Flange, also known as a flange disc or boss, is a component used for connecting shafts to shafts, typically for pipe end connections; it's also used on equipment进出口 for connecting two devices, such as a reducer flange. A flange connection or flange joint refers to a detachable connection formed by the combination of a flange, a gasket, and bolts as a sealed assembly. Pipe flanges are the flanges used for piping in pipeline installations, or on equipment, referring to the equipment's进出口 flanges. Flanges have holes, and bolts are used to tightly secure the two flanges. They are sealed with a gasket. Flanges are available in threaded (screwed) connections, welding flanges, and clamp flanges. Flanges are always used in pairs; low-pressure pipelines can use threaded flanges, while those above four kilograms of pressure use welding flanges. Two flange discs are fitted with a sealing gasket and then securely fastened with bolts. Flanges of different pressures have different thicknesses and require different bolts. Pumps and valves, when connected to pipelines, have corresponding flange shapes for local connections, also known as flange connections. Any connection component used to join two flat surfaces around the edges with bolts and sealed simultaneously is generally called a "flange," such as the connection of ventilation pipes. These components can be referred to as "flange-type parts." 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 part." Smaller items like valves can be called "flange-type parts."