corrosion resistant coating for steel failing on bolts

Corrosion resistant coating for steel offers the best protection

Corrosion resistant coating for steel acts as a barrier between a metal and its environment, increasing its durability and lifespan. The estimated global cost of metal corrosion damage is trillions of euros, and Ireland, with its moisture-heavy and salt-laden air, does not escape the scourge. The good news is, a lot of this loss can be prevented by being proactive, and choosing the right corrosion resistant coatings for steel 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 corrosion coating for steel and metal can help protect the substrate from the elements. Therefore, in this article we will take a look at assessing the corrosivity of environments, types of corrosion resistant coatings for steel and suitable products per corrosion category.

Choose the anti corrosion coating based on the environment’s corrosivity

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. With Ireland having some 2,500km of coastline and some of the wettest weather in the world, it is important to be aware of the exact conditions the coating needs to protect against, as well as how much protection your substrate needs. Historic iron, for example, stands up better than mild steel.

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 corrosion resistant coatings for steel, 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.

Corrosion CategorySuitable forExamples
C1 – very low corrosion riskHeated buildings with clean air, interiors onlyOffices, schools, hotels, shops and other heated premises
C2 – low corrosion riskUnheated buildings, rural areasStorage facilities, sports halls, garages, barns and other unheated buildings
C3 – moderate corrosion riskBuildings with high humidity, urban and industrial areasLaundries, breweries, kitchens, food processing sites and other buildings with moderate humidity
C4 – high corrosion riskChemical manufacturers and swimming baths, industrial and coastal areasIndustrial buildings, chemical plants, swimming pools, ports, and ship- and boat yards
C5 – very high corrosion riskBuildings with almost permanent condensation, offshore and industrial areasWater pipes and other industrial applications (C5I – industrial). Offshore and maritime constructions (C5M – marine)

The 3 types of anti corrosive paints for industrial steel protection

Once you have identified your environment, you can identify the right anti rust treatment for your project and the right anti rust paint specification to protect it for years to come. Choosing the right corrosion resistant coatings for steel allows you to avoid overspending on unnecessary degrees of protection and prevents making the wrong choice.

a screw coated with different corrosion resistant coatings for steel

Applying corrosion resistant coatings for steel makes the structures last longer.

Anti corrosion coating types can be divided into the following categories:

  • Barrier coatings (C1 – C3) – non-porous anti rust coatings designed to prevent corrosive factors coming into contact with the substrate.
  • 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.
  • Inhibitor coatings (C1 – C4) – anti rust treatment which releases a chemical that interferes with the electrolyte and stops the corrosion process.

Rely on a duplex system when the best anti rust coating is needed

A duplex systems relies on the doubling up of anti corrosion coating treatments to provide the strongest form of protection. Mostly a duplex system involves abase coating of hot dip galvanising, used together with a topcoat of anti corrosion paint to use different coating methods to really protect the metal. Anti corrosion powder coating is also used as a top coat. 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:

  • Hot dip galvanisation/ inhibitor coating primer
  • Applying a sealer
  • Intermediate coat (barrier coating)
  • Finishing coat

Anti corrosion treatment options for smaller surfaces

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. A corrosion resistant 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.

A selection of corrosion resistant coatings for steel structures

There are a number of Standards relating to the protection of steelwork from corrosion. For example, Transport Infrastructure Ireland published guidance notes regarding the protection of steelwork against corrosion for roadworks specifications, intended to outline and explain the necessary conditions. It is important to be aware of all requirements.

Here is a selection of products on the market to give you a rough guide as to the price of corrosion resistant coating. 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.

PRODUCTAnti corrosion coating TYPECorrosion Category
Jotun Jotamastic 90Barrier coating: Epoxy coating for above and below water, on concrete or steel, with abrasion and chemical resistance.C1 – C3
Jotun Barrier 90Inhibitor coating: Zinc-rich epoxy containing 90% zinc. Suitable for above water and on steel, with abrasion and water resistance.C1 – C4
Hempel GalvosilCathodic protection: two-component, solvent-borne, self-curing, inorganic zinc silicate with outstanding resistance against weathering and abrasion.C3 – C4
Hempel HempadurGalvanising coating: two-component, epoxy based. It cures to a flexible, well-adhering coating with good abrasion and impact resistance. Contains zinc phosphateC3 – C4
Ultrimax 1Inhibitor coating: Contains zinc phosphate anti-corrosive properties and a high volume of solids. C1 – C3

Corrosion resistant coating manufacturers and contractors in Ireland

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, anti corrosion 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. 

Corrosion resistant coating specialistAddress in Ireland (Eire)
Industrial & Protective Coatings Ltd.Unit 9, Ashbourne Business Centre, Ashbourne, Co. Meath, Ireland
Fleming LtdSt. Johnston, Co., Donegal, Ireland
J.S. McCarthy ltd.Ballymount Retail Centre, Ballymount Road Lower, Dublin 24, D24 ED81, Eire
McConnells CoatingsThe Enterprise Centre, Ballycorus, Dublin 18 Ireland
New Guard Coatings Ltd.38 Main St, Swords Glebe, Swords, Co., Dublin, K67 E0A2, Ireland
Grove EngineeringUnit B2, South City Business Park, Whitestone Way, Tallaght, Dublin 24, Eire
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