Correct Maintenance Strategy
Is your maintenance policy completely wrong?
Most of the defects are coincidences like accidents,
individually unpredictable, and have to be fought in that way
|Traditional approach||Correct approach|
|Components deteriorate automatically. Finally, when approaching the “defect limit” the now defective component has to be repaired.||Similar components (e.g. bearings, switches) do not deliver similar deterioration characteristics. A large number of defects affect only one single component at one single position, while similar components at other spots never fail even though they are similarly stressed.|
|Defects just normally follow from an adequate and conscious design of plant equipment.||Most defects actually occurring had not been anticipated by the design process. They are sub-standard and not wished – just Loss Events!|
|A component, that once had deteriorated, will – after another similar period of time – again develop the similar defect. Most defects are – with other words – “normal” and “chronic“.||Components only suffer repeatedly from a (“Chronic“) defect, either when they are short-life components or when they are sub-standard “Weak Components“, excessively stressed. In practice most plants (except those working under excessive wear) only experience a relatively small part of defects occurring “chronically”.|
|Defects mainly develop out of technical reasons.||Most defects are being produced by faults. This holds even for the larger part of “Chronic Defects” at Weak Components, because
a) they had been produced through human errors during planning, designing, operating, and maintaining,
b) and since they had – after occurring several times – not yet been eliminated (again a non-technical cause)
|You can predict, at which position which component with which probability will fail. Knowing this, you can a) quantitatively figure out the risk (i.e. “Failure Mode and Effects Analysis” or “Reliability Centered Maintenance”) and plan b) preventive maintenance activities and c) logistics for spares||The majority of all defects occur at components and positions, that you can individually not predict. Therefore you for these components cannot a) quantitatively figure the risks and plan b) individual Preventive Maintenance Activities and c) logistics for spares.|
|You can fight or control these defects by servicing (cleaning, lubricating, impregnating and conserving) and by condition-based maintenance (inspections).||Defects cannot be controlled; they must be avoided.
a) You must eliminate “Weak Components”.
b) Occurrence of Sporadic Defects and production of new Weak Components should be fought by means of “Zero Defects Management“.