1. Reinforcement of round air duct: because of its high strength, and the flanges at both ends of the air duct play a certain role in reinforcement, when the diameter of the round air duct is greater than or equal to 800mm, and the length of the pipe section is greater than 1250mm or the total surface area of the pipe section is greater than 4m2, a flat steel reinforcement ring is added every l500mm and fixed with rivets. In order to prevent the seam from cracking during transportation or hoisting, when the diameter of circular air duct is greater than 500mm, both ends of its longitudinal seam shall be fixed with rivets or spot welding.
2. Reinforcement of rectangular air duct: Compared with round air duct, the strength of rectangular air duct is low and it is easy to deform. When the large side length of rectangular air duct is greater than or equal to 630mm, the large side length of thermal insulation air duct is greater than 800mm, the length of pipe section is more than 1250mm, or the single side flat area of low pressure air duct is greater than 1.2m2, and the medium and high pressure air ducts are greater than 1.0m2, in order to reduce the deformation of air duct during transportation and installation, reinforcement measures must be taken during fabrication.
3. Practice of fireproof wrapping of ventilation pipe
(1) If the material of the air duct is not fire-resistant, but may be exposed to open fire, for example, a section of PVC air duct is erected near the heater, it is necessary to do fire prevention treatment.
(2) If the gas conveyed by the air duct is flammable and explosive, it is better to have a fireproof package. For example, a positive pressure air duct conveys exhaust gas with lampblack. The fireproof package can extend the tolerance time of the air duct, avoid burning the air duct, and a large amount of gas overflow will lead to deflagration.
(3) If the gas transported by the air duct is sensitive to temperature, it may be that the gas components are sensitive to temperature and easy to change. At this time, not only thermostatic treatment, but also fireproof treatment should be provided to avoid accidents.
(4) If it is exposed to high temperature and flammable environment, the air duct shall generally have fireproof treatment. Except for the exhaust pipe above the fire stove in the hotel, it is usually made of patterned iron sheet, and the flame can burn to