Anti corrosion coating for extending the life of steel surfaces
Anti corrosion coating acts as a barrier between a metal and its environment, increasing its durability and lifespan. The estimated global cost of metal corrosion damage is billions of rands. The good news is, a lot of this loss can be prevented by being proactive, and choosing the right anti corrosion coating from the start.
To determine the right anti corrosion coating for your project, it is important to factor in the environment and type of metal. Whether corrosion is due to moisture, chemicals, salt spray, or oxidation, steel corrosion protection coating can help protect the substrate from the elements.
Anti corrosion coatings for steel & their multifunctional nature
Anti corrosion coating is essentially a collective name for various types of coatings that protect a substrate from corrosion. An anti corrosion coating can do more than just protect from corrosion, and its multi-functional nature means you can find the exact coating you require. Corrosion is caused by a chemical reaction between a metal and its environment (water or other fluids), typically producing an oxide or a salt of the original metal. The long and the short of it is the metal is weakened, as is the structure it creates. An anti rust coating prevents direct contact between water/fluids and the steel substrate and therefore prevents the corrosion process.
Anti corrosion coatings for steel also have other properties such as chemical resistance, slip resistance or mould and fungi prevention depending on the needs of the surface and environment. Due to the multifunctional nature and possibility to modify anti corrosion coatings for steel, it is possible to find a coating that perfectly corresponds to the requirements.
Choose the best anti rust coating – Corrosive environment categories
To determine the right types of anti corrosive paints for your project, you need to understand the environment and use of the substrate. Particularly its exposure to water, moisture, and other aggressive substances that might be present in the environment. The corrosivity of certain atmospheres has been classified and standardised by the International Organisation for Standardization. The standard divides the degree of corrosivity into 5 categories , C1 to C5, in order of increasing corrosivity. To find the right anti corrosion coating, you need to know how corrosive the environment will be. For example, a coating at C5M level is intended for offshore constructions which are constantly exposed to moisture, but also for small pipes that are equally exposed.
- C1 – very low corrosion risk: Heated buildings with clean air, interiors only.
Suitable for: offices, schools, hotels, shops and other heated premises.
- C2 – low corrosion risk: Unheated buildings, rural areas.
Suitable for: storage facilities, sports halls, garages, barns and other unheated buildings.
- C3 – moderate corrosion risk: Buildings with high humidity, urban and industrial areas.
Suitable for: laundries, breweries, kitchens, food processing sites and other buildings with moderate humidity.
- C4 – high corrosion risk: Chemical manufacturers and swimming baths, industrial and coastal areas.
Suitable for: industrial buildings, chemical plants, swimming pools, ports, and ship- and boatyards.
- C5 – very high corrosion risk: Buildings with almost permanent condensation, offshore and industrial areas.
Suitable for: Water pipes and other industrial applications (C5I – industrial). Offshore and maritime constructions (C5M – marine).
Once you have identified your environment, you can identify the right anti rust treatment for your project and the right anti rust coating specification to protect it for years to come. Following these guidelines will allow you to pick appropriate anti-corrosion coatings, allowing you to avoid overspending on unnecessary degrees of protection or simply making the wrong choice.
Steel corrosion protection with 3 types of anti rust treatments
Anti corrosion coating types can be divided into three categories:
- Barrier coatings (C1 – C3) – non-porous anti rust coatings designed to prevent corrosive factors coming into contact with the substrate.
For example: powder coating, polyurethane paint, chloro rubber paints, Teflon coatings, nano coatings.
- Inhibitor coatings (C1 – C4) – anti rust treatment which releases a chemical that interferes with the electrolyte and stops the corrosion process.
For example: all oil based coatings with corrosion inhibitor additives such as zinc, aluminum, zinc oxide and so on.
- Galvanic coatings/Cathodic protection (C3 – C5) – metal-rich anti rust coating for steel which provide a sacrificial layer. Prevents corrosion by providing a more easily corroded metal (such as zinc) to be the anode to the protected metal’s cathode. Also called the sacrificial anode, this metal will corrode instead of the protected metal.
Combining anti corrosion treatments – The duplex system
When hot dip galvanising is used together with a topcoat of anti corrosion paint or powder it is known as a Duplex System. The duplex systems are applied as anti rust coating for steel and occasionally other metals.
This type of anti rust treatment provides multiple types of protection and the longest-lasting results. Each layer needs to be compatible in order for the system to work effectively. Duplex anti rust coating systems are especially suitable for corrosion categories C3 to C5, and it looks like this:
1. Surface preparation
2. Hot dip galvanisation
3. Inhibitor coating primer
4. Applying a sealer
5. Intermediate coat
6. Finishing coat
Rustproof coatings for smaller substrates and DIY applications
For smaller substrates or do it yourself application up to category C2, painting is also an option. There are also small anti corrosion spray paint cans available for this purpose. An anti corrosion coating spray can be described as an ultra thin fluid film compound which you can spray on any steel or metal surface. In spray form it can protect for up to a year. But keep in mind that more exposed areas that are getting constant abuse from rain and salt will need spraying regularly. With anti rust paint, more long lasting results can be accomplished depending on the coating system you choose. For the best result always opt for a two component anti rust coating with corrosion inhibitor additives, for example a zinc rich epoxy coating.
Anti corrosion coating South Africa – manufacturers, products & services
Corrosion is a common problem on steel structures in South Africa, not the least due to sunshine and occasional rain. Therefore, many international coating companies offer their products in the country together with the local anti corrosion coating manufacturers.
South African anti corrosion coating manufacturers
Let’s first look at the local manufacturers:
|Anti corrosion coating manufacturer||Address|
|Corrocoat SA (Pty) Ltd||PO Box 253, Kasselsvlei 7533, Cape Town|
|Bluchem||Bluchem, 7 Dipka Street, Stikland, 7530, Cape Town|
|3M South Africa (Pty) Ltd||146a Kelvin Dr, Gallo Manor, Sandton, 2199, South Africa|
|Denso||175 Bush Telegraph Avenue,, Northlands Business Park, North Riding 2194|
|Stopaq Southern Africa||Boundary Gardens Office Park, 308 Boundary Road, Honeydew, Gauteng|
Anti corrosion coating products available in ZA
Here below you can find a small selection of anti rust coating products from globally acknowledged manufacturers.
|PRODUCT||Anti corrosion coating TYPE||Corrosion Category|
|Jotun Jotamastic 90||Barrier coating: Epoxy coating for above and below water, on concrete or steel, with abrasion and chemical resistance.||C1 – C3|
|Jotun Barrier 90||Inhibitor coating: Zinc-rich epoxy containing 90% zinc. Suitable for above water and on steel, with abrasion and water resistance.||C1 – C4|
|Hempel Galvosil||Cathodic protection: two-component, solvent-borne, self-curing, inorganic zinc silicate with outstanding resistance against weathering and abrasion.||C3 – C4|
|Hempel Hempadur||Galvanising coating: two-component, epoxy based. It cures to a flexible, well-adhering coating with good abrasion and impact resistance. Contains zinc phosphate||C3 – C4|
|Ultrimax 1||Inhibitor coating: Contains zinc phosphate anti-corrosive properties and a high volume of solids.||C1 – C3|
Keep in mind that for categories C4 and C5 it is not recommended to apply the anti corrosions coating yourself. Please search out a specialist in that case.
Let industrial anti corrosion coatings for steel applied by a professional – services and prices
If you are looking for a professional company to apply the anti corrosion coating for you, it’s important to understand how prices are established before you request a quote. Different coating processes use different methods to calculate the cost of professional application. Hot dip galvanising prices are usually calculated by weight. The galvaniser will quote a price per tonne, and then use the weight of your steelwork after galvanising to calculate the final cost. Unlike galvanising, powder coating prices tend to be calculated by size or surface area.
Regional differences in materials, labour, and equipment can all have an impact on overall costs when contracting an anti rust coating expert. If you want to receive a custom made quote, please contact us.