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Pipeng Free Online Software : Barlow Thin Wall Pipeline Calculators
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Pipeng : Barlows Formula For Thin Wall Pipelines : Wall Thickness Allowable Pressure Difference And Hoop Stress Calculation Module

Barlow Thin Wall Pipeline Calculators

Description : Thin wall pipeline calculators using Barlows formula.

Discussion : Calculate the wall thickness, allowable pressure difference and the hoop stress. Barlows formula is a simple force balance of the external and internal forces on a pipe section.

ΔPa = ( 2 Sa t ) / D

where

ΔPa = Allowable Pipe Wall Delta Pressure
D = Pipe Diameter
Sa = Allowable Hoop Stress
t = Pipe Wall Thickness

To balance the forces in the pipe wall and for the average hoop stress in the pipe wall the diameter is set equal to the pipeline internal diameter ID. However, the stress distribution in the pipe wall varies with radius, with a maximum value at the internal surface of the pipe. Most codes set the pipe diameter equal to the outside diameter (D = OD), or the mid wall diameter (D = Dm) as this partially allows for the variation in stress. If in doubt use the pipe outside diameter (D = OD).

The allowable stress design factor typically varies between 0.4 and 0.7. If in doubt use 0.4 to 0.5.

If you do not have SMYS (specified minimum yield stress) data from material tests, use the material yield stress with a lower design factor. If in doubt use 0.4 as the design factor.

The corrosion allowance should include the depth of threaded joints and or grooves.

If the DoT (diameter over wall thickness ratio) is less than 20 you should use the thick wall calculators.

Figures :

Calculator Tools In This Module:

CALC : Pipe : Wall Thickness 071 : Thin Wall Pipeline Wall Thickness Barlows Formula : Calculator
CALC : Pipe : Wall Thickness 072 : Thin Wall Pipeline Design Pressure From Wall Thickness : Calculator
CALC : Pipe : Wall Thickness 073 : Thin Wall Pipeline Hoop Stress Barlows Formula : Calculator
CALC : Pipe : Wall Thickness 074 : General Pipeline Leak Test Pressure : Calculator
CALC : Pipe : Wall Thickness 075 : General Pipeline Allowable Operating Pressure : Calculator


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Module List

CALC : Pipe : Wall Thickness 071 : Thin Wall Pipeline Wall Thickness Barlows Formula : Calculator

Description : Calculate the nominal wall thickness for thin wall pipeline hoop stress using Barlows formula.

Discussion : The minimum wall thickness for hoop stress from the internal and external pressure, and allowable hoop stress. The diameter in the Barlow formula can be set to either the pipeline outside diameter OD, the pipeline mid wall diameter Dm, or the pipeline inside diameter ID.

Calculation Steps :

  • Allowable hoop stress
  • Pressure difference
  • Hoop wall thickness
  • Nominal wall thickness, ID and D over t ratio

Options :

  • Barlow diameter type : D = OD, D = Dm, D = ID

Input Variables :

  • D = Pipe Nominal Diameter
  • F = Pipeline Hoop Stress Factor
  • Pi = Pipe Wall Delta Pressure
  • Po = External Fluid Gauge Pressure
  • Sy = Pipeline SMYS - Specified Minimum Yield Stress
  • c = Pipe Total Corrosion Allowance
  • d = Diameter Type

Output Variables :

  • ΔP = Pipe Wall Delta Pressure
  • ID = Pipe Nominal Inside Diameter
  • Sa = Allowable Hoop Stress
  • dot = Pipeline Diameter Over Wall Thickness Ratio
  • t = Pipe Hoop Wall Thickness
  • tn = Pipe Nominal Wall Thickness

Calculation :

Sa = F Sy
ΔP = | Pi - Po |
 If d = 1 : D = OD
  t = ( ΔP D ) / ( 2 Sa )
 Otherwise If d = 2 : D = Dm
  t = ( ΔP D ) / ( 2 Sa + ΔP )
 Otherwise If d = 3 :D = ID
  t = ( ΔP D ) / ( 2 Sa + 2 ΔP )
 End of If Block
tn = t + c
ID = D - 2 tn
dot = D / tn

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CALC : Pipe : Wall Thickness 072 : Thin Wall Pipeline Design Pressure From Wall Thickness : Calculator

Description : Calculate the design pressure for thin wall pipeline hoop stress using Barlows formula.

Discussion : The allowable pressure difference and internal pressure for hoop stress from the external pressure, wall thickness and allowable hoop stress.

Calculation Steps :

  • Allowable hoop stress
  • Hoop wall thickness
  • Allowable pressure difference
  • Allowable internal pressure

Options :

  • Barlow diameter type : D = OD, D = Dm, D = ID

Input Variables :

  • D = Pipe Nominal Diameter
  • F = Pipeline Hoop Stress Factor
  • Po = External Fluid Gauge Pressure
  • Sy = Pipeline SMYS - Specified Minimum Yield Stress
  • c = Pipe Total Corrosion Allowance
  • d = Diameter Type
  • t = Pipe Nominal Wall Thickness

Output Variables :

  • ΔPa = Allowable Pipe Wall Delta Pressure
  • Pa = Pipeline Design Gauge Pressure
  • Sa = Allowable Hoop Stress
  • t = Pipe Hoop Wall Thickness

Calculation :

Sa = F Sy
t = t - c
 If d = 1 : D = OD
  ΔPa = ( 2 Sa t ) / D
 Otherwise If d = 2 : D = Dm
  ΔPa = ( 2 Sa t ) / ( D - t )
 Otherwise If d = 3 :D = ID
  ΔPa = ( 2 Sa t ) / ( D - 2 t )
 End of If Block
Pa = ΔPa + Po

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CALC : Pipe : Wall Thickness 073 : Thin Wall Pipeline Hoop Stress Barlows Formula : Calculator

Description : Calculate the hoop stress for thin wall pipelines using Barlows formula.

Discussion : The hoop stress from internal and external pressure and wall thickness. Check that the hoop stress is less than or equal to the allowable hoop stress.

Calculation Steps :

  • Allowable hoop stress
  • Pressure difference
  • Hoop wall thickness
  • Hoop Stress

Options :

  • Barlow diameter type : D = OD, D = Dm, D = ID

Input Variables :

  • D = Pipe Nominal Diameter
  • F = Pipeline Hoop Stress Factor
  • Pi = Pipeline Design Gauge Pressure
  • Po = External Fluid Gauge Pressure
  • Sy = Pipeline SMYS - Specified Minimum Yield Stress
  • d = Diameter Type
  • tc = Pipe Total Corrosion Allowance
  • tn = Pipe Nominal Wall Thickness

Output Variables :

  • ΔP = Pipe Wall Delta Pressure
  • S = Pipeline Hoop Stress
  • Sa = Allowable Hoop Stress
  • t = Pipe Hoop Wall Thickness

Calculation :

Sa = F Sy
ΔP = | Pi - Po |
t = tn - tc
 If d = 1 : D = OD
  S = ( ΔP D ) / ( 2 t )
 Otherwise If d = 2 : D = Dm
  S = ( ΔP ( D - t ) ) / ( 2 t )
 Otherwise If d = 3 :D = ID
  S = ( ΔP ( D - 2 t ) ) / ( 2 t )
 End of If Block

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CALC : Pipe : Wall Thickness 074 : General Pipeline Leak Test Pressure : Calculator

Description : Calculate the pipeline leak test pressure from the design pressure.

Discussion : If the hoop stress in a pipeline is greater than 20% of the yield stress a leak test or pressure test is recommended. The leak test pressure is a multiple of the design pressure. A recommended default value is 1.25. The hoop stress in the pipeline during the leak test should not exceed 90% of yield.

Input Variables :

  • P = Pipeline Design Gauge Pressure
  • f = Pipeline Leak Test Pressure Factor

Output Variables :

  • Pt = Pipeline Leak Test Gauge Pressure

Calculation :

Pt = f P

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CALC : Pipe : Wall Thickness 075 : General Pipeline Allowable Operating Pressure : Calculator

Description : Calculate the pipeline design pressure or allowable operating pressure from the leak test pressure.

Discussion : If the pipeline has been pressure tested or leak tested the allowable operating pressure can be calculated by dividing the leak test pressure by the leak test factor. A default value of 1.25 is recommended for the leak test factor.

Input Variables :

  • Pt = Pipeline Leak Test Gauge Pressure
  • f = Pipeline Leak Test Pressure Factor

Output Variables :

  • P = Pipeline Design Gauge Pressure

Calculation :

P = Pt / f

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