WHAT ARE THE ORIGINAL RIVETS REPLACED WITH WHEN THEY BECOME CORRODED?
Since 1970, as various construction projects and painting projects occur across the Bridge, the original rivets are being replaced with ASTM A-325 high-strength bolts of equal diameter. In the early 1970s, corroded rivets were replaced with ASTM A-325 high-strength bolts dipped in organic zinc rich primer prior to installation. When galvanized ASTM A-325 bolts became available in the mid-1970s, corroded rivets have been replaced with galvanized high-strength bolts. When installing high strength galvanized bolts, they have to be pre-tensioned a certain amount so they “clamp” the connection together rather than “pin it” together. Using a predetermined torque value can result in being either over or under the required pre-tension depending on the roughness of the contact surfaces of the turning elements. Using the “turn of the nut” method sidesteps the potential over or under pre-tensioning problem, but it varies depending on the length of the bolt. So, what is normally done is that worke
