Do we need schedule replacement for critical valve accessories, such as solenoid valves and limit switches, and critical process measuring transmitters according to their life time (for example every 10 years)? during for example plant turn around? we have our gas processing plant turn around every 7 years, and there is suggestion to replace these critical field instruments every 7 years even they are healthy to avoid plant tripping. Is there any thing in IEC-61508 or 61511 stating like that? Please I need your experience/advice in different plants.

 

Why would you want to mess with something that is working?

I would suggest things subject to wear or corrosion might well be suitable for replacement on a regular basis, but a lot of this stuff has normal lifespans of decades.

 

Replacement is not a solution. Even the newly purchased instrument may fail.

I suggest you to check & calibrate the instruments thoroughly & then install. However, replacement shall be required if the instrument fails to calibrate, is damaged or shows sign of wear & tear.