Pressure-temperature derating accounts for what change in allowable stress?

• A. Reduced allowable stress at elevated temperature
• B. Increased yield strength at elevated temperature
• C. No change with temperature
• D. Decreased wall thickness requirement

Answer: (A)

At higher temperatures, most materials weaken: their yield and tensile strengths drop and creep effects become more significant. Pressure-temperature derating reflects this by reducing the allowable stress used in design as temperature rises, ensuring the component remains safe over its service life. So the derating accounts for a reduced allowable stress at elevated temperature. The idea that strength increases with temperature isn’t correct, and assuming no change with temperature isn’t aligned with material behavior. Wall thickness considerations come from meeting the reduced allowable stress, not from a direct rule that thickness must decrease.