How to maintain the Steel Structure Warehouse properly?

With the rapid development of economy, industrial production plants across the country in full swing construction, in which the steel structure plant has a beautiful and generous shape, bright colors, diversification of building types, low cost, short construction cycle, high degree of factory production of steel components, easy installation and construction, flexible layout, while the steel has a light weight, uniform material to facilitate the design of the calculations, recycling, and so on, more and more! It is widely used in modern industrial plants. However, steel structure plant also has a fatal disadvantage that it is not fire-resistant. Although steel is a non-combustible material, but under the action of high temperature in the open fire, with the increase of temperature, its mechanical indexes will be greatly changed, bearing capacity and balance stability will be greatly reduced with the increase of temperature, in 500 degrees Celsius or so, the reduction is more obvious, generally in 15 minutes or so will be due to the loss of load-bearing capacity and collapse.

Therefore, the building steel structure plant to take protective measures. First, the steel components of their own fire protection, so that when the fire temperature rises do not quickly exceed the critical temperature, the prescribed time steel structure in the fire can also ensure stability, to protect the safety of personnel and property; Second, you can set up an effective fire protection zoning of the interior of the industrial plant, to prevent the fire from spreading and spreading to other areas.

I. Fire-resistant protection of steel components of steel structure industrial workshop

As the steel component itself does not reach the fire resistance limit required by the code, it is necessary to take corresponding fire resistance protection measures for the steel component. Commonly used fire-resistant protection measures are fireproof coating method, foaming fireproof paint method and outsourcing fireproof layer method.

1、Fireproof coating method

Fireproof coating method is to spray fireproof coating on steel structure to improve its fire resistance limit. At present, China's steel structure fireproof coating is mainly divided into two types: thin coating type and thick coating type, i.e. thin type (B type, including ultra-thin type) and thick type (H type). The thickness of thin type coating is below 7mm, which can absorb heat and expand and foam during fire to form a foamy carbonized heat insulation layer, thus preventing the heat from transferring to the steel structure, slowing down the temperature rise of the steel structure, and playing the role of fire protection. Its main advantages are: thin coating, light load on the steel structure, better decorative, small area of complex shapes of the steel structure surface coating work is easier than the thick type; thick coating thickness of 8-50mm, the coating is heated not foam, relying on its lower thermal conductivity to slow down the temperature of the steel structure to play a role in fire protection. Both have different performance characteristics, respectively, for different occasions, but, regardless of the kind of product should be qualified through the national testing organizations, before selection.

2、Foaming fireproof paint method

Foaming fireproof paint is made of film-forming agent, flame retardant, foaming agent and other materials manufactured by a fire-retardant paint. Fireproof paint compared with general paint, in terms of physical properties are basically the same, the difference is that after it dries, the film itself is not easy to burn, in case of fire, can delay the flame burned to the combustible paint, has a certain degree of fire performance. According to the test: the general paint and fireproof paint were coated on the board, after drying, with the same flame baking, coated with general paint on the board, less than 2 minutes and paint together with scorching; and coated with non-expansion type fireproof paint on the board, 2 minutes after the emergence of only the phenomenon of negative combustion, static 30 seconds after the immediate extinguishing; coated with intumescent fireproof paint board, even if baked for 15 minutes, even the phenomenon of negative combustion has not appeared. It can be seen, with fireproof paint coated on the surface of the object, once the fire, indeed in a certain time to prevent the fire from spreading, to protect the surface of the object, so as to extinguish the fire to take valuable time.

3、Outer fireproof layer method

The outer fireproof layer method is to add the outer cladding layer on the exterior of the steel structure, which can be cast-in-place molding, or spraying method can be used. Cast-in-place solid concrete cladding is usually reinforced with steel wire mesh or steel bars to limit shrinkage cracks and ensure the strength of the shell. Spraying can be done at the construction site by spraying lime-cement or gypsum mortar on the surface of the steel structure to form a protective layer, which can also be mixed with perlite or asbestos. The outer cladding can also be made of perlite, asbestos, gypsum or asbestos cement, light concrete into prefabricated panels, which are fixed to the steel structure using adhesives, nails and bolts.

II.fire partition of steel structure industrial workshop

Fire partition refers to the local area (space unit) which is divided by fire separation measures and can prevent the fire from spreading to the rest of the same building within a certain period of time. In the building using the division of fire zoning measures, can be used in the building in case of fire, effectively control the fire within a certain range, reduce fire damage, and at the same time for the safe evacuation of people, fire fighting to provide favorable conditions. Commonly used fire zoning practices are set up firewalls and set up independent water curtains, but due to the specificity of industrial production plant, these two methods have shortcomings.

1、Firewall

Firewalls will be separated from the plant to control the spread of fire in civil buildings is a common approach, but in the industrial plant, not only because of the plant was divided into large spaces to affect the permeability, but also from the heart of the continuity of the requirements of the production process as well as the organization of logistics in the plant; if from the point of view of the management of the production, but also not conducive to the management of the production.

2, independent water curtain

Water curtain can play the role of firewall, with independent water curtain for fire separation, is a very good program. Fire water curtain belt is suitable for spray-type nozzle, can also be used in rain shower type water curtain nozzle. The arrangement of water curtain nozzles should not be less than 3 rows, fire water curtain belt formed by the water curtain width should not be less than 5 m. This separation is flexible, unlike the firewall to cut off the workshop, theoretically, how much span can be. In normal production, as if it does not exist, once the fire needs fire separation, it can immediately realize the effective separation. But the independent water curtain for fire separation also has shortcomings: first of all, the amount of water required; secondly, the fire in the plant is often localized, only a few fire extinguishers to solve the problem, but at this time if the start of the water curtain, the production equipment will cause damage to the resulting loss than the loss of local fires. Therefore, it is necessary to strictly control the timing of the start of the water curtain to prevent false starts, so the design is more appropriate to use manual manual start; there is also effective maintenance trouble.

III. Summarization

To summarize, at present, the fire-resistant protection and fireproof partition of the construction steel structure industrial plant respectively adopts the fireproof coating method and independent water curtain is a more common method, but due to the industrial plant due to the production needs, the actual application of each method also have unsatisfactory places. We still need to explore in practice in order to find out better fire protection measures to protect people and property safety in hardware.