In our previous post, we explored the basics of galvanized coatings and their crucial role in preventing corrosion. Today, we will focus on the performance of these coatings within the unique context of the Australian atmosphere. We will look at how local Standards and research have mapped out the corrosivity of different environments across Australia and how these insights help in predicting the durability of galvanized coatings.
Australian Standards and Corrosion Mapping
Australia has established comprehensive Standards to assess and manage the corrosion of metals. Two key Standards are AS 4312 and AS/NZS 2312.2, which provide detailed information on the corrosion rates of steel and zinc in various atmospheric conditions. These Standards are crucial for designers and engineers in estimating the service life of galvanized coatings under specific environmental conditions.
Over the past few decades, extensive research and mapping, notably by the Commonwealth Scientific and Industrial Research Organisation (CSIRO), have further detailed the corrosivity of the Australian climate. This research has helped create a robust dataset that aligns with international Standards like ISO 9223 and ISO 14713.1.
Corrosion Rate Categories
AS 4312 and AS/NZS 2312.2 categorise corrosion rates into several environments, from dry indoors (C1) to extreme oceanic conditions (CX). Each category defines the typical environments and expected corrosion rates for both mild steel and zinc during the first year of exposure. Here is a summarised table from the Standards:
The Online Interpolation Tool
To make this information more accessible, the Galvanizers Association of Australia (GAA) has developed an online interpolation tool. This tool uses data from AS/NZS 2312.2 and AS 4312 to help designers estimate the durability of hot dip galvanizing in various atmospheric conditions. This tool simplifies the complex data, making it easier for users to predict the lifespan of galvanized coatings based on their specific environmental exposure.
You can access this tool here.
In this post, we have examined how Australian Standards and research have mapped the corrosivity of different atmospheric conditions and categorized corrosion rates. These insights are crucial for predicting the durability of galvanized coatings in the diverse Australian climate.
Next, we will explore how specific environmental factors, such as moisture, pollution, and proximity to the sea, impact the performance of galvanized coatings.