Definition(s)
Thermal stress
Self-balancing stress produced by a nonuniform distribution of temperature through the cross section of a component. NOTE Thermal stress may also be present when a constant temperature is applied to a composite of materials with differing coefficients of thermal expansion or to a material that is constrained from expanding or contracting in response to temperature changes.
Source: API TR 1PER15K-1, Protocol for Verification and Validation of High-pressure High-temperature Equipment, First Edition, March 2013. Global Standards