Rust or Bust
Corrosion costs Australia billions of dollars every year. The CSIRO reports that the annual cost is as high as 2–3% of Australia’s GDP.
The Atmospheric Corrosivity Categories Based on AS/NZS 2312.1:2014 provide the technical basis for selection of the appropriate corrosion protection system to suit the intended corrosion environment for the structure and a number of other factors influencing the design outcomes.
The standard classifies 5 atmospheric environments according to their corrosivity, from very low (C1) to extreme (C5). These categories are based on factors such as salinity, humidity, pollution, temperature, and rainfall. The corrosivity of an environment affects the corrosion rate of steel and the durability of coatings.
C1:
Corrosivity: Very Low
Description: Environments in this category are most commonly found inside heated or air-conditioned buildings with clean atmospheres, such as most commercial buildings. They may also be found in semi-sheltered locations remote from marine or industrial influence and unheated or non-air-conditioned buildings.
C2:
Corrosivity: Low
Description: Dry, rural areas and other regions remote from the coast or sources of pollution, and most areas of Australia and New Zealand beyond at least 50 km from the sea. Can extend as close as one kilometre from seas that are sheltered. Typical areas occur in arid and rural inland regions, most inland cities and towns, and suburbs of cities on sheltered bays.
C3:
Corrosivity: Medium
Description: Coastal areas with low salinity. Varies significantly with factors such as winds, topography, and vegetation. Extends beyond about 50 m from the shoreline to about one kilometre inland around sheltered seas. For less sheltered bays, this category extends from 100 m from the shoreline to about 3 to 6 km inland.
C4:
Corrosivity: High
Description: Coastal areas with moderate salinity. Extends from about 50 m to several kilometres inland around moderately sheltered seas. For less sheltered bays, this category extends from about 100 m to several kilometres inland. Typical areas occur in coastal cities and towns such as Sydney, Brisbane, Perth, and Auckland.
C5:
Corrosivity: Extreme
Description: Coastal areas with high salinity. Extends up to about 50 m inland around unsheltered seas or within surf zones. For less sheltered bays, this category extends up to about 100 m inland. Typical areas occur near beachfront and near chemical plants.
To select the right coating system for your application, you must refer to these categories and the corresponding requirements for durability as per AS/NZS 2312.1:2014. If the standards are not followed, selecting the wrong coating system can lead to degredation and corrosion to structures that aren’t correctly protected.
Get in touch today to find out if your coating system is the right choice for your application.
