Steel is strong but vulnerable in a fire: when heated to just a few hundred degrees it loses a significant part of its load-bearing capacity, and an unprotected frame can deform and collapse long before the room itself burns out. Fire protection of steel structures slows the heating of the metal and lets the structure stay stable for the required time. Below we look at why steel needs fire protection, what determines the coating thickness, the types of compounds, how they are applied and how the protection is maintained in service.
Why steel needs fire protection
The task of fire protection is to raise the actual fire-resistance limit of a steel structure to the value required for the specific building. The coating insulates the metal from direct flame and high temperature: thin-layer compounds swell when heated and form a heat-insulating layer, while thick-layer ones create a protective screen straight away. As a result the steel keeps its strength longer, giving people time to evacuate and firefighters time to respond.
What determines the coating thickness
There is no single “thickness for all cases”. The required thickness is determined by two main parameters:
- The required fire-resistance limit of the structure — set by the project depending on the building’s purpose and number of storeys.
- The section factor of the steel — a property of the profile: the more massive the cross-section, the slower it heats and the less coating is needed.
A calculation is made from these parameters, and a specific thickness is assigned for each type of profile. We perform this calculation for your project and provide the technical information for the material.
Types of fire-retardant compounds
Two classes of materials are used for steel; the choice between them depends on the required fire-resistance limit, the service conditions and the appearance requirements.
Thin-layer intumescent paints
Applied in a thin layer, they preserve the geometry of the structure — they are chosen where the metal stays visible. When heated, the paint swells and forms a porous heat-insulating layer. By binder type:
- Water-borne — for indoor and, in a weather-resistant version, outdoor conditions: STABITERM 219 (water-thinnable, weather-resistant) paint and the basic STABITERM 207.
- Solvent-borne — the weather-resistant STABITERM 209 paint for outdoor structures and demanding conditions.
- For a higher limit — STABITERM 217 for structures with a fire-resistance limit up to 120 minutes.
Thick-layer structural compounds
They create a thicker protective layer and are used for high fire-resistance limits and massive structures — for example, the thick-layer STABITERM 221 compound for the structural fire protection of steel.
Surface preparation and priming
The durability of fire protection begins with the substrate. The metal surface is cleaned of rust, mill scale, oils and dirt, and then primed with the GF-021 or equivalent anti-corrosion primer. The primer protects the steel from corrosion and ensures a reliable bond of the fire-retardant layer to the metal. Only over a prepared and primed substrate does the coating perform as stated.
Application and thickness control
The fire-retardant effect is achieved only when the calculated thickness is applied, so control matters during installation:
- Applying in coats. The compound is applied with a brush, roller or airless spray in even coats with inter-coat drying.
- Thickness control. The thickness is checked during the work to reach the calculated value over the whole area of the structure.
- Application conditions. Work is carried out at the temperature and humidity recommended for the material.
Exact parameters (consumption, number of coats, thickness, drying time) are taken from the technical information for the specific compound — we provide it for your facility.
Finishing coat for outdoor conditions
For structures in the open air, a weather-resistant protective enamel, PF-115 or equivalent (as agreed with the manufacturer STABITERM), is applied over the fire protection. It protects the fire-retardant layer from moisture, UV and dirt, gives the structure a finished appearance and extends the service life of the whole system.
Care and inspection
The fire-retardant coating is inspected during service: the integrity of the layer is checked, along with the absence of cracks, delamination and mechanical damage, especially where work is being carried out. Damaged areas are restored with the same compound, preserving the calculated thickness and the fire-resistance limit of the structure.
STABITERM materials
A complete range is used for the fire protection of steel structures: the thin-layer paints STABITERM 219 (water-borne, weather-resistant), STABITERM 209 (solvent-borne, weather-resistant), STABITERM 217 (up to 120 minutes) and STABITERM 207; the thick-layer STABITERM 221 compound; the anti-corrosion primer GF-021 or equivalent and the finishing enamel PF-115 or equivalent (as agreed with the manufacturer STABITERM). We select the materials for your project, calculate consumption and provide technical information.
Why STABITERM
- A complete steel fire-protection system — primer, fire-retardant compound and finishing enamel in one place.
- Materials in stock in Tashkent, next-day delivery to cities across the republic.
- Many years of use on facilities in Uzbekistan — proven effectiveness and long service life.
- Valid certificates and test reports from the Ministry of Emergency Situations of the Republic of Uzbekistan.
- Thickness calculation from the section factor and the required fire-resistance limit, plus a technical information package.
Need fire protection for steel structures at your facility? Leave a request — we will select the compound and calculate consumption →
More about the service: Fire protection of steel structures in Tashkent and Uzbekistan →