Duplex Elbow Fittings – Duplex steel elbows are installed between two lengths of pipe or tubing, allowing a 180¡ã, 90¡ã or 45¡ã change in direction. End machining is used for butt welding when the two ends are different in size, called a reducer or a reducer elbow. Fitting elbows are available as 1D, 1.5D, 2D, 3D, 5D, 6D, 8D, 10D radius 180¡ã elbows, 90¡ã elbows or 45¡ã elbows as short and long radius elbows.