Durability of Hot Dip Galvanizing from Galvanizers Association Australia

Predictability and Durability of Hot Dip Galvanizing

The hot dip galvanizing process has been in use for over 175 years and the predictability of corrosion rates of hot dip galvanizing has been tested in many environments and locations around the world.

The durability of hot dip galvanizing is assessed in any environment by comparing the thickness of the coating with the corrosion rate in the chosen Corrosivity Zone.

The Australian Standard for hot dip galvanizing (AS/NZS 4680) provides information on standard thicknesses, based on the underlying steel substrate. For example, a steel article over 6mm thick will have a minimum of 85 µm and in a C4 zone, a life to first maintenance of between 20 and 40 years.

When a structure is close to a more corrosive zone, then the life to first maintenance will be towards the lower end of the prediction.

Note that hot dip galvanized coatings thicker than 85 µm are not specified in AS/NZS 4680 but the general provisions apply and, together with specific thickness figures, may form a specification capable of third-party verification.

Many structural steel elements (for example, most hot rolled I-beams and channels) are significantly thicker than 6 mm. It is essential to know the composition of the steel to be used (from the test certificate) and the galvanizer should be consulted before specifying, as these thicker coatings may not be available for all types of steel.

Where the steel is suitable, thick coatings may be specified.

Contact Galvanizers Association Australia today to find out more.