What is the SIL requirement or reliability objective?  Are you trying to avoid a nuisance trip due to a solenoid coil failure; or absolutely trip if required?
For codes and standards, what type application Automatic Control Valves such as hydrocarbon process, toxic, heater fuel system, and what country,
Please refrain from using all caps; it's harder to read, and is considered to be shouting.
If your failure was from a loose coil, isn't that a maintenance or component quality problem?  It doesn't matter how much redundancy you have if the equipment isn't being maintained or so is shoddy that there's basically no inherent reliability.  Your design is only as good as the components that you selected for the fabrication.

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