Are there potential problems using stainless steel in contact with aluminum?

[msa8967]

I have an aluminum pot with holes drilled for a ball valve and thermometer. I have used a stainless steel plug, washer and bolt to seal it. When I expose this to both hard water and soft water I am finding lots of mineral deposits on the inside of the kettle. This occurs when I have had the water in the kettle for several hours. I doubt that this would be good for brewing but I wanted to ask if these two different metals are not compatible for brewing.

Any thoughts?

 

[BDB]

Yes. Those two metals don't play nice with each other.

 

[Thakaz]

Dissimilar metals in contact can cause galvanic action where one material begins to corrode the other, they can eventually become fused together. http://en.wikipedia.org/wiki/Galvanic_corrosion
Easy fix, just grab 2 rubber washers or o-rings to isolate the metals from each other.

 

[Minbari]

are you sure it is not just the oxide layer of the AL building up? it is supposed to do that.

 

[msa8967]

Dissimilar metals in contact can cause galvanic action where one material begins to corrode the other, they can eventually become fused together. http://en.wikipedia.org/wiki/Galvanic_corrosion
Easy fix, just grab 2 rubber washers or o-rings to isolate the metals from each other.

Can I use a rubber washer on the inside of the brew kettle to separate the 2 metals? Will exposing the wort to the small rubber ring have any effects on the beer?

 

[WayFrae]

Can I use a rubber washer on the inside of the brew kettle to separate the 2 metals? Will exposing the wort to the small rubber ring have any effects on the beer?

Use a food grade, high temperature silicone o ring.

 

[msa8967]

are you sure it is not just the oxide layer of the AL building up? it is supposed to do that.

There is already a dark gray a dark gray oxide layer on the inside of the kettle. This is more like small white mineral deposits that are flakes.

 

[Minbari]

There is already a dark gray a dark gray oxide layer on the inside of the kettle. This is more like small white mineral deposits that are flakes.

ah ok, it is more than likely just that then. minerals in the water.

I am no metallurgical expert, but I dont see galvanic corrosion happening in 1 hour.

 

[Thakaz]

Use a food grade, high temperature silicone o ring.

This on the inside. If they're touching on the outside you could use another o-ring or just throw some bond breaker tape on there and be done with it.

 

[MindenMan]

http://aluminumsurface.blogspot.com/2009/04/corrosion-between-anodized-aluminum-and.html

I read this article, not bad.