whilst we're on the bolting topic. In regards to the galvanic corrosion of bolts as pointed out by the good dr, people shouldn't underestimate the impact of this process, it is a very real risk, and given that the shank of the bolt is usually hidden by the hanger and the nut, it could be quite dangerous. I have seen cases of galvanic corrosion where a copper plaque that was installed wrong by the builder, had resulted in the entire steel structure beginning to corrode in preference to the copper! The solution is simple, always use like materials, period.
P.S. FYI good dr. there is a common misconception that galvanising is actually a zinc plating process. In actual fact, the galvanising process creates a series of layers (of varying composition) of Zinc Iron alloy, which is why galvanised steel can last for hundreds of years, compared to a coating (i.e. zinc rich paints etc.) which is very easily scratched, and may not last even a decade in exposed conditions |