Flange, also known as flange plate or flange. Flange is a part connected between shafts, which is used for the connection between pipe ends; The flange on the equipment inlet and outlet is also used for the connection between two equipment, such as reducer flange. Flange connection or flange joint refers to the detachable connection of flange, gasket and bolt as a group of combined sealing structure. Pipe flange refers to the flange used for piping in the pipeline device, and the flange used on the equipment refers to the inlet and outlet flange of the equipment. There are holes on the flange, and the bolts connect the two flanges tightly. The flanges are sealed with gaskets. The flange is divided into threaded connection (threaded connection) flange, welding flange and clamp flange. Flanges are used in pairs. Threaded flanges can be used for low-pressure pipelines, and welded flanges can be used for pressures above 4kg. A sealing gasket shall be added between the two flanges and then fastened with bolts. The thickness of flanges with different pressures is different, and the bolts they use are also different. When pumps and valves are connected with pipes, parts of these equipment are also made into corresponding flange shapes, also known as flange connection. All connecting parts that are bolted around two planes and closed at the same time are generally called "flanges", such as the connection of ventilation pipes. 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". Relatively small, such as valves, can be called "flange parts".