The paper describes the function and importance of safety devices on pressure equipment, legal regulations for the necessary scope and periods of functional inspections of safety valves in thermal power plants. The mode of operation of the apparatus for in-site testing and adjustment of safety valves on pressure vessels is described, as well as a comparative presentation of the obtained test results compared to the results obtained by the conventional method that uses hydraulic pressure of the

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... edium for valve spring load. The on-site method uses a motor drive to load the valve spring, and uses sensitive displacement, force and sound sensors to generate signals, which are processed in a suitable software application to obtain test results. Unlike the conventional method, the on-site method allows testing of safety valves without their disassembly from the installation site. A comparison of the test results obtained by the modern method with the test results by the conventional method was made on several safety valves. It has been shown that in addition to better precision, which is important for valves with lower operating pressures, the application of the on-site method shortens the test time several times.