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

Fire protection of steel structures represents an element, which in the majority of cases, it decided to pay special attention. Thus it is necessary to correctly understand what it is and where it is needed.

Why?

Girders, beams, columns and other elements in fire conditions can behave almost unpredictable. We should not forget that their main task is to accomplish its intended purpose – to hold the building for as long as possible, preventing any risk of collapse.

The Metal remains of the fortress exactly to the time until its temperature is equal to ambient temperature. Many do not know about this fact. But if you place it in the environment of high temperatures, over time it will become flexible and plastic. Therefore, if you do not use specialized fire protection of steel structures in fire, he can't last 3-5 minutes.

Melting and bending, but it deals damage of the initial design of buildings and structures, causing the collapse, when people have not had time to fully evacuate. This, consequently, leads to their death. It is for this reason fire protection of metal structures is one of the most important elements to be considered in the development process security of each building. However, you need to properly understand how and when it is provided.

What is it?

Next, we consider when the possible fire protection of metal structures. To date, there are a variety of construction methods, which provides fire protection, such as lining bricks, plaster on metal lath and many others, but in this case we consider not-built technology that can be considered by all architects and planners.

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How is it implemented?

For a SNIP of fire protection of metal structures shall first be provided to buildings and structures, in which various metal bearing elements are open. There is no possibility normally to close or use the course design architect. Thus, we have a building which is not protected by any means supporting metal structures. In this case, at a SNIP of the fire protection of steel structures by coating them with specialized flame-retardant paint. In this case, it is not only the most effective, but, in principle, the only possible method.

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

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

Design

Do Not forget that themselves are specialized paints are not so cheap. This is just one of the reasons to develop a project to provide fire protection of structures. With this project, you will understand how low is the limit of fire resistance of metal structures without fire protection, what is the amount of paint you will need to increase it, and also how many layers of material should be applied to certain elements.

Professional experts are engaged in detailed assessment of all loads that affect a specific construction, calculated fire-resistance, and also the time during which they can perform their direct function in the fire. After that, the calculation of the missing time and carried out the calculations of required thickness of protection layer. So is the design and definition of the price of the works, then the experts begin to implement the plan.

How is the application?

Materials for fire protection of metal structures are applied with the help of specialized airless units. Moreover, their application is only one layer of a certain thickness. The main feature here is that if the fire resistant material is applied too thin layer, in the presence of the slightest drying of the paint starts to curl and burst, but otherwise she just will not have time to dry. This will lead to its fall from the structure. That is why the professional experts in accordance with state standard (GOST) fire protection of metal structures is applied in a certain layer, then he is given time to partially dry, and then apply the next layer. Then by repeating this procedure achieves the required thickness.

It is Worth noting the fact that each layer is flame retardantpaint is closely monitored not only in wet but also in dry residue, and check for shrinkage factor. In addition, the dry layer is also controlled by the use of specialised electromagnetic eddy thickness gauge. If you have a really high quality and the correct implementation of the whole range of necessary procedures, starting from design and ending with a direct application of the material, eventually the coating will last for more than fifty years.

Main features

The Metals in their structure are quite sensitive to fire and basically high temperatures. That is why all treatments 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 heats up very quickly. This leads to a significant reduction in its strength properties. In connection with the fact that steel structures are the most vulnerable element of any building in the process of emergence of a fire, and given the fact that they are made use of in modern construction almost everywhere.

Few people correctly understand that the steel frame fire resistance is quite low and its value is around 0.1-0.4 hours, and in accordance with the existing norms of the fire resistance of any building structure should be in the region of 0.5-2.5 hours depending on what is being specifically considered the building type, and therefore requires fire protection of metal structures. Requirements as to application of such materials govern the correctness of their use, and allow you to do so in the end, really managed to achieve the desired results.

Causes

The Main essence of the metalwork fire protection is to on metal surface created a specialized thermal insulation screen. He is able to keep high temperature and, if necessary, also failed to act on the material flame. This screen significantly slows down the procedure of heating the metal structures in the event of a fire. This provides the time necessary for further evacuation, and save the lives of many people.

There are many methods, which is fire protection of metal structures. The compositions can be applied by conventional methods such as plaster walls with special solutions, concrete overlay or brick and more modern, based on the use of lightweight aggregates and materials, including mineral wool, expanded perlite, or various insulating materials. The price of this procedure directly depends on which specific method was used in a certain situation.

Classification methods

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

• Special fire retardant coating. They are made from cement, liquid glass, granulated mineral fiber.
• Use all kinds of expanding fire-retardant paints, which is a pretty complex system that includes organic and inorganic components. Their main action is entirely based on the swelling behaviour of the composition under high temperatures and further formation of the heat insulating porous layer, whose thickness is only a few centimeters.

The fire Resistance of metal structures without fire protection is quite low, but with the help of these methods the specialists work without any increase to the desired value of 0.75-2.5 hours, depending on which is applied a layer of plaster, and applies fire-retardant paint or light weight coating. Expanding the use of paints in the majority of cases allows to achieve a fire resistance of structures longer than one and a half hours.

The application

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

1. Surface Preparation.
2. A primer.
3. Applying a special paint.
4. Coating.

Special attention is given here to the preparation of metal surfaces for further fire retardant treatment. Improper training in the future, the coating may simply collapse under internal or external influence, whereby the result will be zero. In practice it is possible to meet quite a wide variety of possible States of metal surfaces before applying special coating, and even for those metal structures that have not yet been in operation, in accordance with established state standards is determined by four basic States.

In practice mostly it is accepted to use two basic methods of cleaning-mechanical and chemical. The latter involves the use of specialized rust converters,means for washing the old paint and even the weight of some others. Mechanical technology involves mechanized or fully manual processing. This treatment is performed by means of abrasive tool, kravanja or sandblasting, and its main objective is to obtain an absolutely clean metal surface with a complete absence in her of any coatings.

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

Primer

First layer when applying any fire retardant coating – it is always soil. Moreover, in the majority of cases there is a tendency to use acrylic, which is considered the most versatile. The main objectives of the primer is to ensure corrosion protection of the metal, and also high-quality adhesion to the surface and subsequent layers of coating.

You Need to approach the choice of the ground very carefully, if we are talking about the further flame-retardant treatment. After all, the market can meet a lot of different products that are manufactured in accordance with specifications and not Standards. Basically the soils which are produced on the other, differ in the softening temperature at 90-100 ^OC, while operating temperature fire retardant coating is 220-250 ^OC. Thus, the soil eventually loses its properties, which may cause its deformation and further exfoliation along with applied fire retardant coating. In addition, the use of any of cheap imitations produced only on the other, will lead to increased drying time of applied material, and also reduction or even complete loss of adhesion of the applied fire-retardant coating.

Not everyone understands that it is extremely important to maintain the soil to dry before is applied to itself fire retardant paint, as otherwise the protective coating can simply crack during operation. The application of specialized materials on an old coating or surface pre-primed with paints that are not recommended by manufacturers of fire-retardant paints, then can cause the deterioration of adhesion, and swelling or exfoliation of the coating.