API 520 Safety Valve

An API 520 safety valve (or pressure safety valve, PSV) is an automatic overpressure relief device sized in compliance with the API RP 520 standard to protect pressurized equipment operating at or above 15 psig (1.03 barg). It utilizes an internal direct spring-loaded or pilot-operated mechanism that automatically opens when upstream static pressure exceeds its set point, rapidly discharging gases, vapors, or liquids to arrest dangerous pressure spikes. While API 521 evaluates process safety to establish the worst-case scenario, API 520 provides the hydraulic and thermodynamic equations needed to calculate the valve's exact orifice area, discharge coefficients, and backpressure correction factors. Procurement managers and process safety engineers can ensure strict overpressure protection and precise code compliance by importing certified API 520 safety valves directly from premier manufacturers in China via our advanced B2B commercial platform.