Passive fire protection systems include fire protection cupels which are useful for the fire protection of steel tie rods and structural tensioners in industrial prefabricated buildings.

Many Italian warehouses use an old construction method, i.e., prefabricated load-bearing columns, beams, metal tie rods, roof covers and closure panels.

This type of structure takes a long time to build compared to modern techniques. It is expensive to construct and does not allow for later changes, making it inflexible and of little use in modern construction.

This led industrial construction towards prefabricated warehouses (in pre-stressed reinforced concrete or steel), abandoning the use of masonry, which makes them unsafe in a country at seismic risk like ours. Steel in modern structures provided high mechanical resistance using a reliable solution. However, this is not fire risk-free.

To allow large spans to be reached, before the introduction of prefabricated warehouses, pushing arch vaults were built and, to counteract the stress transmitted from the roof to the side walls steel cable tie rods were used. They played a decisive role in maintaining the structure's tension.

These elements are extremely vulnerable to fire because when the critical temperature of 350°C (test standard EN 1363-1:2012) is exceeded, steel rapidly loses its integrity by undergoing elongation (thermal expansion of the steel that increases proportionally to the temperature). This is critical for applied loads and leads to structural collapse.

It is crucial to protect metal tie-rods against fire by using specific materials with high thermal insulation capable of hindering high temperatures. It is not sufficient for the material used to be classified as non-combustible (class 0), but it must have a degree of thermal insulation that allows the structure to attain a fire resistance equal to or greater than the class of the structure (60'-120'). 

AF Systems provides AF PSR 90-120 fire protection cupels for the circular protection of the metal tie-rods in specific industrial prefabs, particularly those where there are no pillars or intermediate columns, and which have arched roofs or beams made of thin steel profiles.

AF Systems cupels are certified for R 90 and R 120 fire resistance classes and consist of two concentric bodies of high-density rock wool.

The inner cupel is treated on the surface with a special ablative product to lower temperatures using water vapour emission. The outer cupel is coated with a layer of aluminium mesh or, upon request, galvanised sheet metal that can be fixed with self-tapping screws.

AF PSR 90/120 advantages:
- Fast and clean assembly;
- Easy application;
- No assembly INTERRUPTION.