Precautions for safe operation of hot and pressuri

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Precautions for safe operation of repair welding under pressure

Leakage Stoppage Technology of welding under pressure is a special technical means to apply welding technology to leakage stoppage and sealing operation under dynamic conditions. There are many differences between welding under dynamic conditions and welding under normal conditions. Normal welding operations can be carried out when conditions are met, such as groove form, grinding, pre welding cleaning, pre welding preheating, interpass temperature, post welding heat treatment, NDT pneumatic force, etc., so as to obtain qualified welding seams. The realization of the welding process with the pressure explosion plugging technology is that the process parameters of the medium in the production device and transmission pipeline, such as temperature, pressure and flow, will not be reduced. The whole welding process will always be affected by the medium temperature, pressure, vibration and scouring until the leakage is eliminated. Therefore, in terms of safety operation, pressure welding plugging technology should not only operate according to the safety requirements of welding technology, but also operate according to the safety requirements of dynamic plugging technology. The safety precautions of Leakage Stoppage Technology by pressure welding are composed of two parts, namely, the safety precautions of welding technology and the safety precautions of dynamic sealing operation

I. safety precautions for electric welders

1. Before work, you must wear labor protection articles, leather gloves, masks, helmets, insulating shoes, etc. check whether the welding equipment, working place and protective measures meet the safety requirements

2. The electric welding machine must have a good grounding device, and it is not allowed to use pipes or other metal objects to replace the Sichuan grounding wire. The wire must be well insulated, and it must be checked frequently to prevent leakage, and its rotating part must have protection measures

3. The power supply and wiring switch of the electric welding machine should be installed by an electrician. The electric welding machine should be placed in a cool place in Tongxi opera, strictly prevent moisture, and take rain proof and insulation measures

4. Before welding, strictly abide by the hot work management system, and hot work can be carried out only after hot work conditions are met, otherwise hot work cannot be carried out

5. Prepare fire-proof supplies before welding, such as foam fire extinguisher, sand, carbon tetrachloride fire extinguisher, etc

6. When working at heights, the safety regulations for working at heights must be implemented. When welding, the safety belt should be hung at the channel above the side of the welding place. Attention must be paid to the underground and surrounding combustibles to avoid sparks falling and causing combustion

7. When welding inside flammable, explosive, high-temperature and toxic containers, it is necessary to have good ventilation. If necessary, install a ventilator or wear a long tube type protective mask, implement the safety regulations for internal operation of equipment, and hang the safety belt outside the equipment. After work or rest, the welding handle must be taken out of the container

8. The welding handle shall not be placed on the same conductor as the ground wire. It is strictly forbidden to hang the primary wire on the power supply to prevent fire or electric shock caused by short circuit

9. When pulling the wire, pay attention to the surroundings, and don't hang things upside down or drop things to avoid hurting people

10. When transmitting power, you must wear gloves, be sure to use your left hand, and keep your head and body away from the front. To prevent electric arc injury, you must be prepared to cut off power at any time, so as to avoid mechanical failure, burning or damaging the equipment after starting

11. Be sure to wear gloves and change welding rods to avoid electric shock

12. When welding is suspended, the electric welding handle must be placed separately from the weldment to avoid short circuit. Always check the wire, wrap it if there is bad insulation, and deal with the loose joint

13. The welded parts or welding rod heads should be properly placed, and it is not allowed to throw them on inflammable and explosive materials, so as to avoid fire

14. Cut off the power supply when checking and repairing the electric welding machine or wire

15. Welders should have the common sense of rescuing people who get an electric shock, such as artificial respiration, first aid treatment, etc

16. It is not allowed to weld lifting lugs on cast iron or high carbon steel

17. In case of sudden power failure during electric welding, pull the switch off immediately. When you finish your work or leave the site, you should cut off the polyurethane waterproof coating. The price should be higher. Cut off the power supply

18. The electric welding machine should be managed by a specially assigned person. The electric welding machine must pass the safety test. Do you know how to buy the testing machine? It can be operated only after passing the test, and it is forbidden to use non welders

II. Safety precautions for Leakage Stoppage Technology with pressure welding

safety precautions for Leakage Stoppage Technology with pressure reverse welding leakage stoppage technology is a repair welding method that uses welding deformation to achieve the purpose of resealing. Theoretically, this method can repair any kind of crack (excluding the destructive crack of serious deformation caused by strong external force or internal medium explosion) on the pipeline and equipment under pressure when the pressure is lower than 3 MPa. However, due to the complex situation of pipeline and equipment rupture in actual production, it is not suitable to repair with pressure repair welding in many cases. Sometimes even if pressure repair welding can be carried out, accidents may occur in the process of operation

for example, the crack is very wide. Generally, the width of the crack is proportional to its length, that is, the wider the crack, the longer its length. Both ends of the crack have never cracked to crack, and the crack is small to gradually increase. Under normal circumstances, as long as you start from one end and reverse repair welding section by section, the transverse shrinkage stress generated by the weld can tighten the crack section by section. With the repair welding process section by section, the length of the crack will gradually decrease and its width will gradually narrow: therefore, theoretically speaking, the crack should be able to repair welding successfully. If the gas with certain pressure is transported and stored in the pipeline or container in production, when the damage crack is large, the leakage will inevitably be large. The flame ignited by the repair welding ignition may make the operator unable to get close to the crack, close to the crack, and the repair welding work cannot be carried out. It is even possible that the process pipes and containers may be barbecued in the flame for a long time due to the untimely extinguishing of the fire, and the local temperature will rise sharply until it is red, resulting in a reduction in intensity, a sudden burst, and a major accident, which is absolutely not allowed. Therefore, before repair welding under pressure, careful observation, careful analysis, accurate judgment and practical and reliable measures should be taken to ensure the personal safety of the operator and the normal operation of production. This is the primary problem that should be paid special attention to in the repair welding under pressure, and do:

1. Before repair welding under pressure, the cracks and leakage on the pipes and containers in production should be checked and analyzed in detail, Judge whether there are conditions and preparations for improving the performance of relevant equipment with pressure repair

2. Operators and on-site commanders of repair welding under pressure should understand and master the physical and chemical properties of pressure medium in process pipes and vessels. Take practical and reliable preventive measures against the possible harmful consequences

3. Repair welding under pressure should be carried out by experienced and skilled welders. In general, it is not suitable to carry out the test work of repair welding under pressure on the pipes and vessels in production and operation. Instead, the actual operation should be carried out after repeatedly practicing on the test piece, basically mastering the operation method and accumulating some experience

4. When repairing welding under pressure, special safety supervisors should be set up according to the specific situation. It is not suitable to carry out repairing welding under pressure alone

5. When carrying out repair welding under pressure and storing pipelines and containers with toxic, harmful and corrosive media, corresponding protective articles and appliances shall be prepared

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