Flange, also known as a flange disk or rim, is a component used for connecting shafts or for joining pipe ends. It is also used on equipment inlets and outlets, such as reducer flanges, for connecting two pieces of equipment. A flange connection or flange joint refers to a removable connection made up of a flange, a gasket, and bolts, forming a combined sealing structure. Pipe flanges are flanges used in piping systems within equipment, specifically referring to the inlets and outlets of the equipment. Flanges have holes, and bolts secure them tightly together. They are sealed with a gasket. Flanges are available in threaded (screwed) connections, welding flanges, and clamp flanges. Flanges are used in pairs; low-pressure pipelines can use threaded flanges, while those above 4 kg of pressure use welding flanges. Two flange disks are sealed with a gasket and then fastened with bolts. Flanges of different pressures have different thicknesses and require different bolts. Equipment like pumps and valves, when connected to pipes, have corresponding flange shapes, also known as flange connections. Any connection piece that uses bolts to connect two flat surfaces and seal them is generally called a "flange," such as the connection of ventilation pipes. Such components can be referred to as "flange-type components." However, such connections are only 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."