A flange, also called a flange plate or flange, is a part used to connect shafts, for connecting pipe ends; flanges are also used on equipment inlets and outlets for connecting two pieces of equipment, such as gearbox flanges. A flange connection or flange joint refers to a detachable connection consisting of a flange, gasket, and bolts forming a combined sealing structure. Pipe flanges refer to flanges used for piping in pipeline installations; on equipment, they refer to the inlet and outlet flanges. Flanges have holes, and bolts are used to tightly connect two flanges. A gasket is used for sealing between flanges. Flanges are classified as threaded flanges, welded flanges, and clamp flanges.
Flanges are always used in pairs. Low-pressure pipelines can use threaded flanges, while welded flanges are used for pressures above four kilograms. A gasket is placed between two flange plates, and then they are tightened with bolts. Flanges of different pressure ratings have different thicknesses, and the bolts used also differ. Pumps and valves, when connected to pipelines, are also made with corresponding flange shapes, which is also called a flange connection. Any connecting part that uses bolts to connect and seal two planes is generally called a "flange," such as the connection of ventilation ducts. These parts can be called "flange-type parts." However, if this connection is only a part of a device, such as the connection between a flange and a water pump, it is not appropriate to call the water pump a "flange-type part." Smaller items, such as valves, can be called "flange-type parts."
