Flange, also known as a flange disk or rim, is a component that connects shafts to each other, used for pipe end connections; there are also flanges used on equipment inlets and outlets for connecting two devices, such as reducer flanges. A flange connection or flange joint refers to a detachable connection made up of the flange, gasket, and bolt, forming a combination sealing structure. Pipe flanges are flanges used for piping in pipeline installations; on equipment, they refer to the equipment's inlet and outlet flanges. Flanges have holes, and bolts secure the two flanges together. They are sealed with a gasket. Flanges are available in threaded (screwed) connections,焊接 (welded) flanges, and clamping flanges. Flanges are used in pairs; low-pressure pipelines can use threaded flanges, while those over four kilograms of pressure use焊接 flanges. Two flange disks are fitted with a sealing gasket and then bolted together. Flanges of different pressures have different thicknesses and require different bolts. Pumps and valves, when connected to pipes, have corresponding flange shapes for these equipment components, also known as flange connections. Any connection piece that uses bolts to connect and seal two flat surfaces is generally called a "flange," such as the connection of ventilation pipes, which can be referred to as "flange-type components." However, such connections are only a 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 component." Smaller components like valves can be called "flange-type components."