Zzzy criticality code justification, items that support a level i or subsafe critical system/component that has undergone quality assurance during the acquisition process and requires objective quality evidence (oqe) traceable to permanent marking on the material reference number differentiating characteristics

A replaceable item designed to provide a stationary seating surface for a mating, moveable item such as a valve disk or the like. The body may have a flange of various shapes. For diesel and gasoline reciprocating engines, see insert, engine valve seat.