Flange, also called flange flange or flange. Flange is a part that connects between shaft and shaft and is used for connection between pipe ends; it is also useful for flanges on the inlet and outlet of equipment for connection between two equipment, such as reducer flange. 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 refers to the inlet and outlet flanges of the equipment when used on the equipment. There are holes on the flanges, and bolts make the two flanges tightly connected. 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, wire flanges can be used for low-pressure pipes, and welded flanges for pressures of more than four kilograms. A gasket is added between the two flanges and then tightened with bolts. The thickness of flanges with different pressures is different, and the bolts they use are also different. When water pumps and valves are connected with pipelines, parts of these equipments are also made into corresponding flange shapes, which are also called flange connections. All connecting parts that are connected by bolts on the periphery of two planes and are 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". 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". Smaller ones, such as valves, can be called "flange parts".

Flange connection is to fix two pipes, pipe fittings or equipment on a flange respectively, and add flange pads between the two flanges and fasten them together with bolts to complete the connection. . Some pipe fittings and equipment have their own flanges, which are also flange connections. Flange connection is an important connection method for pipeline construction. The flange connection is easy to use and can withstand greater pressure. In the industrial pipeline, in the household, the pipeline diameter is small, and it is low pressure, and the flange connection is not visible. If it is in a boiler room or production site, flanged pipes and equipment are everywhere. [1]

According to the connection method, the type of flange connection can be divided into: plate flat welding flange, neck flat welding flange, neck butt welding flange, socket welding flange, threaded flange, flange cover, neck pair Welding ring loose flange, flat welding ring loose flange, ring groove face flange and flange cover, large diameter flat flange, large diameter high neck flange, eight-shaped blind plate, butt welding ring loose flange, etc.