Elbow fittings installed between two lengths of pipe or tube allowing a change of direction, usually 180°, 90° or 45°. The ends are machined for Butt Welding when the two ends differ in size, it is called a Reducing or Reducer Elbow.

Most elbows are available in short radius or long radius of types. The short radius elbows have a center to end distance equal to the NPS in inches, while the long radius is 1.5 times the NPS in inches.