Steam turbines can be operated at starting and stopping actions with very small volume flows for longer periods. At multi-stage turbine bladings this kind of operation leads to ventilation, i.e. power consumption of individual stages. The ventilation output as transmitted to the medium in the form of heat and transferred to blades and casing. This may lead in the range of the high-pressure blading of a turbine with reheating to inadmissibly high temperatures and thereby to endangering the blading. The article describes the plant-specific and operational presuppositions and the thermodynamic processes at inadmissible heating of an HP-turbine by ventilation. Counter-measures are named and explained.