Lubrication, Bearings, Seals & Packing

Lubrication, bearings, seals, and packing are essential to the reliability of pumps, motors, blowers, mixers, and other rotating equipment. Many equipment failures begin with poor lubrication, contamination, misalignment, excessive vibration, or incorrect seal and packing adjustment.

Operators should understand the basic purpose of these components, recognize signs of deterioration, and know when a condition requires maintenance attention.

Why Lubrication Matters

Lubrication reduces friction between moving surfaces.

Proper lubrication can help:

• reduce wear;
• control heat;
• protect against corrosion;
• extend bearing life;
• reduce energy loss;
• improve equipment reliability.

Common Lubricants

Rotating equipment commonly uses:

• grease;
• oil;
• specialty lubricants specified by the manufacturer.

The correct lubricant depends on equipment design, load, speed, temperature, and operating environment.

Use the Correct Lubricant

Lubricants are not automatically interchangeable.

Using the wrong lubricant can cause:

• poor film strength;
• excessive heat;
• incompatibility;
• seal deterioration;
• bearing failure.

Operators and maintenance personnel should follow approved lubrication specifications.

Grease Lubrication

Grease consists of oil held within a thickener system.

It is commonly used because it:

• stays in place;
• provides good sealing against contaminants;
• requires relatively simple application equipment.

Overgreasing

Too much grease can be harmful.

Overgreasing can cause:

• churning;
• increased temperature;
• seal damage;
• high bearing load;
• premature failure.

More grease is not always better.

Underlubrication

Too little lubricant can cause:

• metal-to-metal contact;
• friction;
• heat;
• wear;
• bearing seizure.

Lubrication Interval

Lubrication frequency may depend on:

• bearing size;
• speed;
• temperature;
• equipment run hours;
• environment;
• manufacturer recommendations.

Lubrication should not be performed simply because grease fittings are visible.

Oil Lubrication

Oil-lubricated equipment may use:

• oil bath;
• splash lubrication;
• circulating oil;
• oil rings;
• constant-level oilers.

Correct Oil Level

Oil level should remain within the approved range.

Low oil can cause:

• inadequate lubrication;
• overheating;
• bearing wear.

Excessive oil can cause:

• churning;
• foaming;
• heat;
• leakage.

Oil Condition

Oil appearance can provide useful information.

Abnormal conditions include:

• milky appearance;
• dark discoloration;
• metal particles;
• foam;
• unusual odor.

Milky Oil

Milky or cloudy oil can indicate water contamination.

Possible sources include:

• seal leakage;
• condensation;
• washdown water;
• process leakage.

Lubricant Contamination

Contamination can include:

• water;
• dirt;
• dust;
• metal particles;
• process chemicals;
• mixed incompatible lubricants.

Contamination can reduce lubricant effectiveness and shorten component life.

Clean Lubrication Practices

Good practices include:

• keeping containers closed;
• using clean transfer equipment;
• labeling lubricant type clearly;
• cleaning grease fittings before use;
• avoiding cross-contamination.

Bearings

Bearings support rotating shafts and allow controlled movement with low friction.

Common bearing types include:

• ball bearings;
• roller bearings;
• sleeve bearings.

Ball Bearings

Ball bearings use rolling balls between inner and outer races.

They are common in motors, pumps, and other rotating equipment.

Roller Bearings

Roller bearings use cylindrical, tapered, or other roller shapes.

They can handle different combinations of radial and axial load depending on design.

Sleeve Bearings

Sleeve bearings support a shaft on a lubricated bearing surface rather than rolling elements.

Proper lubricant film is critical to reliable operation.

Radial and Axial Loads

Bearings may carry:

• radial load, acting perpendicular to the shaft;
• axial or thrust load, acting along the shaft.

Equipment design determines which bearings carry each load.

Common Bearing Failure Causes

Bearing problems can result from:

• insufficient lubrication;
• overlubrication;
• wrong lubricant;
• contamination;
• misalignment;
• imbalance;
• excessive load;
• improper installation;
• vibration;
• normal wear.

Bearing Temperature

Bearing temperature is an important condition indicator.

A rising temperature may indicate:

• lubrication problem;
• misalignment;
• bearing damage;
• excessive load;
• poor cooling.

Trend Bearing Temperature

A single temperature value should be interpreted in context.

A gradual increase above historical normal can be more important than whether the value has reached a general alarm limit.

Bearing Noise

Abnormal sounds may include:

• rumbling;
• grinding;
• clicking;
• squealing.

New bearing noise should be investigated.

Bearing Vibration

Increasing vibration can indicate:

• bearing wear;
• misalignment;
• imbalance;
• loose mounting;
• damaged rotating components.

Misalignment and Bearings

Misalignment between connected shafts can increase bearing load.

Possible results include:

• higher vibration;
• higher temperature;
• coupling wear;
• seal damage;
• shorter bearing life.

Imbalance

Imbalance occurs when rotating mass is not evenly distributed around the shaft.

Possible causes include:

• damaged impeller;
• deposits;
• missing material;
• incorrect assembly.

Imbalance can increase vibration and bearing load.

Bearing Installation

Improper installation can damage bearings before equipment returns to service.

Problems may result from:

• incorrect fit;
• contamination;
• impact damage;
• wrong installation force;
• misalignment.

Do Not Hammer Bearings into Place

Bearing installation should use approved methods and proper tools.

Improper force can damage races and rolling elements.

Mechanical Seals

A mechanical seal controls leakage where a rotating shaft passes through a pump casing or other equipment.

A typical seal includes carefully fitted sealing surfaces.

Reliable operation depends on:

• clean sealing faces;
• proper alignment;
• adequate lubrication or cooling;
• correct pressure conditions;
• controlled shaft movement.

Mechanical Seal Leakage

Unexpected leakage may indicate:

• worn seal faces;
• damaged elastomers;
• dry running;
• misalignment;
• excessive vibration;
• shaft movement;
• incorrect installation.

Dry Running

Many mechanical seals depend on the pumped liquid or a separate flush for lubrication and cooling.

Dry running can cause:

• rapid heating;
• seal-face damage;
• leakage;
• early seal failure.

Seal Flush

Some seal systems use a separate flush or cooling flow.

Operators may need to verify:

• flush flow;
• flush pressure;
• valve position;
• cleanliness.

Loss of Seal Flush

Loss of required flush can cause:

• overheating;
• abrasive wear;
• seal failure.

Repeated Seal Failure

Repeated seal replacement should trigger investigation of the underlying cause.

Possible causes include:

• misalignment;
• shaft deflection;
• bearing wear;
• vibration;
• dry running;
• poor flush conditions;
• wrong seal selection.

Packing

Packing is another method used to control leakage around rotating shafts.

Packing consists of rings of sealing material compressed around a shaft or shaft sleeve.

Packing Leakage

Many packed glands require a controlled amount of leakage for lubrication and cooling.

The correct leakage rate depends on equipment design and manufacturer guidance.

Do Not Overtighten Packing

Overtightening packing can cause:

• excessive friction;
• overheating;
• shaft-sleeve wear;
• packing damage;
• higher motor load.

Excessive Packing Leakage

Too much leakage may indicate:

• worn packing;
• loose gland;
• damaged shaft sleeve;
• incorrect packing installation;
• shaft movement.

Packing Gland Adjustment

Packing adjustments should be made gradually and evenly according to procedure.

Uneven gland adjustment can:

• distort the gland;
• create uneven compression;
• increase shaft wear.

Lantern Ring

Some packed glands use a lantern ring to distribute sealing or flushing water around the shaft.

Its position must align with the flush-water passage.

Packing Flush Water

Flush water can help:

• cool packing;
• lubricate packing;
• reduce solids entry;
• protect the shaft sleeve.

Loss of flush can increase packing wear and temperature.

Shaft Sleeves

A shaft sleeve protects the shaft from wear at the seal or packing area.

Replacing a worn sleeve may be easier and less expensive than replacing the entire shaft.

Shaft Sleeve Wear

Inspect for:

• grooving;
• scoring;
• corrosion;
• uneven wear.

A damaged sleeve can cause persistent leakage even after new packing is installed.

Shaft Runout

Excessive shaft runout means the rotating shaft does not remain perfectly centered.

Possible causes include:

• bent shaft;
• bearing wear;
• improper assembly.

Excessive runout can damage seals and packing.

Couplings and Seal Life

Poor coupling alignment can increase shaft movement and vibration.

This can reduce:

• bearing life;
• seal life;
• packing life.

Vibration and Seal Failure

High vibration can damage:

• mechanical seal faces;
• packing;
• shaft sleeves;
• bearings.

Seal failure may therefore be a symptom of another mechanical problem.

Heat as a Warning Sign

Excessive heat may indicate:

• poor lubrication;
• overgreasing;
• packing too tight;
• bearing damage;
• seal friction;
• misalignment.

Leakage as a Warning Sign

Changes in leakage are useful diagnostic clues.

Examples include:

• gradually increasing seal leakage;
• sudden packing leakage;
• lubricant leakage from a bearing housing;
• water entering oil.

Motor Current as a Clue

Increased friction can raise mechanical load and motor current.

Possible causes include:

• bearing damage;
• packing too tight;
• misalignment;
• mechanical binding.

Lubricant Leakage

Oil or grease leakage can result from:

• overfilling;
• failed seal;
• damaged gasket;
• blocked vent;
• loose connection.

Bearing Housing Vents

Some bearing housings require ventilation.

A blocked vent can increase internal pressure and contribute to oil leakage.

Contamination Prevention

Preventing contamination is often more effective than trying to remove it after it enters the bearing.

Useful practices include:

• good seals;
• clean lubricant storage;
• proper breathers;
• careful washdown;
• clean maintenance practices.

Washdown Practices

High-pressure washdown directed at bearing seals, motors, or lubricant openings can force water into equipment.

Cleaning methods should protect sensitive components.

Lubrication Records

Useful records may include:

• asset;
• lubricant type;
• quantity;
• date;
• run hours;
• person performing the task;
• condition observed.

Color Coding and Labeling

Facilities may use labels or color coding to reduce the risk of mixing lubricants.

The system should clearly identify the approved lubricant for each asset.

Do Not Mix Lubricants Without Approval

Different greases or oils may be incompatible.

Mixing can change:

• consistency;
• lubricating performance;
• temperature behavior.

Routine Bearing Inspection

A routine inspection may include:

• temperature;
• noise;
• vibration;
• lubricant level;
• lubricant condition;
• leakage.

Routine Seal Inspection

Check for:

• leakage;
• flush condition;
• temperature;
• vibration;
• evidence of dry running.

Routine Packing Inspection

Check:

• leakage rate;
• gland temperature;
• flush-water condition;
• shaft-sleeve condition when accessible during maintenance;
• even gland adjustment.

Post-Maintenance Checks

After bearing, seal, or packing work, verify:

• correct assembly;
• correct lubricant;
• correct lubricant quantity;
• normal vibration;
• normal temperature;
• acceptable leakage;
• normal motor current.

New Bearings May Need Close Observation

After bearing replacement, operators should monitor:

• temperature;
• noise;
• vibration;
• lubricant leakage.

Abnormal behavior after maintenance may indicate installation or alignment problems.

New Packing May Require Adjustment

Fresh packing may require careful adjustment during initial operation.

Operators should follow equipment procedure rather than immediately tightening the gland to eliminate leakage.

Mechanical Seal Versus Packing

Remember the general distinction:

• mechanical seals use precision sealing faces;
• packing uses compressed rings around the shaft or sleeve.

Packing may require controlled leakage, while unexpected mechanical-seal leakage usually indicates a problem.

Safe Maintenance

Bearing, seal, and packing work may expose workers to:

• rotating equipment;
• electrical energy;
• stored hydraulic pressure;
• hot surfaces;
• chemicals.

Required lockout/tagout and process isolation procedures must be followed before servicing equipment.

Do Not Adjust Packing Near Unsafe Rotating Components

Any adjustment around operating equipment must follow facility safety procedures and guarding requirements.

If safe access cannot be maintained, the equipment should be isolated before work.

Common Lubrication and Bearing Mistakes

• Assuming more grease is always better.
• Using the wrong lubricant.
• Mixing incompatible lubricants.
• Ignoring contaminated or milky oil.
• Ignoring rising bearing temperature.
• Ignoring increasing vibration.
• Allowing dirt to enter during lubrication.
• Using poor bearing installation methods.
• Failing to investigate repeated bearing failure.

Common Seal and Packing Mistakes

• Running mechanical seals dry.
• Ignoring loss of seal flush.
• Replacing seals repeatedly without correcting vibration or misalignment.
• Overtightening packing to stop all leakage.
• Ignoring shaft-sleeve wear.
• Making uneven packing-gland adjustments.
• Ignoring abnormal seal or packing temperature.

A Practical Bearing Troubleshooting Sequence

1. Review bearing temperature.
2. Listen for abnormal noise.
3. Check vibration.
4. Check lubricant level and condition.
5. Verify correct lubricant.
6. Review alignment and equipment load.
7. Check for contamination.
8. Compare with historical condition.
9. Escalate maintenance if deterioration is confirmed.

A Practical Seal or Packing Troubleshooting Sequence

1. Identify whether the equipment uses a mechanical seal or packing.
2. Observe leakage amount and pattern.
3. Check temperature.
4. Check vibration.
5. Check shaft or coupling condition where appropriate.
6. Verify seal or packing flush if used.
7. Review recent maintenance.
8. Inspect shaft sleeve during maintenance if leakage persists.
9. Correct the underlying cause rather than repeatedly replacing the sealing component.

What to Remember for the Exam

• Lubrication reduces friction, heat, and wear in rotating equipment.
• Both too little and too much lubricant can damage bearings.
• Use the lubricant type and quantity specified for the equipment.
• Lubricant contamination by water, dirt, chemicals, or incompatible products can shorten equipment life.
• Milky oil often indicates water contamination.
• Bearings support rotating shafts and may carry radial, axial, or combined loads.
• Common bearing failure causes include poor lubrication, contamination, misalignment, vibration, excessive load, and improper installation.
• Increasing bearing temperature, noise, or vibration can indicate developing failure.
• Mechanical seals control leakage using precision sealing surfaces.
• Dry running can rapidly damage many mechanical seals.
• Loss of required seal flush can cause overheating and seal failure.
• Repeated seal failure should trigger investigation of alignment, vibration, bearings, shaft movement, and flush conditions.
• Packing consists of compressed sealing rings around a shaft or shaft sleeve.
• Packing may require controlled leakage for cooling and lubrication.
• Overtightening packing can cause overheating and shaft-sleeve wear.
• A shaft sleeve protects the shaft from wear at the sealing area.
• Misalignment and vibration can shorten bearing, seal, and packing life.
• Increasing motor current can sometimes indicate excess mechanical friction.
• Lubrication and maintenance records help identify recurring failures and ensure correct service intervals.
• Required lockout/tagout and process isolation must be used before servicing bearings, seals, packing, and rotating equipment.