Batch Hot Dip Galvanizing of Steel Products to EN ISO 1461: Sector EPD Based on an Average Product

Hot dip galvanizing is the most effective treatment for steel corrosion protection and can be applied to a wide range of steel products that are characterised by many different dimensions, geometries and functions. The operational sequence of the plant is essentially the same and the dimension of the kettles (i.e., the bath of molten zinc) is determined by the typical mix of products to be coated. For example, small components are normally processed by companies operating smaller kettles.

Galvanizing is a corrosion protection process for steel, in which the steel is coated with zinc to prevent it from rusting. The process involves dipping cleaned iron or steel components into molten zinc (which is usually at around 450°C). A series of zinc-iron alloy layers are formed by a metallurgical reaction between the iron and zinc creating a strong bond between steel and the coating. A typical time of immersion is about four or five minutes, but it can be longer for heavy articles that have high thermal inertia or where the zinc is required to penetrate internal voids. Upon withdrawal from the galvanizing bath, a layer of molten zinc will be deposited on top of the alloy layer stopping corrosion of steel in two ways - a physical barrier and electrochemical protection. 

Typical coating thicknesses can range from 45μm to over 200μm and in case of damaged area, a galvanic cell is formed: the zinc around the point of damage corrodes in preference to the steel and forms corrosion products that precipitate on the steel surface and protect it. 

The hot dip galvanized coating is applied according to the requirements of EN ISO 1461.