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ASME B31.1 Power Piping Design Factor

Calculate ASME B31.1 power piping design factors (Weld factor W, Y factor and thinning allowance B).

The Y factor is calculated from diameter for thick wall pipe (D/t < 6), or from temperature for thin wall pipe. The weld factor (W) is only relevant for design temperatures in the creep range. For design temperatures below the creep onset temperature W = 1. The weld factor does not apply for seamless pipe (W = 1). The thinning allowance (B) is an approximate estimate of the thinning on the outside radius due to bending (ASME B31.3 table 102.4.5). A power law curve has been fitted to the data values in the table. Use the workbook ASME B31.1 data tables to look up allowable stress data.

Reference : ANSI/ASME B31.1 : Power Piping (2014)

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CALCULATOR : ASME B31.1 Metal Pipe Diameter And Wall Thickness Schedule [FREE]   ±

Calculate ASME B31.1 metal pipe diameter, minimum wall thickness and pressure design thickness from pipe schedule or user defined diameter and wall thickness (ASME B31.1 section 104.1).

Select the pipe schedule (NPS or ISO), pipe diameter and wall thickness, or use the user defined option. Use the Result Table option to display the pipe schedule with nominal wall thickness, minimum wall thickness and pressure design wall thickness for the selected diameter.

Tool Input

  • schdtype : Schedule Type
  • diamtype : Diameter Type
    • ODu : User Defined Outside Diameter
    • IDu : User Defined Inside Diameter
  • wtntype : Wall Thickness Type
    • tnu : User Defined Wall Thickness
  • ttoltype : Wall Thickness Fabrication Tolerance Type
    • txu : User Defined Negative Wall Thickness Fraction
    • tfu : User Defined Negative Wall Thickness Allowance
  • c : Wall Thickness Corrosion Allowance

Tool Output

  • ID : Nominal Inside Diameter
  • OD : Nominal Outside Diameter
  • OD/tn : Diameter Over Wall Thickness Ratio
  • tf : Wall Thickness Fabrication Allowance
  • tm : Minimum Wall Thickness
  • tn : Nominal Wall Thickness
  • tp : Pressure Design Wall Thickness
  • tx : Wall Thickness Fabrication Fraction
CALCULATOR : ASME B31.1 Section 104.1 Pipe Y Factor From Temperature [FREE]   ±

Calculate the hoop stress Y factor for metals (ASME B31.1 section 104.1). For pipe D / tm > 6, the Y factor is interpolated from table 104.1.2(A). For pipe D / tm ≤ 6, the Y factor is calculated from the equation in section 104.1.1. The calculation is based on the nominal diameter, and the nominal wall thickness.

Tool Input

  • schdtype : Line Pipe Schedule Type
  • diamtype : Diameter Type
    • ODu : User Defined Outside Diameter
    • IDu : User Defined Inside Diameter
  • wtntype : Wall Thickness Type
    • tnu : User Defined Wall Thickness
  • ttoltype : Wall Thickness Fabrication Tolerance Type
    • xfu : User Defined Negative Wall Thickness Fraction
    • tfu : User Defined Negative Wall Thickness Allowance
  • yfactype : Y Coefficient Type
    • Yu : User Defined Y Coefficient
  • Td : Design Temperature

Tool Output

  • D : Nominal Outside Diameter
  • D/tm : Diameter Over Minimum Thickness Ratio
  • Y : Y Coefficient
  • d : Nominal Inside Diameter
  • tf : Wall Thickness Fabrication Allowance
  • tm : Minimum Wall Thickness
  • tn : Nominal Wall Thickness

CALCULATOR : ASME B31.1 Section 102.3 Pipe W Weld Joint Factor From Temperature [FREE]   ±

Calculate the pipe weld joint reduction factor W from the maximum temperature (ASME B31.1 table 102.4.7). For carbon steel the weld joint reduction factor is 1.0.

For other materials, the weld joint reduction factor is interpolated from table 102.4.7.

Note : The calculated weld joint factors are not valid if the metal temperature is greater than the temperature range in appendix A for that particular material.

Tool Input

  • wfactype : Weld Factor Type
    • Wu : User Defined W Factor
    • Tcr : User Defined Creep Temperature
  • T : Design Temperature

Tool Output

  • W : Weld Factor
CALCULATOR : ASME B31.1 Section 102.4 Pipe Bend Thinning Allowance [FREE]   ±

Calculate pipe bend thinning allowance and bend minimum thickness from the straight pipe nominal wall thickness and the bend radius (ASME B31.1 section 102.4 table 102.4.5).

A power law curve has been fitted to the data in table 102.4.5. Use the goal seek option to calculate the straight pipe nominal wall thickness for a required bend minimum thickness. The bend thinning allowance is an estimate only. Actual bend measurements should be checked after bending at the outside bend radius (extrados).

Tool Input

  • schdtype : Line Pipe Schedule Type
  • diamtype : Diameter Type
    • ODu : User Defined Outside Diameter
    • IDu : User Defined Inside Diameter
  • wtntype : Wall Thickness Type
    • tnu : User Defined Miter Bend Wall Thickness
  • ttoltype : Wall Thickness Tolerance Type
    • xfu : User Defined Negative Wall Thickness Fraction
    • tfu : User Defined Negative Wall Thickness Allowance
  • rbtype : Bend Radius Type
    • Ru : User Defined Bend Radius
    • R/Du : User Defined Bend R / D Ratio

Tool Output

  • B : Bend Thinning Factor
  • D : Straight Pipe Outside Diameter
  • D/tn : Straight Pipe Diameter Over Wall Thickness Ratio
  • R : Bend Center Line Radius
  • R/D : Bend Radius Over Pipe Diameter Ratio
  • tf : Straight Pipe Wall Thickness Fabrication Allowance
  • tme : Estimated Bend Minimum Wall Thickness After Thinning
  • tmp : Straight Pipe Minimum Wall Thickness
  • tn : Nominal Wall Thickness

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