Flange, also known as a flange disk or raised rim. A flange is a component used for connecting shafts to each other and for joining pipe ends; it is also used on equipment inlets and outlets, such as reducer flanges. Flange connection or flange joint refers to a removable connection that consists of a combination of flange, gasket, and bolt for a sealing structure. Pipe flanges are the flanges used in piping systems of equipment, specifically referring to the inlet and outlet flanges of the equipment. Flanges have holes, and bolts are used to tightly connect the two flanges. Gaskets are used to seal between the flanges. Flanges are available in threaded (screwed) connections, welding flanges, and clamp flanges. Flanges are used in pairs; low-pressure pipelines can use threaded flanges, while those above 4 kg pressure use welding flanges. A sealing gasket is placed between the two flange disks, and then bolts are tightened. Flanges of different pressures have different thicknesses, and they require different bolts. Pumps and valves, when connected to pipelines, have locally shaped flanges that are also called flange connections. Any connection piece that uses bolts to connect two flat surfaces and is sealed is generally referred to as a "flange," such as the connection of ventilation pipes, which can be called "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 called "flange-type parts."