"TimR" wrote in message
...
I've seen mostly copper inside buildings and have never had a problem
(about 800 locations).

But IIRC copper is anodic to steel, so if the two are connected the
steel pipe should sacrifice itself to protect the copper. If they
were outside or underground I would guess there could be a problem.

Magnesium, Al, Zn strips would help protect the steel and copper. Magnesium
stakes are sold for this purpose, and anodic aluminum is found in water
heaters -- altho alum is proly not very effective after its own oxidized
film occurs.

Copper outside form a protective oxide, like alum -- that green patina. So
copper should be stable outside as well.
--
EA