Flange, also known as a flange dish or raised rim. A flange is a component that connects two shafts or serves as a connection point for pipe ends; it is also used at the inlets and outlets of equipment, such as a reducer flange. Flange connection or flange joint refers to a detachable connection consisting of the flange, gasket, and bolt working together as a sealed assembly. Pipe flanges are the flanges used in piping installations; when used on equipment, they refer to the inlets and outlets of the equipment. Flanges have holes for bolts that secure them together, and they are sealed using gaskets. Flanges come in threaded (screwed) connections, welded connections, and clamp connections. Flanges are always used in pairs; low-pressure pipelines can use threaded flanges, while those over four kilograms of pressure use welded flanges. Two flange discs are joined with a sealing pad and then fastened with bolts. Flanges of different pressure ratings have varying thicknesses and require different bolts. When pumps and valves are connected to pipelines, the equipment components at these points are also shaped as flanges, 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 on ventilation pipes. Such components can be referred to as "flange-type parts." However, such connections are only a part of a single piece of equipment, like the connection between a flange and a pump, so it wouldn't be appropriate to call the pump a "flange-type part." Smaller items like valves can be referred to as "flange-type parts."