SNiP: fire protection of metal structures. Limit of fire resistance of metal structures without fire protection

Fire protection of metal structures is such an element, which in the majority of cases it is customary to pay special attention. In doing so, you need to understand correctly what it is and where it is needed.

Why is it needed?

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

Metal keeps its fortress exactly until its temperature equals ambient temperature. Many do not know about this fact. And if it is placed in a high temperature environment, over time it will become flexible and plastic. Therefore, if specialized fire protection of metal structures is not used, it will not last for 3-5 minutes in the fire.

Melting and bending, it damages the original construction of buildings and structures, provoking a collapse, when people have not yet fully evacuated. 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 process of developing the safety of each building. However, you need to understand correctly how and when it is provided.

What it is?

Next, we will consider when fire protection of metal structures is possible. To date, a variety of construction methods have been used, with 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 realized?

According to SNIP, the fire protection of metal structures should first of all be provided to buildings and structures in which various metal bearing elements are open. At the same time, there is no possibility to close them normally, or the architect's design course is used. Thus, we have a building that has no metal structures that are not protected by any means. In this case, according to SNIP, the fire protection of metal structures is carried out by applying a specialized fire retardant paint on them. In this case, it 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 we paint it with an accessible surface. 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 laid on certain elements, calculate the fire resistance of metal structures without fire protection, and prevent the possibility of cracking or delaminating material during the drying process.

Design

Do not forget that the specialized paints themselves are not so cheap. This is only one of the reasons that make it necessary to develop a project to ensure fire protection of structures. With the help of this project it will be possible to understand how low the fire resistance of metal structures is without fire protection, how much paint will be required to increase it, and how many layers of material should be applied to these or other elements.

Professional specialists are engaged in a detailed assessment of all loads that affect specific designs, calculate fire resistance, as well as the time during which they can perform their direct function in the fire. After this, 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 are carried out, after which the specialists begin to implement the plan.

How is the application carried out?

Materials for the fire protection of metal structures are applied with the help of specialized airless units. And their application is carried out only in one layer of a certain thickness. The main feature here is that if the fireproof material is applied too thinly, then if there is a slight drying out the paint will start to curl and burst, otherwise it will not have time to dry up. This will lead to its fall from the structure. For this reason, professional specialists in accordance with the state standard (GOST), the fire protection of metal structures is applied in a certain layer, 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 monitoring not only in the wet, but also in the dry residue, as well as checking the shrinkage ratio. Among other things, the dry layer is also controlled by a specialized electromagnetic vortex thickness gauge. In the presence of a truly qualitative and correct implementation of the entire range of necessary procedures, from the development of the project to the immediate application of the material, ultimately, the coating will last for more than fifty years.

Key Features

Metals in their structure are quite sensitive to fire and in principle high temperatures. That is why all procedures are carried out only in accordance with a pre-established set of rules (JV). Fire protection of metal structures should be carried out for the reason that the metal itself very quickly heats up. This leads to a significant decrease in its strength properties. In connection with this fact, metal structures represent the most vulnerable element of any building in the process of fire, and this is in view of the fact that they are used in modern construction almost everywhere.

Few people correctly understand that the steel framework has a low fire resistance and its value fluctuates around 0.1-0.4 hours, and in accordance with existing standards, the fire resistance of any construction structure should be in the region of 0.5-2.5 Hours, depending on what type of building is specifically considered, 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 allow you to do so that, in the end, you can really achieve the necessary results.

Causes

The main essence of the fire protection of metal structures is that a special heat-insulating screen is created on the metal surface. It is able to withstand high temperatures, and, if necessary, also does not allow to act on the material of the fire. Such a screen significantly slows down the procedure for heating metal structures in the event of a fire. Due to this, the time necessary for further evacuation and saving lives of many people is provided.

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

Classification of methods

Constructive fire protection of metal structures is carried out by several modern methods:

• Special fire retardant coatings. They are made of cement, liquid glass, as well as mineral granulated fiber.
• The use of all kinds of swelling fire retardant paints, which is a fairly complex system, including organic and inorganic components. Their main action is completely 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 low enough, but with the help of such methods, specialists without any difficulty increase it to the required value of 0.75-2.5 hours, depending on what the layer of plaster is applied, and also whether a fireproof paint or Lightweight coating. The use of swelling paints in the majority of cases allows achieving fire resistance of structures lasting more than an hour and a half.

Features of application

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

1. Surface preparation.
2. Application of a primer.
3. Application of special paint.
4. Coating.

Particular attention in this case is given to the preparation of metal surfaces for further flame retardant treatment. If improperly prepared in the future, the coating can simply collapse under internal or external influences, as a result of which the result of the work done is zero. In practice, one can find a rather wide variety of possible states of metal surfaces before applying special coatings on them, and even for those metal structures that have not yet been in operation, four basic conditions are determined in accordance with established state standards.

In practice, basically, two main methods of cleaning are used - mechanical and chemical. The latter provides for the use of specialized rust converters, means for washing the old paint and even the mass of some others. Mechanical technology also provides mechanized or completely manual processing. Such cleaning is carried out with the aid of an abrasive tool, a brushing or sandblasting, and its main task is to obtain an absolutely clean metal surface with no coating on it at all.

Another obligatory stage of preparation can be called complete degreasing of the surface, which is carried out using specialized organic solvents. The main purpose of this procedure is the complete removal from the surface of the metal of any inorganic or organic fats and oils. The operation is performed just before the first coat of coating is applied, and in the majority of cases it is accepted to combine it with dust removal.

Primer

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

It is necessary to approach the selection of soil very carefully, if it is a question of further flame retardant treatment. After all, in the market you can find a lot of different products that are manufactured in accordance with the specifications, not GOSTs. In general, soils that are produced according to the specifications are characterized by a softening point of 90-100 ° C, while the working temperature of the fire retardant coating is 220-250 ° C. Thus, the ground eventually loses its properties, which can provoke it Deformation and further peeling together with the applied fire retardant coating. In addition, the use of any cheap analogs, produced only on the TU, will lead to an increased drying time of the applied material, as well as a decrease or even a complete loss of adhesion of the applied fire retardant coating.

Not everyone understands that it is extremely important to withstand the soil before it dries completely before the fireproof paint itself is applied, as otherwise the protective coating can simply crack during operation. The application of specialized materials to old coatings or surfaces pre-primed with paint and varnish materials that are not recommended by manufacturers of fire retardant paints may subsequently provoke deterioration of adhesion, as well as swelling or peeling of the applied coating.