The hot dip galvanizing process creates a combination of corrosion protection properties which are unmatched by other coating systems. The thick metallic zinc envelope completely covers the surface of the steel creating a series of metallurgically bonded zinc-iron layers. The tightly adherent middle alloy layers are, in fact, harder than steel core, providing a high level of resistance to mechanical damage in addition to corrosion protection. Since zinc corrodes preferentially providing cathodic protection to areas of bare steel, the structure remains protected even in the event of exposure due to abrasion or impact damage. The sacrificial nature of zinc prevents the exposed steel from corroding, eliminating any undercutting or blistering of the coating.
A hot dip galvanized zinc coating has the capacity to provide maintenance-free protection performance for the designed lifespan of the structure. It has a rate of corrosion proportional to its thickness and directly determined by the environment to which it is exposed - typical lifespan expectations based on an 87 micron thick galvanized coating, for example, range from twenty years in a heavy industrial environment to more than fifty years in a rural one.
Galvanized Coatings are Thicker at corners and edges. The process is "self-inspecting." Any coating problems or inadequacies will be immediately apparent when the steel is withdrawn from the molten zinc. Unlike multicoat paint systems, this allows for immediate corrective action. The coating cross section above shows the relative hardness of the intermetallic layers. Zinc hot dip galvanizing is selected for its fast turnaround, predictable lifespan, unsurpassed reliability, cathodic protection, ease of inspection, and for its cost effectiveness.