If the set pressure of the safety valve is higher than the activation pressure of the SIS, can the safety valve be considered a protection layer for risk mitigation during the SIS classification?
Thread Content
There are two methods for safety measures in case of an increase in reaction pressure: 1. First, the DCS takes action when overpressure occurs; if the pressure continues to rise, then the safety valve activates, and if the pressure keeps rising, finally the SIS takes action； 2. After overpressure occurs, the DCS takes action first; if the pressure continues to rise, the SIS activates; and if the pressure keeps rising, the safety valve finally comes into action ； If we follow the second logic, when determining the SIS classification, can safety valves be regarded as a protection layer to mitigate risks? I’d like to ask all the experts for their opinions
Based on the information you provided, if the second logic is adopted, that is, the SIS activates first when pressure rises and the safety valve activates last, then the safety valve can serve as a protective layer to reduce risks. Because when the SIS activates, the safety valve promptly releases the overpressurized fluid, keeping the pressure within a safe range and thereby ensuring the safety of equipment and personnel. Such safety protection measures can provide higher reliability and security. .
Yes, please check the chemical process safety protection layers; the third layer is SIS, and it is the fourth layer that contains the safety valves. So it is correct for the safety valve to activate after the SIS