Brass/Bronze valves on SS316L pipes on seashore 1

[fpnut]

I have used brass/bronze valves on 316L piping before, and the results have generally been good.

However, this time I'll be using it onshore, next to the sea. Anybody have experience with galvanic corrosion in this case? I'll be piping nitrogen. I'm worried about the atmospheric condition. Is isolating the connection necessary in this case? The connection is NPT thread.

 

[EdStainless]

I am more worried about external corrosion on the 316 than galvanic issues.
External sealant to prevent moisture from entering the threaded joint should be all that you need.

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P.E. Metallurgy, Plymouth Tube

 

[fpnut]

Hi Edstainless,

Thanks for your input.

As for the 316 corrosion, we don't have much choice in materials as this section will be cryogenic. We are looking into other alternatives, but currently we are exploring the use of an aluminium based coating to protect the surface. Have you had similar experience before?

 

[EdStainless]

Lots, if the piping is out where it gets rained on and it never gets hot (even from the sun) then it will be OK.
But if there are places where the rain wont wash it off and it ever gets real hot you could be in serious trouble.
Will the lines be insulated? That has pros and cons also.

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P.E. Metallurgy, Plymouth Tube

 

[fpnut]

It will be rained on, and will be under the sun. But the hottest it will ever get is being under the sun at max 38-40 degrees C.

Lines won't be insulated. Since it's a part of a vapourising system, introducing as much heat as possible is desirable.

 

[EdStainless]

If there is no flow the temp will reach a lot higher than that.
Not only will it be rained on, but when you are running there will be condensation, which should help.
I am concerned about thermal expansion, but that is another issue.

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P.E. Metallurgy, Plymouth Tube