Structural steel protection
When steel heats up during a fire, the structure gradually loses its loadbearing capacity at temperatures between 350oC and 750oC. Depending on the loads and actions on the structure, it would typically fail when the steel reaches temperatures between 500 and 600oC. Therefore, structural steel protection is required to preserve the stability of the building structure in the event of fire. Promat offers a wide range of board, spray and paint products to suit the requirements for any project.
The required thickness of each product depends on:
• The fire resistance requirement (typically 60, 90 or 120 minutes, sometimes even 180 or 240 minutes, in accordance with national legislation and mostly depending on the function and height and the activities inside the building).
• The critical steel temperature (typically 500-600oC and specified in national regulations or by structural engineers). This represents the maximum temperature at which the steel still has sufficient strength left to avoid collapse or large deformations.
• The geometry and the orientation of the steel structure. The thicker the steel elements are, the slower they will heat up. Thinner elements will heat up faster. This is expressed as a “section factor”, which is typically 50-100 m-1 for thick heavy sections and 200-300 m-1 for thin and light sections. The section factor is also influenced by the fire exposure, e.g. on three sides for a beam, on four sides for a column.
Testing by independent institutes is always followed by an assessment, which results in tables that provide the required thickness for the given product depending on fire resistance requirement, critical steel temperature, element type, orientation and section factor.
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