Causes of Corrosion At Copper Plumbing

[Michael Thomas]

When you observe something like this, do what extent do you attribute it to galvanic corrosion, and to what extent to excess flux and incorrect technique?

[Raymond Wand]

Could be the result of both. In reality its irrelevant for the clients need to know as to how it was caused, but more importantly that it be noted for replacement.

[Jerry Peck]

what extent do you attribute it to galvanic corrosion, and to what extent to excess flux and incorrect technique?


In reality its irrelevant

My thought too.

Rather than state one cause is more likely than the other, and be wrong, the right answer is that both, to some degree, could cause that.

I'm not sure there is galvanic corrosion going on, that top fitting looks to be brass, which is compatible with copper. The bottom formed copper fitting to the steel is not good though. I read someplace that machined copper fittings are closer to brass and are compatible with steel (do not require a dielectric fitting) while the formed copper fittings are 'soft enough copper' such that they are not compatible with steel without a dielectric fitting between them.

From what I see in your photo, I see (from bottom to top) steel water heater fitting, steel nipple, formed copper fitting, copper pipe, brass fitting - I suspect most of that is caused by 'leakage at the brass fitting'.

[H.G. Watson, Sr.]

Depending on an isolation plastic or rubber gasket that doesn't last long won't do.

Incorrect bonding.

6-8" bronze or brass fitting between. The steel will still suffer.

Failure to maintain a sacrifical anode and maintain the water heater.

A chip on the lining, condensate on the exterior, flux as you mentioned, aggressive water....

A multitude of possibilities that might be contributory.

Bottom line is the same.

[Mike Truss Guy]

Heat and age are also factors to consider. A typical gas water heater in my city lasts from 4-10 years. At that point they usually rust out and start leaking. They just don't last forever. Mine blew out in the garage and made a heck of a mess. I had the new one installed with a pan under it that drains to the outside in case it leaks again.

Consider this. If the outside plumbing looks like that, imagine how messed up it is on the inside.

[Michael Thomas]

Just ran into this one, pretty classic IMO, that's a drop of water on the bottom of the elbow.