The valves in following services will be considered critical (in the opinion of our Contractor): 
  1)Safety and relief valves. 
  2)Control valves in the severe corrosive/erosive service if specified by Licensor / Owner.
  3)Valves for which Licensor has required specific performance testing like helium testing etc. 
  4)ESD valves in inventory isolation service
  5)Valves with gearbox or actuator on extended bonnet 
  6)Main isolation valves for HHP Boilers in HHP steam service. The valves in vent, drain, instrument isolation and other small diameter valves in HHP steam service are excluded from the critical valves list.
  7)  Two slide valves in Regenerator Flue gas service.
What is the significance of "critical" valve.  Do these require QA testing?
I sometimes see a client specification that mentions critical instruments, critical valves etc.  I rarely see a definition.  Those valves listed with the 4.1.-series appear to be someones definition.  I doubt that these are from an industry standard.  If this is your contractor you could make them comply with the implication.  Perhaps this list is made by the QA department to justify boondoggle trips.  If this is from your client make sure that you comply.

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