Today, the production volumes of intumescent paints comprise a significant part of the entire fire-protection production. At the same time, both uncertified and low-quality products can be often offered within the segment. The main implicit factors of the violation of the intumescent coating quality are the thickness of the layer and the degree of dilution of ready-to-use paint immediately before use. These factors affect the quality of coked foam, i.e., its layer thickness and its density; however, these cannot be detected during the external examination of the paint layer, measuring its thickness and conditional adhesion in accordance with modern standards. The reliability of the results of intumescent coating fire-retardant properties evaluation can only be ensured considering the evaluation of additional parameters of coked foam (strength and homogeneity) applied to protected structures measured in conditions close to real fire conditions.
A methodology of express analysis of intumescent coatings on steel structures has been considered; the analysis aims to determine the expansion rate, strength, and adhesion of protective coating produced based on formed coked foam. The methodology is based on the theoretical studies of the effects of intumescent paint parameters (layer thickness, degree of dilution) on coked foam parameters and contains non-standard methods of intumescent fire-protection parameters. The intumescent coating spot heating method at sampling sites has been developed; the efficiency of the penetromety method to determine the coked foam strength has been proved. These methods are simple and do not require using any expensive equipment. The methodology can be applied to evaluate the fire-retardant coating directly at a construction site by the following parameters: coked foam intumescence, homogeneity of its structure, ultimate strength in compression, and shear-breakout.
It has been established that high values of the intumescence coefficient do not guarantee the reliability of fire protection. The higher the intumescence coefficient is, the lower the thickness and strength of the coked foam. Considering this interdependence of parameters, it is reasonable to establish, on a regulatory basis, the ultimate values of the coked foam intumescence coefficient.
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