Reliability and Maintenance of Motor Operated Valves, in the Romanian Natural Gas Compression and Distribution Stations Iulian VLADUCA, Robert Andrei ISAC, Vicenţiu Liviu RINGHEANU, Emilian TOMA, Carmen PETRE, Ramona-Manuela STANCIUC, Daniela CONSTANTIN, Mirela-Letitia VASILE Romanian Research and Development Institute for Gas Turbines COMOTI, Bucharest, Romania Iulian Vladuca, iulian.vladuca@comoti.ro Abstract. The work defines the philosophy of COMOTI – Romanian Research & Development Institute for Gas Turbines, in the predictability of intervention time in case of defects, respectively the reduction of the cost price of maintenance for its MOVs (Motor Operated Valves), used on its own equipments for natural gas compression, existing in the natural gas compression and distribution sites from Romania. In the present work, the emphasis is on operational reliability and mentability, which are capitalized on the basis of the results regarding the operating behavior, over a certain period of time, of a large number of identical types of MOVs, actually used by the beneficiaries. Keywords. MOV’s, natural gas compression, reliability and mentenance, predictability. 1. Introduction The reliability of a system is always less than that of the weakest component. With each additional construction element, the reliability of the system decreases, so the risk of failure increases. The information regarding the reliability of the MOVs (Motor Operated Valves) used in the COMOTI’s equipments for natural gas compression, is mainly obtained by following the behavior of the products in field operation. In the present paper, MOVs will be named electrical valves or simply valves. Statistical study is done by processing the information obtained from a certain number of elements. The number of elements thus chosen is called the selection volume. The larger the selection volume, the closer the statistical processing results are to reality. During the construction and maintenance of a significant number of compression stations, the main defects that appear in the main electrical drivers of the MOVs are identified that ones that are used for opening and closing the inlet and discharge pipes. The two chosed MOVs for study are size 3, called MOV 3, with max. torque of 270 Nm for the isolation valves from the gas inlet, and size 2, called MOV 2 with maximum actuation torque of max. 150 Nm, for the valves at the gas discharge pipe of the compression installation. Several distribution laws can be used to describe reliability, of which we mention only two: • Exponential distribution. It is applicable when the failure rate is constant, the reliability being in this case: () =  − ∫ () (1) 83 Technium Vol. 21, pp.83-92 (2024) ISSN: 2668-778X www.techniumscience.com