A flange is a component that connects shafts to each other, used for connecting pipe ends; there are also flanges used at equipment inlets and outlets for connecting two devices, such as reducer flanges. A flange connection or flange joint refers to a detachable connection consisting of a combination of flange, gasket, and bolt, used as a sealing structure. Pipe flanges refer to the flanges used for piping in pipeline installations, and when used on equipment, they refer to the equipment's inlet and outlet flanges. Flanges have holes, and bolts are used to tightly connect the two flanges. Gaskets are used to seal between the flanges.

The connection process involves securing two pipes, fittings, or equipment to separate flanges first, then inserting a flange gasket between them and fastening them together with bolts, thereby completing the connection. Some fittings and equipment come with their own flanges and are also considered flange connections. Flange connections are an important method in pipeline construction. They are convenient to use and can withstand high pressure. In industrial pipelines and residential settings, where pipe diameters are small and the pressure is low, flange connections are not visible. However, in boiler rooms or production sites, you will find flange connections on pipes and equipment everywhere.