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The actuator for self-acting control valves is an important component of control valves designed to withstand the effects of seismic conditions in industrial applications. What was once considered an essentially simple control valve actuator has proven to be difficult to analyze, and improvements aimed at increasing its natural frequency are equally challenging. Just like other parts of control valves, the structure of the actuation device has remained essentially unchanged for over a decade; its design capabilities have been proven through years of use in fossil fuel-powered factories, paper mills, oil refineries, and on all kinds of small ships. It was only when control valve manufacturers were required to prove compliance with seismic requirements through testing that changes were made to the design. A drive device consists of two basic components: a bracket and a power unit. The bracket is used to fix the drive device to the valve cover, providing a location for connecting the valve stem to the drive device, as well as a location for installing accessories such as limit switches and positioners found in spring-diaphragm drive devices. The second part is the power source; typical types include spring diaphragms, cylinders, hydraulic jacks, and motors. In most cases, the bracket is made of cast iron and connected to the valve cover using large fastening nuts; however, the design must be modified due to the need to withstand dynamic loads such as those caused by earthquakes. The first change was to the material; the material initially used—cast iron—was highly suitable for the initial design loads, namely the thrust from the main driving mechanism. Cast iron has one problem: it is brittle. Brittle materials are very sensitive to damage caused by large impact loads and low-cycle fatigue loads. Therefore, replacing cast iron with cast steel, typically of the ASTM-216WCB type, is an easy task, as the design and molds remain the same, as does the machining process; only the material changes. The next change will be more difficult; the results of various seismic tests have shown that the connection between the bracket and the valve cover needs to be redesigned. The fastening nuts require higher performance standards than those originally specified. However, the dynamic load test results for seismic resistance reveal some issues: firstly, the bracket is supported by the small seat on the valve cover, which is sufficient to handle the thrust forces generated by the drive mechanism, as all components are under compressive stress. Yet, there isn’t enough supporting surface at the base of the drive mechanism to ensure the highest possible stability of the bracket.