Life consumption evaluation presently represents a high priority topic for Industry and University. In the specific work of this paper, we performed an analysis about the effects of thermal transients on life consumption of steam turbine rotors and an optimization of the thermal transient during runups. This kind of operation, more and more recurrent in power generation, produces a stress in the mechanical elements that could compromise their integrity. The work was developed in its larger part in the MGMV laboratory of the University of Genova, using the equipment (hardware and software) present in this structure, in cooperation with industry. The study moves from a classification of the damage mechanism and from a description of the most important manufacturing technologies of turbine rotors. Then, after a glance at the most important commercial software for estimating life consumption, a classification is given referring to the checks that Ansaldo, the industrial collaborator, performs during its service interventions. Finally, the paper reports the calculation module developed according to the specifications given by the industrial collaborator; the software was developed in Matlab and needs as input the characteristic constants of the rotor and the temperature measurements (with high precision transducers) at the inlet of the HP and IP sections of the turbine. This study confirms that thermal transients are very important to define the rotor’s residual life; the results could help the manufacturer, who designed the machines, and the operators, who run the power plant, to ensure a correct use of the installation, without unexpected failures that could create an economical damage connected with a missed production.