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Threaded Pipe Connection Between Different Metals

Threaded Pipe Connection Between Different Metals

Threaded Pipe Connection Between Different Metals

(OP)
I have an aluminum filter housing that needs to connect to a pumped drain system made of copper.  When the system is in use, it will operate at about 140F.  Thread size is 2" NPT.

What connection should I make between the two materials?  I'm concerned about threaded joint leakage due to differing expansion coefficients, as well as possible galvanic action.

I posted this on the Piping and Fluid forum, but it was ignored.

---KenRad   

RE: Threaded Pipe Connection Between Different Metals

That's a good question for the mfr. I would guess a brass stub then a union. That way they could change the stub quickly and with minimal cost.

RE: Threaded Pipe Connection Between Different Metals

What is the fluid?

RE: Threaded Pipe Connection Between Different Metals

(OP)
The fluid is water, with a slight amount of a detergent.

---KenRad

RE: Threaded Pipe Connection Between Different Metals

Say KenRad,

Unless I'm missing something, you should be able to get a standard dielectric union from a plumbing supply place to handle those two specific metals.

Good luck with it, let us know what you find out!

Old Dave

RE: Threaded Pipe Connection Between Different Metals

I don't think there's galvanic concern between copper and aluminum (possibly similar oxidation potentials) - but don't quote me on this. Air coils are aluminum fins on copper... If you have any doubt, just put dielectric connector (close nipple w/plastic lining). Easy and cheap.

Good luck, CB

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