Anti Corrosion Coating
Rust protection for steel with anti corrosion coating
Anti corrosion coating acts as a barrier between a metal and its environment and increases the substrate’s durability and lifespan. The estimated global cost of metal corrosion damage is trillions of dollars. The good news is a lot of this loss can be prevented by being proactive and making the right choice of anti corrosion coating from the start. When coating metal to prevent rust, it is important to factor in the environment and type of metal. Whether corrosion is due to moisture, chemicals, salt spray, or oxidation, anti corrosion coating for steel and metal can help protect the substrate from the elements.
In this article we look at how coating metal to prevent rust works, the different types of coating, and where to find specialists in Canada.
Anti rust coating is not a single type of paint
Anti rust 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 their multi-functional nature means that it is possible to 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 corrosion coating prevents direct contact between water/fluids and the steel substrate and therefore prevents the corrosion process.
In general, anti corrosion coating is suitable for almost any type of steel and metal and has the following 5 benefits:
- Repels water and other fluids (in the case of barrier coatings)
- Fends off fungi, algae, and moss
- Weather protection against acid rain, salt water, ice and so on
- Chemical resistance
- Additional antifouling, non slip, or self cleaning properties, depending on the coating choice
Buy corrosion inhibitor coating and paint to DIY
The best metal coating to prevent rust by corrosion category
To determine the best anti rust coating for your project, you need to understand the environment and use of the substrate. In particular, 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 Standardisation. 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 metal coating to prevent rust 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 determined the corrosivity of your environment, you can identify the right coating systems for your project and the right anti corrosion coating specification to protect it for years to come. Following these guidelines will allow you to pick appropriate the anti rust coating, allowing you to avoid overspending on unnecessary degrees of protection or simply making the wrong choice.
The 3 types of industrial anti corrosion coating
Anti corrosion coatings can be divided into three categories:
- Barrier coatings (C1 – C3) – non-porous coatings (anti corrosion paint) 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) – release a chemical which 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 coatings 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.
For example: hot dip galvanizing which provides steel (cathode) with a layer of zinc (anode).
Apply anti rust coating by dipping or spraying
The two most common methods for applying an industrial grade anti corrosion coating for steel are hot dip galvanising and thermal (metal) spraying. Barrier coatings and corrosion inhibitor coatings can also be applied by spraying or dipping.
- Hot Dipping is the process of immersing a metal in a bath of metal, often molten zinc,(or a polymer) in order to form a coating. The liquid metal bonds to the substrate and forms an alloy, which is then coated in zinc as it is removed from the bath. Hot dip galvanising uses the principle of cathodic protection, as the zinc coating acts as an anode to its substrate.
- Thermal (metal) spraying applies zinc or aluminium to a substrate by taking the metal in the form of a powder or wire and feeding it into a special spray gun. The metal melts within the gun and can then be sprayed onto the substrate. It does not alloy, but instead works by coating the surface in overlapping metal platelets.
The best anti corrosion coating for steel is a duplex system
When hot dip galvanising is used together with a top coat of anti rust coating or protective powder coat it is known as a Duplex System.
It provides multiple types of protection and the longest-lasting results. Each layer needs to be compatible in order for the system to work effectively. It is especially suitable for corrosion categories C3 to C5 and looks like this:
- Surface preparation: derusting, blasting, removing grease, oil, dirt for optimum adherence.
- Applying a primer: hot dip galvanisation OR applying an inhibitor coating primer depending on the coating system of your choice.
- Applying a sealer: To seal the anti corrosion coating. Often epoxy based.
- Intermediate coat: there may be several layers necessary for optimum protection, depending on the corrosion category.
- Finishing coat: provides appearance and surface resistance, often first line of defence.
Prevent corrosion on smaller substrates with anti rust paint or spray
For smaller substrates or do it yourself application up to category C2, painting at home is also an option. There are also small anti-rust spray paint cans available for this purpose. An anti-rust spray is an ultra thin fluid film compound which you can spray on any steel or other metal surface.
Coating metal to prevent rust with a spray form can protect it for up to a year. Keep in mind that more exposed areas which are getting constant abuse from rain and salt will need spraying regularly. In paint form, longer lasting results can be accomplished depending on the coating system you choose. For the best result always opt for a two component coating with corrosion inhibitor additives, for example a zinc rich epoxy coating.
Find a professional anti corrosion coating specialist in Canada
Keep in mind that for categories C4 and C5 it is not recommended to apply the coating yourself. Please search out a specialist in that case.
If you are looking for a professional company to apply anti corrosion coatings 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 a coating expert. If you want to receive a custom made quote, please contact us.
Here are a few examples of local anti corrosion specialists in Canada. Note that these companies may be located in for example, Toronto, but service a wide area. Here you can find the headquarters’ location.
|Anti corrosion coating specialist||Address|
|Corrosion Free (tested best by the Canadian army!)||Canadian Tire #497, 5970 Mavis Road, Mississauga, ON L5V 2P5|
|Rust Check||6175 Danville Road, Mississauga, ON, Canada L5T 2H7|
|Krown||131 Sheldon Dr. Unit#18, Cambridge, Ontario, N1R 6S2|