How to Ensure Proper Maintenance of Mechanical Seals

Proper maintenance of mechanical seals focuses on proactive monitoring, timely interventions, and adherence to operational limits—all to prevent premature wear, leakage, and unexpected failure. Below is a structured approach to maintain seal performance:

1. Implement Regular Operational Monitoring

Consistent checks help detect early warning signs before they escalate into major issues.

- Leakage Inspection: Check for visible leakage (drops or streams) around the seal. A tiny, intermittent film (≤5 drops/hour for non-hazardous fluids) is normal; excessive or continuous leakage indicates seal face damage or misalignment.
- Temperature Monitoring: Use an infrared thermometer to measure the seal face temperature. For standard seals, temperatures exceeding 80°C often signal friction issues (e.g., dry running, misalignment) and require immediate inspection.
- Vibration & Noise Checks: Unusual vibrations (felt via touch) or grinding noises suggest seal binding, worn components, or shaft misalignment. Compare readings to baseline levels (taken when the seal is new) for early anomaly detection.

2. Maintain Optimal Operating Conditions

Avoid operating the seal outside its rated parameters, as this is a leading cause of accelerated wear.

- Control Fluid Parameters: Ensure the sealed fluid’s temperature, pressure, and viscosity stay within the seal’s design limits. For example:
- Use coolers/heaters to prevent overheating or freezing of the fluid.
- Install filters to remove solids (particle size >50μm can scratch seal faces) from the fluid.
- Prevent Dry Running: Never start the equipment if the seal chamber is empty. Dry running (no fluid lubrication between seal faces) causes instantaneous damage—always prime the system first.
- Stabilize Shaft Speed: Avoid rapid speed fluctuations (e.g., sudden startups/shutdowns). Gradual acceleration/deceleration reduces stress on the seal’s springs and elastomers.

3. Perform Scheduled Preventive Maintenance

Follow a routine maintenance plan based on the seal’s lifespan (typically 1–3 years, depending on usage) and manufacturer guidelines.

- Periodic Disassembly & Inspection: Every 6–12 months (or as recommended), disassemble the seal to check:
- Seal faces: Look for scratches, cracks, or uneven wear (replace if damaged).
- Elastomers (O-rings, gaskets): Check for swelling, hardening, or tearing (replace annually, even if undamaged, as they degrade over time).
- Springs & metal components: Ensure no corrosion, deformation, or breakage.
- Clean & Lubricate: After inspection, clean all components with a compatible solvent (non-corrosive to seal materials). Lubricate elastomers and sliding parts with a fluid-compatible grease (e.g., silicone grease for PTFE O-rings) before reassembly.
- Recheck Alignment: After reassembly, verify shaft coaxiality and seal face parallelism using a dial indicator—misalignment from disassembly can cause rapid wear.

4. Address Issues Promptly

Delay in fixing minor problems leads to costly seal failure and equipment damage.

- Immediate Action for Leakage: If leakage exceeds the acceptable limit, stop the equipment and inspect:
- Loose gland bolts (retighten in a crisscross pattern with a torque wrench).
- Damaged seal faces (replace if scratched or cracked).
- Clogged fluid channels (clean to restore lubrication).
- Replace Worn Components: Never reuse worn parts (e.g., scratched seal faces, hardened O-rings). Use manufacturer-approved replacement parts to ensure compatibility—generic parts often don’t match the seal’s design tolerances.

5. Document & Optimize Maintenance

Record-keeping helps identify patterns and improve maintenance efficiency.

- Maintain a Maintenance Log: Track inspection dates, findings, replacements, and operating parameters (temperature, pressure, RPM). This helps predict when components will fail and adjust maintenance schedules.
- Analyze Failures: When a seal fails, investigate the root cause (e.g., chemical incompatibility, dry running) and update maintenance practices—for example, if seals fail due to solids in the fluid, install a finer filter.