Corrosion on brass, female adapter for vee set in pump

[daspferd88]

I have a brass component from a pump showing signs of corrosion, namely dark reddish/brown spots splattered on it. It's my understanding that this could be signs of dezincification, caused by exposure to water, acid, or salt. Now, I've also seen a greenish/turquoise corrosion on brass as well which I've read is copper sulfates/carbonates as a result of copper oxidation. My question: is the green corrosion simply a later stage of dezincification, i.e. after all the zinc has been selectively leached away, the copper is the next element to react? Or is this type of corrosion simply the result of exposure to different types of chemicals that cause the copper to react and not the zinc?

 

[MikeHalloran]

Go to copper.org . Read. ... a lot.
There are only, what, 10,000 or more standard alloys of copper?
And at least a few hundred that you can actually get from a metals distributor?

Better yet, ask the pump manufacturer to pick an alloy, based on the pumped fluid, which you have so far not revealed.

IMHO, reddish brown is the normal oxidation you get on common brass hardware just from outside air, whereas when some idiot uses acid-based floor cleaner on chromed flush valves, the acid reacts with the zinc, and the remaining copper turns green; that's dezincification.




Mike Halloran
Pembroke Pines, FL, USA

 

[replica]

What type of brass?..if it is 30% Zn and 70% Cu Brass ..then it is prone to dezinfication but if it is 40:60 or manganese Bronze or high tensile brass ..then it is more resistance to dezinfication...Dezinfication will make the brass reddish in color and has low hardness. It is best to cut it and do some metallography and view under optical microscope to confirm.