The Galvanizing Process
To appreciate the design considerations, it helps to understand the basic steps of the galvanizing process. The fundamental steps are:
Soil and Grease Removal -- A hot alkaline or caustic solution removes dirt, oil, grease and soluble markings.
Pickling -- A dilute solution of hot sulfuric acid removes surface rust and mill scale to provide a chemically clean metallic surface. This pickling process, heated to about 150 ° F, attacks the base steel, getting beneath the rust and scale to achieve the adequate cleaning passes thru into the zinc.
Fluxing -- Our "wet" flux is a frothy blanket that floats on the surface of the zinc bath, and is a combination of zinc and ammonium chlorides that clean and protect the previously pickled steel. This flux forms a protective barrier on the steel as it passes thru into the zinc, in addition to removing any oxides that may have formed on the steel's surface.
Galvanizing -- This is where the steel actually gets its silver/grey coatings. The article is immersed into a bath of molten zinc heated to about 830 F. During the process, the steel comes up to the bath temperature and the zinc metallurgically bonds to the steel, creating a series of highly abrasion-resistant zinc-iron alloy layers.
Inspection -- Coating thickness and surface condition inspections complete the process to ensure compliance with specification. Electronic gauges are used to give quick and accurate measurement readings of the coating.