Galvanizing
We would wish to let you know about our business that goes by the name HCI GALVAMET. This business is based in the following address: KHEWAT No.283/259, M.I.E, PART-B, BAHADURGARH. (HARYANA)
HCI GALVAMET is a dynamic HOT DIP GALVANIZING company. We provide full scale solutions for fasteners (nuts &bolts), machine turned and various other sheet metal components and HDG also. We have an integrated state of art facility for Hot Dip Galvanizing process specially for fasteners and other components.
We are ably backed by visionary founders having valuable experience of more than 50 years in the field of specialized chemicals for hot dip galvanizing process. We work in close cooperation with our customers by understanding their exact needs. We request you to kindly register our name in your approved vendor list for HDG.
★.HDG
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 450 °C (842 °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. Galvanized steel is widely used in applications where corrosion resistance is needed without the cost of stainless steel, 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.
Although hot-dip galvanizing has been utilized to protect steel for generations, the galvanizing process continues to evolve with new technologies and creative chemistries. The three main steps in the hot-dip galvanizing process are surface preparation, galvanizing, and post-treatment, each of which will be discussed in detail. The process is inherently simple, which is a distinct advantage over other corrosion protection methods.
★.Surface Preparation
When the fabricated steel arrives at the galvanizing facility, it is hung by wire or placed in a racking system which can be lifted and moved through the process by overhead cranes. The steel then goes through a series of three cleaning steps; degreasing, pickling, and fluxing. Degreasing removes dirt, oil, and organic residues, while the acidic pickling bath will remove mill scale and iron oxide. The final surface preparation step, fluxing, will remove any remaining oxides and coat the steel with a protective layer to prevent any further oxide formation prior to galvanizing. Proper surface preparation is critical, as zinc will not react with unclean steel.
★.Galvanizing
After surface preparation, the steel is dipped in the molten (830 F) bath of at least 98% zinc. The steel is lowered into the kettle at an angle that allows air to escape from tubular shapes or other pockets, and the zinc to flow into, over, and through the entire piece. While immersed in the kettle, the iron in the steel metallurgically reacts with the zinc to form a series of zinc-iron intermetallic layers and an outer layer of pure zinc.
★.Inspection
The final step is an inspection of the coating. A very accurate determination of the quality of the coating can be achieved by a visual inspection, as zinc does not react with unclean steel, which would leave an uncoated area on the part. Additionally, a magnetic thickness gauge can be used to verify the coating thickness complies with specification requirements.
★. Coating Benefits
Hot-dip galvanizing provides a number of benefits to the steel it protects. The metallurgically-bonded zinc-iron alloy layers not only create a barrier between the steel and the environment, but also cathodically protect the steel. The cathodic protection offered by zinc means the galvanized coating sacrifices itself to protect the underlying base steel from corrosion.
The tightly adhered coating, which has bond strength of around 3,600 psi, is also extremely abrasion-resistant, as the intermetallic layers are harder than the base steel (Figure 2). However, even if the coating is damaged, zincs sacrificial action will protect exposed steel up to 1/4 inch away.
In addition to the cathodic protection offered by hot-dip galvanizing, there are a few other characteristics of the coating which provide longevity. First, reaction in the galvanizing kettle is a diffusion process, which means the coating grows perpendicular to the surface, ensuring all corners and edges have at least equal thickness to flat surfaces. Furthermore, the complete immersion in the zinc bath provides total coverage of the steel, including the interior of hollow structures.
★.PROTECTION
The time that steel remains protected from corrosion is proportional to the thickness of the zinc layer, and it is dependent on the climatic conditions, as shown in the graphic below. Generally, the amount of time that a zinc layer offers protection is interpreted as the time from the moment of exposure to the moment that base metal corrosion, "red rust," can be seen on more than 5, of the surface.
Corrosion resistance under climatic influences:
♦ C2- Continental climate
♦ C3- Larger city environments
♦ C4- Moderate industrial or coastal climate
♦ C5- Aggressive industrial climate
Hot-dip galvanizing (HDG) is the process of coating fabricated steel by immersing it in a bath of molten zinc. There are three fundamental steps in the hot-dip galvanizing process; surface preparation, galvanizing, and inspection.
