What happens to the maximum allowable pressure ratings in plastic piping systems as the service temperature rises?

As the service temperature of plastic piping systems rises, the maximum allowable pressure ratings decrease. This phenomenon occurs because most plastic materials used in piping become less rigid and more susceptible to deformation at higher temperatures. The molecular structure of the plastic weakens when exposed to elevated temperatures, which directly impacts its ability to withstand pressure.

Consequently, the material may experience increased stress and potential failure at lower pressures than it would under cooler conditions. Therefore, to ensure safety and system integrity, manufacturers provide pressure ratings that account for temperature variations, indicating a reduction in allowable pressure as temperatures rise. This relationship is crucial for engineering applications to prevent failures in the piping system when operating in high-temperature environments.