We use hot-dip galvanising to ensure that our Steel Yards, Cattle Crushes & other equipment can stand up to the toughest weather conditions. So, just what is hot-dip galvanising, and why do we use it to protect our steel products from corrosion?
Hot-dip galvanising is the process of immersing fabricated steel into molten zinc/alloy. The zinc coating prevents oxidation of the protected metal by forming a barrier. This thick, tough metallic zinc envelope covers the steel surface and seals it from corrosion.
Te Pari livestock equipment is an investment you want to last, so all steel components are hot-dip galvanised. The galvanising actually becomes part of the steel surface for superior rust protection. That’s why we offer our class-leading 10 Year Galvanising Warranty.
The hot dip galvanising process
Steel gets put through several different steps, while it’s in the process of being galvanised. These important steps as outlined by the Galvanizers Association of Australia are included below.
1. Initial degreasing
The first step is ensuring that surface contaminants like oils and paint are carefully removed. This is done as a preliminary treatment, usually through a caustic solution. Some surface contaminants may need to be removed before the steel arrives at the galvanising facility.
2. Acid cleaning
After the initial degreasing, the steel then undergoes acid cleaning or ‘pickling’ which removes rust and any mill scale. Hydrochloric acid is commonly used during this step, although sulphuric acid is an alternative.
3. Hot fluxing
Once the steel has been acid-cleaned, it is then immersed in a flux solution. This solution contains zinc ammonium chloride and will be at a heat of between 50-70°C. The flux solution will remove any oxide film which forms on the steel surface after acid cleaning, preventing further oxidation. The steel is then dried so that it’s ready for hot-dip galvanising.
4. Hot-dip galvanising
In the final stages, the steel is then galvanised by being dipped into molten zinc. This involves completely immersing the steel in a galvanising bath so that the steel’s surface is completely covered by molten zinc. The molten zinc then reacts with the steel to form several zinc alloy layers.
So that the coating or ‘layers’ can form, the steel needs to remain in the galvanising bath until it reaches the same temperature of the molten zinc, 445°C to 465°C. The steel is then slowly pulled out of the bath at a controlled rate so that the outer layer of molten zinc solidifies, and forms a pure outer zinc coating.
When this process is followed, the molten zinc will cover corners and welds, and seal the edges of the steel. It will also penetrate any recesses to provide complete protection to any areas within the steel that could degrade from corrosion. The galvanised coating will be slightly thicker at corners and narrow edges to provide increased protection.
After being pulled out of the galvanising bath, the steel is then cooled in a quench solution, which will also prevent early oxidation of the zinc surface.
The protection that hot-dip galvanising provides
Te Pari equipment has always been hot-dip galvanised and you can see from some of the 20+ year old Yards & Cattle Crushes that are still in use today that they have stood the test of time without rusting! This is a testament to the galvanising process and the high level of protection that it provides from external factors and corrosion.
Pictured above is a photo of an old Te Pari Cattle Crush, still in use after 21 years.
All Te Pari equipment is hot dip galvanised after the parts are cut and welded. This ensures that all the welds have the benefit of the best hot dip galvanised protection. Something to look out for is that some other brands use steel that is galvanised prior to welding and then use an inferior spray-on galvanising paint on welds which doesn’t last as long.
What about the inside steel surfaces?
Te Pari equipment is also designed with holes fabricated into the tube steel so that the hot dip galvanising can get inside the steel to give corrosion protection inside and out. Our modern factory includes numerous robotic welders, CNC laser cutter's and other CNC equipment that help to ensure quality control of the fabrication of our products.
The picture above show the laser cut holes in a Te Pari steel yard panel. These holes allow the hot dip galvanising to protect the inside surfaces of steel as well as the outside which provides longer lasting protection from rust.
Choosing equipment that is hot dip galvanised will drastically increase its longevity and will ensure that it lasts not only a few years, but decades to come. We ensure that our equipment is completely hot-dip galvanised which leaves no corner or surface unprotected.
Pictured above is the Te Pari Factory located in Oamaru, New Zealand.
If you’re considering upgrading your old Cattle Yards, Crush or Sheep Handler with something that you know will last, then we encourage you to get in touch with us to discuss your options. Our team of experts are ready and available to help you with any questions you have. Just contact us here.