarily created as a result of non-routine activities such as maintenance and construction, it is necessary to identify the on-site supervisor, safety officers, workers, and emergency response personnel at the stage of formulating the construction plan. Relevant personnel should receive specialized safety training regarding confined spaces through written safety instructions provided on site. 48. During operations in confined spaces, every effort should be made to utilize openings, holes, and doors in equipment and facilities for natural ventilation. When natural ventilation cannot meet safety requirements, mechanical forced ventilation must be employed. In special circumstances, workers must wear safe and reliable respirators. 49. A ‘Safety Permit for Work in Confined Spaces’ is required for work carried out in such spaces; a ‘High-Height Safety Work Permit’ is necessary for work at heights within confined spaces, and a ‘Firework Safety Permit’ is needed when welding or similar operations are to be performed. 50. Before working in a confined space, count the personnel and tools used. After the work is completed, the person in charge of the work site and the supervisors should urge, guide, and oversee the workers to clean up the site and count the tools and equipment; only after confirming that everything is in order should they leave the work site. 51. The “Ten Prohibitions” for working in confined spaces: First, it is prohibited to enter confined spaces for work without approval ； Second, work shall not proceed without safety and reliability assessment and approval of the work plan ； Third, work is not permitted in confined spaces involving gases and oxygen-deficient environments without ventilation and continuous monitoring measures in place ； Fourth, operations are not permitted unless workers have been informed about hazardous and harmful factors ； Fifth, work is not permitted without a dedicated person verifying the safety measures on site ； Sixth, work is not permitted if safety supervisors are not present on site ； Seventh, personnel who have not undergone specialized training and passed the assessment are not permitted to perform any tasks ； Eighth, operations are not permitted unless all residues have been completely removed ； Nine: Operations are not permitted if emergency rescue measures and equipment are not properly prepared ； Tenth, if the personnel and tools/equipment cannot be accounted for accurately, the entrances and exits must not be sealed off. 52. The “Ten Musts” for working in confined spaces: First, it is necessary to obtain safety permit approval ； Second, reliable separation (isolation) and replacement measures must be taken ； Third, it is essential to adhere to the principle of ventilating first, then conducting tests, and finally carrying out operations ； Fourth, it is necessary to maintain the normal and continuous operation of ventilation facilities ； Fifth, it is mandatory to wear a gas monitor ； Sixth, communication tools must be provided; a safety supervisor should be appointed to maintain contact ； Seventh, operations must be carried out in accordance with operating standards and individual safety technical measures ； Eighth, for confined spaces where work is performed at heights, escape and emergency rescue routes must be provided ； Nine is that it is necessary to keep the entrances and exits unobstructed ； Tenth, in case of any abnormal situation, evacuation must be carried out immediately. 53. Rules for life support during operations in gas-related confined spaces: First, ensure reliable isolation of the gas (install blind flanges or remove a section of piping, close valves, and apply safety locks). Second, purge and displacement are carried out before the operation, and the monitoring shows satisfactory results. Third is continuous ventilation, as well as periodic or continuous monitoring during the operation. 54. Life support rules for work in confined spaces involving material burial: First, the source of the materials must be reliably isolated (separated) or thoroughly cleared. Secondly, the incoming material system is equipped with power-off locks (the local switch is set to the zero position and a lock is placed), and emergency devices such as the belt system emergency pull cords are in a self-locking state. Third, operators must use safety ropes or harnesses, which should be securely fastened outside the confined space. It is strictly prohibited to stand under material storage facilities such as hoppers and silos while poking at the materials. 55. Life safety rules for working in confined spaces containing flammable and explosive materials: First, such materials must be completely removed, and it is not allowed to store them around the work area. Second, ensure continuous ventilation and monitoring during the operation, or fill with water if necessary. 56. Life support rules for work in confined spaces involving drowning hazards: First, ensure the liquid source is reliably cut off (close valves, install physical barriers). Second, the workers must use safety belts or safety ropes and be securely fastened outside the confined space. Third, protective clothing should be used in acidic environments. 57. Life safety rules for work in confined spaces involving mechanical equipment: First, the equipment and facilities must be powered off and tagged, with a clear disconnect point; industrial safety locks should be used when necessary ； Second, implement hardware measures to prevent the rotation of equipment and facilities ； Third, the entrances and exits must not be sealed until all workers have evacuated from the work site. 58. Five common misconceptions during work in confined spaces: First, assuming that since no hazards can be smelled or seen, it’s safe to enter ； Second, it’s just a matter of sticking the head in to have a look; there’s no real intention of entering ； Third, go in and take a look quickly ； Fourth, everything has been checked and there are no issues; testing equipment is not necessary ； Fifth, in the event of an emergency, one can hold their breath and escape. 59. After workers in confined spaces are exposed to danger, relevant personnel on site must immediately call for help; blind rescue efforts are prohibited. When carrying out rescue operations, emergency responders must take proper protective measures and wear necessary breathing equipment and rescue gear. 60. Requirements for emergency equipment in confined spaces: Before carrying out work in confined spaces, emergency responders should be equipped with isolated breathing protection devices such as positive-pressure air respirators with full-face masks or long-tube masks, emergency communication and alarm devices, on-site rapid testing equipment, high-power forced ventilation equipment, emergency lighting equipment, safety ropes or lifelines, and safety ladders. 61. 8 measures to take in case of an emergency during work in confined spaces: First, call for help or alert the authorities ； Second, wait for help before entering ； Third, turn on the ventilation equipment while waiting ； Fourth, evacuate the injured ； Fifth is artificial ventilation ； Sixth, use rescue equipment as much as possible ； Seventh is to organize medical rescue ； Eighth, isolate this area until the cause is identified. 62. Emergency center phone number: 120 ； Fire emergency number: 119. 63. When multiple contractors are involved in the same limited space, the departments responsible for managing external services of each unit shall designate a specific person to uniformly coordinate and manage the contractors’ work related to work safety. Work in confined spaces is a subcontracted task, and both the general contractor and the subcontractor must attend the written safety briefing held on-site by the entity where the confined space is located. 64. Contractors working in “Category 3” confined spaces or in Class A confined spaces must be individuals who have worked at the respective units for at least 3 months. 65. The “four types of personnel” involved in the management and operation of confined spaces (site supervisors, supervisors on site, emergency rescue personnel, and workers) must be able to use correctly monitoring instruments such as C0 detectors, oxygen level analyzers, air respirators, and fire extinguishers, as well as emergency rescue equipment. 66. Contractors carrying out work in confined spaces (including site supervisors, guardians, emergency rescue personnel, and workers) must be individuals who have had at least 6 months of work experience.