The flange is a disc-shaped part, which is the most common in pipeline engineering. The flanges are used in pairs and with the matching flange on the valve. In pipeline engineering, flanges are mainly used for connection of pipelines. In the pipelines that need to be connected, install a piece of flange, low-pressure pipelines can use wire flanges, and welding flanges for pressures above 4 kg. Add a gasket between the two flanges, and then tighten with bolts. Different pressure flanges have different thicknesses and use different bolts.

Flanges are parts that are connected to each other between shafts and are used for connection between pipe ends; they are also useful for flanges on equipment inlets and outlets, and are used for connection between two equipments, such as reducer flanges. Flange connection or flange joint refers to the detachable connection of flange, gasket and bolt as a group of combined sealing structure. Pipe flange refers to the flange used for piping in the pipeline installation, and refers to the inlet and outlet flange of the equipment used in the equipment. There are holes in the flange, and the bolts tightly connect the two flanges. The flanges are sealed with gaskets. Flange is divided into threaded connection (screw connection) flange, welding flange and clip flange. Flanges are used in pairs, low-pressure pipes can use wire flanges, welding flanges for pressures above 4 kg. Add a gasket between the two flanges, and then tighten with bolts. Flanges of different pressures have different thicknesses, and they use different bolts. When the pump and valve are connected to the pipeline, some parts of these equipments are also made into corresponding flange shapes, also called flange connection. All the connecting parts that are closed at the same time by using bolts around the two planes are generally called "flanges". For example, the connection of ventilation pipes, such parts can be called "flange parts". However, this connection is only a part of the equipment, such as the connection between the flange and the pump, it is not easy to call the pump "flange parts". Smaller ones, such as valves, can be called "flange parts".