Upgrade (Reliability)
Any design modification intended to improve the overall reliability of a machine.
Here are machine modifications that can be considered upgrades:
1) Replacing a mechanical seal with one that has a higher design temperature in order to handle process upsets.
2) Replacing a rolling element bearing with one with a higher load rating to better withstand upset loads.
3) Replacing a gear coupling with a disc coupling to extend its operating life.
4) Coating hot section, gas turbine blades to improve their corrosion resistance in order to extend the required time between inspections and maintenance.