Flanges, also known as raised face flanges or rim flanges, are components used to connect shafts to each other, typically for pipe end connections. They are also used on equipment进出口, such as reducer flanges, to connect two devices. A flange joint or flange connection refers to a removable connection that consists of the flange, a gasket, and bolts, forming a combined sealing structure. Pipe flanges are the flanges used in piping systems of equipment, while on equipment, they refer to the进出口 flanges. Flanges have holes for bolts that secure them together, and they are sealed with gaskets. Flanges are available in threaded (screwed) connections, welding connections, and clamping connections. Flanges are always used in pairs; low-pressure piping can use threaded flanges, while pressures above four kilograms require welding flanges. Two flange disks are fitted with a sealing pad and then bolted together. Flange thickness and bolt types vary with pressure ratings. 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 is sealed is generally called a "flange," such as in ventilation pipe connections. These types of 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."