Screwy question...

[daved20319]

Sorry, sometimes I crack myself up :-). And no, my wife doesn't appreciate my sense of humor, either.

I'm rebuilding all my windows, and luckily, none of the steel sheet metal screws holding the Plexiglas inner panes to the outer panes have been frozen or so corroded that they broke. But most of them are pretty rusty, so I'm planning on replacing all of them. My question is, should I stay with the galvanized screws, or would I be better off going with stainless steel? I know that electrolysis is an issue with dissimilar metals, but I can NOT remember if it's more or less of a problem with stainless vs. galvanized. Thanks.

Dave

[NevadaGeo]

Good question, zinc galvanized versus chrome stainless. I suspect the chrome will dissasociate less into the surrounding aluminum than the zinc. It would be nice if there was an aluminum screw strong enough to do the job.
You might try to repost this again in the daylite hours, the thread might disappear before morning.

[samb]

I have used stainless steel screws on aluminum trailers for years and have no problems with dissimilar metals corrosion.
Sam

[Ag&Au]

The reason stainless stains less is because it is less reactive other substances. Galvenizing is coating iron or steel with zinc. So until the galvenizing is broken down, It wil react with other sutances as though it were zinc. Zinc is used in some appliocations as a sacrificial piece of metal allowed to deteriorate to provide corrosion protection to other metals. I would infer from this that galvenizing is not a excellent long term solution. Keep in mind that there are different grades of stainless and I have bought some that has rusted. I am sure the is some other way to identify good from bad stainless, but not knowing what that is for sure, I rely on price.

Ken

[Nuvite-F]

Originally Posted by daved20319

My question is, should I stay with the galvanized screws, or would I be better off going with stainless steel? I know that electrolysis is an issue with dissimilar metals, but I can NOT remember if it's more or less of a problem with stainless vs. galvanized. Thanks.

Go with the stainless screws. Although the nickel and chromium content of stainless steel could create a galvanic couple, it doesn't, because the thing that makes stainless steel "stainless" is that it forms an adherent oxide layer on the surface of the metal that prevents it from oxidizing further.
.

[NevadaGeo]

Originally Posted by w7ts

. I am sure the is some other way to identify good from bad stainless, but not knowing what that is for sure, I rely on price.
Ken

Good stainless won't stick to a magnet, I don't think.

[dwightdi]

300 series stainless steel is non-magnetic. Stain resistant 400 series is magnetic. Fasteners are usually 302 or 304. That is what I usually use. 400 series is capable of being hardened and can be used to make knifes that actually hold an edge. Don't buy a stainless steel knife that is non-magnetic.

[ROBERT CROSS]

POI....replace ALL your exterior screws with stainless....clearance lights etc.

Ask me how I know.

Originally Posted by NevadaGeo

Good stainless won't stick to a magnet, I don't think.

.......yep.

Bob

[scf31]

I work in the Aircraft refurbish department, We always install hardware/fasteners wet with primer when dissimilar metals are used. a rule of thumb.

[Disneysue925]

Originally Posted by scf31

I work in the Aircraft refurbish department, We always install hardware/fasteners wet with primer when dissimilar metals are used. a rule of thumb.

What type of primer?

Thanks,
Sue

[ROBERT CROSS]

Originally Posted by Disneysue925

What type of primer?

Thanks,
Sue

Zinc-chromate or any one of the approved AS sealants.

Usually just a dab of acryl-r on the threads works for me

Bob

[Bob Thompson]

The common grades of stainless steel most of us have access to is Food Grade T304 and Marine Grade 316. There are many other grades, such as those used in medical implants, the above are the common ones. You want the Marine Grade 316 SS. I usually buy at West Marine.

[daved20319]

Thanks for all the responses. Bob, I didn't check prices at West Marine, but I was able to order them from McMaster-Carr for less than a penny apiece. I think I now have everything either here or on the way to wrap this part of the project up by the end of the week, early next week at the latest . Which is good, I'm heartily sick of playing with glass by now. Later.

Dave

[ROBERT CROSS]

Dave,

Got these from McM-C... also stainless....nice up-grade. K 300 series lockable

Bob

[Aerowood]

Originally Posted by Disneysue925

What type of primer?

Thanks,
Sue

Any good epoxy primer is the best

[Ag&Au]

Originally Posted by ROBERT CROSS

Dave,

Got these from McM-C... also stainless....nice up-grade. K 300 series lockable

Bob

A coincidence
I have the same black and silver little master padlocks on my storage doors.
The new latches you bought are identical to the ones that came on my trailer.
Ken