Flange, also known as a flange hub or boss. A flange is a component used for connecting shafts to shafts, typically for pipe end connections; it is also used at equipment inlets and outlets for connecting two devices, such as a reducer flange. Flange connection or flange joint refers to a detachable connection formed by the combination of a flange, gasket, and bolts. Pipe flanges are flanges used for piping in a pipeline system, and on equipment, they refer to the inlets and outlets of the equipment. Flanges have holes, and bolts secure them tightly together. Seals are used between flanges. Flanges are available in threaded (screwed) connections,焊接 (welded) flanges, and clamp flanges. Flanges are always used in pairs; low-pressure piping can use threaded flanges, while flanges for pressures over four kilograms are typically焊接. Two flange disks are sandwiched with a seal, then bolted together. Flanges of different pressures have different thicknesses, and they require different bolts. In the case of pumps and valves, when connected to pipes, the local parts of these equipment items are also made into corresponding flange shapes, also known as flange joints. Any connection part that uses bolts to connect two flat surfaces and seal them is generally called a "flange," such as the connection of ventilation pipes. Such parts can be referred to as "flange-like parts." However, such connections are only a part of a device, like the connection between a flange and a pump, so it is not appropriate to call the pump a "flange-like part." Smaller components like valves can be called "flange-like parts."