fire resistant paint for steel protects metal surfaces

Fire resistant paint for steel is an essential measure of property protection

Strength is one of the main reasons we use steel in building construction. Steel is a tough and strong construction material, used in buildings across New Zealand. However, this strength is challenged by the severe heat of a fire. In a fire, it can take only minutes for unprotected steel to reach critical failure temperature of 550ºC, at which point it loses its capacity to bear heavy loads, leading to structural collapse. In fact, strength loss starts already at 300ºC, which is why you need fire resistant paint for steel.

Fire protection paint for steel can provide the following advantages:

  • Fire protection for up to 120 minutes preventing structural collapse
  • Allowing firefighters more time to get the fire under control
  • Extending crucial evacuation time

In this article we outline the different types of fire resistant paint for steel, and where to find fire resistant paint for steel products and contractors in New Zealand.

Fire resistant paint for steel based on 2 technologies

Anti fire paint for metal can be classified by fire protection method: intumescent or fire retardant. Each of these coating types are further divided by the length of time they provide fire protection for – 30, 60, 90, or 120 minutes. Building regulations require different minimum time requirements which vary depending on building type. You can find more information on this subject in our general passive fire protection article.

marine structures with fire resistant paint for steel

Fire resistant paint for steel structures is an irreplaceable safety measure for marine structures.

  1. Fire retardant paint: A fire retardant paint works by releasing flame-damping gas when heated, which prevents the spread of flame across a surface – usually walls and ceilings. It is less common to use fire retardant paints for steel structures, because they do not have the same insulating properties of intumescent paint. Therefore, this flame resistant paint for metal is usually a topcoat on another anti fire paint.
  2. Intumescent paint: Intumescent paints protect their steel substrate by providing an insulating layer between steel and the fire. Exposure to the heat of a fire triggers a reaction, causing the intumescent paint to expand to up to 50 times its thickness and form a solid foam-like char. This char insulates the steel from the heat, so prolonging the time before it reaches the temperatures that would compromise it. Intumescent paint is the most common fire resistant paint for steel.

For the most effective fireproof paint system, you can use these two paints together, with fire retardant paint as a top coat over intumescent paint. In this case, the flame retarding action prevents the intumescent paint from triggering, adding vital extra time.

Thick and thin film fire resistant paint for steel

Fireproofing coatings can be divided into two broad groups: thin film and thick film coatings. Thin film materials are either solvent based or water based and are mainly used for preventing fires in building. Thick film coatings were originally developed for the off-shore and hydrocarbon industries but have been modified for use in buildings.

Thick film fire resistant coating for steel

Thick films have a higher dry film thickness than thin film coatings, and are usually epoxy based. Originally developed for use with hydrocarbon fires, thick film materials are now also used in harsh or difficult to maintain environments where thin film materials would not work optimally. Examples include external steel in high rise buildings and exposed marine environments. Expansion ratios are typically about 5:1, and attractive finishes are also possible.

Thin film fireproof paint for steel

Thin film fire resistant paint for steel systems generally have three components, a primer, a basecoat, and a sealer coat. These paints are mainly used for 30, 60, and 90 minutes. Thin film materials have a 50:1 expansion ratio; a 1 mm thick coating will expand to about 50mm in a fire. These coatings are both solvent- and water-based, and are available in a range of finishes.

Fire resistant paint for steel products and services in New Zealand

There are many fireproof paint for steel products available on the NZ market. AkzoNobel, Jotun, and PPG all have anti fire ranges. The price and coverage of these coatings are dependent on the degree of fire resistance and film thickness;additionally, correct application contributes to the costs. If you would like any more information regarding fire protection for steel, or would like to be connected with one of our partners for your project, contact us! Our experts are here to help, just use the “Request a quote” button at the bottom of this article and take advantage of our 100% free quote service.


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