Flange, also known as a flange collar or rim, is a component used for connecting shafts to each other, typically for pipe ends. It is also used on equipment for connections between two devices, such as a reducer flange. A flange connection or flange joint refers to a removable connection formed by the combination of flange, gasket, and bolt, serving as a sealing structure. Pipe flanges are those used in piping installations, while equipment flanges refer to the inlets and outlets of equipment. Flanges have holes and bolts that secure them tightly together, with a gasket used between them for sealing. 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 those over four kilograms of pressure require welding flanges. Two flange disks are joined with a sealing pad and then bolted together. Flange thickness and bolt types vary with pressure ratings. Equipment like pumps and valves, when connected to pipes, have corresponding flange shapes, also known as flange connections. Any connection component that uses bolts to connect two flat surfaces and seal them is generally called a "flange," such as in ventilation pipe connections. Such components can be referred to as "flange-type parts." However, such connections are only a 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 items like valves can be called "flange-type parts."