Flange, also known as a flange dish or raised rim. A flange is a component used for connecting shafts to each other and for joining pipe ends; there are also flanges used at equipment inlets and outlets for connecting two devices, such as reducer flanges. Flange connection or flange joint refers to a detachable connection formed by the combination of a flange, a gasket, and bolts. Pipe flanges are flanges used in piping systems within equipment, referring to the inlets and outlets of the equipment. Flanges have holes, and bolts secure them tightly together. They are sealed with a gasket between them. Flanges come in threaded (screwed) connections, welded flanges, and clamp flanges. Flanges are used in pairs; low-pressure pipelines can use threaded flanges, while pipelines above four kilograms of pressure require welded flanges. Two flange disks are joined with a sealing pad and then bolted together. The thickness of flanges varies with pressure, as do the bolts used. In the case of pumps and valves, when connected to pipelines, the local parts of these equipment items are also made into corresponding flange shapes and are referred to as flange connections. Any connection piece used to join two flat surfaces around the circumference with bolts and seal them is generally called a "flange," such as the connections in ventilation pipes, which can be called "flange-like 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-like part." Smaller items like valves can be referred to as "flange-like parts."