Expansion & materials
Pipe thermal expansion
- where
- length change (m; the calculator shows mm)
- linear expansion coefficient (1/K)
- developed pipe length (m)
- temperature rise (K)
Explain this equation
Works out how much a pipe grows in length when it warms up. Use it to plan expansion loops, offsets and clip spacing.
α is the material's linear expansion coefficient, the fractional change in length per degree. L is the pipe length. ΔT is the temperature rise.
Each metre of material grows by the same fraction for each degree of warming, so the change is proportional to both length and temperature rise. The calculator works in metres and shows mm.
Sense check: 10 m of copper (α about 17 × 10⁻⁶ /K) heated by 60 K grows about 10 mm, roughly 1 mm per metre. Plastic pipes can expand eight to ten times as much.
Watch out: the example α is only illustrative. Use the manufacturer's figure for the actual pipe.
Enter your values to see the result.
Good to know
Example coefficient is illustrative. Use the actual pipe material/product and operating range; supports and expansion accommodation need design.
Sources
Results are arithmetic only. Worked examples are not recommended design settings. This library does not provide automatic gas pipe selection, live gas tightness tests, purging procedures, combustion acceptance limits, installation approval or commissioning certification. Manufacturer data and the applicable current method remain essential.