Flange, also known as a flange boss or hub. A flange is a component used for connecting shafts or for joining pipe ends; it is also used on equipment进出口 for connecting two devices, such as reducer flanges. Flange connection or flange joint refers to a detachable joint that consists of a flange, a gasket, and bolts, forming a combined sealing structure. Pipe flanges are flanges used in piping installations; when used on equipment, they refer to the equipment's进出口 flanges. Flanges have holes, and bolts are used to tightly secure the two flanges together. They are sealed with a gasket. Flanges are categorized into threaded (screwed) flanges,焊接 flanges, and clamp flanges. Flanges are used in pairs; low-pressure piping can use threaded flanges, while flanges for pressures over four kilograms are typically焊接 flanges. Two flange discs are fitted with a sealing gasket and then securely fastened with bolts. Flanges of different pressure ratings have varying thicknesses and require different bolts. When pumps and valves are connected to pipes, the corresponding flange shapes are used for these equipment parts, also known as flange connections. Any connection piece that uses bolts to join two flat surfaces and seal them is generally called a "flange," such as the connections in ventilation ducts. These types of components can be referred to as "flange-type components." However, such connections are only a part of a single device, like the connection between a flange and a pump, so it's not appropriate to call the pump a "flange-type component." Smaller components like valves can be referred to as "flange-type components."