In SIS design, it is feasible to use a solenoid valve on the control valve to enable shutdown.

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According to Clause 7.2.2 of the standard GB/T 50770-2013 for SIL2-level safety instrumented functions, control valves should be separated from the basic process control system. The specifications do not require it to be set up independently. Therefore, doing this does not violate the regulations.

SIL2 is determined through calculation. If an electromagnetic valve is installed on the valve, it is possible to calculate that the requirements of SIL2 can be met; certainly, this is feasible. Based on past experience, installing an electromagnetic valve on a standalone control valve usually does not result in a SIL2 rating

The original control valve required SIL2 certification

There’s no need to discuss it; the regulations have clear requirements – go and check them yourself.

First of all, it is possible; adding a solenoid valve to the SIS poses no problem at all； Secondly, is the sealing grade of the valve sufficient? Generally, the control valves of GLOBE models come with a Class IV seal – and those are devices that still leak water even when tightly closed; it’s necessary to verify the seal rating ； Finally, it is necessary to check the response speed, to ensure that the solenoids are all turned off and that the valves can move to their positions properly.

I attended a training session led by a foreign expert; it seems that the highest level for control valves combined with solenoid valves is SIL1. Also, are you sure that the solenoid valve you are using is designed for independent protection, so that the system can still be protected in case this valve fails?

Sharp, hitting the mark exactly. I like your answer. :handshake

A HAZOP assessment is still necessary; the decision should be made based on your actual operating conditions. For example, in the process package for Casale, the outlet valve of its medium-pressure separator is designed in the way you mentioned. Under normal operating conditions, the DCS performs regulation; when interlock conditions are met, the SIS triggers the de-energization of the solenoid valve.

HG/T 21581-2012 contains numerous valve pneumatic circuit diagrams; it is recommended that the original poster take a look.