Flange is a part that connects between the shaft and the shaft, which is used for the connection between the pipe ends; it is also used for the flange on the import and export of the equipment, which is used for the connection between the two equipment, such as the reducer flange. Flange connection or flange joint refers to the detachable connection which is connected by flange, gasket and bolt as a group of combined sealing structure. Pipeline flange refers to the flange used for pipe distribution in pipeline devices, and refers to the inlet and outlet flanges of equipment when used in equipment. There are holes on the flange, and the bolts make the two flanges tightly connected. The flanges are sealed with gaskets. Flanges are divided into threaded connection (threaded connection) flanges, welding flanges and clamping flanges. Flanges are used in pairs, low-pressure pipelines can use wire flanges, and welding flanges are used for pressures above four kilograms. Add a gasket between the two flanges and fasten them with bolts. Different pressure flange thickness is different, they use different bolts. Pumps and valves, when connected to the pipeline, the parts of these equipment and equipment are also made into corresponding flange shapes, also known as flange connections. All in the two plane around the use of bolt connection at the same time closed connection parts, generally known as "flange", such as ventilation pipe connection, this kind of parts can be called "flange parts". However, this connection is only a part of the equipment, such as the connection between the flange and the water pump, so it is not good to call the water pump "flange parts". More small, such as valves, can be called "flange parts".