Flange, also known as a flange boss or hub. A flange is a component used for connecting shafts or for joining pipe ends; it's also used at equipment inlets and outlets, such as reducer flanges. Flange connection or flange joint refers to a removable joint consisting of a flange, a gasket, and bolts, used as a combined sealing structure. Pipe flanges are the flanges used in piping installations, or specifically, the inlet and outlet flanges on equipment. Flanges have holes, and bolts are used to tightly secure the two flanges together. They are sealed using a gasket. Flanges come in threaded (screwed) connections,焊接 (welded) flanges, and clamp flanges. Flanges are always used in pairs; low-pressure pipelines can use threaded flanges, while those above four kilograms of pressure require焊接 flanges. Two flange disks are fitted with a sealing pad and then secured with bolts. Flange thickness and the type of bolts used vary with different pressure ratings. When pumps and valves connect to pipes, these equipment components are often shaped as corresponding flanges and are also referred to as flange connections. Any connection component that uses bolts to connect and seal two flat surfaces is generally called a "flange," such as in ventilation pipe connections. These types of components can be called "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 referred to as "flange-type parts."