Flange, also known as a flange disc or rim, is a component used for connecting shafts or for joining pipe ends. It is also used at equipment inlets and outlets, such as reducer flanges, for connecting two devices. A flange connection or flange joint refers to a removable connection consisting of a flange, a gasket, and bolts, all interconnected to form a combined sealing structure. Pipe flanges are flanges used in piping installations, while those on equipment refer to the equipment's inlet and outlet flanges. Flanges have holes, and bolts secure them tightly together. They are sealed with a gasket. Flanges come in threaded (screwed) connections,焊接 (welded) flanges, and clamp flanges. Flanges are used in pairs; low-pressure pipelines can use threaded flanges, while those above four kilograms of pressure use焊接 flanges. Two flange discs are joined with a sealing pad and then bolted together. Flanges of different pressures have different thicknesses and require different bolts. Pumps and valves, when connected to pipes, have locally shaped flanges that are also called flange connections. Any connection piece that uses bolts to connect two flat surfaces around the edge and is sealed is generally called a "flange," such as the connection of ventilation pipes. These types of parts can be referred to as "flange-like 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-like part." Smaller items like valves can be called "flange-like parts."