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25Iam (Mechanical)
3 Jul 07 14:01
I have read many things online about how brass will corrode in water and then I have read that it will not corrode in water.  I am asking this because I want to order brass nozzle fittings onto the end of a hose. I will be using saltwater as the solution that is going through the hose. Will this damage the nozzle?
Helpful Member!  kenvlach (Materials)
3 Jul 07 20:15
Yes, and some brasses undergo de-zincification, as the zinc preferentially corrodes. But, maybe useful if they can be replaced every few years.


Before salt spray testing


Figure 3. Brass test pieces after 96-hour salt-spray exposure.  The RHS hose barb tested with the clear vinyl tubing attached.

“after 96 hours' salt-spray exposure. The brass products, Figure 3, are clearly tarnished and contain numerous areas covered by a gray-green corrosion product. The corrosion product appears to be thin and adherent, even in threaded regions. “


Figure 7. Brass parts after 1000 alternate immersion cycles in 3.5% rock salt solution.

Note: the zinc plated steel parts comparison tested came out worse; plus corrosion on steel intensified whereas corrosion on brass seemed to form a somewht protective coating.
From
http://www.copper.org/applications/rodbar/alloy360/corrosion_tests.html

kenvlach (Materials)
3 Jul 07 20:18
Oops. The sentence 'The RHS hose barb tested with the clear vinyl tubing attached.' belongs with the bottom photo (Figure 7 in the reference).
EdStainless (Materials)
5 Jul 07 9:54
There are a great number of brass (and bronze) alloys in use.  In general the generic brass used for common fittings is not suitable for marine use.  The desincification can lead to leaking and mechanical failure.
There are quite a few brass alloys that are not exotic that will give fine service is seawater.  The CDA web site has a lot of info.  www.copper.org

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm

strider6 (Materials)
6 Jul 07 2:46
Corrosion behavior of "Brass" in Sea Water is a function of many factors, velocity, pollution..
As Ed said there are a lot of different materials classified as "Brass", eg Naval brass, Aluminum brass.. that are used in Sea Water service and perform well.
Usually alloys with higher Zn content are more susceptible to dezincification and can be suppressed by the presence of small amount of arsenic and other elements.
In my opinion to answer your question and decide the suitability of brass, it would be necessary to know the time of exposure of the fittings to seawater, i think it's not a continuous service, if the water is treated or not and the criticality of service.
in this links you can find more info about copper alloy in seawater:

http://www.copper.org/applications/marine/seawater/seawater_corrosion.html

hope this help

regards

Strider

http://www.corrosionist.com

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