Union Training: PRV Station Without Safety Valve

Scenario

A pressure reducing valve (PRV) station reduces 150 PSI main steam to 15 PSI for a low-pressure heating system. The downstream piping and heating equipment are rated for 30 PSI MAWP (maximum allowable working pressure). The PRV is properly sized and has upstream and downstream isolation valves with a bypass. However, no safety relief valve is installed anywhere on the low-pressure (downstream) side of the PRV station.