An Introduction to the Hot Dip Galvanizing Process

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Galvanizing was known to the world from the beginning of 17th century. It is essential for iron and steel in protecting their life and utility. Science and technology has developed the process of Hot Dip Galvanizing in the 18th century in USA. The first hot dip galvanized iron sheets were imported to Australia in the 1850s. The molten zinc was found to react with steel to form a metallurgical bonded protective coating that had more durability to any other coatings for atmospheric exposure.

Hot-dip-galvanizing

Hot-dip-galvanizing

The characteristics of the coatings applied by these continuous galvanizing technologies are quite different to those of coatings applied by the traditional batch in galvanizing process.While all early hot dip galvanized items were manufactured by dipping them in batches in a molten zinc bath. Different technologies have been developed to more efficiently apply zinc-based coatings to continuously manufactured products such as wire, sheet and tube.

The main difference in the nature of these galvanized coatings is the time that the steel is immersed in the molten zinc alloy. This time is very short (a few seconds) in continuous galvanizing processes, and much longer (4 to 8 minutes) in the hot dip galvanizing process. The resulting zinc-based coatings produced by these processes are quite different and lesser than hot dip galvanizing in their characteristics and performance.

The hot dip galvanized coating is the result of a metallurgical reaction between the steel and the molten zinc, and this reaction will not occur if the steel’s surface is contaminated with paint, grease, oil or rust.Steel fabrications or sections are delivered to the galvanizing plant. These items may contain steels of differing chemistry and surface condition and may be coated with pre-construction primers or other applied protective coatings, including continuously applied zinc coatings.

For this reason, the pre-treatment of the steel sections or fabrications to remove grease, oil, paint and rust is critical to the successful application of the galvanized coating. Acid pickling is done after degreasing and paint removal. Remaining process go through pre-fluxing, galvanizing and quenching. Inspection and dressing is the final process of hot dip galvanizing.

Check Points for Ideal Galvanizer Supplier

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The term ‘galvanizing’ broadly refers to an electro-deposition procedure where a thin layer of another metal is supplemented to an item made of steel. The reason of galvanizing is to defend the base steel by preventing rusting. However, one of the most efficient galvanizing methods does not utilize any electrochemical deposition. It is known as hot dip galvanizing or merely HDG.Galvanizing is one of the most common means of rust prevention and is widely used these days. Since hot-dip galvanizing creates a metallurgical bond between zinc and steel there is no chance of rusting. Hot-dip galvanizing gives you a more uniform coat and you will never have to worry about wear or deterioration. Galvanizing companies usually deal in applications that include automotive body parts, consumer appliances, roofing and walling, metal pails.

There are several points that you may consider while choosing your galvanizer suppliers or galvanizer consultants as a partner.Quality is the most important vital factor for choosing the right galvanizer service provider. Hot dip galvanizing is a specialized process and requires good circumstances and road and rail network. A company that meets these provisions and that too adhering to the highest quality standards must be chosen. Galvanizer suppliers must own the essential knowledge in meeting customers’outlook. Experienced galvanizer suppliers like Prashant galvanizer would be able to perfectly assess your requirements and offer their services in helpful way.

Galvanizer suppliers or galvanizer consultants have dedicated themselves to do their bit to save this planet in order to make surrounding pollution free. For this they use environmentally-suitable, no-lead zinc bath besides adhering to the international standards for environment management. Your choice of a hot dip galvanizing company may also depend on the value extra services that are provided along with the main service. This usually includes additional surface preparation, installations, and assembly operations. Capacity is significant to assess the material handling capacity of the Galvanizer consultant before finalizing any one of them because industrial applications could vary in scale, choose a group with one of the largest material handling capacities both in terms of overall lengths and overall weight. Experienced Staff in a company should have the necessary know-how as an industrial galvanizer.Choosing the correct galvanizing service provider is critical to the success of your industrial application as well as environmental conservation. It is advisable to investigate well before zeroing in on an exacting galvanizing company. Employee security and Health Program is significant to choose a company as that shows the dedication and care of the company to keep its employees safe.

Manufacturing Process of Hot Dip Galvanizing

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The manufacturing process of hot dip galvanizing may vary slightly from plant to plant. The fundamental steps in the galvanizing process in nutshell can be described as under:

The steel articles are dipped into a hot alkaline solution or caustic soda solution to remove dirt, oil, grease, shop oil, and soluble markings for decreasing and caustic cleaning. The article is dipped in rinsing tank containing clean water for cleaning.

Galvanizing-Process

Galvanizing-Process

Second pickling is performed in second pickling tank which contains dilute solution of either hydrochloric or sulfuric acid 10-32% to remove surface rust and mill scale to provide a chemically clean metallic surface. The same article is again washed in rinsing tank containing clean water.The article is then preserved in pickling tank containing dilute solution of either hydrochloric or sulfuric acid 10-12% for first pickling.

Next step is Flux heating system where the steel is dipped in fluxing tank containing usually a zinc ammonium chloride solution to remove oxides and to prevent oxidation prior to dipping into the bath of molten zinc. In the dry galvanizing process, the item is separately dipped in a liquid flux bath, removed, allowed to dry, and then galvanized. In the wet galvanizing process, the flux floats atop the molten zinc and the item passes through the flux immediately prior to galvanizing.

The article is immersed in a bath of molten zinc of 435 to 455 degree Celsius. During galvanizing, the zinc metallurgically bonds to the steel, creating a series of highly abrasion-resistant zinc-iron alloy layers, commonly topped by a layer of impact-resistant pure zinc.

After the steel is withdrawn from the galvanizing bath, excess zinc is removed by draining, vibrating. The galvanized item is then air-cooled or quenched in liquid.

The most important part of hot dip galvanizing shows the value of experience is flux heating system. An experienced and noted hot dip galvanizing consultant in Gujarat Prashant Galvanizers supply Online Flux Filter System that eliminates production downtime. It eliminates or reduces iron content to a minimum in the flux solution which reduces Dross formation in zinc bath. Using Flux Heating system and Online Flux Filter system, zinc consumption is reduced anywhere from 1-2 kg per metric.

The material is due for dispatch after “Passivation” and inspection formalities. Coating-thickness and surface-condition inspections complete the process of hot dip galvanizing.

Hot-Dip Galvanizing In Gujarat

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Galvanization is the process of applying a protective zinc coating to steel, aluminum and iron, in order to prevent rusting. The term Galvanization is derived from the name of Italian scientist Luigi Galvani. Although galvanization can be done with electrochemical and electro-deposition processes but the most common and popular method in present time is Hot Dip galvanizing, in which steel parts are submerged in a solution of molten zinc.

Process of coating of thin layer of zinc on iron, steel and aluminum at a temperature of about 860 °F (460 °C) by a bath of molten zinc is called Hot Dip Galvanizing. It is a form of galvanization. Oxygen (O2) in the atmosphere reacts with the pure zinc (Zn) to form zinc oxide (ZnO), which forms zinc carbonate (ZnCO3) by reacting with carbon dioxide (CO2) of the atmosphere. Generally it looks dull gray and in many circumstances it stops further corrosion, protects the galvanized material from the effects of outside elements. Rust resistance is the main cause of widely use of steel, and can be recognized by spangles on the surface (The size of crystallites in galvanized coatings is a visual feature, known as spangle).

Hot Dip Galvanizing is a factory controlled metallurgical combination of zinc and steel that provides corrosion resistance in a wide variety of environments. Hot Dip Galvanizing protects steel from corrosion in two ways. It provides cathodic protection and barrier protection.

Cathodic protection is commonly applied to a coated structure to provide corrosion control to areas where the coating may be damaged.  It may be applied to existing structures to prolong their life.

Barrier protection is commonly applied to a Hot Dip Galvanizing done surface to protect structure from germs in air or water, which prolongs its life and sustainability.

Prashant Galvanizers expertise of nearly 15 years in galvanizing contractor, manufacturer and supplier of India have an experienced and proficient technicians working team for manufacturing Hot Dip Galvanizing plants. They undertake any kind of critical job like tower line angle, channel and pipe of Shipyard Company, fabrication of tower-line, etc.

Most important and notable fact for Prashant Galvanizers is their un-imaginable capability of manufacturing of automatic/manual galvanizing plant system or 2-in-1 hot dip galvanizing plant system. They have earned a name and fame in a short time among the Galvanizers Consultant in India.