Carbon Steel to Aluminum connections
Carbon Steel to Aluminum connections
(OP)
I have a structure that I am designing where the majority of the roof structure is aluminum sections, however the columns are carbon steel. I plan on specifiying that the columns and any carbon steel connection elements be hot dip galvanized. Is there any fastener precautions I need to take to avoid galvanic corrosion? Should I specify stainless steel or aluminum fasteners over galvanized carbon steel fasteners? Thank you very much for the help.






RE: Carbon Steel to Aluminum connections
BA
RE: Carbon Steel to Aluminum connections
RE: Carbon Steel to Aluminum connections
RE: Carbon Steel to Aluminum connections
RE: Carbon Steel to Aluminum connections
RE: Carbon Steel to Aluminum connections
RE: Carbon Steel to Aluminum connections
RE: Carbon Steel to Aluminum connections
The reason you would galvanize is to remove the drive for the steel to oxidize, but pure aluminum will oxidize preferentially to zinc, based on electrochemical series. The best solution in most cases is to use corrosion resistant primers on all components. Never paint the most exposed parts and not the others, this sets up for focal macrocell corrosion, where one part which is remote but connected sacrifices to prevent corrosion of another - like cathodic protection - but the area of metal sacrificing is small relative to the "protected" material. Best success is probably achieved by priming everything after fabrication but before assembly.
The use of stainless hardware will remove corrosion at the fasteners, but do nothing for cathodic reactions away from the fastener, or between the connected metals.