A seamless steel tube is a non-combustible building material, which has the characteristics of earthquake resistance and bending resistance. In practical applications, a seamless steel tube can not only relatively increase the bearing capacity of the building, but also meet the needs of architectural design aesthetic modeling, and also avoid the defects of concrete and other building materials that cannot be bent and stretched. Popular in the industry, seamless steel tube is used in single-story, multi-story, skyscrapers, factories, warehouses, waiting rooms, waiting rooms, etc. However, as a building material, a seamless steel tube has some unavoidable defects in fire prevention. Its yield point, tensile strength, elastic modulus, and other mechanical properties will decrease sharply with the increase in temperature.

The seamless steel tube usually loses its bearing capacity at a temperature of 450-650 °C and undergoes large deformation, resulting in the bending of steel columns and steel beams. As a result, it cannot be used continuously due to excessive deformation. The fire resistance limit is about 15 minutes. The length of this time is also related to the rate at which the component absorbs heat.

In order to overcome the shortage of fire prevention in the practical application of seamless steel tube material, fire prevention treatment must be carried out, the purpose of which is to increase the fire resistance limit of seamless steel tube to the limit range specified in this standard. design specification. The seamless steel tube heats up rapidly in a fire and deforms and collapses. The measures are varied. The key is to take a different approach depending on the situation. The speed delays the time for the seamless steel tube to heat up and weaken. But no matter which method is used, the principle is the same. The fire prevention measures of several different seamless steel tubes are introduced below.

1. The outer layer.

It is to add an outer layer on the surface of a seamless steel tube, which can be cast in place or sprayed. The cast-in-place solid concrete cladding is usually reinforced with steel mesh or steel bars to limit shrinkage cracks and maintain the strength of the shell. The spraying method can apply a sand pump on the surface of a seamless steel tube to form a protective layer on the construction site. Sand pumps can be lime cement or gypsum mortar or 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 seamless steel tubes with adhesives, nails, and bolts.

2. Add water.

Filling the hollow seamless steel tube with water is the most effective fire prevention measure. This method can keep the seamless steel tube at a lower temperature in the fire, and the water circulates in the seamless steel tube to absorb the heat of the material itself. After the hot water is cooled, it can be recycled, or cold water can be introduced from the pipeline to replace the hot water.

3. Shield.

Set on the wall or ceiling composed of refractory material, or hide the component in the gap between two walls, as long as a little or no refractory material is added, the purpose of fire prevention can be achieved. This is the most economical method of fire protection.

4. Intumescent material.

The seamless steel tube fire-retardant coating is used to protect the components. This method has good fire-proof and thermal insulation performance. The construction is not limited by the geometric shape of the seamless steel tube. Generally, no auxiliary facilities need to be added, and the coating quality is good. It is light and has a certain aesthetic decoration, which belongs to the modern advanced fire protection technology measures.

At present, high-rise seamless steel tube buildings are increasing, especially some super high-rise buildings, and seamless steel tube materials are more widely used. Once a fire accident occurs in a high-rise building, the fire cannot be extinguished in a short time. This requires us to increase the fire protection of building materials in the process of building design to increase its fire resistance limit, and to formulate necessary emergency measures inside the building. Programs to reduce casualties and property damage.