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Polymeric materials, in particular reinforced coatings, are widely used for the repair of worn and damaged plate building components of various types. Coatings made of polymeric materials not only increase the plate components’ thickness and smooth out the surface roughness, but also provide a reduction in stresses in the region of existing holes or perforations. The article presents a calculation technique that allows to increase the accuracy and reliability of determining the ability of coatings made of polymer materials to reduce stress concentration. Mathematical models for determining the stress state parameters of a plate building component with holes covered with a polymer material are obtained. The calculations confirmed that the use of polymeric materials as a coating reduces the normal and tangential stresses arising at the edge of the hole.

The paper examines modelling of the pumping stages when using liquid-ring pumps, for example, in power plants and technological devices. It is important to determine the characteristics of various processes involved in liquid pumping using vacuum because the accuracy of predicting how objects move in such flows cannot be improved without solving the problems related to the calculation of hydraulic and power characteristics of the pumping unit in the network. Cubic spline functions were used as approximating functions when calculating the performance characteristics of a liquid-ring vacuum pump. The dynamics of changes in the pressure in the working vessel during operation of an ELRS-5 pump was considered for different values of the leakage coefficient. Solutions of the Cauchy problem were obtained using the numerical method. The paper presents the results of calculating the dynamics of the process of liquid pumping into the working vessel at different values of the vacuum creation time. As the time increases, the liquid flow rate quickly reaches its maximum value, and then falls with a decrease in the pressure drop. The higher the maximum flow rate, the longer the time.

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The article presents the results of calculations of characteristics for water-ring pumps. Water-ring pumps are energy-saving and high-performance equipment, often used for pumping explosive gases or when working with flammable environ-ment. The design of water-ring vacuum pumps and compressors of many manufacturers is the same. The disadvantage of this type of compressors is their low overall efficiency. The algorithm and examples of determining the characteristics of compressor machines used in modern vacuum installations are considered. Based on the results of processing of experimental data of Erstevak ELRS models, empirical dependences and power consumption parameters are obtained. The isothermal efficiency of the liquid ring pump over the suction pressure has been normalized. Characteristics of isothermal power and efficiency are built. The dependence of the highest isothermal efficiency of the water ring pump on the performance (pumping speed) is obtained.