Flow stresses:

Flow stresses occur while a mass of flowing fluid induces a dynamic pressure on a conduit wall.  A force of the fluid striking the wall acts as the load.   This category of stress might be applied within an unsteady fashion while flow rates fluctuate.  Water hammer is an instance of a transient flow stress.

Thermal stresses 

Thermal stresses exist while temperature gradients are present within a material. Various temperatures generate various expansions and subject materials to internal stress. This category of stress is particularly noticeable in mechanisms operating at high temperatures which are cooled through a cold fluid. Thermal stress is therefore discussed within Module.