When two pipes with various end kinds or diameters need to be connected, a flange adapter is the sort of plumbing fitting that is employed. It is made up of a flange and an adaptor.

The flange is a disc-shaped item with holes around its circumference that is often made of metal and is used to attach other flanges or surfaces to it. The adapter is normally made of plastic or metal and has a flanged end on one end and a socket or threaded connector on the other to attach to the pipe.

The adapter is placed into one pipe end and fastened with a socket or threaded connection when joining two pipes of various sizes or end kinds. Bolts are then used to secure and seal the connection between the flanged end of the adapter and the flange of the second pipe or surface.