Flange, also known as a flange dish or rim, is a component used for connecting shafts to each other or for joining pipe ends; it is also used on equipment for connecting two devices, such as reducer flanges. A flange connection or flange joint refers to a removable connection formed by the combination of flanges, gaskets, and bolts as a sealing assembly. Pipe flanges are flanges used for piping in pipe installations, and on equipment, they refer to the equipment's inlet and outlet flanges. Flanges have holes and bolts are used to tightly secure the two flanges together. Gaskets are used to seal between flanges. Flanges are available in threaded (screwed) connections, welded flanges, and clamping flanges. Flanges are used in pairs; low-pressure piping can use threaded flanges, while pressures above four kilograms require welded flanges. Two flange disks are fitted with a sealing gasket and then securely fastened with bolts. Flanges of different pressures have different thicknesses and require different bolts. In the case of pumps and valves, when connected to pipes, these equipment components are also made in a corresponding flange shape, known as flange connections. Any connection that uses bolts to join two flat surfaces and seal them is generally called a "flange," such as the connection of ventilation pipes, which can be referred to as "flange-like components." However, such a connection is only a part of a single device, like the connection between a flange and a pump, so it's not appropriate to call the pump "flange-like components." Smaller items like valves can be referred to as "flange-like components."