Flange, also known as a flange disc or boss, is a component used for connecting shafts or for pipe ends. It can also be used on equipment inlets and outlets for connecting two devices, such as a reducer flange. A flange joint or flange connection refers to a detachable connection formed by the combination of a flange, a gasket, and bolts. Pipe flanges are the flanges used for piping in pipe installations, while on equipment, they refer to the equipment's inlet and outlet flanges. Flanges have holes, and bolts secure them together. They are sealed with a gasket. 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 four kilograms of pressure require welding flanges. Two flange disks are joined with a sealing pad and then bolted together. Flanges of different pressures have different thicknesses and require different bolts. In pumps and valves, when connected to pipes, these equipment components are also shaped to correspond to flanges, also known as flange connections. Any connection piece that uses bolts to connect and seal two flat surfaces is generally called a "flange," such as the connection of ventilation pipes. Such components can be referred to as "flange-type parts." However, this type of connection is 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."