【Reward-based discussion】Seeking advice on welding issues for outlet pipes of flammable liquid storage tanks
Thread Content
Welding work is being carried out on the outlet pipe of the flammable liquid storage tank (the pipe has been purged and tested successfully); a blind flange has been installed to isolate the side of the pipe that is connected to the tank, and the flammable liquid inside the tank has not been drained. Does welding work require consideration of the discharge risk that may occur when current flows through pipes into the tank? If it needs to be considered, what are the ways to solve it under the current conditions? (Add a ground wire to the pipeline?) ）
Generally, such pipes and equipment are equipped with static grounding devices, so there is no need to consider it separately
Strong recommendation: Do not do this; the risk is too high. Safety issues cannot be just discussed theoretically; they need to be taken seriously. Even if I had a way, I couldn’t tell you! Empty it out, clean it thoroughly, and then proceed!
A ground wire needs to be installed, and cooling and heat-insulation measures must also be taken. It is also necessary to provide appropriate technical explanations regarding which specific flammable gas is involved. Technical safeguards must be put in place.
Does the welding current only form a circuit at the welding point with the welding wire, and does the current in that circuit flow into the tank? It doesn’t make sense, and it doesn’t seem to be emphasized in the standards either. In normal production activities, when it comes to piping at the joints on material pipelines, we simply add a blind flange; but what if the area where materials are present turns into a storage tank? In that case, a different approach is required
Haven’t you encountered situations in production where you had to perform welding and piping work on spouts containing flammable materials? Welding can be carried out by adding a blind plate in all cases; then why do you think the risk level is very high when it comes to storage tanks?
First, the welding torch and the ground electrode form a circuit; under normal conditions it won’t go anywhere else, but it’s important to try to fix the ground electrode as close as possible to the weld point； Secondly, the outlet pipelines of storage tanks are generally equipped with valves, isolation valves, flexible connections, etc., and flange connections are used primarily. If it is felt that using blind plates to block nitrogen for protection is not safe, the short sections can be removed and work can be carried out at a designated area where welding is permitted; welding should be avoided whenever possible in the storage tank area.
This post was last edited by h20090630 on 2020-6-4 23:16: Add a ground wire to the pipeline to ensure fire prevention.