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Bolts for aluminum brackets - SS or Galvanized?

January 30, 2012

Q. I am replacing some rusted-out steel brackets on porch steps with aluminum brackets. There are a lot of these, so cost is an issue, as is life. Should I use SS bolts (galvanic corrosion issues?) or galvanized steel bolts?

Max Harcourt
- St. Thomas, USVI

February 24, 2012

Q. Have roughly the same question: I need to replace rusted screws in an aluminum pool cage in Sarasota, FL, both aluminum to alum. and alum. to concrete. One pool guy said SS screws would corrode the aluminum and render the connection useless. Another pool guy said get the coated SS screws, they're expensive at 50 to 60 cents each so count how many you need. He also said (at age 50), he wouldn't be around when this corrosion became evident. I found coated SS screws at $1.60 each, over $160 per box of 100. Any suggestions as to what to use? I'm tempted to spray paint regular SS screws.

Douglas Vogt
- Sarasota, Florida, USA

February 27, 2012

A. Hi, Max and Douglas.

Personally, I'd go with plain stainless. Stainless screws are commonly used to join aluminum. Although it's true that stainless and aluminum are not galvanically compatible, the surface area of the aluminum is far greater, so the galvanic current should not be excessive. But don't try the reverse.


Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

February 28, 2012

A. Hi guys,

I've used SS bolt in connecting aluminium clamp in HV power for more than 15 years now and this is always our practice, thus there is no problems with respect to galvanizing effect chemically.



Wilfredo H. Meneses
- Doha, Qatar

March 2, 2012

A. My suggestion to you is to maximise your corrosion protection.
Use 316 SS fasteners and use nylon insulating washers.
Belts & Braces.
Hope this helps.

William Doherty
Trainer - Salamander Bay, Australia

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