Maintenance, risks and performances

Maintenance contributes to risks evaluation by observing the degradations of equipment and to risks treatment by repairing the equipment when needed. It also intervenes in the performances of the plant (availability, yield, quality, costs...) and thus constitutes both a shield against severe events and a tool to increase competitiveness. After having briefly presented the maintenance process, its effects on the equipment dependability characteristics are described by analyzing the various types of maintenance tasks. Then, using the criticality matrix which combines the severity and the occurrence of the failures, different areas related to the criticality of equipment failure modes are identified. That makes it possible to distinguish between different maintenance strategies leading to implement various methods (Reliability Centered Maintenance, Risk Based Inspection, sampling maintenance, decision-making process, management of strategic spare parts,...). Operator and owner point of view in maintenance management which conducts to short term or long term strategies are also discussed. This classification of the situations encourages to develop approaches in order to quantify the results of the maintenance process. That will make it possible to rank the maintenance tasks according to their contribution to the risks mitigation and the value provided through availability, costs reduction and life extension. (author)