Preventive Maintenance & Routine Inspection

Preventive maintenance and routine inspection help operators find developing equipment problems before they cause process interruptions or major failures. Many failures give warning signs such as increasing vibration, leakage, temperature, noise, corrosion, or changing equipment performance.

A strong inspection program combines regular operator observations with scheduled preventive maintenance tasks. The goal is not simply to complete a checklist. The goal is to recognize abnormal conditions early and take appropriate action.

What Is Preventive Maintenance?

Preventive maintenance, or PM, is planned maintenance performed before equipment fails.

Examples include:

• lubrication;
• filter replacement;
• bearing inspection;
• belt inspection;
• valve exercising;
• generator testing;
• instrument calibration;
• cleaning;
• scheduled component replacement.

Why Preventive Maintenance Matters

Preventive maintenance can help:

• reduce unexpected failures;
• identify deterioration early;
• maintain equipment efficiency;
• protect standby capacity;
• extend equipment life;
• reduce emergency repair work;
• improve process reliability.

Routine Inspection

Routine inspection is the regular observation of equipment and facility condition during normal operation.

Inspection rounds may include:

• pumps;
• motors;
• blowers;
• valves;
• chemical systems;
• tanks;
• electrical rooms;
• instrumentation;
• standby equipment.

Inspection Is More Than Looking

Operators should use several senses and available instruments.

Useful observations include:

• appearance;
• sound;
• vibration;
• temperature;
• odor;
• leakage;
• flow;
• pressure;
• motor current;
• alarm status.

Know the Normal Condition

Inspection is most useful when the operator knows what normal operation looks like.

For each important asset, useful baseline information may include:

• normal flow;
• normal pressure;
• normal temperature;
• normal sound;
• normal vibration;
• normal current;
• expected leakage;
• normal control mode.

Look for Change

An equipment condition does not have to exceed an alarm limit to deserve attention.

A gradual change may indicate deterioration.

Examples include:

• bearing temperature slowly rising;
• seal leakage increasing;
• motor current increasing;
• pump flow decreasing;
• vibration becoming stronger;
• filter differential pressure increasing.

Trend Versus Single Reading

A single measurement provides a snapshot.

A trend shows direction over time.

For example, a bearing temperature of 150°F may or may not be abnormal depending on equipment design. If that bearing normally operates at 120°F and has increased steadily over several days, the trend is important.

Inspection Frequency

Inspection frequency depends on:

• equipment criticality;
• failure consequence;
• manufacturer recommendations;
• operating history;
• environment;
• availability of monitoring systems.

Critical equipment may require more frequent inspection than noncritical equipment.

PM Frequency

Preventive maintenance may be scheduled based on:

• calendar time;
• run hours;
• number of starts;
• cycles;
• measured condition.

Calendar-Based Maintenance

Calendar-based tasks occur at intervals such as:

• weekly;
• monthly;
• quarterly;
• annually.

This method is simple but may not account for how much the equipment actually operates.

Run-Hour-Based Maintenance

Some tasks are scheduled after a specified number of operating hours.

This can be more appropriate for equipment that does not run continuously.

Examples include:

• engine oil changes;
• blower maintenance;
• bearing lubrication;
• pump inspections.

Start-Based Maintenance

Equipment that starts frequently may experience wear related to number of starts.

Examples include:

• motors;
• starters;
• contactors;
• check valves.

Condition-Based Maintenance

Condition-based maintenance is triggered by measured deterioration instead of only elapsed time.

Examples include:

• increasing vibration;
• oil deterioration;
• rising bearing temperature;
• increasing leakage;
• reduced pump performance.

Use Manufacturer Recommendations

Manufacturer manuals can provide information on:

• lubrication intervals;
• approved lubricants;
• inspection intervals;
• allowable clearances;
• filter replacement;
• seal maintenance;
• recommended operating limits.

Facility experience may justify additional inspections when operating conditions are severe.

Preventive Maintenance Checklists

A checklist helps ensure important items are not missed.

A good checklist should be:

• specific to the equipment;
• clear;
• practical;
• consistent;
• easy to document.

Do Not Use the Checklist Mechanically

An operator should not simply mark every item complete without observing equipment condition.

A checklist supports judgment. It does not replace judgment.

Pump Inspection

A routine pump inspection may include:

• flow;
• suction pressure;
• discharge pressure;
• motor current;
• noise;
• vibration;
• bearing temperature;
• seal or packing leakage;
• lubricant condition;
• foundation condition.

Motor Inspection

Motor checks may include:

• current;
• temperature;
• vibration;
• noise;
• cooling-air passages;
• mounting;
• run hours;
• starts.

Blower Inspection

Blower inspection may include:

• airflow;
• discharge pressure;
• motor current;
• temperature;
• vibration;
• lubricant condition;
• inlet filter condition;
• alarms.

Valve Inspection

Valve inspection may include:

• position;
• external leakage;
• actuator condition;
• unusual noise;
• corrosion;
• ease of operation;
• position indication.

Instrument Inspection

Instrumentation checks may include:

• reasonable reading;
• clean sensor;
• no visible damage;
• no plugged sensing line;
• calibration status;
• comparison with related measurements.

Electrical Room Inspection

Operators may inspect electrical areas for visible conditions such as:

• water intrusion;
• excessive heat;
• unusual odor;
• damaged enclosures;
• blocked ventilation;
• active alarms.

Electrical repair and internal testing should be performed by qualified personnel as required.

Generator Inspection

Standby generator inspection may include:

• fuel level;
• oil level;
• coolant;
• battery condition;
• battery charger;
• alarms;
• leaks;
• automatic-transfer readiness.

Exercise Standby Equipment

Standby equipment should be operated periodically according to facility procedures.

Exercise confirms:

• equipment can start;
• controls work;
• valves move;
• lubricated components operate;
• hidden failures are identified.

Standby Does Not Mean Maintenance-Free

Equipment that rarely runs can still develop:

• corrosion;
• stuck components;
• battery failure;
• seal deterioration;
• lubrication problems;
• control failures.

Lubrication Checks

Routine inspection should verify, where applicable:

• lubricant level;
• lubricant condition;
• leaks;
• correct lubrication interval.

Overlubrication

Too much grease can cause:

• heat;
• churning;
• seal damage;
• bearing problems.

More grease is not automatically better.

Underlubrication

Too little lubrication can cause:

• friction;
• heat;
• wear;
• bearing failure.

Oil Condition

Abnormal oil condition may include:

• milky appearance;
• dark discoloration;
• particles;
• unusual odor;
• rapid level loss.

Leak Inspection

Operators should look for leaks from:

• seals;
• packing;
• flanges;
• valves;
• chemical tubing;
• lubrication systems;
• hydraulic systems.

Small Leaks Matter

A small leak may indicate early deterioration.

Examples include:

• seal wear;
• gasket failure;
• loose fitting;
• corrosion;
• packing problem.

Corrosion Inspection

Corrosion should be monitored on:

• pipes;
• valves;
• tanks;
• supports;
• fasteners;
• electrical enclosures;
• equipment frames.

Surface Corrosion Versus Structural Concern

Not every rust spot means immediate failure.

However, corrosion that causes:

• wall thinning;
• deep pitting;
• loss of structural section;
• leakage;
• damaged fasteners;

requires greater attention.

Housekeeping

Good housekeeping supports maintenance and reliability.

Operators should address:

• standing water;
• oil spills;
• chemical residue;
• loose materials;
• blocked access;
• debris around equipment;
• blocked drains.

Housekeeping Helps Detect Leaks

A clean equipment area makes new leakage easier to identify.

If old oil or water is always present, a new leak may go unnoticed.

Ventilation

Ventilation openings should remain clear where required for equipment cooling.

Blocked ventilation can contribute to:

• motor overheating;
• VFD overheating;
• electrical enclosure temperature problems.

Guards

Guards should remain installed over moving components such as:

• couplings;
• belts;
• shafts;
• other rotating equipment.

Missing or damaged guards should be corrected.

Fasteners and Mounting

Routine inspection may reveal:

• loose bolts;
• damaged anchors;
• cracked grout;
• equipment movement.

Loose mounting can contribute to vibration and alignment problems.

Belts

Belt inspection may include:

• cracking;
• fraying;
• wear;
• tension;
• alignment.

Filters and Strainers

Filters and strainers should be monitored for increasing resistance.

Possible indicators include:

• rising differential pressure;
• reduced flow;
• lower downstream pressure.

Use Differential Pressure

For a filter or strainer:

Differential Pressure = Upstream Pressure - Downstream Pressure

If differential pressure rises over time at similar flow, fouling is likely increasing.

Alarm Review

Routine inspection should include review of recent alarms.

Repeated alarms may indicate:

• equipment deterioration;
• sensor problems;
• poor control settings;
• developing process problems.

Intermittent Alarms

An intermittent alarm should not automatically be ignored because the equipment later returns to normal.

Intermittent problems can be early signs of:

• loose electrical connection;
• sensor failure;
• overheating;
• vibration;
• control instability.

Run Hours

Run-hour records help determine:

• maintenance due dates;
• equipment utilization;
• load balance among redundant units.

Unequal Run Hours

Large differences among similar pumps or blowers may indicate:

• failed alternation;
• one unit unavailable;
• control problem;
• operator preference for one unit.

Start Counts

Start counts can help identify:

• short cycling;
• control problems;
• increased demand;
• equipment wear.

Record Actual Readings

When useful, record actual measurements instead of only writing OK.

Examples include:

• bearing temperature;
• motor current;
• pressure;
• flow;
• vibration reading;
• differential pressure.

Actual numbers make trend analysis possible.

Inspection Routes

Facilities may organize equipment into regular inspection routes.

A route can help ensure:

• consistent coverage;
• efficient use of operator time;
• repeatable observations;
• complete documentation.

Do Not Skip Equipment Because It Is Quiet

Equipment that is not currently operating may still require inspection.

Standby equipment, idle tanks, and out-of-service units may develop deterioration that is not visible from SCADA.

SCADA and Automated Monitoring

SCADA can help monitor:

• flow;
• pressure;
• temperature;
• current;
• alarms;
• run hours;
• starts.

Automated data are useful, but they do not replace field inspection.

What SCADA May Miss

Remote systems may not detect:

• small leaks;
• odor;
• corrosion;
• unusual noise;
• loose hardware;
• housekeeping problems;
• damaged guards.

Inspection Findings

When an abnormal condition is found, the operator should determine the appropriate response.

Possible responses include:

• continue monitoring;
• create work order;
• remove equipment from service;
• notify supervisor;
• request emergency maintenance.

Not Every Defect Requires Immediate Shutdown

The response should consider:

• safety;
• equipment criticality;
• rate of deterioration;
• availability of standby capacity;
• process impact.

Immediate Shutdown Conditions

Depending on equipment and facility procedure, immediate action may be required for conditions such as:

• severe vibration;
• major leak;
• smoke or burning odor;
• rapid overheating;
• uncontrolled mechanical noise;
• serious electrical problem;
• unsafe structural condition.

Document Abnormal Findings

A useful inspection record should describe:

• asset;
• date and time;
• condition observed;
• actual reading where applicable;
• operator action;
• work order number if created.

Write Specific Notes

Weak note:

Motor hot.

Better note:

Motor M-12 bearing housing measured 168°F at 14:20; normal historical reading is approximately 135°F. No unusual noise noted. Work order submitted.

Follow Up on Findings

Inspection is incomplete if a serious abnormal condition is documented but never tracked to resolution.

Follow-up may include:

• repeat measurement;
• maintenance work;
• repair verification;
• trend review.

PM Completion

Preventive maintenance tasks should be closed only after required work is completed and documented.

Records should show:

• date;
• asset;
• task performed;
• condition found;
• parts or lubricant used;
• follow-up required.

Deferred Preventive Maintenance

Sometimes scheduled PM cannot be completed at the planned time.

Possible reasons include:

• equipment cannot be removed from service;
• parts unavailable;
• emergency work has higher priority;
• staff unavailable.

Deferred PM should be rescheduled rather than silently missed.

Review PM Intervals

A maintenance interval may need adjustment if:

• components repeatedly fail before scheduled PM;
• inspections consistently find no deterioration;
• equipment operating conditions change;
• manufacturer recommendations change;
• maintenance history indicates a better interval.

Avoid Unnecessary Maintenance

Too much intrusive maintenance can also create risk.

Unnecessary disassembly can introduce:

• contamination;
• assembly errors;
• misalignment;
• new leaks.

PM should be appropriate to equipment condition and manufacturer recommendations.

Critical Spare Checks

Routine maintenance planning may include verifying that critical spare parts remain available.

Examples include:

• bearings;
• seals;
• belts;
• motors;
• transmitters;
• actuators.

Safety During Inspection

Routine inspection should not expose operators to unnecessary hazards.

Do not:

• remove guards from operating equipment;
• reach near rotating components;
• open energized electrical equipment without authorization;
• enter confined spaces without required procedures;
• touch hot or chemically contaminated equipment unnecessarily.

When Inspection Becomes Maintenance

Observation can often be performed during normal operation.

If the task requires:

• opening guards;
• adjusting internal components;
• disconnecting equipment;
• working near hazardous energy;

required maintenance and energy-control procedures apply.

Common Preventive Maintenance Mistakes

• Performing PM only after equipment begins failing.
• Using the same inspection frequency for all equipment regardless of criticality.
• Checking boxes without actually inspecting equipment.
• Recording only OK instead of useful measurements.
• Ignoring gradual changes because values remain below alarm limits.
• Ignoring standby equipment.
• Overlubricating bearings.
• Ignoring small leaks, corrosion, or loose mounting.
• Relying only on SCADA instead of performing field inspection.
• Ignoring intermittent alarms.
• Failing to create work orders for abnormal findings.
• Deferring PM without rescheduling it.
• Closing PM work without documenting findings.
• Performing unnecessary intrusive maintenance without considering equipment condition.

A Practical Routine Inspection Sequence

1. Review recent alarms and outstanding maintenance issues.
2. Confirm equipment operating status and control mode.
3. Observe flow, pressure, level, or other process values.
4. Review motor current and equipment load.
5. Listen for abnormal noise.
6. Observe vibration.
7. Check temperature where appropriate.
8. Inspect for leakage.
9. Check lubricant level and condition where applicable.
10. Inspect belts, couplings, guards, supports, and visible hardware.
11. Check filters or strainers for increasing resistance.
12. Inspect for corrosion and housekeeping problems.
13. Compare observations with normal historical condition.
14. Record actual readings where useful.
15. Create or update a work order for abnormal conditions.

A Practical PM Program Review

1. Identify critical equipment.
2. Review manufacturer maintenance requirements.
3. Review facility maintenance history.
4. Assign appropriate calendar, run-hour, or condition-based intervals.
5. Create equipment-specific checklists.
6. Track completion of scheduled tasks.
7. Review overdue PM work.
8. Analyze failures that occur between PM intervals.
9. Adjust maintenance intervals when evidence supports a change.
10. Verify that standby equipment is included in the program.

What to Remember for the Exam

• Preventive maintenance is planned work performed before equipment fails.
• Routine inspection helps detect developing problems between scheduled maintenance tasks.
• Operators should know normal equipment condition before they can recognize abnormal condition.
• Trends can reveal deterioration before alarm limits are reached.
• Inspection frequency should reflect equipment criticality, operating history, and manufacturer recommendations.
• PM may be scheduled by calendar time, run hours, starts, cycles, or measured condition.
• Condition-based maintenance uses actual equipment condition to determine maintenance need.
• A checklist supports inspection but does not replace operator judgment.
• Useful inspection measurements include flow, pressure, temperature, vibration, motor current, leakage, and differential pressure.
• Both overgreasing and underlubrication can damage equipment.
• Standby equipment requires inspection and exercising even when it rarely operates.
• Increasing differential pressure across a filter or strainer often indicates increasing fouling.
• Repeated or intermittent alarms should be investigated rather than ignored.
• Actual numerical readings are more useful for trending than repeatedly recording only OK.
• SCADA monitoring does not replace field inspection.
• Abnormal inspection findings should be documented and tracked to resolution.
• Deferred PM should be rescheduled, not silently missed.
• Maintenance intervals should be reviewed using manufacturer guidance and actual equipment history.
• Routine inspection must be performed safely without defeating guards or exposing workers to hazardous energy.
• When inspection becomes servicing or maintenance, required lockout/tagout and other safety procedures apply.