Flange is a part that connects the pipe to the pipe, and is connected to the pipe end. There are bolt holes on the flange, and the bolts tightly connect the two flanges. The flanges are usually sealed with gaskets (flange gaskets). classification According to the material classification, common are cast iron / carbon steel flanges, stainless steel flanges, PVC / PPR flanges, etc.; according to the connection method, they can be roughly divided into threaded flanges and welding flanges, of which welding flanges can be divided into flat welding flange, butt welding flange, flange blind plate and other varieties. Divided according to the tolerance pressure level, common are 0.6Mpa, 1.0Mpa, 1.6Mpa, 2.5Mpa, 4.0Mpa, 6.4 Mpa, 10.0Mpa and so on.