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、矩形風管的加固：與圓形風管相比，矩形風管自身的強度低，易于產生變形。當矩形風管的大邊長大于或等于630mm，保溫風管大邊長大于800mm，管段長度在1250mm以上，或低壓風管的單邊平面積大于1.2m2，中、高壓風管大于1.0m2時，為了減少風管在運輸和安裝中的變形，制作時必須采取加固措施。

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、通風管防火包裹的做法

3. Practice of fireproof wrapping of ventilation pipe

（1）如果風管的材料不耐火，但是又有可能接觸明火，比如說一段PVC材料的通風管被架設在加熱器附近，那么就有必要做防火處理。

(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）如果風管輸送的氣體易燃易爆更好是有防火包裹。比如一個正壓風管輸送帶有油煙的廢氣，防火包裹能延長通風管耐受時間，避免風管燒毀，大量氣體溢出會導致爆燃。

(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）如果風管輸送的氣體對溫度敏感，可能是氣體組分對溫度敏感、容易溫度變性。這時不僅要有恒溫處理，也要有防火處理，以免意外情況發生。

(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）如果是暴露在高溫易燃環境，風管一般都要有防火處理。飯店的火灶上部的排風管除外，其一般用花鐵皮板打造，很多時候火焰能燒到

(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