Flange, also known as a flange disk 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 joint that consists of a flange, a gasket, and bolts, forming a combination seal structure. Pipe flanges are the flanges used for piping in pipeline installations, and when used on equipment, they refer to the equipment's inlet and outlet flanges. Flanges have holes for bolts to securely connect them, and 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 4 kg pressure use焊接 flanges. Two flange disks are sealed with a gasket and then fastened with bolts. Flanges of different pressures have different thicknesses and require different bolts. In the case of pumps and valves, when connected to pipelines, these equipment components are also made in the shape of corresponding flanges, also known as flange connections. Any connection piece that uses bolts to connect two flat surfaces and seal them 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 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 components like valves can be called "flange-type parts."