Flange, also known as a flange boss or rim, is a component used to connect shafts to each other or to pipe ends for connection purposes; it's 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 that consists of a combination of flanges, gaskets, and bolts, creating a sealed assembly. Pipe flanges are specifically used in piping installations, and when used on equipment, they refer to the equipment's inlet and outlet flanges. Flanges have holes and bolts are used to tightly secure them together. They are sealed with gaskets. Flanges are available in threaded (screwed) connections, welding connections, and clamp connections. Flanges are always used in pairs; low-pressure piping can use threaded flanges, while pressures above four kilograms require welding flanges. Two flange discs are joined with a sealing pad and then secured with bolts. The thickness of flanges varies with pressure, as do the bolts used. When pumps and valves are connected to pipes, the local parts of these equipment components are also made in corresponding flange shapes, also known as flange connections. Any connection piece that uses bolts to connect two flat surfaces around the edges and is sealed simultaneously 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 items like valves can be called "flange-type parts."