[RE-wrenches] Galvanic corrosion

[Darryl Thayer]

Alimunium against  galvanize (zinc) is stable, I have been doing this for 40 + years and I have not seen corrosion, I have seen rapid corrosion with copper to galvanize, eating the galvanize up.  Also I have seen copper to Aluminium being corrosive, eating on the aluminum.  Galvanize  is stable and a good electrical conductor, everyone uses it, power compinies and electrical contractors.  since 1900!  The problem is the aluminum getting a Aluminum oxide coating on it and becoming an insulator.  The electrical industry puts a Tin coating on electrical fittings, to protect the connection between copper and galvanized steel.  

Bill brooks published a "Tribal electric Series" once, this told what we could expect from metals in contact.  Aluminum is close to galvanized, so one would expect little reaction.  

By way of comparision I removed and reinstalled a system, AL frames on to galvanized Unistruct, first put up in 1980, I reused all teh same parts.
Darryl 

--- On Thu, 12/30/10, Joel Davidson <joel.davidson at sbcglobal.net> wrote:

> From: Joel Davidson <joel.davidson at sbcglobal.net>
> Subject: [RE-wrenches] Galvanic corrosion
> To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
> Date: Thursday, December 30, 2010, 9:36 AM
> Wrenches,
> 
> Galvanic corrosion has been discussed before, but I am
> hoping that you all have come up with better, faster,
> cheaper ways to fasten and ground aluminum framed modules to
> steel and galvanized steel mounting structures. I am
> particularly interested in how to effectively and
> permanently ground aluminum framed modules to galvanized
> steel and - ready for the big challenge - getting the AHJ's
> approval.
> 
> Best wishes for another wonderful year of fun in the sun.
> Joel Davidson 
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