Maintenance Strategies

Several maintenance strategies are available to plant managers, namely:

• Corrective maintenance

• Preventive maintenance

• Predictive maintenance

• Detective maintenance

Corrective maintenance is the simplest method by which repair is carried out after a failure has occurred. Obviously, if the failed item of equipment is a critical part of the plant, or if it requires substantial repair efforts, corrective maintenance will not be a suitable choice.

Preventive maintenance requires regular maintenance in order to keep troublesome failure modes at bay. In a preventive maintenance strategy, we assume that regular maintenance will prevent major equipment failures and plant shutdowns.

In predictive maintenance, the system monitors several relevant equipment condition parameters, such as vibration, lubricating oil, and temperature, in order to infer the status of the plant facilities. Condition monitoring of rotary equipment, such as pumps, compressors, generators, mixers, and paper machines, can reveal valuable information. The analysis of such data can predict the equipment failure well before the failure occurs. Condition monitoring techniques use the latest analytical methods, such as pattern recognition and neural networks, in order to assess the health of critical process machinery (e.g., generators, compressors, and large pumps). Such analysis will reveal the weak equipment components and prominent failures. Detecting weak components, replacing them, and preventing unscheduled shutdowns can save substantial costs and enhance the useful life of critical equipment.

Detective maintenance applies to devices that only need to work when there is a demand on them (e.g., ESD valves). Shutdown valves may not need to operate for months, or even years. They require periodic checks to ensure that they will operate satisfactorily when there is a demand on them.