Flange, also known as a flange boss or collar. A flange is a component used for connecting shafts to each other and for joining pipe ends; it's also used on equipment进出口 for connecting two devices, such as reducer flanges. Flange connection or flange joint refers to a removable joint formed by the combination of flanges, gaskets, and bolts. Pipe flanges are flanges used in piping installations within equipment, specifically referring to the进出口 flanges of the equipment. Flanges have holes for bolts, which tighten the two flanges together. They are sealed with gaskets between them. Flanges are categorized into threaded connection (threaded flanges),焊接 flanges, and clamp flanges. Flanges are always used in pairs; low-pressure piping can use threaded flanges, while those over four kilograms of pressure use焊接 flanges. Two flange discs are fitted with a sealing pad and then secured with bolts. The thickness of flanges varies with pressure, as do the bolts used. For equipment like pumps and valves, when connected to pipes, the respective parts are shaped into flange-like structures, also known as flange joints. Any connection component used to connect and seal two flat surfaces around the circumference with bolts is generally called a "flange," such as the connection on ventilation pipes. These types of components can be referred to as "flange-like parts." However, such connections are only a 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 components like valves can be referred to as "flange-like parts."