Flange, also known as a flange disc or raised rim. A flange is a component used for connecting shafts to each other, serving as a connection between pipe ends; there are also flanges used at equipment inlets and outlets for connecting two devices, such as a reducer flange. Flange connection or flange joint refers to a removable connection made up of a flange, a gasket, and bolts, forming a combination seal structure. Pipe flanges are the flanges used in piping installations, while on equipment, they refer to the equipment's inlet and outlet flanges. Flanges have holes for bolts to tightly secure them together. Gaskets are used to seal between flanges. Flanges are available in threaded (screwed) connections, welding connections, and clamp connections. Flanges are used in pairs; low-pressure pipelines can use threaded flanges, while those above 4 kg pressure require welding flanges. Two flange discs are joined with a sealing gasket and then bolted together. Flange thickness varies with pressure, and so do the bolts used. Pumps and valves, when connected to pipelines, have corresponding flange shapes for these equipment components, also known as flange joints. Any connection piece that uses bolts to connect two flat surfaces and seal them is generally called a "flange," such as the connection in ventilation pipes, which can be referred to as "flange-like components." 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-like component." Smaller components like valves can be referred to as "flange-like components."