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ASME B31.3 Process Piping Bend

Calculate ASME B31.3 process piping minimum thickness for formed bends, and allowable pressure for miter bends.

Minimum thickness of formed bends is calculated for the inside radius, the oputside radius, and the centerline radius. Bend thinning on the outside radius is estimated using the method from ASME B31.1. The estimated minimum bend thickness after thinning should be ≥ the required minimum bend thickness on the outside radius (extrados). Use the goal seek option to calculate the required straight pipe nominal wall thickness (before bending), for the minimum thickness on the outside radius (after bending).

The allowable pressure for miter bends is calculated from the nominal wall thickness. Use the goal seek option to calculate the required miter bend nominal wall thickness for the design pressure. Use the workbook ASME B31.3 data tables to look up allowable stress data.

Reference : ANSI/ASME B31.3 : Process Piping (2018)

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CALCULATOR : ASME B31.3 Metal Pipe Diameter And Wall Thickness Schedule [FREE]   ±

Calculate ASME B31.3 metal pipe diameter, minimum wall thickness and pressure design thickness from pipe schedule or user defined diameter and wall thickness (ASME B31.3 section 304.1).

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 B31.3 Table A-1 Low Pressure Metal Pipe Yield Stress Tensile Stress And Basic Allowable Stress Schedule [FREE]   ±

Calculate low pressure metal pipe SMYS (Specified Minimum Yield Stress), SMTS (Specified Minimum Tensile Stress) and basic allowable stress schedule (ASME B31.3 table A-1).

Use the Result Table option to display the stress values for the selected stress schedule (click the Result Table button, and then click the make table button).

Tool Input

  • syutype : Stress Schedule Type
  • mattype : Material Type
    • SMTSu : User Defined Specified Minimum Tensile Stress
    • SMYSu : User Defined Specified Minimum Yield Stress
    • Su : User Defined Basic Allowable Stress

Tool Output

  • S : Basic Allowable Stress
  • S/SMTS : Basic Allowable Stress Over SMTS Ratio
  • S/SMYS : Basic Allowable Stress Over SMYS Ratio
  • SMTS : Specified Minimum Tensile Stress
  • SMTS/SMYS : SMTS Over SMYS Ratio
  • SMYS : Specified Minimum Yield Stress
  • SMYS/SMTS : SMYS Over SMTS Ratio
CALCULATOR : ASME B31.3 Table K-1 High Pressure Metal Pipe Yield Stress Tensile Stress And Allowable Stress Schedule [FREE]   ±

Calculate high pressure metal pipe SMYS (Specified Minimum Yield Stress), SMTS (Specified Minimum Tensile Stress) and allowable stress schedule (ASME B31.3 table K-1).

Use the Result Table option to display the stress values for the selected stress schedule (click the Result Table button, and then click the make table button).

Tool Input

  • syutype : Stress Schedule Type
  • mattype : Material Type
    • SMTSu : User Defined Specified Minimum Tensile Stress
    • SMYSu : User Defined Specified Minimum Yield Stress
    • Su : User Defined Allowable Stress

Tool Output

  • S : Basic Allowable Stress
  • S/SMTS : Basic Allowable Stress Over SMTS Ratio
  • S/SMYS : Basic Allowable Stress Over SMYS Ratio
  • SMTS : Specified Minimum Tensile Stress
  • SMTS/SMYS : SMTS Over SMYS Ratio
  • SMYS : Specified Minimum Yield Stress
  • SMYS/SMTS : SMYS Over SMTS Ratio
CALCULATOR : ASME B31.3 Section 304.2 Pipe Bend Wall Thickness From Hoop Stress (Low Pressure Steel Piping) [FREE]   ±

Calculate pipe bend minimum wall thickness (ASME B31.3 section 304.2). The wall thickness measurements should be checked at the mid span of the bend for the inside bend radius (intrados), outside bend radius (extrados), and the bend center line radius.

Bend thinning on the outside radius is calculated using an approximate method from ASME B31.1 table 102.4.5. Use the goal seek option to calculate the required straight pipe nominal wall thickness from the minimum wall thickness on the outside radius.

Tool Input

  • schdtype : Pipe Schedule Type
  • diamtype : Pipe Diameter Type
    • ODu : User Defined Outside Diameter
    • IDu : User Defined Inside Diameter
  • wtntype : Wall Thickness Type
    • tnu : User Defined Straight Pipe Nominal 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
  • bendtype : Wall Thickness Position
  • yfactype : Y Factor Type
    • Yu : User Defined Y Coefficient
  • c : Wall Thickness Corrosion Allowance
  • P : Internal Pressure
  • SE : Design Stress
  • T : Design Temperature

Tool Output

  • B : Bend Thinning Factor
  • D/tn : Straight Pipe Diameter Over Wall Thickness Ratio
  • I : Bend I Factor
  • ID : Straight Pipe Inside Diameter
  • OD : Straight Pipe Outside Diameter
  • R : Bend Center Line Radius
  • R/D : Bend Radius Over Pipe Diameter Ratio
  • Y : Straight Pipe Y Coefficient
  • t : Bend Required Pressure Design Wall Thickness
  • tf : Straight Pipe Wall Thickness Fabrication Allowance
  • tmb : Bend Required Minimum Wall Thickness After Thinning
  • tme : Bend Estimated Minimum Wall Thickness After Thinning (Outside Radius)
  • tmp : Straight Pipe Minimum Wall Thickness
  • tn : Straight Pipe Nominal Wall Thickness
  • xf : Straight Pipe Wall Thickness Fabrication Fraction
CALCULATOR : ASME B31.3 Section 304.2 Pipe Single Miter Bend Maximum Allowable Pressure (Low Pressure Steel Piping) [FREE]   ±

Calculate pipe miter bend maximum allowable pressure for single miter bends (ASME B31.3 section 304.2). Analysis is not required for miter bends with a bend angle less than or equal to 3 degrees (bend half angle θ ≤ 1.5 degrees).

Use the goal seek option to calculate the required nominal wall thickness from the design pressure.

Tool Input

  • schdtype : Pipe Schedule Type
  • diamtype : Pipe Diameter Type
    • ODu : User Defined Outside Diameter
    • IDu : User Defined Inside Diameter
  • wtntype : Wall Thickness Type
    • tnu : User Defined Wall Thickness
  • ttoltype : Wall Thickness Tolerance Type
    • xfu : User Defined Negative Wall Thickness Fraction
    • tfu : User Defined Negative Wall Thickness Allowance
  • c : Corrosion Allowance
  • SEW : Design Stress Table A-1
  • θ : Miter Cutoff Angle Or Half Miter Angle

Tool Output

  • ID : Pipe Inside Diameter
  • M : Transition Length At Ends Of Miter Bend
  • OD : Pipe Outside Diameter
  • OD/tn : Diameter Over Wall Thickness Ratio
  • Pm : Maximum Allowable Internal Pressure
  • r2 : Mean Radius Of Pipe Using Nominal Wall
  • tf : Wall Thickness Fabrication Allowance
  • th : Pressure Containment Wall Thickness
  • tm : Minimum Wall Thickness
  • tn : Nominal Wall Thickness
  • xf : Wall Thickness Fabrication Fraction
CALCULATOR : ASME B31.3 Section 304.2 Pipe Compound Miter Bend Maximum Allowable Pressure (Low Pressure Steel Piping) [FREE]   ±

Calculate pipe miter bend maximum allowable pressure for compound miter bends (ASME B31.3 section 304.2). Analsis is not required for miter bends with a bend angle less than or equal to 3 degrees (bend half angle θ ≤ 1.5 degrees). The analysis is not valid for half bend angles greater than 22.5 degrees. The minimum section centerline length is calculated from the minimum value of R1.

Use the goal seek option to calculate the required nominal wall thickness from the design pressure.

Tool Input

  • schdtype : Pipe Schedule Type
  • diamtype : Pipe Diameter Type
    • ODu : User Defined Outside Diameter
    • IDu : User Defined Inside Diameter
  • wtntype : Wall Thickness Type
    • tnu : User Defined Wall Thickness
  • ttoltype : Wall Thickness Tolerance Type
    • xfu : User Defined Negative Wall Thickness Fraction
    • tfu : User Defined Negative Wall Thickness Allowance
  • c : Corrosion Allowance
  • SEW : Design Stress Table A-1
  • θ : Miter Cutoff Angle Or Half Miter Angle
  • s : Miter Bend Center Line Section Length

Tool Output

  • ID : Pipe Inside Diameter
  • M : Transition Length At Ends Of Miter Bend
  • OD : Pipe Outside Diameter
  • OD/tn : Diameter Over Wall Thickness Ratio
  • Pm : Maximum Allowable Internal Pressure
  • R1 : Effective Radius Of Compound Miter Bend
  • R1min : Minimum Effective Radius
  • r2 : Mean Radius Of Pipe Using Nominal Wall
  • smin : Minimum Miter Bend Center Line Section Length
  • tf : Wall Thickness Fabrication Allowance
  • th : Pressure Containment Wall Thickness
  • tm : Minimum Wall Thickness
  • tn : Nominal Wall Thickness
  • xf : Wall Thickness Fabrication Fraction
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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