Structural Steel Fire Protection
Numerous research programmes show that some types of fully stressed steel sections can achieve a fire resistance of 30 minutes without any additional protection materials being applied. However, these apply to a limited number of steel sections only, based on the allowable Section Factor Hp/A. Section Factor is a common term used in fire protection for steelwork.

Typical building regulations usually require certain elements of structure to be fire resistant for more than 30 minutes and up to a specified minimum period of time. The thickness of any fire protection material depends on a number of factors, such as:

• Duration of fire resistance specified;
• Type of protection used (e.g. board, paint, spray etc);
• Perimeter of the part of steel section exposed to fire;
• Shape and dimensions of the steel section

To determine how these various factors affect the fire resistance, all Promat products and systems have been tested at nationally accredited laboratories around the world to a variety of standards, e.g. BS 476: Part 21, AS 1530: Part 4, DIN 4102 and ASTM E119.

Tests carried out in accordance with BS 476: Part 21 are performed on both loaded and unloaded beams and columns which are clad with fire protection material. Steel surface temperatures are monitored with thermocouples to assess the performance of the cladding. Steel that is fully stressed in accordance with the design guides BS 449 or BS 5950: Part 1 (Australian equivalent AS 4100), begin to lose their design margin of safety at temperatures around 550°C.