When dis-similar metals are in contact, it tends to lead to corrosion. Probably the place where the home inspector is most likely to see this problem is in plumbing systems. Often steel bonding clamps, designed for steel gas pipes, are connected to copper. If the clamp has been there a long time, it is likely that one will see some deterioration of the copper. Probably the most common place to find galvanic action is at water connections on hot water heaters. In the photo, galvanized steel nipples were used to connect the tank to the copper flex lines. This is commonly done by amateurs who do not realize that they should spring fro the extra few cents to buy proper dielectric unions. They look like galvanized nipples to the uninitiated eye but, in fact, they are not. Dielectric unions are designed to allow the connection of dis-similar metals without corrosion. Thanks for stopping by, Steven L. Smith
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Thanks for the tip. I see this all the time and I wondered what was really happening.
Mark,
That is often the case. There are other times where the lines were not tight, even though proper materials were used, and that leads to leaks and rust as well.
Steven: This stuff looks like a very quick invitation to some major water leaks. How can those who think they are fixing things... be so "unaware." Maybe "oblivious" is a better word.
I have never heard of a diabetic unions. Are they anti sugar front?
James... very funny. I guess the next thing you're going to bring up is needing galvanized steel nipple clamps for the galvanized steel nipples ?? Just wondered ? I do, however, think we're getting just a little too personal, here... :)
James took my thunder!! Well, at any rate, I see this problem nearly every day. It is amazing how often plumbers cannot recognize steel vs. galvanized.