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Pipeng Free Online Software : Lames Thick Wall Pipeline Calculators
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Pipeng : Lames Equation For Thick Wall Pipelines : Wall Thickness Allowable Pressure Difference And Hoop Stress Calculation Module

Lames Thick Wall Pipeline Calculators

Description : Thick wall pipeline calculators using Lames formula.

Discussion : Calculate the wall thickness, allowable pressure difference and the hoop stress. Lames formula accounts for the variation in stress through the pipe wall. The stress has a maximum value at the internal surface of the pipe. Tresca combined stress is used as the yield criteria.

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 greater than 20 you should use the thin wall calculators.

Figures :

Calculator Tools In This Module:

CALC : Pipe : Wall Thickness 074 : General Pipeline Leak Test Pressure : Calculator
CALC : Pipe : Wall Thickness 075 : General Pipeline Allowable Operating Pressure : Calculator
CALC : Pipe : Wall Thickness 081 : Thick Wall Pipeline Wall Thickness Lames Equation : Calculator
CALC : Pipe : Wall Thickness 082 : Thick Wall Pipeline Design Pressure From Wall Thickness : Calculator
CALC : Pipe : Wall Thickness 083 : Thick Wall Pipeline Tresca Combined Stress Lames Equation : Calculator
CALC : Pipe : Wall Thickness 084 : Thick Wall Pipeline Radial and Tangential Stress Distribution Lames Equation : Calculator


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Module List

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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CALC : Pipe : Wall Thickness 081 : Thick Wall Pipeline Wall Thickness Lames Equation : Calculator

Description : Calculate the nominal wall thickness for thick wall pipelines using Lames formula.

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

Calculation Steps :

  • Allowable hoop stress
  • Pressure difference
  • Wall thickness
  • Id and DoT ratio

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

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 |
t = D / 2 ( 1 - √( 1 - ( 2 ΔP ) / Sa ) )
tn = t + c
ID = D - 2 tn
dot = D / tn

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CALC : Pipe : Wall Thickness 082 : Thick Wall Pipeline Design Pressure From Wall Thickness : Calculator

Description : Calculate the allowable internal pressure difference across the wall thickness for thick wall pipelines using Lames formula.

Discussion : The allowable pressure difference and internal pressure from allowable hoop stress and wall thickness.

Calculation Steps :

  • Allowable hoop stress
  • Hoop wall thickness
  • Pressure difference
  • Internal pressure

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
  • 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
ΔPa = Sa / 2 ( 1 - ( 1 - 2 t / D ) 2 )
Pa = ΔPa + Po

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CALC : Pipe : Wall Thickness 083 : Thick Wall Pipeline Tresca Combined Stress Lames Equation : Calculator

Description : Calculate the combined tresca stress for thick wall pipelines using Lames formula.

Discussion : Combined hoop stress and radial stress using Trescas formula. Check that the tresca combined stress is less than or equal to the allowable tresca stress. To calculate the tresca combined stress.

Calculation Steps :

  • Allowable hoop stress
  • Hoop wall thickness
  • Pressure difference
  • Tresca combined stress

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
  • tc = Pipe Total Corrosion Allowance
  • tn = Pipe Nominal Wall Thickness

Output Variables :

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

Calculation :

Sa = F Sy
ΔP = | Pi - Po |
t = tn - tc
S = ( 2 ΔP ) / ( 1 - ( 1 - 2 t / D ) 2 )

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CALC : Pipe : Wall Thickness 084 : Thick Wall Pipeline Radial and Tangential Stress Distribution Lames Equation : Calculator

Description : Calculate the tangential (hoop), radial and tresca combined stress distribution in a thick wall pipeline using Lames formula.

Discussion : The stress distribution varies with radius. the maximum stress occurs at the inside radius. To calculate the stress distribution.

Calculation Steps :

  • Internal and external radius
  • Lame constants C1 and C2
  • Radial stress adn hoop stress
  • Tresca combined stress

Input Variables :

  • D = Pipe Nominal Diameter
  • Pi = Pipe Wall Delta Pressure
  • Po = External Fluid Gauge Pressure
  • r = Pipe Nominal Radius
  • tn = Pipe Nominal Wall Thickness

Output Variables :

  • C1 = Lame Stress Constant C1
  • C2 = Lame Stress Constant C2
  • Ri = Pipe Nominal Inside Radius
  • Ro = Pipe Nominal Outside Radius
  • Sc = Pipeline Tresca Combined Stress
  • Sh = Pipeline Hoop Stress
  • Sr = Pipeline Radial Stress

Calculation :

Ro = D / 2
Ri = Ro - tn
C1 = ( Pi Ri 2 - Po Ro 2 ) / ( Ro 2 - Ri 2 )
C2 = ( ( Pi - Po ) Ri 2 Ro 2 ) / ( Ro 2 - Ri 2 )
If r <= Ro AND r >= Ri
  Sr = C1 - C2 / r 2
  Sh = C1 + C2 / r 2
  Sc = | Sh - Sr |
Otherwise
  Sr = 0
  Sh = 0
  Sc = 0
End of If Block

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