Flange, also known as a flange disc or boss, is a component used for connecting shafts or for joining pipe ends. It can also be used on equipment inlets and outlets, such as reducer flanges, for connecting two devices. A flange connection or flange joint refers to a removable connection formed by the combination of flanges, gaskets, and bolts as a sealing assembly. Pipe flanges are flanges 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 connect the two flanges. Gaskets are used to seal the flanges. Flanges are available in threaded (screwed) connections,焊接 (welded) flanges, and clamping flanges. Flanges are used in pairs; low-pressure piping can use threaded flanges, while those above four kilograms of pressure use welding flanges. A sealing gasket is placed between the two flange disks, and then bolts are tightened. Flange thickness varies with pressure, and so do the bolts used. In the case of pumps and valves, when connected to pipes, the local parts of these equipment items are also made into corresponding flange shapes, also known as flange connections. Any connection piece that uses bolts to connect two flat surfaces and is sealed is generally called a "flange," such as the connection of ventilation pipes. Such parts can be referred to as "flange-type components." However, this type of connection is only a part of a device, such as the connection between a flange and a pump, so it's not appropriate to call the pump a "flange-type component." Smaller items like valves can be called "flange-type components."