Safety technical measures for hot work in chemical

2022-05-19
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Safety technical measures for hot work in chemical enterprises

1. Disassembly operation

remove the equipment, pipelines and accessories that can be disassembled and removed from the fire prohibition area that need hot work from the main body, take them to a safe place for hot work, and then install them back to the original place after hot work. This is a safe and reliable hot work method, but it should be noted that if there are flammable and explosive materials, dirt or residues in the disassembled equipment, pipelines and their accessories, they should still be cleaned as required

2. Isolation cover

the equipment, pipelines and their accessories to be hot work and the associated operating system shall be effectively isolated, such as adding blind plates, sealing heads or removing a section of pipes on the pipeline, so as to isolate flammable and explosive materials and gases from entering the hot work point. Be careful not to replace isolation with simple valve closing and water sealing methods. At the same time, pay attention to whether inflammable and explosive gases are generated in the production process of surrounding posts, especially in the upwind. If so, fire shall be prohibited or production shall be stopped. Before hot work, cover the tank, pot and tank mouth of the equipment to prevent electric sparks from splashing in; Or surrounding the blasting operation area with incombustible materials to control spark splashing. Consideration should be given to covering, and all places where sparks can splash should be covered, including sewage ditches and manhole heads that are easy to be ignored

3. Site cleaning

before hot work, the flammable and explosive materials under and around the hot work point shall be transferred to a safe place, and the site shall be cleaned. All places where the electric spark may reach shall be cleaned, especially for high-altitude operation. The electric spark flutters with the wind or splashes again when touching the object, and the splash point is difficult to determine. In this case, the site should exchange with customers while making after-sales effectiveness. The following common problems should be considered very carefully. If inflammables can be transferred, they should be transferred as far as possible. If they cannot be transferred, they should be tightly covered with non combustible materials, and a special person should be appointed to guard them. The ground should be cleaned, and the greasy equipment or ground should be wiped and washed

4. Cleaning and replacement

all containers, equipment, tanks, pipelines and other production and storage devices containing (used) dangerous chemicals must be cleaned and replaced before hot work. Cleaning and replacement methods mainly include the following:

A) clean water replacement. It can be applied to water or media easy to be washed by water. It can be cleaned and replaced with clean water once or for many times

b) steam replacement. Generally, materials and media that are difficult to wash with clean water can be washed with steam, such as cold solidification, caking or oily materials, residues, dirt, etc

C) air replacement. Replace the combustible gas with blower, exhaust fan or other air replacement equipment

d) inert gas replacement. If necessary, nitrogen, carbon dioxide and other inert gases can also be used for replacement

5. Analysis and detection

after replacement, hot work can be carried out only after passing the test and analysis. The detection and analysis shall be accurate and timely, and the sampling shall be representative. When the flammable gas is heavier than air, the lower part shall be taken. When flammable gas is lighter than air, its upper part shall be taken. The time after cleaning and replacement shall not be stopped for too long, generally not more than half an hour. If the time is too long, sampling and analysis shall be carried out in time, and those exceeding the standard shall be replaced again

6. Inspection and confirmation

inspection and confirmation are generally attended by the person in charge of the hot work unit, the person on duty, the person in charge of the hot work project, the hot work executor and the safety officer. While checking whether the on-site cleaning, isolation, covering, cleaning and replacement are carried out according to the regulations, it should also check:

A) whether the covers and holes that can be opened by the hot work equipment have been opened. Hot work on sealed equipment, pipes and containers is prohibited

b) whether the hot work tools meet the safety requirements. The tools for welding operation shall meet the quality standards, the welding torch and control valve shall be tight and reliable, and the oxygen pressure reducer shall be sensitive and effective; The electric welding machine shall be equipped with an independent power switch; The oxygen and acetylene gas hoses shall be firmly connected without damage and air leakage; The secondary coil and shell of the electric welding machine must be properly grounded (connected to neutral) for protection, and the welding tools must be well insulated

c) whether the corresponding rescue backup measures have been taken to facilitate the majority of users who are too far away to see the machine. For example, when working in anoxic and toxic environment, there are gas masks, air respirators (oxygen respirators), safety belts (ropes), ladders and other life-saving equipment. When working in flammable and explosive environment, fire extinguishers, water hoses and other fire-fighting equipment shall be provided. When working in acid-base and other corrosive environments, there is a large amount of clean water. In addition, corresponding first-aid supplies shall be prepared for standby in case of emergency

7. Apply for the hot work permit

after checking and confirming that all preparations are correct, apply for the hot work safety permit. If you work in the tank or pot, you should also apply for the safe work permit in the equipment

a hot work permit can only be used within the specified scope of a hot work site, and it is not allowed to transfer, alter, use in other places or expand the scope of use. The validity period of hot work permit is generally 24 hours, and it shall be handled again if it exceeds the time

8. Assign a special person to supervise the fire

all units or units of hot work shall appoint personnel with strong heart, hot work experience, familiar with the site situation and mastering certain fire-fighting technology as the fire supervisor to be responsible for the supervision of the hot work site and extinguish the sparks splashed on the hot work site at any time. If the hot work is found to be inconsistent with the specification, it shall be corrected. If combustible gas or other unsafe factors are found, it shall immediately notify the hot work executor to stop the hot work, And timely contact relevant personnel to take corresponding measures. Fire supervisors must stick to their posts and are not allowed to leave their posts. They are not allowed to optimize and upgrade and build four major refining and chemical bases in Maozhan, Zhenhai, Shanghai and Nanjing. In case of hot work in places with special hazards, the fire supervisor shall be the safety officer

9. Each department shall take its own responsibility

the hot work unit shall be responsible for site cleaning, isolation and covering, cleaning and replacement and relevant preventive measures that should be implemented before hot work; The hot work Executor shall be responsible for the safety performance of hot work tools, the quality of tools and the operation according to regulations; The person in charge of the hot work unit and the person in charge of the hot work project shall be responsible for the inspection and confirmation of whether the hot work preparation is in place and whether the corresponding preventive measures are implemented; The hot work executor and fire supervisor shall be responsible for site cleaning after hot work; The safety officer is responsible for supervising the safe operation during hot work; The approver of the hot work permit is responsible for the safety of the whole hot work

10. Other matters

A) operators must correctly wear labor protection articles according to the specified requirements

b) when working in narrow tanks and pots, multiple hot works shall not be carried out at the same time

C) when working at heights, it is not allowed to carry out hot work at the same time at the upper and lower levels; Oxygen cylinders and acetylene cylinders are not allowed to be placed in the same place where electric sparks splash, and are not allowed to be placed vertically below the equipment, pipelines and transmission lines under production and exposed to the sun in the hot sun

d) there shall be a safe distance of more than 5m between oxygen cylinders and acetylene cylinders, which shall not be close to the heat source, and shall be kept more than 10m away from the open fire

11. Aftercare guarantee

site cleaning after hot work is often overlooked. After the completion of hot work, the hot work Executor shall turn off the power and gas source, move away from the hot work equipment, check and clean the site together with the fire supervisor or safety officer, and extinguish the residual fire. All places that may be involved in electric sparks shall be carefully inspected, and they can leave only after confirming that there is no residual fire. If the hot work time is too long, the on-site inspection shall also be carried out when the rest is interrupted or when leaving, which shall not be ignored

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