Flange, also known as a flange disc or boss, is a component used for connecting shafts to shafts, typically for pipe end connections; it is also used on equipment inlets and outlets, such as reducer flanges. A flange connection or flange joint refers to a detachable connection made up of the flange, gasket, and bolt, functioning as a combined sealing structure. Pipe flanges are the flanges used in piping installations, while on equipment, they refer to the equipment's inlets and outlets. Flanges have holes, and bolts secure them tightly together. They are sealed with a gasket. Flanges come in threaded (screwed) connections,焊接 (welded) flanges, and clamp flanges. Flanges are always used in pairs; low-pressure pipelines can use threaded flanges, while those above four kilograms of pressure require welding flanges. Two flange discs are joined with a sealing pad and then bolted together. Flange thickness and螺栓 types vary with pressure ratings. Pumps and valves, when connected to pipes, have corresponding flange shapes for local connections, also known as flange joints. Any connection piece that uses bolts to connect two flat surfaces and is sealed is generally called a "flange," such as in ventilation pipe connections. These types of components can be referred to as "flange-type parts." However, such connections are only part of a device, like the connection between a flange and a pump, so it's not appropriate to call the pump a "flange-type part." Smaller components like valves can be called "flange-type parts."