Flange, also known as a flange collar or rim, is a component used for connecting shafts to each other, typically for pipe end connections; it is also used at equipment inlets and outlets, such as reducer flanges. A flange connection or flange joint refers to a removable connection formed by the combination of a flange, a gasket, and bolts. Pipe flanges are the flanges used in piping installations within equipment, referring to the inlets and outlets of the equipment. Flanges have holes and bolts that secure them tightly together, with a gasket used for sealing between the flanges. Flanges are available in threaded (screwed) connections,焊接 (welded) flanges, and clamp flanges. Flanges are used in pairs; low-pressure pipelines can use threaded flanges, while those above 4 kg of pressure use焊接 flanges. Two flange discs are joined with a sealing pad and then bolted together. Flange thickness and bolt types vary with pressure ratings. Pumps and valves, when connected to pipelines, have corresponding flange shapes for local connections, also known as flange joints. Any connection piece that uses bolts to connect two flat surfaces and seal them is generally called a "flange," such as the connections in ventilation ducts. 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."