The authors' experience in the modernization of commercial heat exchangers in steam turbine units is discussed with the individual features of the operation of these exchangers at specific thermal power plants taken into account. The variety of conditions under which heat exchanges operate in specific engineering subsystems requires an individualized approach to the model solutions that have been developed for modernizing these systems. New piping systems for commercial heat exchanges have undergone industrial testing and are in successful operation at a wide range of thermal power plants.Extending the service life and increasing the operational efficiency and reliability of heat exchangers in steam turbine units at thermal power plants are of great current interest [1,2]. Modernizing heat exchangers operating at thermal power plants involves less expense than replacing the entire heat exchanger and is mainly aimed at eliminating structural defects that have been identified. This is done both when worn out components are replaced and in the course of planned major overhauls, so that the efficiency and operational reliability of the heat exchangers and the steam turbine unit, as a whole, can be increased substantially.The major engineering solutions for improvement of commercial heat exchanger units in the steam turbine units of thermal power plants must, first of all, be directed at raising the efficiency and reliability of their piping systems, since they are the most subject to wear during operation [1 -5]. The choice of approaches and modern engineering solutions for the improvement of heat exchangers must meet a number of specifications, including:-accounting for the specific operating conditions; -raising the efficiency of the heat exchanger while retaining reliability or increasing reliability while maintaining efficiency; -improving or sustaining repairability and maintainability; and, -meeting the standards and rule of the supervisory agency Rostekhnadzor.The improvement of heat exchangers is a rather complicated system problem. A large number of factors at different levels which influence the efficiency and reliability of a heat exchanger have to be taken into account, along with its relationship to the engineering subsystems of the steam turbine unit of a thermal power plant [1 -5]. The choice of a modernization scheme involves solving a specific optimization problem where the target function or criterion determining the choice may be any of various characteristics, such as raising the thermal efficiency or the thermal capacity of the heat exchanger, or increasing its operational reliability or repairability [1].It has been shown [1 -3] that determining the approach for improving a heat exchanger can be divided structurally into three stages: a stage for analyzing the initial data, a stage of computations and accounting for a number of operational and design-engineering factors, and a stage of technical and economic analysis and validation. One of the most important stages in the analysis is the use of ...