WHY GALVANIZING ?
Steel is strong. Its use throughout the world is to provide inherent strengths for buildings, bridges, pipelines, towers, trailers, cars etc. But steel is also weak ! It is susceptible to the unrealizing and often unseen effects of corrosion. Simple steel rusts losing its structural integrity and surrendering its strengths. However, steel which has been properly protected against the dangers of atmospheric attack can retain its strength for many years. Most importantly, IT WON’T RUST.
No other method of protection matches Galvanizing because of the unique combination of :
• Low initial cost
• Outstanding durability
• Predictable performance
• Low to zero maintenance
• Resistance to both atmospheric and impact damage
• Easy for quality control and inspection
There is only one way to provide guaranteed protection that is stronger than steel and that is through Hot Dip Galvanizing.
METALLLURGY OF GALVANIZED COATING:
HOT DIP GALVANIZING PROCESS:
Galvanizing is the practice of immersing clean, oxide-free steel into molten zinc to form a protective coating over the metal. The coating is bonded metallurgically to the steel and this coating helps to protect the surface against corrosion.
The zinc coating protects the steel in two ways:
• The base metal is protected from the atmosphere by the zinc coating.
• The zinc coating provides cathodic (or sacrificial) protection. This is because zinc has a greater electro-negativity than iron or steel, so it will corrode in preference to the base metal.
The principal method of making steel resist corrosion is by alloying it with another metal, Zinc. When steel is submerged in melted zinc, the chemical reaction permanently bonds the zinc to the steel throug h galvanizing. Therefore, the zinc isn't exactly a sealer, like paint, because it doesn't just coat the steel; it actually permanently becomes a part of it.
The zinc goes through a reaction with the iron molecules within the steel to form galvanized steel. The most external layer is all zinc, but successive layers are a mixture of zinc and iron, with an interior of pure steel. These multiple layers are responsible for the amazing property of the metal to withstand corrosion-inducing circumstances, such as saltwater or moisture.
Zinc also protects the steel by acting as a "sacrificial layer." If, for some reason, rust does take hold on the surface of galvanized steel, the zinc will get corroded first. This allows the zinc that is spread over the breach or scratch to prevent rust from reaching the steel.