Definition(s)
Thermal ratcheting
Progressive incremental inelastic deformation or strain that can occur in a component subjected to thermal cyclic loading. NOTE Thermal ratcheting causes cyclic straining of the material due to thermal loads, which can result in failure by fatigue and/or cyclic incremental deformation of a structure.
Source: API TR 1PER15K-1, Protocol for Verification and Validation of High-pressure High-temperature Equipment, First Edition, March 2013. Global Standards