History tells us that Galvanising steel dates back to around 500AD. It is believed that it commenced in India but by the mid 1600's was a common practice throughout Europe and the rest of the then civilized world.
Galvanised steel is now most commonly found in the construction industry where everything from industrial support beams, to heating and airconditioning components, through to chickenwire is protected against rust attack in this tried and proven way.
What is Galvanisation?
Galvanisation is the process of applying a protective zinc coating to steel, to prevent rusting. The most common method is hot-dip galvanizing, in which parts are submerged in a bath of molten zinc. Galvanizing protects in two ways:
Source: Wikipedia
How does galvanising help the life of a gabion basket
Yarrabee's galvanised steel gabion baskets are constructed using 5mm steel, welded at all joints in the 50mm x 50mm mesh, which is then hot dipped to protect the entire basket. Take a look at the following link which gives a more detailed analysis of how galvanising works and more importantly how it works in Australian conditions Galvanizers Association of Australia (GAA) -
"No commercial coating for protecting steel has proven to be more serviceable and of such predictable performance in the Australian atmosphere than hot dip galvanizing. Its good performance is due to its inherent corrosion control, high resistance to mechanical damage and its inertness to the high to extreme UV prevailing over most of the Australian continent" - GAA
Lets get a little more technical:
Zinc coating of steel is referred to as "Galvanising". How good the galvanising is i.e. how long it will protect the metal below, can be calculated using the following formula. This in simple terms gives a number to the "thickness" of the coating relative to the thickness of the steel it is covering. That number is used in calculating life expectancy as you will see further down in this blog. Yarrabee's gabion Baskets are coated with a "Coating Mass" 280 g/m2, so using the equation below we reach a "Coating Thickness" of 39.2 as follows:
How long will Galvanised Gabion Baskets last?
Primarily, the most important influencing factor impacting on the life of a galvanised gabion basket is climate. The Australian Government produced the below map which identifies the various climatic conditions across the continent. Another influencing factor is other forms or corrosive materail in the atmosphere e.g. heavy salt content in some coastal regions.
Beneath the folloowing map, the various climates are shown as "Corrosive Categories" from which you will note that Victoria falls into the temporate area and has a clasification of C2. Although not evident on the map, there will be isolated areas in very exposed oceanfront locations which may push into category C3- but these will be rare in Victoria.
Corrosive Category C1
Corrosivity = Very Low
Locations = Desert zone
Corrosive Category C2
Corrosivity = Low
Locations = Temperate zone with low pollution & Desert zone
Corrosive Category C3
Corrosivity = Medium
Locations = Temperate zone with medium pollution & Subtropical and tropical zones with low pollution
And here's what we have been working towards
From this graph, remembering our equation which gave us our "Coating Thickness" of 39.2, we can see that the expected life span of our gabion baskets in corrosive category "C2" areas is 50 years+ and even in the more corrosive "C3" regions, 20 years plus can be expected.
In short when buying Gabion baskets ensure that the coating thickness has been calculated properly and adequate "Coating Thickness" is confirmed. Or do it the safe way- buy Yarrabee gabion baskets!!