Stainless Steel/ Aluminium reaction

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onleyb

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Bizarre, my thread did get tangled! Thanks guys for your replies but here it is again in case I missed anything. Any suggestions would be good. I plan to use some stainless steel screws in an aluminium panel. Although on a boat, it's not anticipated the fixings will be subject to water. Can anyone tell me if these disimiliar metals will react? I plan to make an access panel for a petrol fuel tank and clearly do not want the flange falling of due to any type of corrosion. Thanks in advance
 
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I plan to use some stainless steel screws in an aluminium panel. Can anyone tell me if these disimiliar metals will react?

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Sure they will react.. if they will be any humidity between them.. (very comon in a boat!) and in a short period of time, they will be completely welded together..

One possibility is to use a "sizing" product (like Loctite one - www.loctite.com) before puting the screws in place..
 
My advice would be DON'T DO IT.
As you rightly identified you can't afford the joint to fail, especially with PETROL in the tank.
Get a proper bolted flange and lid made up and welded in place (I know it's a big job) or get a new tank.

Cheers.
 
Agree with others, but another ideamight be...I wd imagine your panel isn't subject to intense pressure/strain. Do you mean you plan to use "set screws" - or tapered self tappers? Either way you could assemble the whole thing with stainless, and then replace each one with an aluminium screw- if you can find them. They are a bit specialist at the moment but becoming more common eg for automotive weight-saving.

This is just an idea - i haven't tried it. Flamings welcome...

edit: if you do use s/s, use nylon washers which at least will keep the corrosion away from the head/ally area hence make unscrewwing much harder. Also if poss make sure the head is allen key type (cap screw) or hex rather than pozidriv/phillips which won't be so good to get hold of later...
 
Old thread I know but I thought you would find this useful. As mentioned as soon as you put two alloys together with a gap on the Galvanic Series chart, this would lead to Galvanic Corrosion. Stainless and Aluminium is a bad combination once you add an electrolyte like salt water. This is why Stainless Screws tend to eat Aluminium masts badly. Best the dissimilar metals are isolated with Tef Gel or Durlac or something like this. Tef Gel is best as it also lubricates the thread, doesn't go hard and so later can be un-done.
 
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