Abstract
For the purpose of control and overpressure protection in pipeline systems of power industry and pressure vessels, indirect-action valves consisting of a main valve and a pilot valve are often used. Such devices are characterized by smaller reliability due to complication of their structure depending on operability of these two valves. A pilot valve controlling the whole safety system is the weakest element of the system. It is especially typical of machines operated in severe conditions, since life of sensing elements quickly decreases during work with high-temperature and polluted media. The authors considered the ways for improving reliability of pressure control systems operated in severe conditions by redundancy of the sensing element of the valve with a system equipped with a metal bellows. The authors analyzed reliability of initial systems and redundant systems at various operating temperatures.
Highlights
The increase in the capacity of processing units used in nuclear and oil-and-gas industries, as well as in operating characteristics thereof, place increasingly higher demands on their trouble-free operation
pilot valve (PV) executed in a form of spring-type valve units are influenced by such negative factors as wear and tear, stress and high and low medium temperatures; in a result of which reliability of safety valve operation decreases leading to faults and consequential partial and complete failures of the safety system [2, 3]
Analysis of failures of pilot valves in pressure control systems During PV operation, its elements are influenced by such negative factors as wear and tear, stress, corrosion, high and low temperatures, and their rapid change, in a result of which reliability of the valves decreases leading to their faults and consequential failures
Summary
The increase in the capacity of processing units used in nuclear and oil-and-gas industries, as well as in operating characteristics thereof (pressure, consumption and temperature), place increasingly higher demands on their trouble-free operation. PVs executed in a form of spring-type valve units are influenced by such negative factors as wear and tear, stress and high and low medium temperatures; in a result of which reliability of safety valve operation decreases leading to faults and consequential partial and complete failures of the safety system [2, 3]. 2. Analysis of failures of pilot valves in pressure control systems During PV operation, its elements are influenced by such negative factors as wear and tear, stress, corrosion, high and low temperatures, and their rapid change, in a result of which reliability of the valves decreases leading to their faults and consequential failures. The advantage of a redundant system at small temperatures is not big, yet the efficiency of redundancy becomes more prominent together with the increase in temperature due to high reliability of a metal bellows at the predetermined operating characteristics
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