E121

Monitor gland drip rate: 0-1 drop/minute acceptable; >1 drop/minute indicates excessive wear. Measure shaft radial deflection (should not exceed 0.003-0.005 inches). If eccentric wobble transfers to seal area, face contact is compromised.

Disassemble pump at 700-1000 hour intervals to measure rotor/stator internal clearances. Look for abrasion patterns on ridges and grooves of rotor. Check for fluid leakage from pump body. Replace stator if wear exceeds manufacturer tolerances; worn stator allows clearance increase and fluid escape.

Monthly: Check bearing temperature via infrared or bearing housing thermocouple. Quarterly: Monitor vibration signatures (velocity spectrum via FFT, API 610 standards). Bearing wear produces distinct rumble sound vs. cavitation (gravel sound). Replace grease every 4-5 months; ensure U-joints and connecting rod bearings are not stiff (transmits radial motion to seal).

Record baseline suction/discharge pressures at each operating point. Listen for cavitation (gravel-like noise). Check for ship pitching/rolling effects on tank levels. Verify suction strainers are clean, suction valve fully open, suction lift within design margin, and fluid temperature below boiling point. Maintain adequate NPSH margin (typically >2 metres for seawater systems).

For seawater service, verify all wetted parts are Bronze or Duplex Stainless Steel (cast iron fails via graphitic corrosion). Inspect mechanical seal faces and O-rings for salt crystallization. Monitor for unusual discoloration, pitting, or surface roughness. Verify grease seals are intact to prevent saltwater ingress into bearing cavities. Check impeller surface for corrosion initiation.