⚠️ 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.
Magnetic drive pumps were designed to eliminate mechanical seal failures. They succeeded. Then they created a different problem: a pump that fails internally with almost no external warning until it's already too late.
No seal leaks. No telltale drip on the floor. Just a quiet, sealed containment zone where things go wrong in private. This checklist is built around finding those problems before they stay hidden long enough to matter.
For a full overview of pump PM strategy, see centrifugal pump preventive maintenance.
How to Use This Checklist
Record specific findings, not checkbox answers. "Outer magnet housing at 127°F, baseline 112°F" is a finding. "Temp OK" is a liability. Trend your readings over time — a mag-drive pump's internal failure signatures are subtle, and a single reading tells you almost nothing without context. The value is in what changed between last month and this month. If you find something that deviates from baseline, write it down completely. A WO# without a description is not a record.
Field Checklist — Critical Tasks
Visual Inspection
| Task | Freq | Type |
|---|---|---|
| Inspect pump casing and containment shell for cracks, corrosion, pitting, or visible damage. Note any surface degradation that may indicate internal wear or chemical attack. | Monthly | MEC |
| Check for leaks at all mechanical connections including suction and discharge flanges, vent/drain plugs, and casing joints. Magnetic drive pumps are sealless — any external leakage indicates a serious containment failure. | Every PM | MEC |
Operational Checks
| Task | Freq | Type |
|---|---|---|
| Listen for abnormal operating sounds: grinding, rattling, or cavitation noise. A magnetic drive pump running dry or with a broken inner magnet assembly will often produce a distinctive sound change. | Every PM | ALL |
| Verify pump flow rate and discharge pressure are within expected operating range. Compare to baseline values. Significant deviation may indicate impeller damage, magnet decoupling, or bearing wear. | Monthly | MEC |
| Inspect drive magnet housing and rear casing for heat buildup using an IR thermometer or thermal gun. Elevated temperature can indicate magnet slippage, dry running, or fluid breakdown in the containment zone. | Monthly | MEC |
| Check motor operating amperage and compare to nameplate full-load amps. Sudden drop in amperage on a mag-drive pump may indicate decoupling of the inner/outer magnet assembly — investigate immediately. | Monthly | ELE |
| Check motor bearing temperature and verify within acceptable range. Inspect motor for abnormal vibration using a handheld vibration pen or by touch. Flag any readings outside baseline. | Monthly | MEC |
| Verify strainer or inlet screen (if installed) is clean and unobstructed. Restricted suction flow can cause cavitation and accelerated internal component wear. | Monthly | MEC |
Mechanical Inspection
| Task | Freq | Type |
|---|---|---|
| Inspect coupling between motor shaft and outer magnet assembly for secure connection, corrosion, or visible cracking. Check set screws or keyway retention. | Quarterly | MEC |
| Inspect pump base and mounting hardware for loose fasteners, corrosion, or structural cracking. Verify pump is properly aligned with no evidence of base flex or movement. | Quarterly | MEC |
| Inspect suction and discharge piping for excessive vibration, misalignment, or stress on pump flanges. Piping strain can cause premature casing and bearing wear. | Quarterly | MEC |
Reference Checklist — Full Task Library
Visual Inspection
| Task | Freq | Type |
|---|---|---|
| Inspect pump casing and containment shell for cracks, surface pitting, corrosion, or signs of chemical attack. Document condition. Any breach of the containment shell on a mag-drive pump is a critical failure — escalate immediately. | Monthly | MEC |
| Verify zero external leakage at all flanged connections, drain/vent plugs, and casing joints. Magnetic drive pumps are sealless — external liquid presence is a containment failure, not a seal leak. Requires immediate shutdown and investigation. | Every PM | MEC |
Operational Checks
| Task | Freq | Type |
|---|---|---|
| Listen for abnormal operating sounds during normal operation: grinding, squealing, rattling, or cavitation. Loss of prime, dry running, or a fractured inner magnet assembly will typically produce audible changes. Investigate any deviation from baseline. | Every PM | ALL |
| Measure and record motor operating amperage under normal load. Compare to nameplate FLA and baseline trend. An unexplained drop in amperage on a mag-drive pump strongly suggests inner/outer magnet decoupling — shut down immediately and verify. | Monthly | ELE |
| Monitor and record pump flow rate and discharge pressure. Compare to design specifications and historical baseline. Degraded output may indicate impeller damage, internal wear, or partial magnet slippage. | Monthly | MEC |
| Use an IR thermometer or thermal camera to measure temperature at the outer magnet housing and rear containment area. Elevated heat indicates friction from a failed bearing, dry running condition, or magnet slip. Document readings and trend over time. | Monthly | MEC |
| Check motor bearing temperature at drive end and non-drive end using a contact thermometer or IR gun. Compare to baseline. High bearing temps may indicate lubrication failure, misalignment, or overload. | Monthly | MEC |
| Remove and inspect suction strainer or inlet screen. Clean if necessary. Document restriction level. A restricted strainer on a mag-drive pump can rapidly induce cavitation and internal wear. | Monthly | MEC |
| Verify correct rotation direction prior to startup after any motor or electrical work. Incorrect rotation on a centrifugal mag-drive pump will not pump fluid but will still run — internal dry-running can destroy bearings and containment shell rapidly. | Annually | ELE |
Mechanical Inspection
| Task | Freq | Type |
|---|---|---|
| Perform vibration measurement at motor drive end, non-drive end, and pump casing using a calibrated vibration meter. Record and trend readings. Increases in overall vibration level may indicate bearing wear, rotor imbalance, or cavitation. | Quarterly | MEC |
| Inspect drive magnet assembly coupling to motor shaft — check for corrosion on the key/keyway, security of set screws or retaining hardware, and any visible cracking in the magnet housing. Re-torque to spec if accessible. | Quarterly | MEC |
| Inspect suction and discharge piping for excessive stress, misalignment, or vibration-induced movement at the pump flanges. Piping strain can deflect the pump casing and accelerate bearing and containment wear. Use piping supports/hangers as needed. | Quarterly | MEC |
| Inspect pump base plate and mounting fasteners for looseness, corrosion, or cracking. Verify grout condition (if grouted) for voids or cracking. Re-torque anchor bolts to specification. | Quarterly | MEC |
| Inspect suction and discharge flanges for leakage, flange face condition, and gasket integrity. Verify bolt torque if accessible. Gasket material must be compatible with the pumped fluid. | Semi-Annually | MEC |
| Perform motor shaft alignment check (laser or dial indicator) between motor and outer magnet assembly. Record and document. Correct as needed. Misalignment causes accelerated bearing wear and vibration. | Annually | MEC |
| Review pump run hours since last internal inspection. If run hours or service interval exceeds manufacturer recommendation, schedule containment shell, inner magnet assembly, and bearing inspection. Mag-drive pump internals can fail without obvious external warning. | Semi-Annually | MEC |
| Confirm availability and condition of critical spare parts: containment shell, inner magnet/impeller assembly, carbon sleeve bearings, and compatible gasket sets. Verify spares match current pump model and are stored properly. | Annually | MEC |
| Review maintenance history for recurring issues: repeated amperage anomalies, heat spikes, or vibration increases. Identify root cause trends. Document findings and update PM intervals or procedures as warranted. | Annually | MEC |
Electrical Inspection
| Task | Freq | Type |
|---|---|---|
| Verify motor insulation resistance using a megohmmeter (500V test). Record MΩ value and trend over time. Investigate readings below 1 MΩ. Confirm motor leads are disconnected from VFD or starter before testing. | Annually | ELE |
| Inspect electrical connections at motor terminal box: check for corrosion, loose terminals, and proper conductor sizing. Verify conduit seal integrity on wash-down or outdoor installations. | Semi-Annually | ELE |
Failure Modes This Checklist Targets
Magnet Decoupling When the inner and outer magnet assemblies lose synchronization — usually from overloading, dry running, or fluid loss — the pump stops moving fluid while the motor keeps spinning. Amperage drops suddenly. Nothing leaks. The damage is already done by the time you notice.
Dry Running No mechanical seal means no obvious indication of a lost prime. A mag-drive pump running dry can destroy carbon sleeve bearings and the containment shell within minutes. Abnormal sound and elevated rear-casing temperature are the earliest warnings.
Containment Shell Degradation The containment shell is the only barrier between the pumped fluid and the motor side of the drive assembly. Chemical attack, pitting, erosion, and thermal cycling all weaken it over time. External inspection catches surface degradation. Internal inspection catches the rest — which is why scheduled teardown intervals matter.
Carbon Sleeve Bearing Wear Most mag-drive pumps use product-lubricated carbon sleeve bearings. Any condition that interrupts fluid flow to those bearings — cavitation, loss of prime, contamination — causes accelerated wear. Rising vibration and noise are the primary indicators.
Cavitation Restricted suction, high fluid temperature, or incorrect pump sizing creates vapor bubbles that collapse violently against internal surfaces. The distinctive cavitation sound is audible before measurable damage accumulates. A clean strainer and proper suction head are the first line of defense.
Piping Strain Suction and discharge piping that's misaligned, inadequately supported, or thermally stressed transfers load directly to the pump casing and flanges. Over time this causes casing distortion, flange leakage, and bearing wear. It also makes alignment impossible to maintain.
