A hole is drilled in the gas pipe to install an instrument valve

This post was last edited by ZZJJAA70 on 2009-9-3 at 22:05. According to the original poster, it is either a pressure-free gas pipeline that has not been purged, or a gas pipeline that is in operation under pressure. Based on this, I believe neither of the two options is safe. The first option will undoubtedly lead to deflagration accidents, while the second option, although seemingly thorough and taking into account the need to prevent sparks from being generated by the drill bit, remains absolutely unsafe due to the following factors: 1. There are too many uncertainties related to the pipeline itself, such as its thickness, degree of corrosion, material composition, and the presence of carbonization. 2. Even if the pipeline meets the welding requirements, if the gas inside it (or residual gas) is trapped and not able to flow, it will expand rapidly when heated during welding. 3. “After welding, start drilling and keep adding water to prevent sparks.” Or keep adding lubricant while drilling.” It isn’t only open flames or sparks that can cause gas to explode; generally, the ignition point of gas is 651 degrees, meaning that gas under the right conditions at this temperature will catch fire. Even when drilling iron in water, a certain cutting temperature must be reached at the very tip of the drill bit where the cutting takes place in order to effect cutting. Therefore, water removes only the temperature generated by cutting mass transfer, not the temperature at the cutting point. The safest approach is to perform welding after replacement.

We have done this kind of thing before too; it doesn’t matter whether water is added or not! It doesn’t matter if a fire breaks out anyway; low pressure is just something that might cause a fire. If the pressure is high, the likelihood of a fire is very low; due to the fast flow rate of the gas, ignition cannot occur

Theoretically, it’s not possible. This approach involves many security risks. But in practical applications, there are also successful cases in some individual units – that’s just luck! It cannot be taken lightly!

Drilling holes in the main gas pipeline is generally a last resort under normal operating conditions. From a safety perspective, I personally do not approve of this approach. But for some reason, it’s not impossible to do either. As long as there is positive pressure in the gas main, drilling with a drill won’t cause an explosion; combustion may occur due to high temperatures, but the pressure in the gas main is generally not very high, and the diameter of the drill hole is also not large. Even if combustion does occur, preventing the supply of oxygen will not cause significant disruptions to the process or equipment.

This method is completely feasible; our workshop has tried it several times as well. We can analyze this: first of all, it’s a gas pipeline, not one carrying explosive gases, and its diameter is relatively large, so there is no issue of expansion caused by welding ； Furthermore, when drilling, water is added for two purposes: to cool down and to isolate the air in the high-temperature area around the drill bit.

Holes can be made in desulfurization towers; there is a special tool for that. It can probably reach 150. It’s best to refuel.

I agree with the opinion from floor 5: \"As long as there is positive pressure in the gas main, drilling with a drill won’t cause an explosion; combustion may occur due to high temperatures, but the pressure in the gas main is generally not very high, and the diameter of the drill hole isn’t large either. Even if combustion does occur, preventing oxygen from reaching the area will not cause significant disruptions to the process or equipment.\"