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Pipe Expansion Formula

Finding the expansion of pipe is relatively easy using the formula for "linear expansion". There are many reasons beside trade school to know these calculations and apply the knowledge gained into your building plans.

Here are the factors you will need to know in order find the change in length (ΔL - change of length)of a section of pipe for various temperatures. Please note all of the units will be metric in the following examples.

  • ΔT -(change of temperature)
    This is the difference between the initial temperature and the final temperature of the pipe.
  • L - Initial length of the pipe
  • a - Coefficient of linear expansion for the material.

The formula to find the thermal expansion of pipe would look like this:

ΔL = a L ΔT

Using the formula

To keep this simple (I know it can look confusing), lets suppose we need to find how much a 10m length of copper pipe will change given a 40C change in temperature. The coefficient of linear expansion of copper is 0.000017, so a=0.000017 for this example.

ΔL = 0.000017 x 10 x 40

ΔL = 0.0068m or 7mm

Material typeCoefficient of thermal expansion (a)spacer
ABS73.8 x 10-6spacer
Aluminum22.2 x 10-6spacer
Brass18.7 x 10-6spacer
Cast iron10.4 x 10-6spacer
Cement10.0 x 10-6spacer
CPVC66.6 x 10-6spacer
Concrete14.5 x 10-6spacer
Glass pipe4.0 x 10-6spacer
Copper16.6 x 10-6spacer
Iron12.0 x 10-6spacer
Lead28.0 x 10-6spacer
PEX 02 barrier140 x 10-6spacer
PEX-AL-PEX24 x 10-6spacer
Polyethylene (PE)200 x 10-6spacer
Polyethylene terephthalate (PET)59.4 x 10-6spacer
Polypropylene (PP)90.5 x 10-6spacer
PVC110 x 10-6spacer
Rubber77 x 10-6spacer
Steel13 x 10-6spacer
Wood Framing3.7 x 10-6spacer