Flow-induced vibration in safety relief valves (SRV’s) in high-energy piping systems such as power plants is identified as the source of many SRV failures. The mechanism is an unstable coupling of vortex shedding at the mouth of the valve with the side branch acoustic resonance. Characteristics of the problem and computerized methods of acquiring data lead to positive identification of flow-induced vibration. Pulsation and vibration data recorded from several valves in power plant steam service are presented for comparison of stable and unstable configurations. Based on this data, a rational design procedure utilizing the relationship among Strouhal number, Mach number, and stub dimensions has been developed to eliminate an existing problem or to prevent one in a new piping system. Proper side branch sizing coupled with flow stabilization techniques provide for the design of a main pipe to safety valve transition piece which has been shown to be successful in several applications.