Galvanising - The Basics
What is Galvanising?
Galvanising is a corrosion protection method for steel and iron. It involves the application of a zinc coating to fabrications and is one of the most widely used methods when it comes to protecting these from corrosion and the resulting degradation. Hot dip galvanising is the most common method of applying this protective coating.
Why galvanise metals?
Metal that is exposed to the elements on a continual basis will inevitably oxidise and rust far more rapidly than metals with some form of protection. Galvanising offers superior protective properties than paint or any other coating system. In fact, many engineering and construction projects will specify galvanised fabrications in their list of requirements in order to ensure a long and maintenance-free lifespan for the finished product.
In addition, galvanised steel is often a far more cost effective in comparison to alternatives like stainless steel and aluminium.
How does galvanising protect things?
In order to prevent corrosion, it is necessary to stop water or oxygen from coming into contact with metallic surfaces. There are a number of ways to do this including painting, oiling, plastic coating or plating. The problem with these methods is that they do not always provide a durable or reliable finish and often require regular maintenance. If they are not maintained, over time, when damage occurs, sections of the underlying steel rust and these protective coatings fall away, compromising the integrity of the metal below.
Hot dip galvanising, however, has proven to be a far more effective, long-lasting solution. This is due to the fact that the addition of a zinc coating not only forms a barrier to the elements, but also acts as a sacrificial anode which is the primary component of a galvanic cathodic protection system.
Essentially this means that the zinc bears the brunt of any corrosion due to exposure to the elements or submersion, instead of the underlying steel. This ensures that even when damage to the galvanising layer and exposure of the metal beneath it occurs, the underlying metal will still be protected. So unlike with other coatings, small damaged areas do not need to be touched up, saving both time and money when it comes to maintenance.
Which applications is galvanised metal suitable for?
Galvanised metals are suitable for use in a variety of applications and are widely used in a number of industries from engineering to construction.
Galvanised sheet metal may be used to manufacture the following:
- Balconies
- Canopies
- Ducts
- Fences
- Frames for buildings
- Ladders
- Outdoor furniture
- Railings
- Staircases
- Support beams
- Walkways
Other applications include:
- Bikes, cars, planes, trains: Many vehicle, plane and train components are made up of galvanised metals.
- Electronics: Electronic goods such as computers, washing machines, air conditioners and hairdryers all need to be protected from the elements and especially moisture, as such, galvanised metal casings and parts are used in their manufacture. In addition, precision instrument casings may also be subject to a zinc coating as a protective measure.
- Pipes: For the most part, galvanised piping has replaced the cast iron and lead pipes of decades gone by. Depending on the purity of an area’s water supply, its proximity to electrical grids, the thickness of the zinc coating applied, and whether it was applied to both the interior and exterior of the pipe or not, galvanised piping has a life expectancy of approximately 70 years. This is far superior to other modern alternatives like plastic.
- Security Gates and Bars: To ensure the integrity and reliability of these products over the years, galvanising is necessary to ensure that weakened spots due to rust and corrosion do not compromise their effectiveness.
- Playground and outdoor equipment: Any metal structure that will exist and be utilised outdoors benefits from a protective galvanised coating.
These are just a few examples of the numerous applications of hot dip galvanising. All it takes is a quick look around and you’re sure to be able to identify just what an integral part it plays in many aspects of our daily lives.
Got a galvanising project that you need assistance with? As the largest capacity galvanisers in the Southern Hemisphere, we’re here to help.