Constructive fire protection of structures. Constructive fire protection or thin layer fire protection coatings

Fire protection metal structures is an element that, in the majority of cases, it is customary to pay special attention to. At the same time, you need to correctly understand what it is and where it is needed.

Why is it needed?

Bearing beams, I-beams, columns and other elements can behave practically unpredictably under fire conditions. At the same time, do not forget that their main task is to fulfill their direct purpose - to hold the building for the longest possible time, preventing any risks of collapse.

The metal retains its strength exactly until its temperature is equal to the temperature environment... Many are unaware of this fact. And if placed in an environment of high temperatures, over time, it will become flexible and ductile. Therefore, if specialized fire protection of metal structures is not used, it will not last even 3-5 minutes in fire.

By melting and bending, it damages the original structure of buildings and structures, provoking collapse when people have not yet had time to fully evacuate. This, accordingly, turns into their death. It is for this reason that the fire protection of metal structures is one of the most important elements taken into account in the design of the security of each building. However, you need to correctly understand how and when it is provided.

What it is?

Next, we will consider when fire protection of metal structures is possible. Today, a wide variety of construction methods, with the help of which fire protection is provided, such as brick lining, plaster on the grid and many others, but in this case we are considering non-building technologies that can be taken into account by any architects and designers.

How is this implemented?

According to SNIP, fire protection of metal structures should first of all be provided to buildings and structures in which various metal load-bearing elements are open. At the same time, there is no way to close them normally, or the architect's design move is used. Thus, we have a building that has load-bearing metal structures that are not protected by any means. In this case, according to SNIP, fire protection of metal structures is carried out by applying specialized fire retardant paint to them. In this case, this is not only the most effective, but, in principle, the only possible way.

It would seem that everything is extremely simple: we buy fire retardant paint and paint the available surface with it. At first glance, it may seem that such methods of fire protection of metal structures can be used by ordinary painters or cheap workers. In fact, this simplicity is only apparent and superficial.

To ensure the full implementation of this fire protection project, you need to know exactly how many layers of paint should be placed on certain elements, calculate the fire resistance limit of metal structures without fire protection, and also prevent the possibility of cracking or peeling of the material during the drying process.

Design

Do not forget that specialized paints themselves are not as cheap. This is just one of the reasons forcing the development of a project to ensure fire protection of structures. With the help of this project, it will be possible to understand how low metal structures are without fire protection, how much paint will be required to increase it, and also how many layers of material should be applied to certain elements.

Professional specialists are engaged in a detailed assessment of all loads that affect specific structures, calculate the fire resistance, as well as the time during which they can perform their direct function in fire. After that, the missing time is calculated and the required thickness of the protection layer is calculated. This is how the design and determination of the price of the work carried out is carried out, after which the specialists begin to implement the planned plan.

How is the application carried out?

Materials for fire protection of metal structures are applied using specialized airless units. Moreover, their application is carried out only in one layer of a certain thickness. The main feature here is that if the fire-retardant material is applied too thin, then in the presence of the slightest drying, the paint will begin to curl and burst, and otherwise it simply will not have time to dry. This will cause it to fall off the structure. That is why professional specialists, in accordance with the state standard (GOST), apply a certain layer of fire protection of metal structures, after which it is given time for partial drying, and then the next layer is applied. Then, by repeating this procedure, the required thickness is achieved.

It is worth noting the fact that each layer of fire retardant paint is under close control not only in wet, but also in dry residue, and the shrinkage coefficient is also checked. Among other things, the dry layer is also monitored with a dedicated electromagnetic vortex thickness gauge. In the presence of a really high-quality and correct execution the entire range of necessary procedures, from the development of the project to the direct application of the material, ultimately the coating will be able to last more than fifty years.

Key Features

Metals are structurally quite sensitive to fire and, in principle, high temperatures. That is why all procedures are carried out only in accordance with a predetermined set of rules (SP). Fire protection of metal structures should be carried out for the reason that the metal itself heats up very quickly. This leads to a significant decrease in its strength properties. In connection with this fact, metal structures are the most vulnerable element of any building in the process of a fire, and this is taking into account the fact that it is customary to use them in modern construction almost everywhere.

Few people understand correctly that steel frame the fire resistance limit is quite low and its value fluctuates in the region of 0.1-0.4 hours, and in accordance with existing standards, the fire resistance of any building structure should be in the region of 0.5-2.5 hours, depending on which one is specifically considered type of building, and that is why fire protection of metal structures is required. The requirements for the application of such materials regulate the correctness of their use, and also make it possible to make sure that in the end it is really possible to achieve the necessary results.

Causes

The main essence of fire protection of metal structures is to create a specialized heat-insulating screen on the metal surface. It is able to withstand high temperatures, and, if necessary, also does not allow fire to act on the material. Such a screen significantly slows down the process of heating metal structures in the event of a fire. This provides the time required for further evacuation and saving the lives of many people.

There are many methods by which fire protection of metal structures is carried out. The compositions are applied both in traditional ways, like plastering walls with special solutions, concreting or laying brickwork, and more modern ones, based on the use of lightweight aggregates and materials, including mineral fiber, expanded perlite, or all kinds of thermal insulation materials... The price of this procedure directly depends on which particular method was used in a particular situation.

Method classification

Constructive fire protection metal structures are carried out using several modern methods:

Special fire retardant coatings... They are made from cement, liquid glass, and granular mineral fibers.
The use of all kinds of intumescent fire retardant paints, which is a rather complex system that includes organic and inorganic components. Their main action is entirely based on the swelling of the composition under the influence of high temperatures and the further formation of a heat-insulating porous layer, the thickness of which is only a few centimeters.

The fire resistance of metal structures without fire protection is rather low, but with the help of such methods, specialists easily increase it to the required value of 0.75-2.5 hours, depending on which layer of plaster is applied, as well as on what is used fire retardant paint or lightweight cover. The use of intumescent paints in the majority of cases makes it possible to achieve fire resistance of structures lasting more than one and a half hours.

Application features

The application of special materials can be divided into four main steps:

Surface preparation.
Primer application.
Application of special paint.
Coating.

In this case, special attention is paid to the preparation of metal surfaces for further fire retardant treatment... With improper preparation in further coverage can simply collapse under internal or external influence, as a result of which the result of the work performed will be zero. In practice, you can find a fairly wide variety of possible states of metal surfaces before applying a special coating on them, and even for those metal structures that have not yet been in operation, in accordance with the established state standards four basic states are defined.

In practice, it is generally accepted to use two main cleaning methods - mechanical and chemical. The latter provides for the use of specialized cleaning agents. old paint and a lot of others. Mechanical technology provides for mechanized or completely manual processing... Such cleaning is carried out using an abrasive tool, brushing, or its main task is to obtain an absolutely clean metal surface with a complete absence of any coatings on it.

Another mandatory stage of preparation is complete surface degreasing, which is carried out using specialized organic solvents. The main purpose of this procedure is complete removal from the metal surface of any inorganic or organic fats and oils. The operation is carried out immediately before the first coating layer is applied, and in the majority of cases it is customary to combine it with dust removal.

Primer

The first layer when applying any fire retardant coating is always a primer. Moreover, in the majority of cases, it is customary to use acrylic, which is considered the most versatile. The main tasks of the primer are to ensure the metal, as well as high-quality adhesion to the surface and subsequent layers of the coating.

It is necessary to approach the choice of soil extremely carefully when it comes to further fire retardant treatment. Indeed, on the market you can find a lot of different products that are manufactured in accordance with technical specifications, and not GOSTs. Basically, soils that are produced according to TU differ in softening temperature at the level of 90-100 ° C, while working temperature the fire retardant coating is 220-250 o C. Thus, the soil eventually loses its properties, which can provoke its deformation and further flaking together with the applied fire retardant coating. Among other things, the use of any cheap analogs produced only according to TU will lead to an increased drying time of the applied material, as well as a decrease or even complete loss of adhesion of the applied fire retardant coating.

Not everyone understands that it is extremely important to withstand the soil until it dries completely before applying the fire retardant paint itself, otherwise protective covering may just crack during operation. Application of specialized materials to old coatings or surfaces previously primed paints and varnishes, which are not recommended by the manufacturers of fire retardant paints, can subsequently provoke a deterioration in adhesion, as well as swelling or peeling of the applied coating.

It unites the complex under itself technical activities aimed at improving the ability to withstand fire. In building structures, due to it, the possibility of a fire is noticeably reduced. The degree of fire resistance must comply with the established standards fire safety.

Constructive fire protection of metal structures leads to a limitation of the area of flame spread. The level of smoke and concentration of poisonous gases is noticeably reduced.

Reliable fire protection. What is it?

To improve the indicators of resistance to fire, certain materials can be used in the structure. They can be lightweight and applied to a particular surface. After their application, a kind of heat shield is formed.

Methods for creating constructive fire protection:

The use of plaster;

Brick lining;

Concrete coating;

Installation of various coatings.
The main goal is to provide maximum protection for steel elements. The period of time during which this protection must remain in effect is no more than 150 minutes.

Plaster, brick lining

These methods are universal. They are suitable for use in almost any environment. On the other hand, they are quite labor intensive. Among other things, you will have to thoroughly prepare the surface of the object.

Constructive fire protection of this type cannot always be used in relation to complex structures... Optimum strength cannot be guaranteed for the cover if trusses or other complex components are covered with plaster.

There are disadvantages to brick lining. First, they significantly increase the load on the foundation. Secondly, you have to spend much more time on the construction process in general. Thirdly, difficulties in subsequent repairs cannot be ruled out. Constructive fire protection with bricks pays off when it is necessary to process metal products, as well as to strengthen them.

note that classic options fire protection no longer meets the currently established standards and requirements. Fire resistance cannot be adequately achieved with conventional paints. Brickwork, like concreting, not only requires a lot of labor, but also increases the load on the base.

Plastering the traditional way assumes layer-by-layer reinforcement. This presents additional difficulties. Such a structure can become covered with cracks as soon as sharp temperature changes or vibrations are noted. In the end, it will collapse completely.

All of the above circumstances have led to the fact that materials based on basalt fibers are increasingly used. They are often used when installing air ducts. They also have a proven track record when it comes to protecting metal components in various buildings.

Fire protection from basalt materials

This technique has become commonplace. This was facilitated by numerous advantages:

Low cost;

Low price;

Extreme ease of installation.
The service life of the material is long. It often approaches the duct life. At the same time, we have to talk about the aesthetic appearance basalt fire protection.

Protection of metal products today

Over the past few years, fire protection materials have become much more advanced. Lightweight materials are often used for building metal structures. These are fibers as well thermal insulation boards from basalt.

Metal structures are heat sensitive. They tend to heat up quickly when ignited. This contributes to a decrease in some of the characteristics of the material. First of all, this is true in relation to the strength of the metal.

Constructive fire protection using basalt is based on the creation of a heat-insulating screen on the surface. It effectively resists heating of the structure, slows it down.

The fire resistance and durability of the entire building or structure depends on the characteristics of building structures. They are made mainly of metal, but in low-rise construction, attic spaces and in some other cases wood is used. Each material and specific design has a fire resistance limit. If the untreated object has an indicator below the norm, which is determined by the current construction and fire regulations, then resort to methods of increasing it.

Material properties

Fire resistance limit - the period of time during which a material resists fire. It is known that the exponent y wooden structures without treatment usually does not exceed 15 minutes. Constructive fire protection helps to increase it. It allows you to reduce the rate of spread of fire, as well as the appearance of smoke, the formation of corrosive gas.

The creation of constructive fire protection of building structures is possible by several methods:

covering with concrete, plaster;
shielding;
brick lining;
cladding with slabs and sheet material;
filling voids inside metal structures;
combination of materials and methods (fire protection system of structures).

All materials for structural fire protection must be certified (with rare exceptions), for which they are subjected to tests. There are also requirements for environmental safety. They contain the effects of fire by preventing ignition or smoldering.

The material fits snugly to the structure, it is not allowed to detach even on small areas... In addition, it must be durable and resistant to environmental influences during the operational period. Additionally, they can serve decorative coatings, improve heat and noise insulation in the room.

The choice of materials for structural fire protection depends on the characteristics of the object. The choice is largely influenced by the design or working documentation for fire safety. It contains parameters, takes into account the type and properties of the structure. If they are of the same type in the building, then the calculation is simplified. The joints and transitions are taken into account, their fire resistance limit cannot be less overall indicator for the whole structure. However, the complex configuration increases the overall fire resistance due to the distribution of loads and heat to the various elements.

Structural fire protection system - a set of methods and materials for appropriate processing. An example is foil-clad basalt slabs and an adhesive composition with additional fire-retardant functions for metal structures. This complex of constructive fire protection also includes fasteners.

Methods for protecting metal

For metal structures, a screen is created to restrain the effects of heat.

Effective constructive methods are cementing or brickwork. However, they have practically been abandoned today. Cement and bricks increase the load on building structure, decrease usable space in room. Laying and grouting is time consuming, but durable and versatile.

Mineral fibers for fire protection of such structures are mainly represented by sheets in rolls. They are considered environmentally friendly, since basalt fibers are produced from natural materials without any chemical additives. Plates or sheets must be semi-rigid.

Fastening is done with anchors and frames. Flaw basalt slabs- the need for additional processing structures with anticorrosive compounds, which requires constructive fire protection. Basalt slabs are widely used to protect metal air ducts in combination with other means.

The voids inside the structures are filled with special compounds. So the thickness of the structure increases, and the heating rate decreases. When choosing means of constructive fire protection for metal, they are guided by the section, the higher this indicator, the greater the resistance.

Certain rules have been created for applying a fire retardant coating to metal structures. A thick layer of fire protection when plastering on a metal structure requires reinforcement with a special mesh with small cells. Then the reliability and tightness of fit will be ensured. Fire protection for metal can only be carried out using proven means.

For reinforced concrete structures, the principle of selection and method of structural fire protection is similar, but additionally, the characteristics of concrete are taken into account. In case of fire, his integrity is violated, cracks, ruptures appear cement stone... This promotes sagging metal fittings... As a result, the stability of the building is compromised.

Another way of fire protection of metal structures is coating with special compounds. The method is used for hard-to-reach places, allows you to save free space and not add stress to the structure. Fire retardant coatings are based on water or chemical solvents.

When working with solvent-based formulations, it is necessary to observe fire safety rules and use protective equipment, since these coatings have a pungent odor and increased flammability.

However, their advantages are in the possibility of using at low temperatures and covering with decorative materials.

Constructive fire protection various designs made of metal is permissible in the form of protective plates with the inclusion of drywall and its reinforcement with non-woven fiberglass. This is an expensive method, but it increases the fire resistance up to 4 hours. Untreated metal structures are sheathed with pre-cut sheet material, as a result, additional efforts or the use of others are not required fire retardant materials... The choice of sheet thickness depends on the characteristics of the structure, in particular on the thickness of the metal.

Wood protection methods

Wood - available material for construction, but because of its flammability, its use is very limited. Wooden structures often serve as a support in places with little load, but they also require processing. Structural protection of wood and metal structures differs significantly in the selection of materials.

By current regulations it is difficult to determine which species will meet the requirements, as well as to calculate the necessary indicators. In practice, constructive fire protection of wooden structures is provided mainly by impregnations and paints, which are called chemical method fire protection. Sometimes it is appropriate to use basalt slabs or sheets, as a universal and easy-to-install product.

As additional fire protection of wood structures in a building or structure, they are used mineral materials, gypsum-fiber tiles, plasters with heat-insulating effect. For wooden rafters and roof lathing, a method of insulation is provided mineral wool, which restrains the heating of the structure.

There is no regulation on compulsory certification means of constructive fire protection of wooden structures. Therefore, many use methods for simple fire protection based on the characteristics of the object and those provided by the manufacturer.

Protection of cable lines

Cables are often laid in a line that runs through floors and other similar structures. They also need structural fire protection, especially at critical points. Additional functions such fire protection - extending the service life and eliminating small defects associated with the cable sheathing.

In this case, the fire resistance limit should not be less than that of the structure. To do this, collect cable penetration from various materials, but most often they use foil mineral wool (basalt) slabs and intumescent compositions. Produce paints, mastics, pastes on water and chemical basis... There are options for indoor and outdoor use. Such a constructive method of fire protection cable lines is designed for long-term operation and requires periodic inspection and testing.

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