Flange, also known as a flange disk or raised rim. A flange is a component used for connecting shafts to each other, serving as a connection point for pipe ends; there are also flanges used at equipment inlets and outlets for connecting two devices, such as reducer flanges. Flange connection or flange joint refers to a removable joint consisting of a flange, a gasket, and bolts, all interconnected as a combined sealing structure. Pipe flanges are flanges used for piping in pipeline installations; when used on equipment, they refer to the equipment's inlet and outlet flanges. Flanges have holes, and bolts secure the two flanges together. Flanges are sealed using a gasket. Flanges come in threaded (screwed) connections, welded flanges, and clamp flanges. Flanges are used in pairs; low-pressure pipelines can use threaded flanges, while those above four kilograms of pressure require welded flanges. Two flange disks are joined with a sealing gasket and then fastened with bolts. Flanges of different pressures have varying thicknesses and require different bolts. In the case of pumps and valves, when connected to pipes, the local parts of these equipment items are also made in corresponding flange shapes, also known as flange joints. Any connection component that uses bolts to connect two flat surfaces around the circumference and is sealed simultaneously is generally called a "flange," such as the connection of ventilation pipes, which can be referred to as "flange-type components." However, such a connection is only a part of a single device, like the connection between a flange and a pump, so it is not appropriate to call the pump a "flange-type component." Smaller items like valves can be called "flange-type components."