Oilfield Pipe Stretch Calculator

Pipe Stretch Calculations for Tubing, Drill Pipe, and Rods

The stretch of a pipe under tensile load can be calculated using the formula:

ΔL=F×LA×E\Delta L = \frac{F \times L}{A \times E}ΔL=A×EF×L​

Where:

  • ΔL = Pipe Stretch (in inches or feet)

  • F = Applied Force (lbs)

  • L = Pipe Length (inches or feet)

  • A = Cross-Sectional Area of Pipe (square inches)

  • E = Modulus of Elasticity (psi)

1. Pipe Stretch for Tubing

For API tubing, the modulus of elasticity (E) for steel is typically 30,000,000 psi.

ΔL=F×LA×30,000,000\Delta L = \frac{F \times L}{A \times 30,000,000}ΔL=A×30,000,000F×L​

  • Example Tubing Sizes & Areas:

    • 2-3/8" OD, 4.6 lb/ft → A = 0.44 in²

    • 2-7/8" OD, 6.5 lb/ft → A = 0.60 in²

2. Pipe Stretch for Drill Pipe

Drill pipe also follows the same formula, but typically has a higher load-bearing capacity.

  • E (Steel Drill Pipe) = 30,000,000 psi

  • E (High-strength Alloy Pipe) = 32,000,000 psi

Common drill pipe areas:

  • 3-1/2” OD, 13.3 lb/ft → A = 0.89 in²

  • 4” OD, 14.0 lb/ft → A = 1.10 in²

  • 5” OD, 19.5 lb/ft → A = 1.76 in²

ΔL=F×LA×E\Delta L = \frac{F \times L}{A \times E}ΔL=A×EF×L​

3. Pipe Stretch for Rods (Sucker Rods)

For sucker rods, the formula remains the same, but the modulus of elasticity varies.

  • E (Steel Rods) = 30,000,000 psi

  • E (Fiberglass Rods) = 3,000,000 psi

Common sucker rod areas:

  • 3/4" rod → A = 0.44 in²

  • 7/8" rod → A = 0.60 in²

  • 1" rod → A = 0.79 in²

ΔL=F×LA×30,000,000\Delta L = \frac{F \times L}{A \times 30,000,000}ΔL=A×30,000,000F×L​

Quick Pipe Stretch Approximation

For steel pipe, an approximate stretch equation is:

ΔL≈F×L106×W\Delta L \approx \frac{F \times L}{10^6 \times W}ΔL≈106×WF×L​

Where:

  • W = Pipe Weight per Foot (lb/ft)

This provides fast estimations without complex calculations.