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RE: electrical reaction between steel and aluminum

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I'm also unfamiliar with the situation, but the connections could be
loosened and a PVC shim inserted to achieve the separation.  You should also
use SS bolts or there will be galvanic reactions with those, too.

Jack
_______________________________________________

I would suggest that the question of "can we live with this?" is for you
to answer.  I would tend to think that my response would be "no", but then
I am not familiar with the actual situation.  For example, if the
connection between the aluminum and steel a structural connection (i.e. is
load going through the connection)?  If yes, then I would think that the
corrosion would be a definite problem.  If no, then the corrosion could
only be an aesethic problem.

And yes, there will be corrosion.  A galvanic reation (if I recall
correctly) between the two dissimilar metals WILL occur.  Bascially,
aluminum + steel = big NO NO unless there is something to break the direct
physical connection (i.e. something like a rubber isolation pad, etc).

The key is to provide some sort of "break" between the steel and aluminum.
Unfortunately, I don't know of any way to do that with out pulling out the
"construction erasor" (i.e. demo the work) and rebuilding it per the
design.

Scott

On Mon, 26 Feb 2001, Drew A. Norman, SE wrote:
> Dear SEAINT list service subscribers:
> 
> Jeff Kao, staff engineer of Drew Norman and Associates, requests for
advise or suggestion on the issue of electrical reactions between two
dissimilar metals.  I am currently working on a project involving stair
modification at a store in LA.  The architect calls for glass guard rails as
a fall protection for an exit stair.  Guard rails are made of aluminum and
mounted to steel beams.  We specified coating of asphaltic paint to prevent
corrosion due to electrical reaction of these dissimilar metals.  The
contractor however failed to apply this coating and the stair is already
built.  The inspector denied to grant the certificate of occupancy on the
basis the stair is not built per design.  The architect asked to waive the
coating requirement.  Can we live with this?  Does anyone have any
suggestion or remedy to this problem other than tearing down the stair and
rebuild it per design?  You immediate input on this matter will be greatly
appreciated.
> 
> Sincerely,
> 
> Jeff Kao     
> 



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