Pipeline Engineering

Pressure Relief Valve Sizing - Liquid without Capacity Certification

This tool was developed based upon API Standard 520 to size and select liquid service pressure-relieving devices (PRV) when a ASME Code capacity certification is not required or was never established. This method assumes an effective coefficient of discharge, Kd= 0.62, and 25% overpressure. An additional capacity correction factor, Kp, is needed for relieving pressure other than 25% overpressure.

Kd is the rated coefficient of discharge that should be obtained from the valve manufacture. For a preliminary sizing estimation, an effective discharge coefficient of 0.62 can be used.