Predictive Maintenance

From RunToFail to ConditionBasedMonitoring

RTF Run to failure or Breakdown Maintenance: maintenance actions are taken only after breakdown.

Preventive Maintenance or Scheduled Maintenance: maintenance actions after specific time intervals of operation, regardless the condition of the engines.

Predictive Maintenance or CBM Condition-Based Maintenance : maintenance actions are taken according to the actual condition of the operating engines, which is assessed through appropriate condition monitoring procedures.

One of the major challenges for Industrial plants users is to ensure high level ofengine availability and reliability, and efficient operation during their complete life-cycle. For this purpose, various maintenance approaches have been introducedover the years:

Why CBM

Corrective/reactive maintenancecan have severe performancecosts, and preventive/ scheduledmaintenance replaces partsbefore the end of their useful life.

CBM optimizes the tradeoffbetween maintenance costs andperformance costs by increasingavailability and reliability whileeliminating unnecessarymaintenance activities.

CBM

Condition based maintenance allows preventive and corrective actions to bescheduled at the optimal time, thus reducing the total cost of ownership. Today,improvements in technology are making it easier to gather, store and analyze datafor CBM. In particular, CBM is highly effective where safety and reliability is theparamount concern such as the aircraft industry, semiconductor manufacturing,nuclear, oil and gas, and so on.

The goal of condition based maintenance is to spot upcoming equipment failure somaintenance can be proactively scheduled when it is needed – and not before. Assetconditions need to trigger maintenance within a long enough time period before failure, sowork can be finished before the asset fails or performance falls below the optimal level.

Predictive maintenanceRelies on maintenance based on trends acquired by equipment data.

Predictive maintenance is based on predicting when an asset needs attentionrather than simply replacing a part, when it could last longer.

It deals with online data, machine conditions are constantly monitored and dataare constantly analyzed.

CBM program:

• Data Acquisition part, where data are acquired from engines under monitoring

• Data Processing part, where the acquired data are validated and transformed properly according to the requirements of the decision-making techniques that follow

• Decision Making part, where a number of methods and techniques are applied to obtain the current health condition of the engine and recommend maintenance plans

CBM Benefits & Investments

CBM is performed while the asset is working, this lowers disruptions to normal operations

Reduces the cost of asset failures

Improves equipment reliability

Minimizes unscheduled downtime due to catastrophic failure

Minimizes time spent on maintenance

Minimizes overtime costs by scheduling the activities

Minimizes requirement for emergency spare parts

Optimized maintenance intervals (more optimal than manufacturer recommendations)

Improves worker safety

Reduces the chances of collateral damage to the system

Condition monitoring test equipment is expensive to install, and databases cost money to analyze

Cost to train staff – you need a knowledgeable professional to analyze the data and perform the work

Fatigue or uniform wear failures are not easily detected with CBM measurements

Condition sensors may not survive in the operating environment

May require asset modifications to retrofit the system with sensors

Unpredictable maintenance periods

Benefits Investments

Predictive Maintenance Techniques

The predictive maintenance principle is to use a combination of measurement onprocess and machinery, to evaluate equipment condition.

Several technologies are available:

Predictive Maintenance Tools

VIBRATION ANALYSIS

THERMOIMAGE

NDT/VISUALINSPECTION

PERFORMANCE TEST

OILANALYSIS

P-F curveThe P-F Curve chart is one of the most important tools for a reliability centered maintenance plan.

Data collectionAll the method described before, needs to analyze machine data.

Data can be collected from the system by two different methods:

Spot readings: can be performed at regular intervals using portable instruments (Pruftechnik)

Continuous readings: Sensors can be retrofitted to equipment or installed during manufacture for continuous data collection (Condition monitoring par 2.2 and remote diagnostic cap.3)

Type of Data Acquisition & AnalysisIn addition to Vibration Analysis, wide range of data acquisition and analysis are oriented to assistthe RCA process and Troubleshoot machine problems.

• Machine and Shaft alignment

• Torsional vibration analysis

• Thermographic analysis

• Machine support and casing displacement analysis

• Combustion chamber vibration monitoring

• Enclosure temperature analysis

• Combustion emission analysis

• Noise emission analysis

• Process data analysis

• Control System diagnostic

• …

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