Epoxy coated TMT bar, one of the best TMT bars in India, are a highly corrosion resistant variant of steel bars which are protected by Fusion Bonded Epoxy (FBE) coating. Fusion Bonded Epoxy coating, commonly referred to as FBE coating is widely used to protect concrete TMT bars, steel pipes, piping connections etc. used in construction. FBE coatings are in the form of dry powder at normal atmospheric temperature. The powder is applied electrostatically to the surface of cleaned hot steel bars and cured to form a protective film after undergoing various chemical processes. The epoxy coated bars last longer due to the protective film and thereby contribute to the quality of construction.
Advantages of Epoxy Coated bars:
The superior corrosion protection can extend the life of the epoxy coated TMT bars, resulting in significantly lower lifecycle costs over time.
Requires Less Maintenance
It needs little maintenance that leads to substantial savings in labour costs. It is flexible to allow straight bars to be bent during fabrication on a special mandrel to protect the coating from damage.
Epoxy powder coated bar is a sustainable solution that is environment friendly.
Studies have shown that structures built with epoxy last longer than similar structures made with black steel.
Epoxy coating is very cost-effective as it adds very little to the overall cost of the structure and lifecycle.
As the technique is factory based, it enables uniform thickness of coating which adds to the quality of production.
The bonding of coating with steel TMT bars is high as it has excellent adhesive property.
Offers Barrier Protection
The Fusion Bonded Epoxy coating acts as an insulator for electrochemical cells and offers barrier protection to steel which prevents entry of chloride ions through it.
Process of manufacturing Epoxy TMT Steel Bars:
TMT bar is cleaned for surface contamination such as grease and oil by solvent cleaning. Shot blast cleaning is the most commonly used method for preparation of steel surfaces. This effectively removes rust, scales, slats etc. from the surface and produces an industrial grade of a clean and rough surface finish.
Heating can be achieved by using several methods, but the most efficient method is induction heating. TMT bars are passed through a high frequency alternating current along with a magnetic field, which heats according to the required FBE coating application temperature. Typical application temperature for a stand-alone FBE is 225°C to 245°C.
Epoxy Powder Application
The FBE powder is placed on a fluidisation bed. The heated TMT bar is passed through the coating booth with number of electrostatic epoxy spray guns and the dry powder is sprayed (cloud formation) on the hot TMT bar. Here, the powder particles are suspended in a stream of air which is electrically charged due to which epoxy powder particles are attracted to the grounded TMT bar. As soon as the charged epoxy powder particles hit the hot TMT bar, they melt and flow into the anchor profile. The heat also initiates a chemical reaction which causes the epoxy powder molecules to form cross linked polymers which give the coating its beneficial properties.
Curing and Cooling
Epoxy coated TMT bars are given a thermal treatment by keeping them at 225°C for a duration recommended by epoxy powder manufacturer resulting in fully cured coating. The coated bars are passed through a cooling tunnel after curing, where water is sprayed on the bars to cool them. The bars are then transferred to the final inspection rack for testing and inspection.