The plate flange connection is to fix two pipes, pipe fittings or equipment on a flange plate respectively, add flange pads between the two flange plates, and fasten them together with bolts to complete the connection. Some pipe fittings and equipment have their own flanges, which are also flange connections. Flange connection is an important connection method for pipeline construction. The flange connection is easy to use and can withstand greater pressure. In industrial pipelines, flange connections are widely used. In the home, the pipe diameter is small and it is low pressure, and the flange connection is invisible. If in a boiler room or production site, there are flanged pipes and equipment everywhere. Compared with the neck flange, the flat flange can be divided into carbon steel flat flange and stainless steel flat flange according to the material.