The bridge is 70 years old and is in the process of being fully abrasive blasted and repainted.
Most of the rivets that are corroded have been in locations where they is higher humidity / moisture and the painting system has failed.
Aluminum or stainless is not a option due to galvanic corrosion.
I'm working on a pedestrian bridge that have some 20,000 rivets of which 10% are corroded. The corroded rivets range from no head left to only a small amount of head missing. It is easy to decide what to do with those both ends of the spectrum, but how do I decided when where is the point where...
