High thermal stresses can occur either as a result of temperature change in assemblies of materials of different expansion rates, or the kind of large temperature gradient present in a typical heat exchanger.
Thermal stress analysis can show regions in an assembly which are subjected to high stresses and can be used to develop a strategy for limiting these stresses to safe levels. Such solutions might include a mechanical approach of allowing movement and distortion, or a thermal approach where temperature gradients are reduced by modifying heat paths.