What is Galvanizing?
Galvanizing is where a metal (usually iron or steel) is coated with a layer of zinc to help protect it from the environment in which it is used or stored. The reaction for galvanization will only occur on clean surfaces and therefore in order to achieve a high-quality finish, the surface on the metal must be properly prepared. Any force of dirt, grim, grease or oil are considered to be contamination and will lead to flakiness or the finish peeling off easier than it should. A number of processes can be used to pre-treat the material such as shot blasting where the surface is cleaned or stripped using abrasives.
The protection offered by galvanization is heavily dependent upon the environment in which it is situated. Although galvanizing is generally regarded as giving a product a life of a number of decades, if the environmental impacts are kept to a minimum, it can last without rust in excess of 100 years.
However, if the galvanized item is situated on a cliff face in a coastal region with frequent and high levels of rainfall, this life will be significantly reduced. Supplementary treatments such as painting will help to extend the products life.
Hot dip galvanizing is the process whereby metal is immersed into a bath of molten zinc at a temperate of 450 °C (842 °F) to give the material a thick, robust outer layer of zinc alloys. On occasion, where an additional coat is required e.g. it is painted at a later stage, the zinc coating will be thinner to ease the application of the additional coating. Once the material is removed from the bath (5 minutes is usually sufficient to provide the required coating), it is then quenched in water or air cooled to allow handling.
For the galvanization of threads, see the threading page.
Learn more about galvanizing, what it is, galvanized iron and its benefits with B.B. Price.
