How to Measure Centre Line Radius (CLR) of Pipe Bends

  • Identify the bend you want to measure. CLR is the radius from the centreline of the bend, not the outer wall.
  • Measure the Outside Diameter (OD) of the pipe first; this is required for calculating CLR.
  • Place the bend flat on a table so both legs are resting evenly.
  • Measure the leg length:
    Measure from the tangent point (where the straight section ends) to the apex of the bend.
  • Find the midpoint:
    Divide the measured leg length by 2. This gives the horizontal distance from the tangent point to the bend centreline.
  • Calculate CLR:
    CLR = half the leg length minus half the pipe OD.
  • Cross-check:
    A standard CLR is usually 1D, 1.2D, or 1.5D, where D = outside diameter.
    If your calculated CLR ≈ OD × 1.0, 1.2, or 1.5, the measurement is correct.
  • Record the radius your pipe most closely matches (e.g., CLR = 76 mm → 1.5D for 50.8 mm pipe)