Opportunity-Based Preventive Maintenance

By preference, preventive maintenance is carried out on units during periods when they are not required for operation. Such periods can be created artificially (annual shutdowns, which are costly) or can be due to external events, in which case they are called maintenance opportunities. It is difficult to make efficient use of these opportunities as they occur randomly and are of restricted length. At each of these opportunities a maintenance engineer is faced with the problem which maintenance packages, if any, he should carry out and with what priority.