Thermoplastic Pipes - Temperature and Strength Derating

With increased temperature the strength of thermoplastic piping materials derates

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Thermoplastic materials loose their strength to pressure and tension with increasing temperature. The table below can be used as a guide to common thermoplastics and their derated strength with temperature. Manufacturing data should always be consulted.

Derating Factor
Temperature		PVDF	CPVC	PVC	PB	PEX	PE
(^oC)	(^oF)	PVDF	CPVC	PVC	PB	PEX	PE
21	70	1.0	1.0	1.0	1.0	1.0	1.0
27	80	0.9	1.0	0.9	1.0	0.9	0.9
32	90	0.9	0.9	0.8	0.9	0.9	0.9
38	100	0.8	0.8	0.6	0.9	0.9	0.8
43	110	0.8	0.8	0.5	0.8	0.8	0.8
49	120	0.7	0.7	0.4	0.8	0.8	0.7
54	130	0.7	0.6	0.3	0.7	0.8	0.5
60	140	0.6	0.5	0.2	0.7	0.7	0.4
66	150	0.6	0.5	¹⁾	0.7	0.7	0.2
71	160	0.5	0.4	¹⁾	0.6	0.7	¹⁾
82	180	0.5	0.3	¹⁾	0.5	0.6	¹⁾
93	200	0.4	0.2	¹⁾	0.4	0.5	¹⁾
104	220	0.4	¹⁾	¹⁾	¹⁾	¹⁾	¹⁾
121	250	0.4	¹⁾	¹⁾	¹⁾	¹⁾	¹⁾
138	280	0.3	¹⁾	¹⁾	¹⁾	¹⁾	¹⁾

¹⁾ The thermoplastic is not resistant for long term service at this temperature. Operating conditions should be avoided.

PVDF - PolyVinylidene Fluoride
CPVC - Chlorinated Polyvinyl Chloride
PVC - Polyvinyl Chloride
PB - Polybutylene
PEX - Cross Linked Polyethylene
PE - Polyethylene

Plastic Pipes Temperature Derating Diagram

thermoplastic pipes effect of temperature on strength and stiffnes diagram

Example - Higher Temperature and Reduced Strength

If operating pressure for a 6" Schedule 80 CPVC pipe is 167 psi, the maximum operating pressure at 150^oF (66^oC) is reduced to

167 psi x 0.5 = 83.5 psi

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