Daily Maintenance of Twin-Screw Pumps
The core of daily maintenance for twin-screw pumps lies in preventive inspection + regular servicing, aiming to reduce failure rates and extend service life. Maintenance is divided into three categories: pre-shift inspection, in-shift inspection, and periodic maintenance. Details are as follows:
I. Pre-Shift Inspection (completed 5–10 minutes before startup)
Lubrication Oil Inspection
Check oil levels in the bearing housing and gearbox; ensure the oil level is at the center of the sight glass. Oil must be clean, free of impurities, and non-emulsified.
Verify that the lubricating oil grade matches the operating conditions (high-viscosity oil for high-viscosity media, high-temperature synthetic oil for high-temperature applications).
Replenish with the same grade oil if the level is low; if degraded, completely drain the oil, clean the oil tank, and refill with new oil.
Seal System Inspection
Mechanical seal: Check that the flushing line is unobstructed and flushing press
ure is stable (0.1–0.2 MPa higher than medium pressure). Observe for leakage; leakage ≤ 5 drops per minute is acceptable.
Packing seal: Check the tightness of the gland bolts to ensure no obvious leakage. Replace packing if hardened or aged.
Pipeline and Valve Inspection
Confirm suction flanges and connections are tight with no air leakage; discharge valves should be slightly open to avoid pressure surge at startup.
Check the inlet filter for clogging and clean promptly if blocked.
Electrical and Drive Inspection
Check that the motor ground wire and power cables are securely connected, and control cabinet indicators are normal.
Rotate the pump shaft by hand for 2–3 revolutions to ensure smooth rotation, no jamming or abnormal noise.
II. In-Shift Inspection (every 1–2 hours during operation)
Operating Condition Monitoring
Sound: Listen for abnormal noise (metal friction, severe vibration) from the pump, motor, or coupling.
Temperature: Bearing housing temperature ≤ 75℃; motor temperature rise ≤ rated value (generally ≤40℃). Stop immediately if temperature rises sharply.
Parameters: Inlet and outlet pressure and flow remain stable within rated ranges without large fluctuations.
Leakage Monitoring
Continuously observe the shaft seal, pipeline flanges, and pump joints for leakage. Handle leaks promptly (adjust gland for minor dripping; shut down for serious leakage).
Medium Condition Monitoring
For media containing particles: monitor filter differential pressure. Stop and clean the filter if pressure is too high to prevent particle intrusion and screw wear.
For high-viscosity media: check the heat-tracing and insulation system to avoid excessive viscosity and overload.
III. Periodic Maintenance (graded by operating hours)
| Maintenance Interval | Maintenance Items |
|---|---|
| Every 1000 hours | 1. Replace lubricating oil, clean oil tank and filter.2. Inspect coupling elastic pads; replace if aged or damaged.3. Align pump shaft and motor shaft concentricity. |
| Every 3000 hours | 1. Check screw meshing clearance and pump liner wear; repair or replace if clearance is out of tolerance.2. Disassemble mechanical seal and inspect seal faces; replace if severely worn.3. Check bearing internal clearance; replace bearings if clearance is excessive. |
| Every 8000–10000 hours | 1. Full disassembly and overhaul; replace aged seals and wearing parts.2. Test rotor dynamic balance to ensure smooth operation.3. Perform pressure test on pump casing and pipelines to locate hidden leaks. |
IV. Special Operating Conditions – Maintenance Notes
Corrosive media: Regularly inspect corrosion of the pump casing and screws. Use corrosion-resistant materials (316L, Hastelloy, etc.) and shorten maintenance intervals.
Gaseous media: Regularly check the gas-liquid separator to ensure effective gas separation and avoid gas binding damage.
Long-term shutdown: Drain all medium from the pump chamber to prevent solidification or corrosion. Apply anti-rust oil to bearings and seals. Rotate the shaft manually once per month to prevent seizure.
