Flange, also known as a flange disc or raised boss. A flange is a component used for connecting shafts to each other and for joining pipe ends; it is also used at equipment inlets and outlets, such as reducer flanges. Flange connection or flange joint refers to a removable connection consisting of a flange, a gasket, and bolts, all interconnected to form a combined sealing structure. Pipe flanges are flanges used for piping in pipe installations; when used on equipment, they refer to the equipment's inlet and outlet flanges. Flanges have holes, and bolts secure the two flanges together. Gaskets are used to seal between flanges. Flanges are available 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 pipelines with pressures of four kilograms or more use焊接 flanges. Two flange disks are joined with a sealing pad and then fastened with bolts. Flanges of different pressures have different thicknesses, and different bolts are used for them. Pumps and valves, when connected to pipes, have locally shaped flanges that correspond to the equipment, also known as flange connections. Any connection piece that uses bolts to connect two flat surfaces and seal them is generally called a "flange," such as the connection of ventilation pipes. Such components can be called "flange-type parts." However, this type of connection is only a part of a single piece of equipment, such as the connection between a flange and a pump, so it's not appropriate to call the pump a "flange-type part." Smaller components like valves can be referred to as "flange-type parts."