Flange, also known as flange or flange. Flange is a part of shaft to shaft connection, which is used for the connection between pipe ends; it is also used for the connection between two equipment, such as reducer flange, which is used on the inlet and outlet of equipment. Flange connection or flange joint refers to the detachable connection of flange, gasket and bolt as a group of combined sealing structure. Pipeline flange refers to the flange used for piping in pipeline installation, and the flange used on equipment refers to the inlet and outlet flange of equipment. There are holes on the flange, and bolts make the two flanges tightly connected. The flange is sealed with gasket. The flange is divided into threaded connection (threaded connection) flange, welding flange and clamp flange. Flanges are used in pairs, low-pressure pipeline can use threaded flange, more than four kilograms of pressure using welding flange. Add a gasket between the two flange plates, and then fasten them with bolts. The thickness of flange under different pressure is different, and the bolts used are also different. Pumps and valves, when connected with the pipeline, the local parts of these equipment are also made into the corresponding flange shape, also known as flange connection. All the connecting parts which are connected by bolts and closed at the same time around two planes are generally called "flange", such as the connection of ventilation pipes, which can be called "flange parts". But this kind of connection is only a part of the equipment, such as the connection between the flange and the water pump, it is not good to call the water pump "flange parts". Relatively small, such as valves, can be called "flange parts".