Flange, also known as a flange disk or rim, is a component used for connecting shafts to each other or for joining pipe ends. It is also used on 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 combined sealing structure. Pipe flanges are those used for piping in pipe systems, while equipment flanges refer to the inlets and outlets of equipment. Flanges have holes for bolts, which secure the flanges together. They are sealed with a gasket. Flanges come in threaded (screwed) connections, welded flanges, and clamp flanges. Flanges are used in pairs; low-pressure piping can use threaded flanges, while pressures over four kilograms require welded flanges. Two flange disks are sealed with a gasket and then bolted together. Flanges of different pressures have varying thicknesses and require different bolts. Equipment like pumps and valves, when connected to pipes, have corresponding flange shapes, also known as flange joints. Any connection piece that uses bolts to connect and seal two flat surfaces is generally called a "flange," such as in ventilation pipe connections. These types of parts 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 equipment like valves can be called "flange-type parts."