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Several coating references are provided at the end of this section. BASICS OF PROTECTIVE COATINGS The Corrosion Process A clear understanding of the corrosion process is essential to understand the steps to inhibit corrosion with protective coatings. SYSTEMS PAGE 26 Oxygen combines with iron, the major element in steel, to form rust. This electrochemical process returns the iron metal to the state that it existed in nature—iron oxide. The most common form of iron oxide or iron ore found in nature is hematite (Fe203), which is equivalent to what we call rust.

Slight residues of rust and paint may be left in the lower portion of pits if the original surface is pitted. OTHER SUBSTRATES In addition to steel, there are other surfaces that must be coated for aesthetic, safety or corrosion inhibition purposes. These surfaces must also be prepared properly for coating. Concrete. Concrete should be coated for the protection from moisture penetration and the resulting physical damage of spalling. There are several factors to consider when preparing concrete to receive coating.

Columns may share common footing. Figure 16. Double-column movement connection Connection with long horizontal slots and finger tight bolts. Beam Movement Joint Seated connection with slide bearing pad and finger tight bolts. Stiffener Figure 17. Seated slide-bearing connection SYSTEMS PAGE 20 FLOOR VIBRATION Movement of floors caused by occupant activities can present a serious serviceability problem if not properly considered and prevented by the design of the structural system. Humans are very sensitive vibration sensors - vertical floor movement of as little as forty thousandths of an inch can be very annoying.