Flange, also known as a flanged disk or rim. A flange is a component used to connect two shafts or to join pipe ends; it is also used at the inlets and outlets of equipment, such as reducer flanges. 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 flanges used in piping installations within equipment, referring to the inlets and outlets of the equipment. Flanges have holes, and bolts are used to tightly connect the two flanges. A gasket is used to seal between the flanges. Flanges come in threaded (screwed) connections, welding flanges, and clamp flanges. Flanges are always used in pairs; low-pressure pipelines can use threaded flanges, while pipelines above four kilograms of pressure should use welding flanges. A sealing gasket is placed between the two flange disks, and then bolted together. Flanges of different pressure ratings have different thicknesses and require different bolts. In pumps and valves, the local components that connect to pipelines are also made into corresponding flange shapes, also known as flange connections. Any connection piece that uses bolts to connect two flat surfaces around the periphery and is sealed 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, this type of connection is only a part of a single device, such as 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."