For process engineers, the most important information is the pipe Internal Diameter (ID), as this is used in line sizing calculations. As discussed above, for a given Nominal Pipe Size (NPS), the pipe Outside Diameter (OD) remains constant. As the pipe schedule changes, the ID of the pipe changes. | Piping Engineering World

The dimensions of an elbow depend on several factors: 1. Nominal Pipe Size (NPS) 2. Radius Type – Short Radius (SR) or Long Radius (LR) 3. Angle – Common types are 90°, 45°, and 180° 4. Schedule/Class – Defines the wall thickness --- 📐 Common Elbow Dimensions (ANSI/ASME B16.9) 1. Long Radius (LR) 90° Elbow Center to End (A) = 1.5 × NPS NPS (in) Outside Diameter (mm) Center to End A (mm) 1" 33.4 38 2" 60.3 76 4" 114.3 152 6" 168.3 229 8" 219.1 305 10" 273.0 381 12" 323.9 457 --- 2. Short Radius