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Corrosion issues with Aluminum, Copper and Stainless Steel

Q. I am constructing a project utilizing a knock-down aluminum tube frame. I wish to use hard copper elbows to join aluminum tube frame members. The elbows must be permanently joined to one frame member at each knock-down joint. The means of attaching the elbow to the tubing must be able to withstand torsional stress without breaking. I've considered gluing the joints with epoxy or using stainless steel pop-rivets. The tubing is the same size as 1/2" ID copper.

I realize that there are galvanic issues with these materials (AL/CU, AL/SS). Being that this is a prototype, I am willing to accept this problem if I can get some idea of how serious it will be. If I use epoxy, will I lessen the chances of this happening since the epoxy may insulate the joints to some extent? Also, being that the tubing is so small, the rivets will be small also. How will galvanic corrosion effect the performance of the pop-rivets and holes? Is there another effective means of fastening these components together that I have not tried?

Keith Rundquist
Facilities Manager - Chicago, Illinois, USA
2004

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Q. Hi- We are looking at sprinkler proofing some existing electrical equipment. We want to use aluminum metal to achieve this protection. However, I have been told by a consultant that dissimilar metals will not work. They state that the aluminum will react with the zinc contained in the ASA61 paint on each panel. Is this true? Do we have to use stainless steel or metal? We have completed over 20 panels with aluminum so we would like to get a professional answer with regard to this reaction. Just to let you also know the basement area houses many panels along with a many batteries at this phone center. Should I be worried about the acidic nature of the batteries and its possible reaction with aluminum? Please advise.

Robert Kost
- Winnipeg, Manitoba, Canada
2004