Damage to power valves and their input control

Abstract

Energy valves occupy a key place in the reliability of NPP power equipment. The valves are installed on the pipelines connecting practically all main and auxiliary equipment of the power plant, besides, the valves are widely spread in power plants. The analysis of the situation shows that the prerequisites for the failure of the valves can be divided into four groups. The table of the main faults and damages of valves according to the results of analysis of data of NPP repair shops is presented. It is shown that the main problems of the valve are tied to two factors: aging and wear of the valve, i.e. problems of its operation and errors in design and manufacture, which are already factory reasons. Input control of valves at NPPs is mainly of documentary nature, i.e. check of completeness of documentation and equipment details. The equipment is also inspected for visible damage. Repair and installation companies also do not carry out special tests for the valves, relying on the confidence in the manufacturer. It is proposed to implement at power plants a method of selective input control of the valve. The proposed type of inlet inspection connects almost all basic parameters of the valve - its nominal diameter, inlet pressure at the guaranteed closure of the valve, the permissible medium flow and the nominal torque. The results of experimental studies carried out on real valves have shown the effectiveness of such a method of control, which allows not only to establish the level of passage of the valve, but also to determine the required force of valve closure by electric actuator. In addition, this method of control allows you to identify inoperable valve, which can not be done visual control. Such control will allow to detect not only design errors, but also the divergence of flow characteristics of the same type of valve and valve passage at its regular closing.