Flange is a kind of disc-shaped parts, which is more common in pipeline engineering. Flanges are used in pairs. In pipeline engineering, flange is mainly used for pipeline connection. In the pipeline which needs to be connected, each piece of flange is installed. The low-pressure pipeline can use the wire flange, and the welding flange can be used under pressure of more than 4 kg. Sealing points are added between the two flanges and then bolted. Flanges under different pressures have different thicknesses and bolts. When the pump and valve are connected with the pipeline, the parts of these equipment are also made into corresponding flange shape, also known as flange connection. Where two planes are connected by bolts and closed at the same time, they are generally referred to as "flanges", such as the connection of ventilation pipes, which can be called "flanges". But this connection is only part of a device, such as the connection between flange and pump, so it is difficult to call the pump "flange parts". Comparatively small, such as valves, can be called "flange parts".