Hot Dip Galvanizing
What is Hot-Dip Galvanizing?
Hot-dip galvanising (HDG) is the process of coating fabricated steel by immersing it in a bath of molten zinc. There are three fundamental steps in the hot-dip galvanising process; Surface preparation, galvanizing and inspection.
Hot-Dip Galvanizing provides a number of benefits to the steel it protects. The Metallurgical-bonded zinc-iron alloy layers not only create a barrier between the steel and the environment, but also cathodically protect the steel. The cathodic protection offered by zinc means the galvanised coating sacrifics itself to protect the underlying base steel from corrosion. The tightly adhered coating, which has bond strength of around 3600 psi, is also extremely abrasion-resistant, as the intermetallic layers are harder than the base steel. However,, even if the coating were damanged, zincs sacrificial action will protect exposed steel upto1/4inch away.
In addition to the cathodic protection offered by hot-dip galvanizing, there are a few other characteristics of the coating which provide longevity.First reaction in the galvanizing kettle is a diffusion process, which means the coating grows perpendicular to the surface, ensuring all corners and edges have at least equal thickness to flat surfaces. furthermore, the completed immersion in the zinc coating naturally develops an imprevious layer of corrosion products on the surface, know as the zinc patina. The patina, cathodic protection, complete coverage and all of these other features, provide hot-dip galvanized steel with along, manitenance-free service life. the time of first maintenance for hot-dip galvanized steel can be seen in this chart