Protect steel from rust with anti corrosion coating
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 pounds. The good news is, a lot of this loss can be prevented by being proactive, and choosing the right anti rust 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, anti rust coating for steel and metal can help protect the substrate from the elements.
Anti rust coating is not a single type of paint
Anti corrosion coating is essentially a collective name for various types of coatings that protect a substrate from corrosion. An anti corrosion paint 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.
In general anti corrosion coating is suitable for almost any type of steel and metal, and has the following benefits:
- Repels water & other fluids (in case of barrier coatings)
- Fends off fungi, algae, and moss
- Weather protection against acid rain, salt water, ice and so on
- Chemical resistance
- Plus, depending on the types of anti corrosive paints you opt for: anti fouling, non slip or self cleaning properties
Determine the right corrosion category to choose the best anti rust treatment
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.
The 3 types of industrial anti corrosion coating for steel protection
The types of anti corrosive paints 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.
Metal anti rust coating by dipping or spraying
The two most common methods for applying a industrial grade metal anti corrosion coating are hot dip galvanisation and thermal (metal) spraying:
- Hot Dipping is the process of immersing a metal in a bath of metal, often molten zinc, 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 is melted 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 rust coating for steel is a 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:
- Surface preparation: derusting, blasting, removing grease, oil, dirt for optimum adherence.
- 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: several layers may be necessary for optimum protection, depending on the corrosion category and the chosen anti rust paint.
- Finishing coat: provides appearance and surface resistance, often first line of defence.
Anti rust paint for smaller substrates
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 for an anti rust treatment. 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, longer 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 products & prices UK
Here is a selection of products on the market to give you a rough guide as to the price of anti corrosion paint. 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.
|PRODUCT||Anti corrosion coating TYPE||Corrosion Category||Price Indication (rrp)||Packaging|
|Jotun Jotamastic 90||Barrier coating: Epoxy coating for above and below water, on concrete or steel, with abrasion and chemical resistance.||C1 – C3||£199.95||20 L|
|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||£159.95||8.75L|
|Hempel Galvosil||Cathodic protection: two-component, solvent-borne, self-curing, inorganic zinc silicate with outstanding resistance against weathering and abrasion.||C3 – C4||On request||15L|
|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||£507.00||20L|
|Ultrimax 1||Inhibitor coating: Contains zinc phosphate anti-corrosive properties and a high volume of solids.||C1 – C3||£150.00||20 L|
Find a professional anti corrosion coatings specialist near you
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 throughout the UK 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. Here are a few examples of local anti-corrosion coatings specialists in the UK:
|Corrosion prevention Company||Specialisation|
|Metal Improvement Company Ascot Drive Derby DE24 8ST United Kingdom||Thermal Spraying|
|Surface Technology Lyons Park Coventry CV5 9PF United Kingdom||Barrier coatings, Galvanic coatings, Cathodic protection|
|EM Coatings Enterprise Way, Vale Park Worcs WR11 1GX United Kingdom||Barrier coatings, Galvanic coatings, Inhibitor coatings|
|Impreglon UK ltd Kingsbury Link, Trinity Road West Midlands B78 2EX United Kingdom||Barrier coatings, Galvanic coatings|