Procedures and control methods regarding fire protection of metal structures
02.08.2017

When exposing steel to temperatures over 200⁰C its mechanical features will be affected. It will become easily breakable due to a reduced elasticity degree.

When the temperature goes above 500⁰C the steel structures lose more than half of their support capacity.

In order to avoid these negative effects and for insuring an optimum protection it is recommended to cover the metal surfaces with a layer of thermofoaming paint. They are generally immune to low temperatures but when exposed to high ones (over 200-250⁰C) they transform themselves into carbonic foam able to protect the surface they cover.

In order to be able to develop projects in the fire protection area the companies must be specially authorized and own following set of equipment:

blasting installation
equipment for applying thermofoaming paints
nozzles set
device for measuring and controlling the adhesiveness level of the paint
device for measuring the dry layer of paint
device for measuring and controlling the level of humidity and the temperature of the metal surface
device for measuring the wet layer of paint
standards for cleaning levels
devices for surface preparation

Insuring the fire protection with theromfoaming paint implies series of steps:

Surface preparation

Cleaning the surface before applying paint is to be done through blasting it with steel grit. In order to determine the cleanness level one can use an Elecometer 128.

Roughcasting the metallic structure

The primer will have an anticorrosive purpose and its lifetime will depend on the climatic conditions during application, the temperature of the surface to be treated, the Dew Point and the relative humidity plus the thickness of the layer. As a rule, the temperature of the surface should be at least 3⁰C above the Dew Point. Applying the primer on a humid surface will influence the adhesiveness level. When the air temperature is too low, the drying time will increase. Therefore it is recommended to permanently monitor the climatic conditions during application. In order to do it one can opt to use an Elcometer 319.

On the other hand if the primer layer is too thick there is a risk that it will get broken during drying. Furthermore it is clear that this will also involve an unnecessary consumption of paint.

In order to obtain the optimum layer’s thickness it is recommended to use an Elcometer 112.

When knowing the degree of solid compound from the primer (usually stipulated on the packaging of the paint) and the thickness of the wet layer one can determine the thickness of the dry layer based on the following formula:

The thickness of the dry layer of primer = the thickness of the wet layer x % of solid compound existing in the primer

For checking the final results of the application one can choose to use an Elcometer 456, which will measure the final thickness of the paint’s layer.

For verifying the adhesiveness degree of the primer it is recommended to opt for a specialized kit – the Elcometer 107.

Applying thermofoaming paint

The application of the paint can be done only after insuring that the primer has been dried. The conditions related to humidity, temperature and layer thickness are to be respected in this case as well. For measuring the final results of the process one can use following devices: