Steel Structures are one of the most common materials used in building construction, owing to its high strength and ductility. Although structural steel is non-combustible, its integrity can be compromised at high temperatures.
Building regulations require certain elements of a structure to have fire resistance. Whether or not an element requires fire resistance depends on the size the building, what it will be used for and what the function of the element is.
When exposed to fire, steel constructions lose some of their mechanical strength. Heavily loaded steel will lose its designed safety margin at temperature around 550°C – regardless of its grade.
2. Intumescent Paints
Solvent and water-based intumescent painting are applied to the steel surface for fire protection of the steel buildings. These paints expand dramatically when subjected to high temperatures protecting the covered steel from high temperatures.
Figure 1 : Intumescent Paint
Thin film intumescent coatings are mainly used in buildings where the fire resistance requirements are 30, 60 and 90 and 120 minutes. They can be applied either on-site or off-site.
Thin film intumescent coatings are more common in the industry, but for extreme temperatures heavy-duty thick film coatings are used.
Both solvent-based and water-based coatings can be used to achieve attractive surface finishes. Thin film intumescent can easily cover complex shapes and post-protection service installation is relatively simple.
Boards are commonly used materials for steel construction fire protection. They offer the smooth, boxed appearance. Board installation have minimal impacts to the other construction activities and they have simpler quality control measures. Fire protection boards are produced in specialized factories and them consistent thickness and quality. Board protection does not require any paint on the steelwork.
Figure 2 : Fire Protection Board
Installation details of the boards are published by the producers. They are generally used for interior fire protection applications. Different kind of boards offer different surface finishes. For ideal product, it is recommend to consult the board traders.
Spray material is produced by cement based material or gypsum in combination with lightweight aggregates.
Spray protection has the advantage of covering complex shapes and details. The major cost of the spray application is the labour cost therefore total costs do not increase linear when protection thickness increased.
Figure 3 : Fire Protection Spray
If an aesthetic finish is required, sprays are not ideal due to their appearance. Spray application is a wet trade which have a significant effect on site operations. A proper after cleaning of the floors is essential due to the nature of the spray operations.
It is a reliable and efficient fire protection application because it can be applied quickly and is suitable for complex steel members and details of the structure such as fasteners.
Passive fire protection materials insulate steel structures from the effects of the high temperatures that may be generated in fire. While some applications such as intumescent painting can be applied off site, most of the solutions are conducted on site.
The ideal method of steel construction fire protection will be decided according to the site conditions, budget, and fire resistance duration and finish expectancy.