schematic diagram – Strength reduction of steel at high temperatures
why needs fire protection?
Steel itself is a non-combustible material and does not catch fire like wood. However, in the event of a fire, as temperatures rise, the strength and load-bearing capacity of steel decline rapidly, and structural members may deform, become unstable, or even cause the entire structure to collapse.
Therefore, the key to fire protection in steel structures lies in controlling the rise in temperature and slowing the rate of strength loss, ensuring that the structure remains in a safe condition for a specified period during a fire.
So, Steel structure buildings must take fire protection measures. By improving the fire resistance rating of the structure, the steel is prevented from reaching its critical temperature too rapidly in the event of a fire, thereby avoiding severe deformation or collapse of the structure.
In doing so, they buy precious time for firefighting operations and the safe evacuation of personnel, while also minimizing potential economic losses and reducing the risk of casualties.
Two Main Methods of Fire Protection
Coatings are the most commonly used and cost-effective method for the fire protection of steel structures. Based on their fire-protection mechanisms, they are primarily categorized into two types:
Upon exposure to fire, the coating rapidly expands and foams to form a charred thermal insulation layer up to dozens of times the thickness of the original coating; suitable for applications requiring a fire resistance rating of 0.5 to 2.0 hours.
These coatings are relatively thin (ultra-thin type ≤3 mm; thin type 3–7 mm), lightweight, and aesthetically pleasing; suitable for exposed indoor steel structures.
These utilize inorganic thermal insulation materials as aggregates, relying on the materials’ inherently low thermal conductivity to provide insulation.
The coating thickness ranges from 7 to 45 mm, achieving fire resistance ratings of 1.5 to 3.0 hours.
Suitable for structural components with higher fire resistance requirements, such as columns and beams in high-rise buildings.
Important Note: In accordance with the GB 14907-2018 standard (KHOME steel structures are constructed based on Chinese GB standards):
The coating thickness for intumescent fireproof coatings for steel structures shall be no less than 1.5 mm, while the coating thickness for non-intumescent fire-retardant coatings for steel structures shall be no less than 15 mm.
Ultra thin Intumescent Fireproofing coatings – White -
Thin Intumescent Fireproofing coatings – Granular & white -
Ultra thin Intumescent Fireproofing coatings – Gray -
Thin Intumescent Fireproofing coatings – Granular & gray -
Non-intumescent Fireproofing coatings – Cement-based -
Non-intumescent Fireproofing coatings – Gypsum-based
Which fire protection method should be recommend?
| Steel Building Facility | Recommendation Protection | Reason |
|---|---|---|
| Airports, Stadiums,Exhibition Halls | Intumescent Coating | High appearance requirements, exposed steel |
| Commercial Complexes, Office Buildings | Intumescent Coating | High appearance requirements, numerous internal components are exposed. |
| Industrial Buildings, Warehouses | Select according to building code requirements | Consider factors such as cost, construction schedule, and aesthetics. |
| Hangars, Power Plants,Petrochemical Plants | Non-intumescent Fireproofing coating | Thick coating, durable, low cost |
| Underground Spaces,Tunnels | Non-intumescent Fireproofing coating | Poor ventilation, high humidity. spray or mortar more stable |
Construction of thin-coated steel structure with fireproof coating
Steel structure fireproof coating construction
- When the surface of the steel substrate is rust-removed and anti-rust treatment meets the requirements, and the dust and other sundries are removed, the construction can be carried out.
- The bottom layer is generally sprayed. The thickness of each spray should not exceed the thickness of the previous one. It must be sprayed again after the previous one is dried.
- When spraying, ensure that the coating is completely closed and the outline is clear
- The operator should carry a thickness gauge to detect the thickness of the coating and ensure that the spraying reaches the thickness specified in the design
- When the design requires the coating surface to be smooth and smooth, the last coating should be troweled to ensure that the outer surface is even and smooth.
Construction of fire retardant coating for thick-coated steel structure
The thick-coating steel structure’s fireproof coating should be sprayed by a pressure-feeding sprayer. The air pressure should be 1. The diameter of the spray gun should be the same as that of the ingredients.
The spraying construction should be completed in stages. The thickness of each spraying should be done after the previous one is basically dried or cured. The spraying protection method should be determined according to the construction design requirements.
During the construction process, the operator should use a thickness gauge to detect the thickness of the coating and stop spraying until it meets the thickness specified in the design.
After spray coating, mastoids should be removed to ensure evenness
Which components of steel structures should be provided with fire protection?
In steel structures, components requiring fire protection treatment primarily include steel columns, steel beams, roof structures, and connection joints. Fire protection for these components is crucial for enhancing the building’s overall fire resistance.
As the primary load-bearing elements of steel-structured buildings, the fire resistance of steel columns directly impacts the building’s overall safety. Consequently, steel columns must undergo rigorous fire protection treatment. Typically, fire-resistant coatings or fire-resistant boards are used to encase the columns, thereby extending their fire endurance.
Steel beams also play a vital role in steel-structured buildings. To enhance their fire resistance, appropriate fire protection measures are required. Similar to steel columns, fire-resistant coatings can be applied; additionally, fire resistance can be improved by increasing the beam’s cross-sectional dimensions or by using fire-resistant steel materials.
As the “crown” of the building, the roof structure’s fire resistance cannot be overlooked. Steel-structured buildings often utilize lightweight steel framing or space frame structures for their roofs. To improve roof fire resistance, measures such as installing fire-resistant boards or applying fire-resistant coatings can be implemented. These measures effectively inhibit the upward spread of fire and protect the roof structure from fire damage.
Connection joints serve as the interface between various components in a steel structure, and their fire resistance is critical for maintaining the building’s overall stability. High-temperature resistant fireproofing materials can be used to encase or fill these joints, ensuring they retain their stability and load-bearing capacity during a fire.
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K-home Steel Structure Co., Ltd covers an area of 120,000 square meters. We are engaged in the design, project budget, fabrication, and installation of PEB steel structures and sandwich panels with second-grade general contracting qualifications. Our products cover light steel structures, PEB buildings, low-cost prefab houses, container houses, C/Z steel, various models of color steel plate, PU sandwich panels, eps sandwich panels, rock wool sandwich panels, cold room panels, purification plates, and other construction materials.