Adding ball valve to aluminum stock pot?

Hello I am looking to adding a ball valve to my 4mm thick aluminum stock pot. But I don’t if the stainless or brass ball valve will react with the aluminum?

If you’re using a weldless you should be fine. Over time any dissimilar metals can react through contact.
With a weldless valve contact is limited due to O-rings and you can disassemble and thoroughly dry between uses.

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I would recommend stainless regardless.

For materials to not react in a harsh environment (such as boiling wort), you want to be within around 0.15 to 0.2V on the galvanic series. Brass and bronze is around 0.4 - 0.45V. Grades of stainless will be at 0.5 to 0.6V, whereas aluminum alloys can be anywhere from 0.75 to 0.95V depending on their copper content. The bronze ball valve will be the most reactive with the aluminum, so I’d go with the stainless.

Seems like if a weldless valve has O rings or gaskets on both sides the dissimilar metals would not be a factor. Could always add one if needed.

You will love having the valve BTW.

They won’t, until you submerge them into an electrolytic solution. Then you’ll have a battery, with the aluminum serving as your sacrificial anode.

I don’t there will be a major issue with either valve, but the brass one will be more likely to strip small amounts of aluminum into the wort, and may be damaging to the oxide layer that protects the aluminum.

Makes sense. Kind of like on our boat outdrive. Would “pickling” the brass valve with hydrogen peroxide and vinegar make any difference? I think John Palmer suggested that to remove stuff used in the production of brass parts. After doing that my brass parts lost the shiny look like they took on some kind of oxide layer.