Seamless pipe is a building material that will not burn, and it has the characteristics of earthquake resistance and bending resistance. However, after the seamless steel pipe is put into use, there are some unavoidable defects in fire prevention. Its mechanical properties, such as yield point, tensile strength and elastic modulus, will drop sharply due to the addition of temperature.
The seamless steel pipe generally loses its bearing capacity at a temperature of 450 ~ 650 ℃, and undergoes great deformation, resulting in the bending of steel columns and beams, resulting in unsustainable use due to excessive deformation.Generally, the fire resistance limit of unprotected seamless steel pipes is about 15 minutes. The length of this time is also related to the rate at which the component absorbs heat. In order to make the steel pipe material overcome the lack of fire protection in use, fire prevention treatment must be carried out, and the intention is to increase the fire resistance limit of the steel pipe to the limit planning of the design code rules. There are various methods to avoid the deformation and collapse of the seamless steel pipe due to sensitive heating in a fire. The key is to use different methods according to different situations.For example, the use of thermal insulation and refractory materials to block the flame directly burns the steel pipe, reducing the speed of heat transfer and delaying the time for the temperature rise and strength of the steel pipe to weaken. But no matter which method is adopted, the principle is the same.
Fire protection method of seamless steel pipe:
1. Outer layer. It is to add an outer coating on the surface of the seamless steel pipe, which can be cast-in-place or sprayed. The cast-in-place solid concrete outer cladding is generally reinforced with steel mesh or steel bars to restrain the shortening of cracks and ensure the strength of the shell. The spraying method can apply a sand pump to the surface of the steel pipe to form a protective layer at the construction site. The sand pump can be lime cement or gypsum mortar, 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 to make prefabricated panels, which are fixed on the steel pipe with adhesives, nails and bolts.
2. Water-filled water jacket. Filling the hollow steel pipe with water is the most useful method of protection against fire. This method enables the steel pipe to maintain a lower temperature in a fire, and the water circulates in the steel pipe to absorb the heat of the material itself. The heated water can be recirculated after cooling, or cool water can be introduced from the pipeline to replace the heated water.
3. Shield. The seamless steel pipe is arranged in the wall or ceiling composed of refractory materials, or the components are hidden in the open space between two walls, and the purpose of fire prevention can be achieved only by adding a small amount of refractory materials or without adding them. This is the most economical method of fire protection.
4. Expand the material. The steel pipe fireproof coating is used to protect the components. This method has the advantages of good fireproof and heat insulation performance, and the construction is not constrained by the geometry of the steel pipe.Generally, there is no need to add auxiliary equipment, and the coating quality is light, and there is a certain beautiful decorative effect, which belongs to the modern preemptive fire protection technology method.
The seamless steel pipe generally loses its bearing capacity at a temperature of 450 ~ 650 ℃, and undergoes great deformation, resulting in the bending of steel columns and beams, resulting in unsustainable use due to excessive deformation.Generally, the fire resistance limit of unprotected seamless steel pipes is about 15 minutes. The length of this time is also related to the rate at which the component absorbs heat. In order to make the steel pipe material overcome the lack of fire protection in use, fire prevention treatment must be carried out, and the intention is to increase the fire resistance limit of the steel pipe to the limit planning of the design code rules. There are various methods to avoid the deformation and collapse of the seamless steel pipe due to sensitive heating in a fire. The key is to use different methods according to different situations.For example, the use of thermal insulation and refractory materials to block the flame directly burns the steel pipe, reducing the speed of heat transfer and delaying the time for the temperature rise and strength of the steel pipe to weaken. But no matter which method is adopted, the principle is the same.
Fire protection method of seamless steel pipe:
1. Outer layer. It is to add an outer coating on the surface of the seamless steel pipe, which can be cast-in-place or sprayed. The cast-in-place solid concrete outer cladding is generally reinforced with steel mesh or steel bars to restrain the shortening of cracks and ensure the strength of the shell. The spraying method can apply a sand pump to the surface of the steel pipe to form a protective layer at the construction site. The sand pump can be lime cement or gypsum mortar, 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 to make prefabricated panels, which are fixed on the steel pipe with adhesives, nails and bolts.
2. Water-filled water jacket. Filling the hollow steel pipe with water is the most useful method of protection against fire. This method enables the steel pipe to maintain a lower temperature in a fire, and the water circulates in the steel pipe to absorb the heat of the material itself. The heated water can be recirculated after cooling, or cool water can be introduced from the pipeline to replace the heated water.
3. Shield. The seamless steel pipe is arranged in the wall or ceiling composed of refractory materials, or the components are hidden in the open space between two walls, and the purpose of fire prevention can be achieved only by adding a small amount of refractory materials or without adding them. This is the most economical method of fire protection.
4. Expand the material. The steel pipe fireproof coating is used to protect the components. This method has the advantages of good fireproof and heat insulation performance, and the construction is not constrained by the geometry of the steel pipe.Generally, there is no need to add auxiliary equipment, and the coating quality is light, and there is a certain beautiful decorative effect, which belongs to the modern preemptive fire protection technology method.
