PPR Pipe Thermal Expansion Coefficient and Calculation Guide

The linear thermal expansion coefficient of standard PPR pipe is approximately 0.15 mm/m·°C. SPK's current technical table uses 0.035 mm/m·°C for glass-fibre reinforced PPR and 0.030 mm/m·°C for aluminium-foil reinforced PPR.

How to calculate PPR pipe thermal expansion

Formula: ΔL = L × α × ΔT

ΔL: Change in length (mm)
L: Pipe run length (m)
α: Linear expansion coefficient (mm/m·°C)
ΔT: Difference between installation and operating temperature (°C)

Example: If the temperature of a 10 metre standard PPR run changes by 40 °C, the calculated expansion is 10 × 0.15 × 40 = 60 mm. The same example gives approximately 14 mm for glass-fibre reinforced pipe and 12 mm for aluminium-foil reinforced pipe.

Standard, glass-fibre and aluminium PPR comparison

Pipe construction	Coefficient α	10 m / ΔT 40 °C example
Standard PPR	0.15 mm/m·°C	60 mm
Glass-fibre reinforced PPR	0.035 mm/m·°C	14 mm
Aluminium-foil reinforced PPR	0.030 mm/m·°C	12 mm

The result informs the design of fixed points, sliding supports, routing and expansion compensation. Confirm the final installation against the project conditions and current product technical documentation.

PPR thermal expansion tables

Standard PPRα = 0.15 mm/m·°C

Pipe lengthL (m)	Temperature changeΔT (°C)
Pipe lengthL (m)	10	20	30	40	50	60	70	80	90	100
1	1.5	3	4.5	6	7.5	9	10.5	12	13.5	15
2	3	6	9	12	15	18	21	24	27	30
3	4.5	9	13.5	18	22.5	27	31.5	36	40.5	45
4	6	12	18	24	30	36	42	48	54	60
5	7.5	15	22.5	30	37.5	45	52.5	60	67.5	75
6	9	18	27	36	45	54	63	72	81	90
7	10.5	21	31.5	42	52.5	63	73.5	84	94.5	105
8	12	24	36	48	60	72	84	96	108	120
9	13.5	27	40.5	54	67.5	81	94.5	108	121.5	135
10	15	30	45	60	75	90	105	120	135	150

Glass-fibre reinforced PPRα = 0.035 mm/m·°C

Pipe lengthL (m)	Temperature changeΔT (°C)
Pipe lengthL (m)	10	20	30	40	50	60	70	80	90	100
1	0.35	0.7	1.05	1.4	1.75	2.1	2.45	2.8	3.15	3.5
2	0.7	1.4	2.1	2.8	3.5	4.2	4.9	5.6	6.3	7
3	1.05	2.1	3.15	4.2	5.25	6.3	7.35	8.4	9.45	10.5
4	1.4	2.8	4.2	5.6	7	8.4	9.8	11.2	12.6	14
5	1.75	3.5	5.25	7	8.75	10.5	12.25	14	15.75	17.5
6	2.1	4.2	6.3	8.4	10.5	12.6	14.7	16.8	18.9	21
7	2.45	4.9	7.35	9.8	12.25	14.7	17.15	19.6	22.05	24.5
8	2.8	5.6	8.4	11.2	14	16.8	19.6	22.4	25.2	28
9	3.15	6.3	9.45	12.6	15.75	18.9	22.05	25.2	28.35	31.5
10	3.5	7	10.5	14	17.5	21	24.5	28	31.5	35

Aluminium-foil reinforced PPRα = 0.030 mm/m·°C

Pipe lengthL (m)	Temperature changeΔT (°C)
Pipe lengthL (m)	10	20	30	40	50	60	70	80	90	100
1	0.3	0.6	0.9	1.2	1.5	1.8	2.1	2.4	2.7	3
2	0.6	1.2	1.8	2.4	3	3.6	4.2	4.8	5.4	6
3	0.9	1.8	2.7	3.6	4.5	5.4	6.3	7.2	8.1	9
4	1.2	2.4	3.6	4.8	6	7.2	8.4	9.6	10.8	12
5	1.5	3	4.5	6	7.5	9	10.5	12	13.5	15
6	1.8	3.6	5.4	7.2	9	10.8	12.6	14.4	16.2	18
7	2.1	4.2	6.3	8.4	10.5	12.6	14.7	16.8	18.9	21
8	2.4	4.8	7.2	9.6	12	14.4	16.8	19.2	21.6	24
9	2.7	5.4	8.1	10.8	13.5	16.2	18.9	21.6	24.3	27
10	3	6	9	12	15	18	21	24	27	30

Reduced-expansion PPR options

To confirm product selection against operating temperature, pressure and run length, contact the SPK technical team.