Torsion and compression testing have been used to simulate microstructure evolution of industry processes. Additionally, mathematical modeling of the industry hot rolling processes has been carried out by several researchers. These models employed equations published in the literature describing kinetics of softening, grain size evolution and grain growth. Validation of the models was carried, in some cases, by comparing the microstructure or the average stress per pass, the latter as calculated from industry rolling mill loads. In the present work, torsion simulation and industry trial results were used to validate the mathematical model presented. Equations used in the model were mostly taken from literature and appropriate modifications were implemented concerning basically two points: a) the transfer time between CMM and SRM, a step in the production line typical for seamless rolling and rather unusual for other industry rolling processes and b) the chemical composition used in tube rolling industry where C equivalent values are usually higher than those used in the rolling of flats.