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	Diagram of a Typical Pilot-Operated Safety Relief Valve. Click image for a larger view.
	Simulated PSV Instability Shows High Amplitude Pressure Pulsations Coupled with Piston Oscillations.
	High-Frequency Pipe Shell Mode and Finite Element Model of Flare System Piping for Predicting Acoustic Fatigue Stress Analysis. Click image for a larger view.

Pressure safety valves and blowdown valves receive only intermittent use, but proper lifting and sealing performance is critical for safety and containment of a process fluid. The dynamic behavior of these valves is strongly coupled with their inlet piping configuration, and unstable behavior can occur when inlet pulsations and valve piston oscillations reinforce each other. High-energy impacts resulting from a PSV instability can damage the valve seat, preventing resealing once system pressure has dropped to desired levels.
 

High-frequency valve noise can also result in acoustic fatigue failures of downstream piping in blowdown or flare systems. Southwest Research Institute (SwRI) offers multiple analysis capabilities to identify and solve PSV-related problems:

• Simulating interaction between valve dynamics and inlet piping fluid dynamics to predict PSV instabilities

• Strouhal analysis of riser branches to analyze vortex shedding excitation of PSV

• PSV exhaust noise analysis and acoustic fatigue analysis of downstream piping

• Evaluating design options to avoid PSV instabilities and acoustic fatigue failures

For more information about pressure safety valve analysis capabilities at SwRI or how you can contract with SwRI, please contact Tim Allison, Ph.D., at tallison@swri.org or call (210) 522-3561.

machinery.swri.org

| Fluids and Machinery Engineering Department | Mechanical Engineering Division | SwRI Home |

Southwest Research Institute^® (SwRI^®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 11 technical divisions.

January 03, 2013