Flange, also known as a flange disk or rim, is a component used to connect shafts to each other, typically 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 detachable connection made up of the flange, gasket, and bolts, acting as a combined sealing structure. Pipe flanges are flanges used for piping in pipeline installations; when used on equipment, they refer to the equipment's inlet and outlet flanges. Flanges have holes for bolts, which secure the two flanges together. Gaskets are used between flanges for sealing. 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 typically use welded flanges. Two flange disks are joined with a sealing gasket and then tightened with bolts. Flanges of different pressures have varying thicknesses and require different bolts. Pumps and valves, when connected to pipes, have locally shaped flanges corresponding to these equipment parts, also known as flange connections. Any connection piece that uses bolts to connect two flat surfaces around the edges and is sealed 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 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."