Is it necessary to disconnect the oil inlet and outlet pipelines when welding inside the tank?
Thread Content
Everyone, a new oil tank has been built, but no oil has been poured into it yet. To carry out modifications inside the tank, explosive welding is required. However, the inlet and outlet pipelines are filled with gasoline, and they have been separated from the tank body using blind flanges. In this situation, is it still necessary to disconnect the inlet and outlet pipelines from the tank body?
There is gasoline in both the inlet and outlet pipelines. If these pipelines have never been connected to the tank, it’s fine as long as they remain disconnected from it; but if they were previously connected, it is recommended to be extremely cautious before performing any work on the tank! ! Prevent internal leakage of the valve from causing oil and gas to accumulate in the tank! Be sure to carefully test the gas inside the tank before performing any welding work! As for whether it is necessary to disconnect the pipeline again after isolating it with a blind flange, it is generally not required. In your case, after installing the blind flange, it is advisable to purge and replace the connection pipelines between the valve and the tank. Safety first!
Doesn’t one need to consider the risk posed by stray currents generated by welding flowing through the oil pipelines?
To disconnect, make the storage tank a separate entity; this is safer.
Current is certainly generated during the welding process, and this is one of the causes of fire accidents. However, the three elements necessary for a fire to occur are: a heat source, combustible material, and an oxidizing agent – all of which are essential. The current generated during welding serves as the heat source; if the pipes are properly insulated to prevent the presence of oxidizing agents, in other words, if there are no leaks, then a fire will not occur. Additionally, during project construction, it is necessary to ground the pipes. During production, static electricity grounding checks must be carried out annually. Before maintenance, the safety management department also checks the static electricity grounding at the maintenance sites. The standards for welding require that connections be made as close as possible; long-distance wiring for bridging is not allowed. As long as strict checks are in place at every stage, I don’t think the issue you’re concerned about is a problem. It's just my personal opinion; different views are welcome for discussion
Directly disconnect the flexible metal hose that connects the oil tank to the pipelines, and check the grounding of the oil tank as well as the detection of flammable gases inside the tank. The hammering during welding is close to the welded area
There are already blind flanges, so there is no need to disconnect the storage tank from the pipelines. It is sufficient to conduct a gas analysis inside the tank before performing any welding work. Stray currents can generally have an impact, but since the storage tank is grounded, the effect is minimal.