Thermoplastic Pipes - Temperature and Strength Derating

Increased temperature derates the strength of thermoplastic piping materials

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)
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

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) 0.5

    = 83.5 psi

Related Topics

  • Pressure Ratings - Pressure ratings of pipes and tubes and their fittings - carbon steel , stainless steel, plastic, copper and more
  • Material Properties - Material properties - density, heat capacity, viscosity and more - for gases, fluids and solids

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