charisma
New member
I want to fit a stainless seacock to an existing skin fitting. I'm not sure if the existing fitting is bronze or brass. Will I have problems with corrosion between the different metals?
Cheers
Cheers
mixed metals
- Thread starter charisma
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Chris_Robb
Well-known member
In short - Don't do it. You will set up a galvanic cell between the brass/bronze and the stainless - you will have problems.
I did not know that you could get a stainless steel seacock. Are you sure that it is not a brass/chromed one?
I did not know that you could get a stainless steel seacock. Are you sure that it is not a brass/chromed one?
AndrewB
Well-known member
While mixing metals in contact should in general be avoided, you will not have too much trouble with stainless and phosphor bronze, which are reasonably compatible.
Brass though is seriously bad as electrolysis will quickly leach out the zinc, and it will crumble.
If you are not sure which you have, its not easy to tell them apart. Brass is a bit more coppery in colour and a little softer to scratch. Beware that there are other, less common types of bronze that are not suitable.
Care is also needed using stainless steel underwater, as some grades suffer from crevice corrosion.
For a good introduction to this problem, see <A target="_blank" HREF=http://marinesurvey.com/yacht/corrosion_1.htm>David Pascoe's Marine Surveyor</A> site.
Brass though is seriously bad as electrolysis will quickly leach out the zinc, and it will crumble.
If you are not sure which you have, its not easy to tell them apart. Brass is a bit more coppery in colour and a little softer to scratch. Beware that there are other, less common types of bronze that are not suitable.
Care is also needed using stainless steel underwater, as some grades suffer from crevice corrosion.
For a good introduction to this problem, see <A target="_blank" HREF=http://marinesurvey.com/yacht/corrosion_1.htm>David Pascoe's Marine Surveyor</A> site.
Trevor_swfyc
New member
I have a bronze prop and a stainless shaft no problems with these.
I thought stainless was considered to be fairly useless for setting up a cell which in our case is good news.
Trevor
I thought stainless was considered to be fairly useless for setting up a cell which in our case is good news.
Trevor
ccscott49
Active member
Stainless and proper bronze, no problem, stainless and brass big problems. Brass is brassy looking!! and bronze tends to have a coppery colour, where it hasn't been machined. A lot of cheaper skin fittings are brass.
G
Guest
Guest
you can use a stainless shaft and a bronze prop when a sacrificial zinc anode is nearby. it further helps that the oxide surface film on the stainless is untouched.
if you were able to get a stainless inner to fit (say) a blakes seacock, you would risk electrolytic corrosion because no zinc nearby, and you would be continuously removing the protective caot on the stainless as you turned the handle which wold also allow corrosion.
best not use stainless in this application in my view. cough up for the proper proprietary product (try saying that without your teeth in!)
i've always fancied glass re-inforced nylon , but have never tried it myself nor heard from anyone who has - so dont know if it is any good or not.
if you were able to get a stainless inner to fit (say) a blakes seacock, you would risk electrolytic corrosion because no zinc nearby, and you would be continuously removing the protective caot on the stainless as you turned the handle which wold also allow corrosion.
best not use stainless in this application in my view. cough up for the proper proprietary product (try saying that without your teeth in!)
i've always fancied glass re-inforced nylon , but have never tried it myself nor heard from anyone who has - so dont know if it is any good or not.
