Preventing dezincification in brass fitting using electroless nickel 2

[tmech77]

We are thinking of having de-ionized water running through (1/2 inch tube OD) brass compression fittings. The brass is alloy 360 and as such has a zinc content of about 40%. I have heard that if the zinc content in the brass is about 15% or higher, that it has a tendency to leach out of the brass, which would cause it to deteriorate and eventually leak. I have also heard that if you plate the brass fitting with electroless nickel that the nickel would mitigate or even prevent the leaching of the zinc. Water in our system is de-ionized and at 76 F. I have two questions:

1. How thick should the plating be in order to prevent the zinc from leaching out? It can not be too thick because it can not be so thick that it would cause problems on the threads and prevent the parts from being able to be screwed together.

2. If we do not use electroless nickel plating on the brass fittings, how long approx. would they last before the zinc is leached out to the point that a leak could occur?

Thank you.

 

[metengr]

I would use dezincification resistant (DZR) brass or silicon bronze fittings. Plating can contain defects resulting in rapid pin hole leaks to the brass fittings under DI water.

 

[MikeHalloran]

Won't ANY metal add ions to your de-ionized water?


Mike Halloran
Pembroke Pines, FL, USA

 

[mcgyvr]

Why not use PEX/polyethylene/PVDF or other similar plastic piping vs a metallic piping?
DI water is very aggressive at attacking metal and stripping ions from it..

 

[TVP]

I concur with metengr-- 360 brass is not suitable for long-term exposure to DI water.