Bolts through Aluminum
Bolts through Aluminum
(OP)
Sample situation:
Aluminum angle ledgers attached to wall, wall sign with aluminum angle stringer to hang off ledger. What type of bolts are best to fasten along the length (exclude aluminum bolts)?
Steel manual and other sources show that a mechanically deposited or hot dipped bolt would be best, with stainless steel being a second best choice. All assuming exterior exposure, but not in a terribly corrosive environment or receiving salt spray. Couple this with aluminum and zinc being super close on galvanic series.
I am curious about this because I feel like literature says one thing, but I get comments back from plan checkers and other PE's from third party reviewers saying another thing..."people" aare frequently championing stainless steel "just because" of the name of it (I feel).
Can we field some comments please?
Aluminum angle ledgers attached to wall, wall sign with aluminum angle stringer to hang off ledger. What type of bolts are best to fasten along the length (exclude aluminum bolts)?
Steel manual and other sources show that a mechanically deposited or hot dipped bolt would be best, with stainless steel being a second best choice. All assuming exterior exposure, but not in a terribly corrosive environment or receiving salt spray. Couple this with aluminum and zinc being super close on galvanic series.
I am curious about this because I feel like literature says one thing, but I get comments back from plan checkers and other PE's from third party reviewers saying another thing..."people" aare frequently championing stainless steel "just because" of the name of it (I feel).
Can we field some comments please?





RE: Bolts through Aluminum
RE: Bolts through Aluminum
RE: Bolts through Aluminum
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RE: Bolts through Aluminum
Aluminium and stainless steel are at opposite ends of the galvanic chart. Having said that, I have used a lot of stainless steel fasteners on aluminium on scientific equipment, most of it airborne, and I have not seen corrosion.
How are you finishing your aluminium. If you don't need to be conductive, you should anodize it.
--
JHG
RE: Bolts through Aluminum
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.
RE: Bolts through Aluminum
How much salt will it see?
The worse the conditions the more it favors double weight galvanized steel fasteners.
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P.E. Metallurgy, Plymouth Tube
RE: Bolts through Aluminum
Large amount of aluminum area compared to bolts.
No salt spray, minimal direct water exposure. Basically, I called out galvanized fasteners to save my client money - I think it a better option all things considered, but I got a comment back from a plan checker to switch to stainless. Client doesn't want t incur cost and I don't think its necessary, in fact, I personally think its a worse decision...hence why I posted the question here...
RE: Bolts through Aluminum
galvanic series
Fastenal Galvanic Corrosion