Flange, also known as a flange collar or rim. A flange is a component used to connect shafts to each other or to connect pipe ends; it is also used at equipment inlets and outlets, such as reducer flanges. Flange connection or flange joint refers to a detachable joint made up of the flange, gasket, and bolts, acting as a combined sealing structure. Pipe flanges are the flanges used for piping in pipe 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. The space between flanges is 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 those above 4 kg of pressure require welded flanges. Two flange discs are fitted with a sealing pad and then bolted together. Flange thickness and bolt types vary depending on the pressure rating. Pumps and valves, when connected to pipes, have corresponding flange shapes for local connections, also known as flange joints. Any connection piece that uses bolts to connect two flat surfaces around the circumference and is sealed is generally called a "flange," such as in ventilation pipe connections. These types of components can be referred to as "flange-type parts." However, such connections are only 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 referred to as "flange-type parts."