B) Temperature Limitations
Under pressure, for IPEX Schedule 40 and 80 PVC, the
average system operating temperature ranges from 40°F
(4°C) to 140°F (60°C). For IPEX Schedule 80 CPVC, the
average pressure system operating temperature ranges from
40°F (4°C) to 200°F (93°C). For applications outside these
ranges please contact IPEX representatives.
C) Pressure/Temperature Relationship
Thermoplastic material strength is sensitive to temperature.
Standard PVC and CPVC pipe pressure ratings are all
determined at an ambient temperature of 73°F (23°C).
Generally, as the operating temperature falls below the basis
temperature of 73°F, there is an increase in hoop strength
and a subsequent increase in pressure rating. However, as
the operating temperature rises above the basis temperature,
strength decreases. In the former, usually no consideration is
made to the design process and the incremental strength is
considered part of the safety factor. However, compensation
should be made for operating temperatures above 73°F
(23°C). A temperature correction factor, as shown in Table 9
must be applied to reduce the pressure rating.
Note: The temperature correction factors in Table 9 only
apply to pipe and fittings. For adjustments to valve pressure
ratings please consult the Thermoplastic Valve Manual
(Volume 7 in the IPEX Industrial Technical Manual series) or
IPEX representatives.