Improving reliability of valve protective devices by applying the method of a system element redundancy
To provide protection from the excess pressure on technological units with high unit capacity, pilot-operated safety valves (POSV) are used. They differ from the safety spring valves by higher flow rate and high impermeability with the setting pressure. Moreover, POSV have less reliability because of the complex structure, their reliability depending on workability of both pilot and main valves. The pilot valve controlling the whole preventive system has still been a drawback of the POSV. It is topical during some technological processes with high temperature, e. g. in crude oil and gas refining, because a sensor service life decreases sharply at high temperature. The ways of improving reliability of pilot-operated safety valves (POSV) by means of valve sensor redundancy by the system with metal bellow are considered in the article. The reliability of virgin and redundant systems at various temperatures is analyzed.