Threaded flange is a kind of non-welded flange by processing the inner hole of the flange into pipe thread and matching with the threaded pipe to realize the connection. Compared with the flat welding flange or the butt welding flange, the threaded flange has the characteristics of convenient installation and maintenance, and can be used on some pipelines that are not allowed to be welded on site. The alloy steel flange has sufficient strength, but it is not easy to weld, or the welding performance is not good, you can also choose the threaded flange. However, when the temperature of the pipeline changes sharply or the temperature is higher than 260°C and lower than -45°C, it is recommended not to use threaded flanges to avoid leakage.