Flanges are the interconnected parts between shafts and are used for the connection between pipe ends; they are also used as flanges on the inlet and outlet of equipment for the connection between two pieces of equipment, such as reducer flanges. The flange connection or flange joint refers to a detachable connection in which flanges, gaskets and bolts are connected to each other as a set of combined sealing structures. Pipe flange refers to the flange used for piping in the pipeline installation, and used on equipment refers to the inlet and outlet flanges of the equipment.