This article discusses the problem of thermal loads in main components of supercritical steam turbines. The main source of these loads is the temperature of the expanding steam that the components are exposed to. However, in case of a turbine component of a tubular form,the convection on the opposite surface, the unheated one, is also important. Additional steam flow past the unheated surface may lower thermal loads and provide better operating conditions. The research described in this article analyses the possibilities, range, and limitations of such an adjustment in order to obtain better thermal state in the components of the turbines.