Hot-dip galvanization is a form of galvanization. It is the process of coating iron and steel with zinc, which alloys with the surface of the base metal when immersing the metal in a bath of molten zinc at a temperature of around 449 °C (840 °F).
When exposed to the atmosphere, the pure zinc (Zn) reacts with oxygen (O2) to form zinc oxide (ZnO), which further reacts with carbon dioxide (CO2) to form zinc carbonate (ZnCO3), a usually dull grey, fairly strong material that protects the steel underneath from further corrosion in many circumstances.
Building design and construction process — step by step
The process of hot-dip galvanizing results in a metallurgical bond between zinc and steel, with a series of distinct iron-zinc alloys. A typical hot-dip galvanizing line operates as follows:
1. Caustic cleaning
Steel is cleaned using a degreasing solution. This removes oil/grease, dirt, and paint.
The degreasing solution is rinsed off the steel in water (optional if acidic degreaser is used).
The steel is pickled in an acidic solution to remove mill scale.
The pickling solution is rinsed off with water
5. Flux solution
A flux, often zinc ammonium chloride is applied to the steel to inhibit oxidation of the cleaned surface upon exposure to air. The flux is allowed to dry on the steel and aids in the process of the liquid zinc wetting and adhering to the steel.
The steel is dipped into the molten zinc bath and held there until the temperature of the steel equilibrates with that of the bath.
7. Zinc Bath
The steel is cooled in a quench tank to reduce its temperature and inhibit undesirable reactions of the newly formed coating with the atmosphere.
Benefits Of Galvanizing
Galvanized steel is widely used in applications where corrosion resistance is needed and is considered superior in terms of cost and life-cycle.
Like other corrosion protection systems, galvanizing protects steel by acting as a barrier between steel and the atmosphere. However, zinc is a more electropositive (active) metal in comparison to steel. This is a unique characteristic for galvanizing, which means that when a galvanized coating is damaged and steel is exposed to the atmosphere, zinc can continue to protect steel through galvanic corrosion, it self-repairs when damaged, sacrifices itself to protect the base metal.
Hot dip galvanizing offers coverage both externally and internally within hollow sections, is environmentally sustainable, has good impact and abrasion-resistance and a maintenance-free life of 50 years or more. Galvanized steel is widely used in applications where corrosion protection is needed
Applications of Galvanized Steel
Galvanized Steel has versatile applications. It can be installed outdoors and indoors, where ever higher service life of the steel is required and corrosion protection is needed to maintain functionality of the product.
Some of the major consumers of galvanized steel are the following industries
Our Plant Locations
Hylite Group has in all 3 galvanizing lines strategically located to cater to industries in the Mumbai- Pune region.
The Hylite group is a one stop solution to all coating needs. Even when it comes to galvanizing we are the only sundry galvanizing company who has 3 baths of different sizes to cater to a variety of customers irrespective of job specifications, size and location.
Design for Hot Dip Galvanising
Inspection of work before dispatch to the Galvaniser
Fabricated assemblies, casting and other components for hot dip galvanising should be inspected and any significant surfaces identified before dispatch to the galvaniser to ensure that the following points conform to design requirements. This may avoid costly rectification and delays at the galvinishing plant.
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