Local 7 Wiki

Section 51: Rise Method for a 90 Degree Elbow

PreviousNext

Required Information

  • Pipe Call-out Size
  • Insulation thickness
  • Number of pieces
  • Center Line Radius
  • Radius

Formulas and Measurements

  • Divide the number of degrees of a 90 degree elbow by the number of miters that are to be used in the fitting.
  • Example: 90 / 8 = 11.25 Determine the Center Line Radius Rise.
  • Use the formula to find the Center Line Radius Rise.
  • Number of pieces for the elbow is 8 Center Line Radius length is 12" Find the tangent of the degrees and multiply that by the Center Line Radius length.
  • The formula for that is: Tangent Angle x Center Line Radius = Rise Find the Rise of an 8" Long Radius 90 Degree Elbow Example: Tangent Angle x C.
  • Length = Rise 0.1989 x C.
  • Length = Rise 0.1989 x 12 = Rise 2.3869 = Rise Converted to a fraction 2.3869 = 2 25/64 Center Line Radius Rise & half the Rise = 1 3/16"

Procedure

  1. Step 1

    Determine the Angle of the Miter. Divide the number of degrees of a 90 degree elbow by the number of miters that are to be used in the fitting. Example: 90 / 8 = 11.25

  2. Step 2

    Determine the Center Line Radius Rise. Use the formula to find the Center Line Radius Rise. Example: Pipe is an 8" long radius elbow Insulation thickness is 1 1/2". Number of pieces for the elbow is 8 Center Line Radius length is 12" Find the tangent of the degrees and multiply that by the Center Line Radius length. The formula for that is: Tangent Angle x Center Line Radius = Rise

  3. Step 3

    Find the Rise of an 8" Long Radius 90 Degree Elbow Example: Tangent Angle x C. L. R. Length = Rise 0.1989 x C. L. R. Length = Rise 0.1989 x 12 = Rise 2.3869 = Rise Converted to a fraction 2.3869 = 2 25/64 Center Line Radius Rise & half the Rise = 1 3/16"