.PPR Piping Systems in Uganda

Linear Expansion


Linear expansion of pipes is directly proportional to the heat subjected to the pipe material. Hence, cold water pipes have practically no linear expansion and could be neglected in the installation design.

 On the other hand, expansion of pipes is significant in warm water and heating installations and in extreme temperature varying environments, and therefore needs to be considered. Formula for Calculation of Linear Expansion

The linear expansion ∆L is calculated according to following formula:

 ∆L=α• L•∆T

Where: ∆L Expanded length (mm)
α Coefficient of linear expansion (mm/mK)
L Length of segment in (mm)
∆L Temperature difference between working and installation Linear Expansion Calculation

 Example: Assuming you need to calculate the expansion (∆L) of a standard RAKtherm pipe segment

(L) of 1.6 meters at a maximum working temperature of 70°C.

You know that the RAKtherm standard pipe has a coefficient of linear expansion of (α = 0.15).
You know that the installation was executed at the typical ambient temperature of 25°C.

 ∆L =α•L •∆L or ∆L = 0.15 *1.6 *(70°C -25°C) =10.8 mm

That means you can expect a linear expansion of 10.8 mm for this segment of pipe if the temperature difference is respected. Alternatively, you can quickly obtain the result from the following table for different types of pipe: