aluminum fittings in a stainless tank?

[pybyr]

as I try to finalize and move forward with my "stratification baffle" for use in my 409 stainless unpressurized tank, I'm running into the fact that stainless fittings and flanges are fiercely expensive

anyone have any reaction on how aluminum would hold up in a solution of regular water, as long as it is isolated from actual contact with the stainless by way of non-electrically-conductive rubber or silicone hose or spacers?

Thanks

 

[steam man]

Unless you have ultra-pure water I would think that you would have the makings of a battery. My guess is that the aluminum would dissolve over time. There are reaction charts for dissimiliar metals.

Mike

 

[DaveBP]

In the marine environment, stainless and aluminum together is a no-no. I've seen a number of aluminum masts that had rotted out where stainless hardware was mounted to them. But loctite thread sealer is enough to prevent it. Keeps the salt water from getting into the contact area, I guess. So they don't seem bent on destroying one another like some combinations.

Lots of different alloys of aluminum out there; some not very corrosion resistant in fresh water. The 5000 series is used a lot in marine hull frames and plates. If you're just thinking of sheet metal and pop rivets, aluminum flashing is cheap and easy to get and holds up to a certain amount of moisture. Consider it a disposable prototype material. If plumbing and fittings are part of the design, check out MSC. Not the cheapest, but a great source for plotting and scheming.

http://www.mscdirect.com

 

[pybyr]

Thanks guys- shortly after I posted the question, I was flipping through my big McMaster-Carr catalog and spotted polypropylene fittings- which may be my answer- temp resistant, and not too expensive.