Wiktionary
nonreplaceable
a. Not replaceable, unable to be replaced.
Usage examples of "nonreplaceable".
The criterion for selection of pilots then, as Charley had heard it, and as he believed, was “anyone who was demonstrably unlikely to crash a nonreplaceable airplane.
In fact, it was easier and quicker to change a BAR's 20-round magazine than it was to recharge with a stripper clip the nonreplaceable five-shot magazine of a Springfield rifle.