Pressure relief valves
Pressure gauge manometer for valves
Scratches and scratches in the vertical direction on both the disk holder shaft and the guide bore indicate that the valve was exposed to an operating pressure very close to its opening pressure. Note: PRVs that operate on high-temperature water boilers or in services with organic fluids are more susceptible to leaks than those that operate with saturated or superheated steam. For these applications, the highest possible differential pressure between the valve opening pressure and
the boiler operating pressure is always recommended, as long as its values are compatible with the safety and cost of the equipment.
Conclusion
The operating pressure of the protected equipment should be limited to 90 % of the valve opening pressure whenever the process fluid is compressible, or 20 % if the fluid is liquid, thus avoiding damage to the valve and even loss to the process due to
a possible unexpected shutdown for PRV maintenance and fluid losses. When operators respect the recommended operating margin, according to the process fluid and valve design, associated with a regular inspection, the maintenance task becomes easier, and the valve’ s useful life is also extended. Thus, the maximum operating pressure is the one that is commonly adjusted based on some percentage of the protected equipment’ s own MAWP in relation to the valve opening pressure to avoid premature( unexpected) actuation of the valve or constant openings, in addition to allowing for normal process pressure fluctuations due to consumption variations, etc.
About the author Arthur Mathias is an industrial mechanical and chemical technician and a Member of ISA. Now a consultant, he has been active since 1985 in the maintenance, inspection, specification and sizing of valves. Arthur provides training and technical courses, and is the author of Válvulas: Industriais, Segurança e Controle published by ARTLIBER EDITORA.
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