A steel tower spends its whole life outside. Wind, rain, salt air and industrial fumes attack every exposed member, so the protection system is not a detail, it is the service life.
We galvanize almost every member after fabrication. The anchor bolts are left out because they need to stay adjustable. The zinc coat is measured by plate thickness. On members 5 mm or thicker, the coating reaches at least 86 µm; on thinner members, at least 65 µm. Done correctly, the finish is expected to hold up for about 30 years.
The surface should be smooth, free of burrs, drips and rough lumps, with no bare steel showing. When it is hammered, the zinc stays bonded and neither peels off nor bubbles. Where transport knocks a spot bare, we clean the rust and touch it up before erection.
Once the tower is standing, the base plate and anchor bolts need a final seal. The gap under the foot plate is filled with fine concrete, and the exposed bolts and plate are boxed in with low-strength concrete, at least 50 mm thick. That last step keeps water out of the joint and is what stops the base from rusting first. We re-check the zinc thickness with a gauge before each order ships.
