Aluminum Pads, Connecting Hardware Choice

[milwaukeebob]

I have an electrical application requiring the connection of two flat aluminum surfaces. The connection requires bolting hardware. Ideally the hardware would be aluminum. Unfortunately due to project schedule and availability, aluminum hardware is not available. My choice is to use stainless steel or yellow chromate alloy hardware. This is for an outdoors electrical connection in non-corrosive, non-coastal environment. We typically use SS hardware on all electrical connections but my concern is galvanic corrosion between the aluminum surface and SS flatwashers...but the SS hardware does have the advantage of being more corrosion resistant then the chrommate.

Comments and feedback is much appreciated. Thanks

 

[cloa]

I don't see a problem- no electrolyte unless rainwater is trapped and even then pure water is a poor electrolyte needs some salt to be bad- no galvanic corrosion.

 

[milwaukeebob]

Thanks cloa. Excellent point.

 

[KENAT]

What treatment, if any, do the AL plates have? Does this treatment go into the mounting holes?

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[adamgnt]

Hi Bob,

I take it the aluminum pads are not designed yet. I would open up the mounting holes by one standard increment before anodizing, then simply use a plastic isolation shoulder washer at the connect points. This way you can use your SS or galvanized hardware with no risk of galvanic corrosion at the electrical contact points.

Cheers!
--Adam