The topic of this thesis is "CALCULATION OF THE STRENGTH OF THE FEED TANK OF THE COGENERATION PLANT BOILER". Calculations were made manually and in the PROBAD program. The shell and floor are made of P265GH material, while the tubes are made of P235GH material. As part of the work, the calculation of the casing, floor and additional pipes was made. Pressure vessels are described in more detail in the introductory section. While in the further part of the work, the calculation was made using both standards. The container is loaded only to the internal pressure. The EN 13445-3 2021 standard was used to calculate the strength according to the EN standard, which is also the latest edition of the standard. While ASME section VIII part 1 was used for calculation according to ASME standard. The budget was also made in the PROBAD program. The program works in such a way that the user selects the norm to work according to and selects the pressure vessel and its parts together with the connections in the program. It is necessary to enter certain input data and after that the program displays the solution. At the end, the obtained solutions are presented in a table. A comparison of the obtained results was made manually and in the PROBAD program for both norms.