Flange, also known as a flange disc or rim, is a component used for connecting shafts or for joining pipe ends; it's 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 flanges, gaskets, and bolts for a sealing structure. Pipe flanges are the flanges used for piping in pipe systems, or for equipment inlets and outlets on equipment. Flanges have holes and bolts that secure them tightly together, with gaskets used for sealing between them. Flanges are available in threaded (screwed) connections,焊接 (welded) flanges, and clamp flanges. Flanges are typically used in pairs; low-pressure pipelines can use threaded flanges, while those above four kilograms of pressure use焊接 flanges. Two flange discs are joined with a sealing gasket and then bolted together. Flange thickness varies with pressure, as do the bolts used. In pumps and valves, the parts that connect to pipes are also made into corresponding flange shapes, 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 single 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."