Pipe Stretch - Audit

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Pipe stretch, release 1, issued 7 March 2010. AUDIT version.

This worksheet exists in two versions. They are identical apart from the way they are formatted. The Work version hides intermediate calculations and allows the user to see the results just below the inputs. This is useful for quick “what-if” games, changing various inputs to see what works best. The Audit version displays all intermediate calculations.

Description

This worksheet will calculate the change in length of pipe due to a) it’s own weight when submerged in fluid, b) additional axial load (tension or compression) and c) a change in the average temperature.

 

1.2

 

psi/ftSG or kg/lppgkPa/mlb/ft3lb/bbl

Mud density. Jmudsg

 

1000

 

ftm

Steel vertical length. L_Vsteel

 

5

 

4.276

 

inmm

Pipe OD and ID. L_Dpipe & L_dpipe

 

10

 

FC

Average temperature change. 

Enter a -ve value if the temperature drops

 

250000

 

lbfkgf

Additional load. Fα

Enter a -ve value if axial compressive force

  

Click when modified to update the result.

Entered values in SI units;

Constants and coefficients;

SG for steel

Youngs Modulus for steel

Steel coefficient of thermal expansion

Calculate steel SG – mud SG

Calculate volume of steel if 1 cm x 1 cm x length

Average force over the length = half the total force at the top. Calculate the force in Newtons arising from half the buoyant mass of steel

Stress = load / area. Average stress due to own weight;

Additional stress due to extra axial force;

Total stress;

Strain = stress / YM. Strain due to axial stress;

Thermal strain due to temperature change;

Total strain;

Strain = stretch / original length so stretch = strain x original length.

Total pipe length after strain

RESULTS

Original length of pipe

Length of pipe due to

axial and thermal strain

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