Unnecessary component replacement exposes the machine to wide range of potential failure causes such as improper assembly, improper installation, component mal-function, component improper handling procedure and so on.
In addition, preventive maintenance can cause a mindset that automatically determines maintenance and component replacement at every turnaround regardless of component conditions. This can be a costly practice.
In one case study for a large gas turbine, bearings and seals were inspected in a planned shutdown. Deteriorations were found and seals and bearings were replaced.
It was decided to disassemble the gas turbine to inspect the interior machine condition for the possible cause of seal and bearing problems. No significant abnormality was found within the gas turbine and it was reassembled. Time-based maintenance, even if by chance, led to proper, on-time and correct replacement of components cannot identify cause of component wear-out or deterioration. In the example, if seal and bearing parameters were properly monitored for change, only the bearing and seal change would have been made without the unnecessary step of disassembling the machine.
