Hot dip galvanizing process

Hot dip galvanizing process

hot dip galvanizing process

Hot dip galvanizing is a process for steel corrosion protection that consists of specific surface preparation and dipping it into a bath of molten zinc alloyed at 450 °C for 3-10 minutes. Following this process, a coating is formed on the steel surface due to the reaction between Fe and Zn having a metallurgical bond with the substrate, consisting of several layers of inter-metallic compounds with different concentrations of zinc. This coating has a very good resistance to corrosion, abrasion, impact, thermal shock etc.

Here are the main steps of the hot dip galvanizing process:

 

Reception and inspection

Checking of surface condition, adequate design for galvanizing and vent and drainage holes that allow access and flow of surface preparation solutions and molten zinc on both interior and exterior surfaces.

 

Jigging

Jigging products on racks or other special devices that are subsequently transferred by cranes to the surface preparation tanks.

 

Degreasing

Degreasing is a chemical cleaning process whose goal is to remove dirt, easily soluble oils, grease, water soluble dyes and other contaminants from the surface.

 

Pickling

Acid pickling is a chemical cleaning process, following the degreasing, which removes rust, shearing or other contaminants before galvanizing.

Usually water insoluble dye, abundant grease and welding slag cannot be removed in the cleaning steps mentioned above, they must be removed by the beneficiary before sending the products to galvanizing.

 

Fluxing

Fluxing is the final surface preparation process before hot dip galvanizing. Pickled products are immersed in the zinc chloride and ammonium chloride fluxing solution. The fluxing purpose is to provide additional and final cleaning of the steel until it enters the molten zinc bath. Fluxing also provides a temporary barrier corrosion protection to prevent subsequent formation of rust on the steel.

 

Drying

Components are hot air dried before being immersed in molten zinc bath to evaporate moisture and dry flux layer.

 

Hot dip galvanizing

Hot dip galvanizing process involves dipping the products, cleaned of rust, mill scale and other contaminants in a bath of molten zinc. It reacts with the steel to form a uniform coating, metalurgically bound to the substrate, composed of several phases of iron / zinc alloys, with a layer of pure zinc at the surface which has a bright and shiny appearance, specific to galvanized products.

Certain steel compositions react excessively with the zinc resulting thick layers with a less attractive appearance which however do not adversely affect the corrosion resistance of the products.

hot dip galvanizing process

 

Dejigging and cooling

Products are dejjiged from the racks and are allowed to cool down in the air.

 

Fettling and inspection

Products are cleaned, weighed and then inspected carefully in terms of layer thickness, appearance and compliance with the requirements of SR EN ISO 1461.

 

Packaging and delivery

Hot dip galvanized components are packed and prepared to be collected or delivered to the beneficiaries.

 

Use, storage and transport

Hot dip galvanizing is a corrosion protection process performed in order to prevent steel rusting (oxidation). A hot dip galvanized metal object can be stored, transported and used in any natural weather conditions, in air, water, in soil or on soil. In any of these circumstances the role of hot dip galvanization corrosion protection is not affected. Instead, the aesthetic appearance of the deposit may change. White stains may appear or different shades, zinc flower, shiny or matte surfaces etc. All these aesthetic changes of the got dip galvanized surfaces occur due to triggering the mechanism by which zinc protects the steel and prevents the rusting (oxidation) thereof. In recent years, the aesthetic appearance of hot dip galvanization has been increasingly emphasized. However, one must point out that hot dip galvanizing primarily serves as corrosion protection. Changes in the appearance of galvanized surfaces that can arise from multiple natural causes are unrelated to the purpose for which the galvanization was performed i.e., corrosion protection.

 

Our address:
4 Industriei Street
420063 Bistrita, ROMANIA
Contact:
Phone: (+40) 263 234 312
Fax:     (+40) 263 234 278

Located in Bistrita, a town of profoundly Saxon tradition, BETAK Company aligns with the tradition of Transylvanian manufacturers, famous in Europe thanks to the top quality products compliant with the most demanding standards in the field.From the legal point of view, BETAK S.A. [joint-stock company] was founded in 1992. Its activity was started in 1995 by commissioning a small manual electrogalvanization plant in a rented facility, with only one employee.Currently, BETAK S.A. is a market leader in the production of galvanized steel strips, one of the leading manufacturers of safety guard rails in Romania, manufacturer of various steel structures and supplier of corrosion protection services by hot dip galvanizing and electrogalvanization.

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