RECOMMENDATIONS ON FIRE PROTECTION SELECTION

FIRE RESISTANCE CLASS R, minutes

Paints

Plasters

Plates

Methods and means of fire protection of steel structures are determined at the stage of development of the fire protection works design subject to the main factors:

- class of fire resistance of structures in accordance with the degree of fire resistance of the building;

- calculated cross-section coefficients of structures (profile or box);

- calculated critical temperatures of steel elements;

- conditions of operation of the fire protective coating.

Fire protection may imply the use of coatings of cladding and heat-insulating type, the fire protection effect of which is determined by the thermophysical properties of the protective material used, as well as the use of reactive type coatings, which bulk under high temperatures and form a heat-insulating coke layer on the protected surface.

The most common fire protective materials include structural fire protective materials (slabs, mats, segments, shells, ceramic stone products, blocks), fire protective plaster mixtures and thin-layer reactive coatings of the intumescent (bulking) type.

Reactive coatings are thin-layer fire protective materials which form a dense insulating layer when exposed to fire, and protect the structure from thermal effects. These fire protection means are also called thin-layer intumescent (bulking, thermally expandable) coatings.

Types of fire protective materials for fire protection

Modern intumescent paints are water highly filled compositions or compositions diluted with organic solvents. The procedure for applying them to the structure to be protected is a little different from the methods of applying usual paints and varnishes.

Thin-layer type coatings provide a good aesthetic appearance of building structures and, as a rule, do not require additional treatment of the surface with protective paints and enamels, unless required by the operating requirements.

Characteristics of the main types of intumescent paints

Properties	Water	Diluted with organic solvents	Epoxy	With thermally expanded graphite
Conditions of application	Above 5 °С; not affected by humidity	Above 0 °С; humidity up to 80%	Above 5 °С; humidity up to 80%	Above 0 °С; humidity up to 80%
Operation	indoors	indoors	Indoors and outdoors	Indoors and outdoors
Volatile organic compounds (VOCs)	Virtually absent	Up to 35%	Up to 20%	Up to 65%
drying time	8 hours	8 hours	24 hours	10 hours
toxicological factors	minimum effect	Hazardous to health and the environment	Average effect	Hazardous to health and the environment
Recommended nominal fire conditions	Standard	Standard	Standard and hydrocarbon	Standard and short-term hydrocarbon

The quality of intumescent paints is determined by the following main characteristics:

• flame retardant performance of the material,

• technological effectiveness of application and restoration,

• resistance to environmental impacts and warranty period of the coating,

• operating conditions of the coating.

As a rule, fire protective dry construction mixtures (plasters) are cement or gypsum compositions with a complex of light fillers and special additives, which form coatings with high adhesion to steel surfaces and relatively low density (400-600 kg/m3). Compounds are supplied in the form of dry construction mixtures, which are applied to the surface of metal structures with a thickness of 10-50 mm, depending on the required fire resistance class, which can reach R 240.

Plaster should be chosen for fire protective treatment in cases where the required fire resistance limit of steel structures exceeds R60 (in some cases R45) and the use of fire protective paints for such fire resistance classes is not economically feasible, there are high requirements for environmental characteristics due to complex configurations or location of the structure.

Characteristics of the main types of fire protective plasters

Properties	Cement	Gypsum
Conditions of application	Above 5 °С; not affected by humidity	Above 0 °С; not affected by humidity
Operation	Indoors and outdoors	Indoors (without protective layer)
Volatile organic compounds (VOCs)	No	No
Primary drying time	24 hours	3 hours
Time of gaining the main strength characteristics	28 days subject to regular surface moistening	7 days
Toxicological factors	Minimum effect	Minimum effect
Recommended nominal fire conditions	Standard and hydrocarbon	Standard and hydrocarbon

Due to their identical fire protective efficiency, the choice between gypsum and cement plasters can be determined by two main factors: gypsum plaster mixtures should be used in case of a short period for fire protective treatment. Cement plaster should be selected for outdoor use or in conditions of high humidity, but you should bear in mind that cement plaster coatings require additional regular moistening of surfaces to gain the main operational characteristics. It should also be noted that gypsum-based plaster materials are the cheapest materials in the fire protection segment.

In addition to high fire protection efficiency and relatively low cost of the material, fire protective construction mixtures have a number of other advantages:

- delivery to the construction site in dry form, long shelf life;

- versatility in the use for fire protection of metal, concrete products and designs, air ducts, cable ducts;

- absence of harmful conditions at the time of application and high labor productivity;

- preservation of physical and mechanical and fire protective properties of the coating after a short-term fire;

- low loads on the elements of building structures.

Fire protective plates and fiber sheet materials represent constructive methods, the fire protective effect of which is determined by the thermophysical properties of the material used. The fire resistance class of steel structures achieved with the use of fire protection plates can be up to R 300.

The fire protection efficiency of such materials is determined visually on the basis of two main parameters: conformity of the thickness to the data of the Certificate of Conformity and preservation of the integrity of the protective structure at all stages of life of the material — acceptance, storage, installation, operation.

As a rule, fire protective boards are silicate, perlite, vermiculite, perlite-cement, vermiculite-cement, mineral wool, gypsum fiber analogues of fire protective plaster mixtures, and are almost identical to the latter in terms of fire resistance they provide. However, the method of installation of fire protective plates is a dry construction technology, which creates a number of preferences when fire protection works are performed: no expensive equipment is needed, plates can be installed at any time of the year and in conditions when the use of wet technologies is unacceptable for any technological or other reasons. The production cycle does not include a stage of drying the covering and its finishing, which significantly reduces the duration of fire protective treatment.

In addition, according to the manufacturers' warranty, fire protective plates are the most durable fire protective material, their service life is not less than 30 years, which indicators are much higher than similar indicators of fire protective plasters. This difference is primarily due to the fact that in the case of plaster, the service life is determined first by the condition of the anti-corrosion layer of the metal structure, and fire protective plaster peels and cracks in the process of operation upon the destruction of the anti-corrosion coating. In case of facing with plates, there is no direct contact of fire protective material with the metal structure, and the protective coating does not change for a very long time in the absence of mechanical destructive impacts.

Choice of fire protective material to ensure a standardized fire resistance class of metal structures

Based on the general ideas about the cost-effectiveness and operation capabilities of fire protective materials for steel structures, it should be noted that

· In order to ensure fire resistance of R30 class, it is most appropriate to use thin-layer intumescent coatings;

· Fire resistance class R45, R60 can be provided with paints, plasters and plates. The priority of use of a certain material can be determined by additional conditions such as the cost of fire protection, configuration of steel elements, operating conditions and the fire exposure expected.

· Starting with fire resistance class R90, slabs and plasters are the most reliable material to ensure fire protection efficiency and operation characteristics.

The use of fire protective materials to provide appropriate fire resistance limits.

Selection of fire protective material based on operating conditions

The durability of the fire protective covering depends on the operating conditions of the covering, which should be declared in the manufacturer’s technical documentation.

Operating conditions for moderate climates

Atmospheric corrosion category	DSTU ISO 12944-2:2019		Location categories GOST 15150-69
Atmospheric corrosion category	Outdoors	Indoors
С1 Very low	-	Heated rooms with a clean atmosphere, for example: offices, stores, schools, hotels	Y1	Outdoors (effect of a number of climatic factors characteristic of a macroclimatic region with a moderate climate).
С2 low	Atmosphere with low pollution. Mostly rural areas.	Unheated premises with possible condensation, for example warehouses, gyms.	Y2	Under a canopy or in premises with temperature and humidity fluctuations insignificantly different from fluctuations outdoors, and with relatively free access to outdoor air (no direct exposure to solar radiation and precipitation).
С3 medium	Urban or industrial atmospheres, moderate pollution with sulfur dioxide. Coastal areas with low salinity level.	Production facilities with high humidity and some air pollution, for example, food processing plants, laundries, breweries and dairies.	Y3	Indoor premises with natural ventilation without artificially regulated climatic conditions, with temperature and humidity fluctuations significantly less than outdoors (without direct exposure to solar radiation and precipitation).
C4 high	Industrial and coastal areas with moderate salinity level.	Chemical plants, swimming pools, coastal shipyards and ship-repair yards.	Y;	Premises with artificially regulated climatic conditions, for example, in closed heated or refrigerated and ventilated industrial and other, including well-ventilated underground premises.
С5 very high (industrial)	Industrial areas with high humidity and aggressive atmosphere and coastal areas with high salinity level	Buildings or premises with almost constant condensation and high pollution level	Y5	Premises with high humidity, for example, in unheated and unventilated underground premises.
CХ extreme	Maritime areas with high salinity level and industrial areas with extreme humidity and aggressive atmosphere	Industrial areas with extremely high humidity and aggressive atmosphere

In accordance with the provisions of ETAG 018 (EAD 350402-00-1106), four types of operating conditions X, Y, Z1, Z2 are distinguished:

• type X — fire protective covering intended for operation in any conditions (both indoors and outdoors, in environmental conditions);

• type Y — fire protective coverings intended for use indoors or in semi-indoor premises with partial exposure to the environment (temperature below 0 °C, limited exposure to ultraviolet radiation), but without not exposed to rain;

• type Z1 — fire protective coverings intended for use in premises with high humidity, except for those intended for operation at temperatures below 0 ° C;

• type Z2 — fire protective coverings intended for indoor use without exposure to high humidity, except for those intended for operation at temperatures below 0 C.

Use of fire protective materials depending on the operating conditions

Operating conditions
Z2	Z1	Y	X
Fire protective paints	fire protective paints with a covering layer. Epoxy paints
Fire protective plasters		Fire protective cement-based plasters
Fire protective plates

Consideration of the main factors when choosing fire protection means

The table shows the comparative characteristics of the most common passive fire protection means, which can serve as a guide when choosing a fire protection material to ensure the required fire resistance classes, subject to the configuration of protected steel structures, environmental and aesthetic requirements and operating conditions.

Main characteristics and areas of application of fire protection methods, subject to their features

Characteristic	Fire protective plasters	Fire protective plates	Intumescent paints
Fire resistance class	up to R240	up to R300	up to R120
Hazard class	4 low-hazardous substance	4 low-hazardous substance	2-4 low-hazardous substance (water based) hazardous epoxy substance) highly hazardous substance (diluted with organic solvents)
Operating conditions according to ETAG 0181)	Y, Z1, Z2	X, Y, Z1, Z2	Z1 (with protective coating), Z2
Smoke generation factor m2/g	0.5 - 1	0.5 - 1	500 - 700
Advantages	high fire resistance limit, low cost of materials, environmental friendliness in operation and absence of toxic products of combustion, possibility of use outdoors	high fire resistance limit and long service life, increased protection against vibrations due to mechanical fastenings to the structure, repairability, absence of corrosive effect on metal, good finishing properties, environmental friendliness in operation and absence of toxic products of combustion, exact control of thickness of a fire protective layer, dry assembly method	minimum thickness and weight load on the structure, technological efficiency of fire protection works, repairability, increased protection against vibration, good finishing properties
Disadvantages	labor-intensive application, complexity of restoration and repair, low finishing qualities, weak adhesion to the surface, low protection against vibrations.	need for the arrangement of special fastening systems and elements, limited use for fire protection of structures with a complex configuration	limited operating conditions and fire protective efficiency, high toxicity of combustion products
Area of application	for constructions with common configuration (columns, beams, notch-boards, crossbars)	for structures with simple configuration (columns, beams)	for structures of any configuration (columns, beams, notch-boards, crossbars, trusses, joints, etc.)