Pipe Flanges are widely used as a popular category of pipe fittings. A flange is used to mechanically connect two pipes together. It can also be used to mechanically connect a pipe to a tee, valve, choke or any other piece of equipment. Flanges are available in round, square, and rectangular shapes. In some cases, flanges are usually in the shape of a ring or a plate to form a rim at the end of a pipe when fastened to the pipe.