K-2501 is really crucial equipment for HCU-1 process which its duty is recycles gas compressor. It has been in servicing for 27 years. Further to latest overhaul there were almost major parts replaced such as rotor, bearings and seals. Unless a coupling which serve to transmit driving power from steam turbine to compressor was reused. Ref. to design life assessment as per discuss with vendor (Eagle Burgmann), they suggested that this coupling need to be get refurbishment if the coupling was used over 7 years. Hence a 100% spare coupling would keep for future replacement.