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Hot-Dip Galvanizing Process

An artful sculpture glinting under the sun, a sturdy bridge arcing over a rushing river, a beautiful architectural wonder: all these steel structures utilize hot-dip galvanizing for corrosion protection. Throughout the world, new technologies and creative chemistry continue to evolve this 150 year old process. Once used only for corrosion protection, hot dip galvanizing is now specified for its cost-effectiveness, versatility, durability, longevity, and sustainability. Hot dip galvanizing: protecting steel for generations!

Hot-dip galvanizing is the process of immersing fabricated steel into a bath of molten zinc. A wide variety of shapes and sizes can be galvanized from small nuts and bolts to large structural beams to intricate artistic pieces. Galvanizing facilities are available throughout North America, and steel can be galvanized year-round. Prior to immersion in the zinc kettle, the steel must be chemically cleaned to remove all oil and grease, dirt, mill scale, and oxides. After cleaning and drying, the steel is immersed in the molten zinc. The 98 % pure zinc bath is heated to 830 degrees Fahrenheit. While in the kettle, the zinc metallurgically reacts with the iron in the steel to form a series of inter metallic layers. After the steel is removed and cooled, it is inspected to check the zinc coating thickness and appearance. Any sharp rips or spikes are removed, and the thickness is measured. The final look of the galvanized coating can vary from piece to piece. The appearance is determined by steel chemistry, zinc bath composition, and cooling rates. Whether bright and shiny or a matte gray, the final visual appearance does not affect its corrosion protection.

While hot dip galvanizing is primarily specified for its superior corrosion protection, it may also be chosen for its durability, maintenance-free longevity, environmental sustainability, and aesthetics. Steel is an abundant and efficient building material, but when exposed to the atmosphere it immediately begins to corrode. The hot-dip galvanized coating provides three levels of corrosion resistance: barrier protection, cathodic protection, and the zinc patina. The hot-dip galvanized coating effectively protects steel from the environment, providing barrier protection. Galvanizing also provides cathodic protection meaning the zinc will corrode first to protect the underlying steel. Even if the coating is scratched, the surrounding zinc will continue to resist corrosion of the steel. As zinc is exposed to the environment, it naturally forms byproducts on the surface known as the zinc patina. The zinc patina further slows the corrosion rate of the zinc and acts as an additional environmental barrier.

Galvanized steel products deliver proven durability. Even in harsh conditions, the inner metallic layers formed in the galvanizing kettle make the coating harder than the base steel. This provides unparalleled abrasion resistance. Galvanizing also provides uniform protection. The zinc coating grows perpendicular to the steel so corners and edges have the same thickness as flat surfaces. The immersion process also ensures hollow and tubular structures are evenly coated and protected inside and out. Because of its maintenance-free longevity, hot-dip galvanized steel is utilized in some of the harshest environments. Commonly used on structures exposed to the atmosphere, galvanized steel can provide over 70 years of maintenance-free corrosion protection. Hot-dip galvanizing is commonly used to protect steel embedded in soil and concrete, or submerged in water. Galvanized steel has a proven record of longevity in all of these environments. Maintenance-free longevity also delivers economic value. A final cost of hot-dip galvanizing can amortized over the entire life of the project. Hot-dip galvanized steel is highly sustainable, and provides many environmental benefits. Zinc is a natural element, essential to life and abundantly found in the Earth's crust. Zinc and steel are 100 % recyclable, making galvanized steel safe for future generations. Galvanized steel offers an attractive natural finish that blends with its surroundings. But, if the natural metallic gray finish does not suit the project, the coating can be painted or powder coated for additional aesthetic appeal. 

As the world continues to evolve, it's important to construct a better environment for the future. The natural finish of hot-dip galvanized steel transcends time with little environmental or economic impact, all while providing superior corrosion protection, durability, longevity, and beauty. Hot-dip galvanizing: protecting steel for generations, sustaining the environment, and maintaining your quality of life!

 


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