Pipe Thermal Expansion Calculator
The Pipe Thermal Expansion Calculator computes linear expansion (ΔL = α × L × ΔT) for 6 pipe materials and sizes expansion loops using ASME B31.1 guidelines. It includes an interactive SVG expansion visualization, supports metric and imperial units, and covers temperatures from cryogenic to high-pressure steam — free, no signup required.
Pipe & Temperature Parameters
Material Expansion Coefficients
| Pipe Material | Coefficient (in/in/°F) | Coefficient (mm/m/°C) | Allowable Stress (psi) | Elastic Modulus (psi) |
|---|---|---|---|---|
| Carbon Steel | 6.33e-6 in/in/°F | 0.0114 mm/m/°C | 15,000 | 29.5M |
| Stainless Steel 304 | 9.60e-6 in/in/°F | 0.0173 mm/m/°C | 15,000 | 28.0M |
| Stainless Steel 316 | 8.90e-6 in/in/°F | 0.0160 mm/m/°C | 15,000 | 28.0M |
| Copper | 9.80e-6 in/in/°F | 0.0176 mm/m/°C | 6,000 | 17.0M |
| PVC | 3.00e-5 in/in/°F | 0.0540 mm/m/°C | 2,000 | 0.4M |
| CPVC | 3.40e-5 in/in/°F | 0.0612 mm/m/°C | 2,000 | 0.4M |
| Cast Iron | 5.90e-6 in/in/°F | 0.0106 mm/m/°C | 10,000 | 14.5M |
| Aluminum | 1.28e-5 in/in/°F | 0.0230 mm/m/°C | 8,000 | 10.0M |
ご提案はありますか？
新しいツールのリクエストや改善提案をお待ちしています — Slackコミュニティにご参加ください！
What is Pipe Thermal Expansion?
Pipe thermal expansion is the increase in length of a pipe when its temperature rises. The linear expansion formula is ΔL = α × L × ΔT, where α is the coefficient of linear expansion (per °C), L is the original length, and ΔT is the temperature change. For example, a 100-meter carbon steel pipe heated from 20 °C to 120 °C will expand approximately 120 mm. Without proper expansion accommodation (expansion loops, bellows, or slip joints), the resulting thermal stress can cause pipe failure, flange leaks, or equipment damage.
How to Use This Calculator
- Select the pipe material (Carbon Steel, Stainless Steel, Copper, PVC, CPVC, or Cast Iron)
- Enter the total pipe length in meters and the nominal pipe diameter
- Enter the installation temperature (ambient/cold fill) and operating temperature
- Click Calculate to see the total expansion, expansion per meter, and coefficient used
- Review the expansion loop sizing section for recommended loop leg length and bend radius
Frequently Asked Questions
Which pipe material expands the most?
PVC and CPVC have the highest thermal expansion coefficients — about 5× greater than steel. PVC expands at approximately 54 × 10⁻⁶/°C compared to carbon steel at 12 × 10⁻⁶/°C. Copper (16.5 × 10⁻⁶/°C) and stainless steel (17.3 × 10⁻⁶/°C) fall in between. This means plastic piping systems require more expansion compensation per unit length.
What is an expansion loop and how does it work?
An expansion loop is a U-shaped section of pipe that absorbs thermal movement through flexing. As the pipe expands, the loop legs flex inward, preventing stress buildup at anchors and equipment. The loop size depends on pipe diameter, expansion amount, and allowable bending stress. The ASME B31.1 formula gives the minimum loop leg length as L = √(3 × D × ΔL / Sₐ).
How much does a steel pipe expand per 100 meters?
Carbon steel (α = 12 × 10⁻⁶/°C) expands approximately 1.2 mm per meter per 100 °C temperature rise. For a 100-meter run going from 20 °C to 120 °C (ΔT = 100 °C), the total expansion is about 120 mm (4.7 inches). This must be accommodated with expansion joints or loops to prevent stress.