Development of test methods for fire-retardant coatings of steel engineering structures during operation

Introduction. Prediction of the durability of flame-retardant coatings of steel engineering structures and preservation of their performance during operation remain important research directions. There is a lack of normative documents in the field of fire protection, regulating the process of testing of flame-retardant coatings during operation, as well as determination of their durability (service life).

Aim. To develop test methods for determining the resistance of flame-retardant coatings of steel engineering structures exposed to climatic factors, preservation of their fireproof and anti-corrosion properties during operation.

Materials and methods. Test specimens included 600 x 600 x 5 mm plates made of 08kp and 08ps sheet steel according to State Standard 16523-97 and State Standard 9045-93 with a flame-retardant agent applied on the front side.

Results. Methods for testing thin-layer intumescent and structural flame-retardant coatings during operation are proposed. The methodology of accelerated climatic testing of specimens coated with thin-layer intumescent flame-retardant coatings (flame-retardant paints) corresponds to State Standard 9.401-2018. These coatings are inherently high-solid paint materials. A new methodology, sequence, and modes of testing are developed for structural flame-retardant coatings. The subsequent assessment of fireproof properties of coatings and their preservation is carried out by the methods of fire protection efficiency according to State Standard R 53295-99 and the methods of thermal analysis. These methods imply comparison of the characteristics of the initial flame-retardant coating and those obtained after sample aging. The preservation of fireproof properties by thin-layer intumescent and structural coatings is additionally evaluated by the intumescence coefficient and the change in thermal conductivity, respectively.

Conclusions. Test methods for flame-retardant coatings of steel engineering structures during operation are developed. Threshold levels of changes in their properties are established. After accelerated climatic tests, fire protection efficiency should not decrease by no more than 20 %. For structural fire protection, an increase in thermal conductivity by no more than 5 % is permitted. For thin-layer coatings, the arithmetic mean value of the intumescence coefficient should not decrease by no more than 30 % of the initial value.

Implications. The developed methods were used in the preparation of a draft national standard of the Russian Federation “Steel engineering structures with fireproof coatings. Test methods for anticorrosion properties and resistance to climatic factors during operation” to ensure regulatory fire safety requirements for these structures.

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