Pipe Thermal Expansion
Linear expansion coefficients for common pipe materials, with the growth of a 10 m run worked out for typical temperature changes — and the axial stress that develops if the pipe cannot move. Design values on the 20–100 °C engineering basis; the stated ranges cover the spread across published sources.
| Material | α (10⁻⁶/K) | Range (10⁻⁶/K) | ΔT 30 K (mm/10 m) | ΔT 50 K (mm/10 m) | ΔT 100 K (mm/10 m) | Restrained σ (elastic), ΔT 50 K (MPa) |
|---|---|---|---|---|---|---|
| Carbon steel | 12 | 11.3–12.8 | 3.6 | 6.0 | 12.0 | 120 |
| Stainless steel (304/316) | 16.5 | 15.9–17.3 | 4.9 | 8.2 | 16.5 | 161 |
| Ductile iron | 11 | 10.4–11.8 | 3.3 | 5.5 | 11.0 | 94 |
| Copper | 16.8 | 16.4–17.3 | 5.0 | 8.4 | 16.8 | 98 |
| Aluminium | 23.5 | 22.5–24 | 7.0 | 11.8 | 23.5 | 81 |
| PVC-U | 70 | 50–80 | 21.0 | 35.0 | 70.0 | creep |
| CPVC | 65 | 60–70 | 19.5 | 32.5 | 65.0 | creep |
| ABS | 100 | 90–110 | 30.0 | 50.0 | 100.0 | creep |
| PP-R | 150 | 120–180 | 45.0 | 75.0 | 150.0 | creep |
| PE (HDPE / PE100) | 180 | 150–200 | 54.0 | 90.0 | 180.0 | creep |
α is a mean linear-expansion design value on the 20–100 °C basis; growth scales linearly with length (mm/10 m × run length ÷ 10). The restrained-stress column uses σ = E·α·ΔT with typical Young's moduli — plastics are omitted because they creep rather than hold elastic stress. For plastics, confirm α against the pipe manufacturer's datasheet; grades vary.
An unrestrained pipe run changes length in proportion to its length and temperature change:
- — length change (m; multiply by 1,000 for mm)
- — linear expansion coefficient (1/K; the table lists 10⁻⁶/K)
- — run length between anchor points (m)
- — temperature change from the installation temperature (K)
If the pipe is fully restrained, the growth is converted into axial stress instead — independent of length and diameter:
- — axial stress (Pa), — Young's modulus (Pa)
For carbon steel that is about 2.4 MPa per kelvin — a fully restrained line heated by 100 K reaches ~240 MPa (elastic basis, assuming no yielding), which approaches or exceeds the yield strength of common pipe-steel grades. It is why piping codes require flexibility analysis for lines with significant temperature change, and why hot piping is designed to flex (loops, offsets, bellows) between deliberate anchor points rather than being clamped rigid, and why the anchor forces on a line that is held straight are so large.
- Metal coefficients are mean linear-expansion values on the 20–100 °C engineering basis, consistent with the ASME B31.3 Appendix C / EN 13480-3 class data used for flexibility analysis (α rises slowly with temperature; code tables give the exact mean value to your design temperature for formal stress work).
- Plastic coefficients are typical manufacturer values (PVC-U, CPVC, ABS, PP-R, PE pressure-pipe grades); the spread between suppliers and grades is real, which is why each row carries a range — use the datasheet value for the pipe actually being installed.
- Every design value sits inside its stated range, and the ranges bracket the classic handbook figures (CRC, Perry's, supplier data) — enforced by an automated check in the repository, alongside the ΔL and σ arithmetic anchors quoted on this page.
- Young's moduli for the restrained-stress column are typical room-temperature values (steel 200, stainless 195, ductile iron 170, copper 117, aluminium 69 GPa).
- Pipe dimensions and weights for the same materials are in the pipe schedule tables and pipe weight chart.
Frequently Asked Questions
How much does steel pipe expand with temperature?
Why do plastic pipes expand so much more than metal?
What happens if a pipe cannot expand?
How is pipe thermal expansion accommodated?
What temperature difference should I design for?
Does thermal expansion affect the hydraulic calculation?
Temperature matters to the fluid too
SimuPipe evaluates density, viscosity and vapour pressure at your set fluid temperature across the whole network — the hydraulic side of the same design question.