Flange, also known as a flange boss or rim, is a component used for connecting shafts to each other or for joining 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 consisting of a flange, a gasket, and bolts, which together form a sealing assembly. Pipe flanges are specifically for piping in equipment installations, while equipment flanges refer to the inlets and outlets of the equipment. Flanges have holes and bolts are used to securely fasten them 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 4 kg pressure require焊接 flanges. Two flange disks are joined with a sealing pad and then bolted together. The thickness of flanges varies with pressure, as do the bolts used. When pumps and valves are connected to pipelines, the respective parts of these equipment pieces are also shaped into flange-like configurations, also known as flange connections. Any connection piece that uses bolts to join two flat surfaces and is sealed is generally called a "flange," such as in ventilation pipe connections. These types of parts 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 components like valves can be called "flange-type parts."