What's the Difference? Complete Guide to Maintenance: Preventive, Predictive and Corrective

Industrial and equipment maintenance is a fundamental pillar to ensure the operability, safety and longevity of any organization's assets. Choosing the right maintenance strategy has a direct impact on operating costs, equipment availability and accident prevention. In this comprehensive guide, we will explain the differences between the three main approaches: preventive, predictive and corrective maintenance.

Preventive Maintenance: Prevention as a Pillar

Preventive maintenance consists of systematic and scheduled interventions, carried out at predefined intervals or according to established criteria (such as operating hours), with the aim of reducing the probability of failures or the degradation of equipment or components.

Technical Language: Maintenance plans, routine inspections, lubrication, torque retightening, scheduled replacement of components with defined service life (bearings, seals, filters), instrument calibration.

Examples:

• Change the lubricating oil in a gear reducer every 2,000 hours of operation.

• Visual and functional inspection of safety devices (safety valves, protection relays) every quarter.

• Replace compressed air filters annually.

  
  

Applications: Industries with continuous processes (chemical, petrochemical), transportation systems (rail, subway), safety equipment (fire extinguishers, alarm systems), where failure can generate costly shutdowns or significant risks.

Importance: Reduction in the occurrence of unexpected failures, increased equipment lifespan, performance optimization, predictability of maintenance costs, better planning of maintenance shutdowns.

Frequency: Determined based on manufacturer's recommendations, failure history, technical standards (ABNT, ISO), legislation and equipment criticality (time-based maintenance - TBM, or usage-based maintenance - UBM).

Predictive Maintenance: Monitoring to Predict

Predictive maintenance uses data monitoring and analysis techniques to monitor the operational condition of equipment and components, with the aim of detecting and diagnosing possible failures at an early stage, allowing planned interventions before the breakdown occurs.

Technical Language: Vibration analysis, infrared thermography, lubricating oil analysis, non-destructive testing (NDT) such as ultrasound, radiography and liquid penetrant, monitoring of process parameters (temperature, pressure, flow), analysis of electric motor performance.

Examples:

• Identification of misalignment in a pump shaft through vibration spectrum analysis.

• Detection of overheating points in electrical connections using thermography.

• Assessment of the wear level of a bearing through ultrasound noise analysis.

• Verification of contamination and physical-chemical properties of a hydraulic oil.

  
  

Applications: Highly critical rotating equipment (turbines, compressors, pumps), electrical systems, equipment with a history of complex failures and high downtime costs, metal structures subject to corrosion or fatigue.

Importance: Prevention of catastrophic failures, optimization of maintenance intervals (interventions only when necessary), reduction of costs with spare parts and labor (avoiding unnecessary replacements), increased reliability and availability of equipment.

Frequency: Variable, defined by the condition of the equipment and the degradation rate of the monitored parameters. Data collection and analysis can be continuous (online systems) or periodic (scheduled inspections with measuring instruments).

Corrective Maintenance: Action After Failure

Corrective maintenance is performed after a failure or breakdown of equipment occurs, with the aim of restoring it to normal operating conditions. This approach can be planned (when the failure is identified and repair can be scheduled) or unplanned (emergency maintenance due to an unexpected shutdown).

Technical Language: Fault diagnosis, repair, replacement of damaged components, emergency intervention, downtime, root cause analysis (RCA).

Examples:

• Replacing an electric motor that has suddenly failed.

• Repairing a leak in a pipe.

• Replacing a faulty electronic board in a control panel.

  
  

Applications: Non-critical or redundant equipment, systems where the cost of implementing preventive or predictive maintenance is higher than the cost of correction, equipment with a low failure rate.

Importance: Restoration of equipment functionality, continuity of production (after intervention).

Frequency: Unscheduled, occurs upon identification of the failure.

Comparasion between Maintenance Types

Feature	Preventive Maintenance	Predictive Maintenance	Corrective Maintenance
Main Objective	Prevent failures from occurring	Predict the occurrence of failures	Restore functionality after failure
Periodicity	Scheduled (time, usage)	Variable (equipment condition)	Unscheduled (after failure)
Intervention	Systematic, at defined intervals	Subject to monitoring and diagnosis	Reactive, after failure
Costs	Lower repair costs, planning costs	Initial investment in technology, monitoring costs	Generally higher repair costs, downtime costs
Impact on Production	Scheduled shutdowns, less overall impact	Optimized stops, minimum impact	Unplanned shutdowns, greater impact
Equipment Lifespan	Potentially bigger	Larger, with precise interventions	May be shorter due to unforeseen failures
Complexity	Minor	Major (requires specialized technical knowledge)	Variable (depends on the complexity of the failure)

Choosing the ideal maintenance strategy is not a one-size-fits-all approach. The intelligent combination of the three methodologies – known as hybrid maintenance – is often the most effective. Analyzing the criticality of the equipment, the costs involved, the history of failures and the company’s objectives are crucial factors in defining the most appropriate maintenance strategy for each asset. Investing in a well-structured maintenance plan that takes into account the particularities of each piece of equipment and process is essential to ensuring the operational efficiency, safety and competitiveness of any organization.

Do you need preventive, predictive or corrective maintenance solutions? Talk to E.S.A!

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