Safety measures for hot work in tank areas

For hot work to be carried out under pressure without gas displacement, the requirements for \"special hot work\" must be strictly followed; approval procedures for hot work must be completed, and all relevant safety regulations regarding hot work must be adhered to. ? 2. Before carrying out welding repairs, it is necessary to understand the condition of the area to be repaired. Based on the location, shape, size, material, and production history of the cracks and holes, a welding repair plan should be formulated, and a dedicated person should be assigned to ensure that safety measures are implemented. The construction plan shall be reviewed and approved by relevant departments such as machinery, production scheduling, fire protection, and safety, and submitted to the company or the chief engineer for approval. ? 3. For hot work tasks carried out under pressure without displacement, the workshop supervisor and process technician must provide direct supervision, with a dedicated person assigned to oversee the operation. For welding tasks that are particularly difficult or dangerous, relevant departments such as production, logistics, and safety, along with the general manager and chief engineer, must be present at the site in person. Firefighters and gas protection personnel must also be on site for supervision. ? 4. Welders must possess a high level of skill; it is not allowed for welders who lack knowledge, do not have the necessary certificates, have unstable skills, or lack experience to perform welding under pressure. During the welding process, it is essential to strictly control the oxygen content in the system to no more than 0.5%; the system must always be under positive pressure, and welding under negative pressure is absolutely not allowed. Its pressure should be maintained at 50-150 millimeters of water column. ? 5. Positions responsible for controlling the oxygen content in the system should be assigned to personnel who are skilled and have experience in operating such systems. When an increase in oxygen content is detected, the frequency of analysis should be increased, with attention paid to the trend of changes. When the oxygen content exceeds 0.5%, welding repair work must be stopped immediately. ? 6. A U-tube manometer should be installed on the equipment used for welding repairs, and a dedicated person should be assigned to closely monitor changes in system pressure. When a sudden increase or decrease in pressure is detected, going outside the range of 150–50 millimeters of water column, work must be stopped immediately. Operations can resume only after the cause has been identified and appropriate measures have been taken. ? 7. At welding sites where work is carried out under pressure without gas displacement, ventilation must be adequate to ensure that any leaking gases can be removed promptly. There must be no dead corners in the area above the welding site where flammable gases can accumulate. If the crack is large, the amount of gas leaking is significant, and the gas composition in the area around the hot work is complex, it is necessary to strictly follow the regulations for carrying out hot work in order to prevent explosions and poisoning. ? 8. When welding is difficult due to severe corrosion, poor strength, or other issues in the area to be repaired, a direct current welder should be used primarily; an alternating current welder can also be employed in such cases. The type of welding rod should match that of the material being welded. ? 9. A sufficient amount of fire extinguishing equipment and gas masks should be available at the welding site; axial flow fans should be installed if necessary. The access routes on site will be kept clear. ? 10. Before starting hot work, it is necessary to report to the production scheduler and obtain approval. During the hot work, unified command should be maintained, roles should be clearly defined, responsibilities assigned to specific individuals, close cooperation should be ensured, process analysis should be strengthened, and production stability preserved. The personnel in the relevant production sections and positions, upon receiving the notice to carry out hot work, should check and take all necessary preventive measures as well as make emergency preparations to avoid any impact on production. ? 11. Before starting work involving open flames, it is necessary to explain in detail to all the workers involved the safety construction plan, safety measures, precautions, and procedures for handling various situations. The workshop supervisor, safety officer, and process technician should conduct a thorough inspection of the implementation of safety measures, and all relevant personnel should be in their positions. ? 12. Once the preparation is complete, the workers should put on gas masks (the use of oxygen respirators is strictly prohibited). They then enter the welding area from the upwind side, cover the steel plates to be welded within the pre-determined area, hold them firmly in place, ignite the combustible gas, and begin welding. When igniting flammable gases, it is prohibited to face holes or cracks to prevent injury from flames caused by a sudden increase in pressure. ? 13. If the combustible gas cannot be ignited, the cause should be checked. If certain inert gases (or water vapor) are introduced into the system, turning the combustible gas into a non-flammable mixture that cannot be ignited, a gas mask should be worn to prevent poisoning. ? 14. During welding, if the weld joint expands and welding becomes impossible, the machine should be stopped for handling. When welding a gas holder, if the flame grows larger and it is necessary to extinguish it, the holder can be quickly lowered so that the area where welding is taking place is submerged in the water tank. ? 15. After welding repair is completed, any remaining flames at the site must be completely extinguished. It is necessary to carefully check whether the results meet the quality requirements, and the work must be approved by the workshop where the equipment is located. ? 16. When production is unstable, the cracks and holes are too large, the welded areas are severely corroded or too thin, and pressure cannot be controlled, hot work under pressure without gas displacement should not be carried out; it is preferable to use non-hot-work methods such as patching with adhesives. ? 17. The scope of application of these regulations is limited to low-pressure gas systems and low-pressure ammonia systems.

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Work is not carried out on the tank itself, but on the pipes connected to it. To prevent sparks from occurring at the pipeline flanges, it is located within the fire dike. . . .

Ensure that the drains and vent valves within 20 meters of the area where welding is to take place are blocked with asbestos and wetted down； The combustible gas detector test passed, with no leaks detected ； If conditions permit, steam can be used to shield the area around the hot work site ；

I’m not sure whether you are a state-owned enterprise or an individual. I have dealt with problems similar to the one you mentioned; I didn’t see it in person, but what you’re referring to is the flange connected to the tank. First, it’s necessary to purge that section of the pipeline, second, blind plates should be used for isolation, and third, it’s important to fill the inner walls of the pipeline with clay before installing the blind plates, so that everything can be cleaned up after the welding work is completed. As for the issue of electricity conducting, no sparks will be generated; you just need to connect the live wire near the area where welding is being done.

I’m worried that the electric current could affect the storage tank and lead to a flash explosion of light oil. .

In private enterprises, I know the safest approach is to completely insulate and isolate the storage tanks, disconnect them at the flanges, and install blind plates (blind plates with bolt holes) to fully sever the pipelines from the tanks. However, the company still needs to carry out production activities and blend oils, so it’s impossible to treat the entire tank area in this manner.

This issue is worth exploring; indeed, there is no relevant information available, but its practical significance is great.