Regarding the connection of pipes made of different materials
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Dear sea friends, can carbon steel flanges be connected to 304 ones? The mesons inside the tube are alkaline solutions. Will it affect the service life?
It cannot be joined in this way; welding of dissimilar steels is not allowed by the standards. That flange should also be replaced with 304.
Welding is no problem, but connecting it in this way definitely won’t work; the alkali solution should be connected to a stainless steel flange, or a carbon steel loose flange can also be used
It’s not possible; due to electrochemical corrosion, flange connections must be used for steel pipes made of different materials
It’s not possible; flange connections are required to join steel pipes of different materials
Welding carbon steel and 304 stainless steel is no problem, but 304 stainless steel welding rods must be used. It’s fine to use 304 stainless steel pipes for transporting alkaline solutions; however, if carbon steel flanges are used, the service life will be significantly reduced. Alkaline solutions should be handled using 304 stainless steel flanges; if no such flanges are available, or if carbon steel flanges must be used, it is best to bend the 304 stainless steel pipes and use slip flanges instead.
Currently, there are still many cases where stainless steel pipes are fitted with carbon steel flanges; welding them presents no problems. However, for applications where strict requirements are imposed on the medium, or in cases of stainless steel process pipelines that require continuous operation without interruption, it is best to use flanges made of a material that is compatible with that of the pipes.
When stainless steel and carbon steel are welded together, the carbon steel can contaminate the stainless steel, but it’s not a major issue; however, it’s better to avoid doing this. There’s no problem using carbon steel for alkaline solutions, as we use carbon steel in such applications anyway.
Carbon steel flanges and 304 can be connected together: slip-on flanges pose no problem. It is also fine to screw the flange’s internal threads into the pipe’s external threads. Carbon steel flanges and 304 can be connected together: welding is no problem, provided that this is the design chosen by the design team.
The welding is fine; the question is whether the medium conditions are suitable
For 304 pipes, it is best to use 304 flanges; if carbon steel flanges must be used, then the pipes should also be made of carbon steel. As long as the concentration of the alkaline solution is not too high and the temperature is not too high, there will be no problem.