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RE: Protecting Steel from Rusting Due to Aluminum Mate

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Ed,

Good old industrial paint will not give you the separation that you should
have to prevent dissimilar metal galvanic corrosion.  Adding galvanizing
just adds one more dissimilar metal to the mix and can exacerbate corrosion.

Depending on the connection, I prefer a sheet of PVC (or some other plastic)
to provide definitive separation.  Connect the materials with a good SS
bolt.  (Use at least a type 318 SS bolt.  If you just say SS bolt, you will
get an 18-8 which is not a very good stainless.)  

You could also consider a bituminous coating to provide the separation.  

Basically the separation materials are trying to:
A.	Protect the surface
B.	Electrically separate the materials. (This is where some coatings
come up short.)

Regards,
Harold Sprague


> -----Original Message-----
> From:	Ed Fasula [SMTP:tibbits2(--nospam--at)metro.lakes.com]
> Sent:	Friday, May 12, 2000 1:49 PM
> To:	seaint(--nospam--at)seaint.org
> Subject:	Protecting Steel from Rusting Due to Aluminum Mate
> 
> Have any of you had to protect steel that has to be bolted up to Aluminum
> for exterior use?  Is good industrial paint good enough?  How does
> galvanization affect things?
> 
> Thanks,
> Ed 
>