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, to connect two devices. A flange connection or flange joint refers to a detachable connection consisting of a flange, a gasket, and bolts, forming a combined sealing structure. Pipe flanges are flanges used in piping installations, and when used on equipment, they refer to the equipment's inlet and outlet flanges. Flanges have holes, and bolts secure the two flanges 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 piping can use threaded flanges, while those above 4 kg pressure use焊接 flanges. A sealing pad is placed between the two flange disks, and then bolts are tightened. Flanges of different pressures have different thicknesses and require different bolts. When pumps and valves are connected to pipes, the respective parts of these equipment are also shaped like flanges, known as flange connections. Any connection piece that uses bolts to connect two flat surfaces around the circumference and is sealed is generally called a "flange," such as the connection of ventilation pipes. These types of components can be referred to as "flange-type parts." However, such a 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 components like valves can be called "flange-type parts."