With rapid economic development, industrial production workshops are in full swing around the world. Among them, the steel structure workshop has beautiful appearance, colorful colors, diversified building types, low cost, short construction period, the high degree of industrialization of steel component production, installation The construction is simple and the layout is flexible. At the same time, steel has many advantages such as lightweight, uniform material, easy design and calculation, and recyclability. It is increasingly used in modern industrial workshops. But the steel structure workshop also has a fatal flaw that is not fire-resistant. Although steel is a non-combustible material, under the action of open flame and high temperature, as the temperature increases, its mechanical index will change greatly, and the bearing capacity and balance stability will decrease greatly with increasing temperature, at about 500 degrees Celsius The decrease is more obvious, generally, it will collapse due to loss of load-bearing capacity in about 15 minutes.
Therefore, protective measures are taken on the building steel structure workshop. One is to protect the steel components themselves against fire so that they do not quickly exceed the critical temperature when the temperature of the fire rises. The steel structure can also ensure stability in the fire within a specified time to ensure the safety of personnel and property; the second is to protect the industrial workshop An effective fire compartment is set up inside to prevent the fire from spreading and spreading to other areas.
Since the steel member itself reaches the fire resistance limit that is not required by the standard, it is necessary to take corresponding fire protection measures for the steel member. Commonly used fire protection measures include fire-retardant paint method, foam fire-retardant paint method and outer fire-retardant layer method
1. Fireproof coating method
The fireproof coating method is to spray fireproof coating on the steel structure to improve its fire resistance limit. At present, fireproof coatings for steel structures are mainly divided into two types: thin coating type and thick coating type, namely thin type (B type, including ultra-thin type) and thick type (H type). The thickness of the thin coating is less than 7mm, which can absorb heat and expand and foam during a fire to form a foamed carbonized thermal insulation layer, thereby preventing heat from being transferred to the steel structure, delaying the temperature rise of the steel structure, and playing a role in fire protection. Its main advantages are thin coating, light load on the steel structure, and good decoration. It is easier to apply on the surface of the steel structure with a small area and complex shape than the thick type; the thickness of the thick type coating is 8-50mm, the coating Does not foam when heated, and relies on its lower thermal conductivity to delay the rise of the temperature of the steel structure, thus playing a role in fire protection. Both have different performance characteristics and are suitable for different occasions.
2. Foam fire retardant paint method
Foam fire retardant paint is a kind of flame retardant paint made of various materials such as film forming agent, flame retardant, foaming agent and so on. Compared with general paint, fire retardant paint has the same physical properties. The difference is that after it is dried, the paint film itself is not easy to burn. In case of fire, it can postpone the flame to the combustible material painted, and has certain fire resistance. According to the test: apply general paint and fire retardant paint on the wooden board separately, dry it, bake it with the same flame, apply the general paint on the board, and scorch together with the paint in less than 2 minutes; After 2 minutes, only smoldering occurred, and immediately extinguished after standing for 30 seconds; even after baking for 15 minutes, the smoldering phenomenon did not appear even when the board was coated with intumescent fireproof paint. It can be seen that the use of fire-resistant paint on the surface of the object can prevent the fire from spreading and protect the surface of the object in a fixed time, thus taking precious time for fire fighting.
3. Outsourcing fireproof layer method
The outer layer fireproof layer method is to add an outer layer on the outer surface of the steel structure, which can be cast-in-place or sprayed. The cast-in-situ molded solid concrete outer cladding is usually reinforced with steel wire mesh or steel bars to limit shrinkage cracks and ensure the strength of the outer shell. The spraying method can spray lime cement or gypsum mortar on the surface of the steel structure at the construction site to form a protective layer, or it can be mixed with perlite or asbestos. At the same time, the outer cladding can also be made of perlite, asbestos, gypsum or asbestos cement, and light concrete into prefabricated panels, which are fixed on the steel structure with adhesives, nails, and bolts.
Fire prevention zone refers to a local area (space unit) that 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. The use of fire partitioning measures in buildings can effectively control the fire within a certain range in the event of a fire in the building, reduce fire losses, and provide favorable conditions for safe evacuation and fire fighting. Commonly used fire zoning practices include setting up firewalls and setting up independent water curtains, but due to the particularity of industrial production workshops, both methods have disadvantages.
The firewall is used to separate the workshop to control the spread of fire. It is a common method in civil buildings, but in industrial workshops, not only does the large space of the workshop affect its permeability but it also requires the continuity of the production process and the workshop. Internal logistics organization; from the perspective of product management, it is not conducive to production management.
2. Independent water curtain
The water curtain can act as a firewall, and using an independent water curtain for fire separation is a very good solution. The fire-proof water curtain belt should adopt spray nozzles or rain shower nozzles. The arrangement of the water curtain sprinklers should not be less than 3 rows, and the width of the water curtain formed by the fireproof water curtain should not be less than 5m. This separation method is flexible. Unlike a firewall that cuts off the workshop, in theory, it can be any span. In normal production, it is as if it does not exist. Once there is a fire requiring fire separation, it can immediately achieve effective separation. However, the independent water curtain is also insufficient for fire partitioning: first, the water demand is large; second, the fire in the workshop is often localized. Only a few fire extinguishers can solve the problem. Damage to production equipment, resulting in greater losses than local fires. Therefore, it is necessary to strictly control the start timing of the water curtain to prevent misoperation, so it is more appropriate to use manual start during the design; there is also the trouble of effective maintenance.
In summary, at present, the fire-resistant coating method and the independent water curtain of the steel structure industrial workshop for fire protection and the fire protection zone are more common methods, but due to the production needs of the industrial workshop, each method is unsatisfactory in actual application local. We still need to continue to explore in practice in order to find out better fire protection measures and ensure the safety of personnel and property on the hardware.
Qingdao Yili Steel Structure professionally undertakes steel structure design, budget, dismantling, rendering, and production. Steel structure workshop, steel structure warehouse, agricultural steel structure building. For more questions, please consult the customer service of steel structure for consultation