Managing pressure is critical for most process manufacturing & production operations. Pressure relief valves (PRVs) protect against overpressure conditions and are often considered the last line of defense from catastrophic failures.
Standards such as ASME Pressure Relief Devices PTC 25-2014 and API RP 520, Part I-2014 identify types, sizing and practices for effective overpressure management.
In a Processing article, Monitoring pressure relief valves as part of a digital ecosystem reduces cost and improves performance, Emerson’s Marcio Donnangelo and Marcelo Dultra describe how continuous monitoring:
…can identify when pressure incidents happen while monitoring valve conditions to simplify maintenance programs.
PRVs are need for any pressurized system:
…to let internal pressure escape before it overcomes the mechanical strength of the equipment.
Sizing these devices is critical since if:
…pressure can’t be released faster than it can be generated, then the valve is too small. If the valve is too large, it could become unstable during a release.
Marcio and Marcelo describe two common types of PRVs—direct spring load and pilot operated. For direct spring loaded PRVs, the pressure must overcome the spring force holding the valve closed. Pilot operated PRVs:
…use system pressure to hold themselves shut. Opening is governed by a pilot valve, which is set at the specified opening pressure.
For continuous monitoring, wireless acoustic transmitters:
…are now available and designed for mounting directly to pipes adjacent to valves, direct spring load PRVs, pilot operated PRVs, steam traps and other common fluid handling equipment. They sense vibrations in the discharge pipe due to turbulences generated by fluid flowing through the valve and transmitted directly through the pipe wall.
…can measure the amount of lift on direct spring valves and log the time and duration of a release event. By multiplying the orifice diameter of the valve and the amount of lift, it is possible to calculate the volumetric release of each relief event…
For pilot operated PRVs, wireless differential pressure (DP) transmitters measure:
…the difference between the system and holding pressure [which] provides reliable monitoring. If the holding pressure drops, the main valve will open.
Read the article for more how continuous monitoring avoids small leaks over long time intervals, how it helps optimize maintenance practices, and built-for-purpose operational analytics applications to turn this additional data into actionable information.
Visit the Plantweb digital ecosystem section on Emerson.com for more on these technologies and how they help improve performance in safety, reliability and efficiently.