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WHAT IS HOT-DIP GALVANIZING?

Galvanizing methods such as hot-dip galvanizing, electrogalvanizing and mill galvanizing are the main covering operations which are used for protection of the steel, iron or steel coils from corrosion.

The history of galvanizing starts from 1742...

The history of galvanizing starts from 1742 when Paul Jacques Malouin, a French chemist described a method of coating iron by dipping it in molten zinc in his presentation to the French Royal Academy. Thirty years later, Luigi Galvani, an Italian physician discovered more about this electrochemical process that occurs between metals. The term galvanization appeared in the lexicon by Michael Faraday, an English scientist and in 1829, he discovered zinc’s sacrificial action. Then, Stanislas Sorel, a French engineer obtained a patent for the galvanizing process. In 1870, the first galvanizing plant opened in the United States.

Hot-Dip Galvanizing Processin 3 steps

Hot-dip galvanizing process consists of three basic steps: Surface Preparation, Galvanizing, and Inspection.

Surface Preparation

Surface preparation is the most important step in the application of the cover because incorrect cleaning of the surface is the cause of a coating failure.

Galvanizing

After cooling process, the zinc coating is metallurgically bonded to the steel.

Inspection

In the end, a variety of simple physical and laboratory test is performed to determine the thickness of the steel.

HOT-DIP GALVANIZING is the most used process of coating iron or steel with a protective layer of zinc. It provides a tough, metallurgically bonded zinc coating that completely covers the steel and prevents it from corrosion. The galvanizing reaction only occurs on a chemically clean surface. Clean steel is dipped into molten zinc at a temperature of around 842 °F (450 °C), then it is covered with a robust coating which is formed by the reaction between the iron and zinc.
Hot-dip galvanizing process consists of three basic steps:
-Surface Preparation
-Galvanizing
-Inspection

Surface preparation is the most important step in the application of the cover because incorrect cleaning of the surface is the cause of a coating failure. Degreasing, Pickling, and Flux Solution include the Surface Preparation procedure. This process starts with the cleaning of the surface from all rust, dirt, grease, oil, and mill scale. Rust is removed by pickling the steel in the heated sulfuric acid. Fluxing is the final step of the surface preparation. The dipping of the steel in flux tank removes oxides. Flux can be applied in wet or dry ways. In the dry galvanizing process, the material is dried before the immersion in molten zinc. A layer of liquid zinc ammonium chloride is floated on the top of the bath of molten zinc in the wet galvanization. The steel is removed from the bath and left to cool in a quench tank.

After cooling process, the zinc coating is metallurgically bonded to the steel. Spangle is the crystallized pattern which appeared on the surface of the steel after galvanizing. In the end, a variety of simple physical and laboratory test is performed to determine the thickness of the steel. It is one of the most important components in detecting the quality of a galvanized coating. The uniformity, adherence, and appearance should also be checked. The performance of the galvanized coverings has been proved under numerous environmental conditions, extreme hot and cold temperatures. Hot-Dip Galvanizing may protect the steel from corrosion for up to 50 years.

Get quote from us about your galvanizing machinery needs. Tell us all the details.

Get quote from us about your galvanizing machinery needs. Tell us all the details.

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