No.	Temperature Grade	Category	Connecting pipe，flange	Draft tube material
1	T≤350°	I	Q235A	Q235A
2	350°＜T＜650°	II	Q235，16Mn	16Mn
3	650°＜T＜1200°	III	16Mn	16Mn

XB Air Duct Fabric Expansion joint(Round) owns excellent sound absorption and noise reduction function, it can remit pipeline error and noise which caused by draught fan vibration, and well compensated pipeline vibration which caused by air duct draught fan, also excellent protective effect on tired-resistance of pipeline. Air duct fabric expansion joints are made from high-grade fabrics that help absorb sound waves created by mechanical vibrations or other sources. The flexible material allows for thermal expansion without compromising structural integrity or reducing efficiency when compared with rigid metal materials such as aluminum or steel. Additionally, these types of joints can be designed to fit any specific needs due to their flexibility and range in sizes available on the market today.One major advantage that air duct fabric expansion joints have over traditional metal ones is their ability to eliminate creaking noises caused by thermal cycling within the system itself; something which cannot be achieved with rigid metals because they tend to become brittle upon repeated heating cycles. Furthermore, since these fabrics can expand easily alongside temperature changes inside the system - it helps protect against potential damage caused by extreme pressure applied during temperature fluctuations which can lead to cracks or even leaks if not addressed properly.