Flange, also known as a flange boss or rim, is a component used for connecting shafts to shafts, typically for pipe end connections; it is also used on equipment进出口 for connecting two devices, such as reducer flanges. A flange connection or flange joint refers to a removable connection made up of the flange, gasket, and bolts, which together form a sealing assembly. Pipe flanges are the flanges used for piping in pipe installations; on equipment, they refer to the equipment's进出口 flanges. Flanges have holes and bolts that secure the two flanges together. They are sealed with a gasket. Flanges come in threaded (screwed) connections, welded flanges, and clamp flanges. Flanges are used in pairs; low-pressure pipelines can use threaded flanges, while those over 4 kg of pressure use welded flanges. A sealant pad is placed between the two flange disks and then secured with bolts. Flange thickness and bolt types vary with pressure ratings. Pumps and valves, when connected to pipelines, have corresponding flange shapes at their connection points, also known as flange joints. Any connection piece that uses bolts to connect and seal two flat surfaces around the perimeter 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 a flange and pump connection, so it's not appropriate to call the pump a "flange-type part." Smaller components like valves can be called "flange-type parts."