I am trying to find more information on what options you provide for coating Transmission Line Steel Tower Structural Bolts (ASTM A394 and similar), coating(s) for highly corrosive environments (such as near the ocean).
The A394 specification provides specially provision for the Zinc Hot Dip Galvanization coating, However it doesn’t specifically prevent the use of other coatings. We would suggest the use of the recommended alternative which is Type 3 weathering steel that will provide corrosive protection and is listed within the A394 standard.
Type 3 Weathering Steel
These high strength fasteners have atmospheric corrosion resistance and weathering properties. This means that Type 3 structural bolts are designed to weather and rust over time. Unlike Type 1, their rust acts as a protective barrier or “coating” that seals the bolt.