Modification of Passivation Unit in Continuous Galvanizing Line

Abstract

Galvanizing is the process of giving a protective zinc coating to steel or iron, to avoid rusting. The most common method is hot-dip galvanizing, in which steel in coil form is dipped in a bath of molten zinc. Galvanizing protects in two ways: it generates a coating of corrosion-resistant zinc which prevents corrosive substances from reaching the more delicate part of the metal and increases the life of steel. The zinc serves as a protecting layer so that even if the coating is removed by scratching, the exposed steel will still be protected by the remaining zinc coating. Hot-dip galvanizing deposits a thick rough zinc layer that may be excessive. In the case of automobile bodies, where additional glossy paint will be applied, a thinner form of galvanizing is applied by electro galvanization. The hot-dip process changes the mechanical properties of the material by doing continuous annealing in furnace. For cleaning mixture hydrogen and nitrogen is preferred. The zinc layer provided by hot dip galvanizing is insufficient for products that will be constantly exposed to corrosive materials such as moisture. The project work is on Passivation unit of hot dip galvanizing line. In this project problems occurred in passivation are rectified.