Steel rapidly loses its load-bearing capacity at high temperatures. The purpose of passive fire protection coatings is to delay this loss, ensuring the structure remains standing for the intended duration.
Principle of operation
Intumescent coating, under normal conditions, is a thin layer of paint. At fire temperatures, it expands, forming an insulating carbon layer and reducing the heating rate of the steel element. The system is not a single layer; primer, intumescent coat, and a suitable topcoat work together according to the project.
Target resistance time
The required time is determined by the project's fire design and is expressed in minutes. R30 indicates thirty minutes, and R120 indicates one hundred and twenty minutes. As the duration increases, the required coating thickness also increases.
Section factor is decisive
For the same target duration, the same thickness is not applied to every element. The decisive parameter is the section factor; it is calculated as the ratio of the element's cross-sectional area to the perimeter exposed to fire and is denoted by Hp/A.
Elements with a high section factor, i.e., thin-walled and wide-surfaced profiles, heat up faster and require a thicker coating. Therefore, it is necessary to share the element list and section information at the quotation stage.
Critical temperature and loading table
The third variable in thickness calculation is the critical steel temperature. This temperature, determined based on the load carried by the element, is evaluated together with the product manufacturer's approved loading table to determine the required dry film thickness.
The final system is verified with the product manufacturer's test and ETA documents and the client's specification. Depending on the project and product approval, EN 13381-8, EN 13501-2, and relevant fire design requirements are taken into consideration.
Application record
Record-keeping in fire protection application is more critical than in corrosion protection. Coat thickness, curing conditions, mesh or reinforcement requirements, and final measurements are recorded; these records may be requested during the building permit process.
Bu yazı genel bilgilendirme amaçlıdır. Her projede sözleşme, müşteri şartnamesi, boya üreticisi dokümanları ve güncel standart baskıları esas alınır.