Flange, also known as a flange disk or rim. A flange is a component used for connecting shafts to each other and for joining pipe ends; it's also used at equipment inlets and outlets, such as reducer flanges. Flange connection or flange joint refers to a removable connection that consists of a flange, a gasket, and bolts, forming a combined sealing structure. Pipe flanges are those used for piping in pipe installations, and when used on equipment, they refer to the equipment's inlet and outlet flanges. Flanges have holes for bolts, which secure the flanges together. Seals are used between flanges. Flanges are available in threaded (screwed) connections, welding flanges, and clamp flanges. Flanges are used in pairs; low-pressure piping can use threaded flanges, while pressures over four kilograms require welding flanges. Two flange disks are fitted with a seal, then secured with bolts. Flange thickness varies with pressure, as do the bolts used. Pumps and valves, when connected to pipes, have parts shaped as corresponding flanges, also known as flange joints. Any connection component that uses bolts to connect two flat surfaces and seal them is generally called a "flange," such as in ventilation pipe connections. Such components can be referred to as "flange-type parts." However, this type of connection is 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."