Rusting between galvanized and copper

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  #1  
Old 01-17-05, 06:02 PM
latuszek
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Rusting between galvanized and copper

Here is a picture of the union connecting the galvanized cold water supply to the new copper pipe that the water heater guy ran to the water heater. Why is it rusting? Did he use the wrong stuff without the spacer or something?

Thanks for your help!

 
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  #2  
Old 01-17-05, 06:24 PM
Join Date: Dec 1999
Location: Northeastern NC On The Albemarle Sound
Posts: 10,952
That rusting is due to galvanic corrosion caused by electrolysis between two dissimilar metals (galvanized steel pipe and brass valve).
There should be a dielectric union between the galvanized elbow and the brass valve to prevent it.

DIELECTRIC UNION
Needs to be re-plumbed properly.
I'm sure that plumber knows better. He either didn't have one with him (which he should have had before the job call), or he's deliberately looking for a $ervice call back to repair "your" problem, which he created.
Good Luck!
Mike
 
  #3  
Old 01-17-05, 08:39 PM
latuszek
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thanks for the info Mike. Does everything else look right? (between the brass and copper)

Thanks again,
Dan
 
  #4  
Old 01-17-05, 11:08 PM
Join Date: Dec 1999
Location: Northeastern NC On The Albemarle Sound
Posts: 10,952
That's getting a little corroded also from that nearby galvanic action, but the dielectric union will correct that, too. Copper to brass without a dielectric union is O.K. (both are red metals).
You can repair this yourself. Turn off the main water valve, drain down the line, cut the copper line with a tubing cutter, and unscrew the valve and the galvanized nipple from the elbow.
Install the dielectric union between the galvanized elbow and the brass valve. You will need to sweat (lead-free solder) a copper coupling in to re-connect the copper line, and maybe a copper piece and copper male threaded fitting between the dielectirc union and the valve.
Wrap 2-3 flat wraps of teflon tape on all male threads clockwise only as the threaded end faces you.
Good luck!
Mike
 

Last edited by Mike Swearingen; 01-17-05 at 11:19 PM.
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