Flange, also known as a flange disc or raised boss. A flange is a component that connects two shafts or serves as a connection point for pipe ends; it's also used at equipment inlets and outlets, such as a reducer flange. A flange connection or flange joint refers to a removable joint formed by the combination of a flange, gasket, and bolt. Pipe flanges are specifically for piping connections within equipment, while those on equipment refer to the inlets and outlets. Flanges have holes, and bolts secure them together. They are sealed using a gasket. Flanges come 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 those over 4 kg of pressure require welding flanges. Two flange discs are sealed with a gasket and then bolted together. Flanges of different pressures have different thicknesses and require different bolts. Equipment like pumps and valves, when connected to pipes, have parts shaped like flanges, also known as flange joints. Any connection piece that uses bolts to join two flat surfaces around the perimeter and seal them is generally called a "flange," such as ventilation pipe connections. 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."