⚠️ Disclaimer: These tasks are guidelines only. They do not include lockout/tagout (LOTO), energy isolation, or other safety requirements. Review and verify suitability for your specific equipment and application. Add all required safety procedures per your company's policies and regulatory requirements before use. You are responsible for the safe and appropriate execution of all maintenance activities.
Rotary pumps are simple by design. A few lobes, gears, or vanes moving fluid through tight internal clearances. No impeller dynamics. No cavitation thresholds to obsess over. The simplicity is real — but it's also why these pumps get ignored until the day production calls.
The failure modes are quiet. Internal clearances wear gradually. Seals weep before they spray. Bearings run warm before they fail loud. A PM that catches these early costs almost nothing. One that doesn't will cost you a pump.
This checklist covers standard rotary pump PM — gear pumps, lobe pumps, vane pumps, and similar positive displacement designs. It is structured for field execution by technicians and reference use by managers building or auditing PM programs.
For the full pump PM framework this checklist fits into, see centrifugal pump preventive maintenance.
How to Use This Checklist
Record every finding with specificity. "Bearing housing warm — 78°C at north end" is a finding. "OK" is a liability. If you're trending data — pressures, temperatures, seal condition — the trend is the point. A single reading means almost nothing. Four readings over eight months tells you whether you're ahead of the failure or behind it.
A bad finding looks like this: "Suction pressure reading 12 PSI, baseline is 18 PSI — strainer may be partially clogged, scheduled for inspection next week." A checkbox answer looks like this: "Checked." One of these gets used in a failure analysis. The other gets filed and forgotten.
Field Checklist — Critical Tasks
Visual Inspection
| Task | Freq | Type |
|---|---|---|
| Inspect pump exterior for leaks at the casing, shaft seal, and all flanged connections. Note any seepage or staining. | Every PM | MEC |
| Inspect mechanical seal for leakage. A small amount of weeping may be acceptable on some seals — confirm site standard. Excessive leakage or spray is a defect. | Every PM | MEC |
Operational Checks
| Task | Freq | Type |
|---|---|---|
| Check pump operating sounds and vibration by feel. Abnormal noise, rattling, or excessive vibration warrants immediate investigation. | Every PM | MEC |
| Verify suction and discharge pressure gauges are reading within normal operating range. Record readings if trending is required. | Every PM | MEC |
Mechanical Inspection
| Task | Freq | Type |
|---|---|---|
| Check pump coupling for wear, cracking, or looseness. Inspect flexible element (spider, disc, etc.) for deterioration. Tighten any loose fasteners. | Monthly | MEC |
| Inspect pump bearings for noise or elevated temperature while running. Use IR thermometer to check bearing housing — flag if above ambient + 40°C or manufacturer limit. | Monthly | MEC |
| Check pump base plate and mounting bolts for looseness, cracking, or corrosion. Retorque fasteners as needed. | Quarterly | MEC |
| Verify pump shaft alignment using a dial indicator or laser tool if coupling has been disturbed or pump shows signs of vibration. | Annually | MEC |
Electrical Inspection
| Task | Freq | Type |
|---|---|---|
| Inspect motor electrical connections at the terminal box for looseness, corrosion, or heat discoloration. Torque to spec. | Semi-Annually | ELE |
Lubrication
| Task | Freq | Type |
|---|---|---|
| Lubricate pump bearings per manufacturer specifications — correct lubricant type, quantity, and interval. Do not over-grease. | Quarterly | MEC |
Reference Checklist — Full Task Library
Visual Inspection
| Task | Freq | Type |
|---|---|---|
| Inspect pump exterior, casing, and all flanged connections for leaks, staining, or corrosion. Document findings and compare to prior PM notes. | Every PM | MEC |
| Inspect mechanical seal area for active leakage. Confirm acceptable leak rate per site standard. Log condition and trend over time. | Every PM | MEC |
Operational Checks
| Task | Freq | Type |
|---|---|---|
| Check pump for abnormal noise or vibration while running. Investigate immediately if cavitation, rattling, or grinding is detected. | Every PM | MEC |
| Record suction and discharge pressure gauge readings. Compare to baseline or design operating pressures. Investigate differential pressure outside of normal range. | Every PM | MEC |
| Verify flow rate or output is consistent with normal operation (if flow indication is available). Reduced output may indicate wear ring degradation, impeller damage, or cavitation. | Every PM | MEC |
Mechanical Inspection
| Task | Freq | Type |
|---|---|---|
| Inspect pump coupling — check flexible element for cracking, wear, or compression set. Verify fasteners are tight. Replace flexible element showing 25%+ deformation or cracking. | Monthly | MEC |
| Check pump and motor bearing housing temperatures using an IR thermometer or contact thermometer. Record readings. Bearings running above ambient + 40°C or manufacturer limit should be flagged. | Monthly | MEC |
| Inspect pump shaft seal — packing, lip seal, or mechanical seal — for leakage, wear, or deterioration. Tighten packing gland or replace mechanical seal if leakage exceeds acceptable limits. | Monthly | MEC |
| Inspect pump casing wear rings and impeller clearance if accessible. Increased clearance beyond manufacturer tolerance (typically >0.015") indicates wear and reduced efficiency. | Quarterly | MEC |
| Check pump base plate for levelness, cracks, or grout deterioration. Inspect anchor bolts and retorque to spec. Damaged or deteriorated grout should be scheduled for repair. | Quarterly | MEC |
| Inspect suction strainer or inlet screen for plugging or debris. Clean or replace as needed. A clogged strainer will cause cavitation and premature pump wear. | Quarterly | MEC |
| Inspect all process piping connections at the pump for leakage, vibration fatigue cracking, or support issues. Verify pipe supports are intact and not transferring stress to the pump casing. | Annually | MEC |
| Perform a full pump teardown inspection: inspect impeller for erosion, pitting, cavitation damage, or buildup. Measure impeller OD and compare to new dimensions. Replace if outside tolerance. | Annually | MEC |
| Replace mechanical seal or packing if showing wear, weeping beyond site standard, or at manufacturer-recommended interval — whichever comes first. Document seal type, size, and materials used. | Annually | MEC |
Lubrication
| Task | Freq | Type |
|---|---|---|
| Lubricate pump bearings per manufacturer specification — confirm lubricant type, quantity, and application method. Log lubricant used and quantity applied. | Quarterly | MEC |
Electrical Inspection
| Task | Freq | Type |
|---|---|---|
| Inspect motor electrical connections at the terminal box — check for looseness, corrosion, or heat discoloration. Torque to spec and clean as needed. | Semi-Annually | ELE |
| Perform insulation resistance (megger) test on pump motor windings to ground. Record results in MΩ. Values below 1 MΩ require immediate follow-up; trend all readings over time. | Semi-Annually | ELE |
| Measure and record motor operating current on all applicable leads. Compare to nameplate FLA and prior readings. Investigate upward trends or readings exceeding 105% FLA. | Semi-Annually | ELE |
Alignment Verification
| Task | Freq | Type |
|---|---|---|
| Verify pump shaft alignment using a laser alignment tool or dial indicator. Misalignment is a leading cause of seal failure and bearing wear. Document and correct if outside tolerance. | Semi-Annually | MEC |
Program Review
| Task | Freq | Type |
|---|---|---|
| Review all PM records, trend data (pressures, temperatures, current, vibration), and defect history for this pump. Identify deteriorating trends and adjust PM scope or frequency as warranted. | Annually | MEC |
Failure Modes This Checklist Targets
Internal Clearance Wear As rotating elements — lobes, gears, or vanes — wear against the casing, internal clearances increase and volumetric efficiency drops. The pump moves, but less and less of what it should. Pressure and flow checks catch the functional decline before the wear becomes terminal.
Mechanical Seal Failure Rotary pumps moving viscous, abrasive, or chemically aggressive fluids put real demands on shaft seals. Heat, pressure cycling, and fluid contamination degrade the seal face over time. Trending seal condition at every PM catches the transition from weeping to failure before it becomes a containment event.
Bearing Failure Misalignment, over-greasing, under-greasing, and contamination all accelerate rotary pump bearing wear. Temperature trending and listening to the bearing housing at every PM catches degradation that a quarterly or annual-only inspection will miss entirely.
Coupling Deterioration Flexible coupling elements absorb misalignment and vibration, but they don't do it indefinitely. A deteriorated spider or disc transmits shock loads directly to the shaft and bearings. A monthly visual and tactile check catches this early. A coupling that fails in service does not.
Suction Strainer Plugging A partially clogged strainer starves the pump of flow and creates the pressure differential conditions that accelerate internal wear. It is one of the simplest failure modes to prevent and one of the most common reasons rotary pumps fail prematurely.
Shaft Misalignment Misalignment is the leading cause of both seal failure and premature bearing wear in rotary pumps. It often develops gradually — thermal growth, pipe stress, or vibration-induced looseness — and goes undetected until the seal starts leaking or the bearing starts failing. Periodic alignment verification is the only way to catch it before it compounds.
