Galvanized pipe on wet return

Steve_210

Changing a boiler today what are the consequences of galvanized pipe on wet return obviously it was something somebody had left over from a job

Jamie Hall

Galvanized pipe rusts. Remarkably rapidly. The possible consequences are slow returns from the rust clogging things up and, eventually leaks. If possible I'd replace it either with black iron or, since it's a wet return, copper.

Steve_210

Yes I know how to replace it with copper just didn’t know what the consequences were thanks

Steve_210

Strange galvanizes is used outside because it doesn’t rust

retiredguy

I was told by the "old timers" that the galvanized coating would be compromised by boiler water with a low PH and that is why galvanized pipe was never used in a boiler system.

mikeg2015

Worse, in some cases the galvanized flakes off. I believe hte low PH speeds up corrosion as mentioned. It has poor chemical resistance in general. That’s by it’s sort of OK for potable water, but not as good as plastic or copper.

Galvanized still rusts outdoors, only much, much slower than plain steel that rusts instantly the protective film of machining oil is gone.

Jamie Hall

Remember too that galvanized pipe is usually steel, not iron. Steel rusts like mad once the galvanic coating is breached. Black iron rusts very slowly.

Steve_210

Correction yes galvanized will rust but much slower a lot of codes required galvanized for outdoor gas pipework