Thread: Dielectric unions

When using brass, copper, and galvanized piping in any combination is a dielectric union needed between each?

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Last I checked, brass is used as the dialectic union between copper and galvanized pipe.

Thanks Bruce. I did further research on this forum and it seems like there are some mixed opinions, but more towards what you said. Seems like if you see that it's been that way for several years and no electrolysis viewed then what the heck. I still comment about steel hangers in contact with copper pipe even when it looks just fine cause I have photos of it not looking fine too.

Here is what the NC Plumbing Code says:

605.24 Joints between different materials.

Joints between
different piping materials shall be made with a mechanical
joint of the compression or mechanical-sealing type, or as permitted in Sections 605.24.1,605.24.2 and 605.24.3. Connectors or adapters shall have an elastomeric seal conforming to ASTM D 1869 or ASTM F 477. Joints shall be installed in accordance with the manufacturer's instructions.

605.24.1 Copper or copper-alloy tubing to galvanized
steel pipe.

Joints between copper or copper-alloy tubing
and galvanized steel pipe shall be made with a brass fitting
or dielectric fitting. The copper tubing shall be soldered to
the fitting in an approved manner, and the fitting shall be
screwed to the threaded pipe.

605.24.2 Plastic pipe or tubing to other piping material.

Joints between different grades of plastic pipe or between
plastic pipe and other piping material shall be made with an

approved adapter fitting.

For potable water systems brass is considered to be compatible with copper and with steel as brass is an alloy which contains copper and tin, and there are two basic classes of brass: white brass (has more tin in it) and red brass (has less tin in it).

When you get to piping which handles chemicals, then brass is no longer considered a dielectric fitting, indeed, brass may need a dielectric fitting from copper or from steel - all depends on the chemical in the piping.

Isn't bronze that has tin and brass has zink?

Originally Posted by Denny Waters

Isn't bronze that has tin and brass has zink?

Denny,

You are correct - brass is copper and zinc and bronze is copper and tin.

Me bad.