Pipe Bends ,Pipe Elbows

A BEND is the generic term for what is called in piping as an "offset" - a change in direction of the piping. A bend is usually meant to mean nothing more than that there is a "bend" - a change in direction of the piping.
An elbow is a pipe fitting installed between two lengths of pipe or tubing to allow a change of direction, usually a 90° or 45° angle , though 22.5° elbows are also made. The ends may be machined for butt welding, threaded (usually female), or socketed, etc. When the two ends differ in size, the fitting is called a reducing elbow or reducer elbow.
Elbows are categorized based on various design features as below:

• Long Radius (LR) Elbows – radius is 1.5 times the pipe diameter.
• Short Radius (SR) Elbows – radius is 1.0 times the pipe diameter.
• 90 Degree Elbow – where change in direction required is 90°.
• 45 Degree Elbow – where change in direction required is 45°.