Dredging Mud Pump Common Faults & Repair Methods | Maintenance Manual

2026-04-13 12:31:19     Category：Technical Resources     Browse number：294     Release time：2026-04-13 12:31:19

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Dredging Mud Pump Common Faults, Maintenance and Repair Manual (On-site Practical Version)

Table of Contents

I. Purpose and Working Principle of Dredging Mud Pump

II. Common Faults and Handling Methods of Dredging Mud Pump

III. Maintenance and Repair Operation Cases

IV. Standard Operation and Maintenance of Dredging Mud Pump

V. Equipment Healthy Operation and Safety Guidelines

I. Purpose and Working Principle of Dredging Mud Pump

(1) Purpose

Specialized for dredging, mud digging, desilting, and river/port mud pumping operations, transporting mud, sludge, and sand-containing water to realize underwater dredging work.

(2) Working Principle

The power machine drives the crankshaft to rotate, which drives the piston to reciprocate through the crosshead. Under the alternating action of the suction valve and discharge valve, mud suction and discharge are completed, realizing continuous high-pressure transportation of mud. The whole machine is divided into the power end (crankshaft, connecting rod, gear, bearing) and the hydraulic end (pump head, valve group, piston, seal).

II. Common Faults and Handling Methods of Dredging Mud Pump

1. No Mud/Water Suction After Startup

Handling Methods: Disassemble and clean the suction valve to remove mud and sand; Replace the O-ring of the valve seat; Install the gasket and tighten the water drain plug; Open the relief valve to release air and run at low speed to exhaust; Unblock the suction pipeline and suction port.

2. Motor Does Not Rotate

Handling Methods: Increase the diesel engine speed to ≥1500r/min and hydraulic pressure to ≥10MPa; Overhaul the hydraulic system and relief valve; Repair or replace the hydraulic motor; Re-shift and lock the positioning device; Inspect and replace damaged parts.

3. Large Fluctuations in Flow and Pressure

Handling Methods: Thoroughly clean the suction valve and its surroundings; Replace the O-ring; Tighten the piston sleeve or replace the piston; Fully inspect the sealing points and repair.

4. Loud Noise from Pump Body

Handling Methods: Shift correctly and lock; Adjust the bearing clearance to a reasonable value; Adjust with gaskets or replace the bearing bush; Replace damaged parts; Ensure the suction pipeline is sealed and unobstructed; Eliminate cavitation and water hammer.

5. Excessively High Temperature of Crankcase

Handling Methods: Drain oil to the calibrated oil level; Add 0.1mm gaskets on both sides of the bearing bush; Adjust the bearing clearance; Keep the oil circuit unobstructed and the oil clean.

6. Valve Box Leakage (Vulnerable at Hydraulic End)

Handling Methods: Regularly replace the valve seat and valve disc; Clean the fitting surface during installation, no oil application; Turning + welding repair for surface leakage; Direct scrapping and replacement for penetrating cracks.

7. Bearing Burnout

Handling Methods: Regularly clean the oil circuit and check smoothness with air blow; Keep the oil level between the oil gauge scales; Store oil in a sealed manner and keep it clean; Shift smoothly to avoid impact; Select bearings from regular manufacturers.

8. Other Common Faults

• Oil/Slurry Leakage from Drain Hole: Causes (J-shaped seal ring damage, excessive oil filling, loose piston); Handling (Replace seals, adjust oil level, fasten/replace piston)

• No Pressure Gauge Display: Causes (Lack of oil in buffer, damaged rubber diaphragm); Handling (Fill with engine oil, replace diaphragm)

• Cylinder Head/Valve Cover Leakage: Causes (O-ring damage); Handling (Replace O-ring, apply butter before assembly to prevent edge cutting)

• Safety Valve Leakage/Inaction: Causes (Damaged steel ball/valve seat, rust, blockage by sand); Handling (Replace parts, derust, clean valve port)

• Pressure Failure to Rise: Causes (Low speed, insufficient fuel supply, buffer failure); Handling (Increase speed, fill buffer with oil/replace diaphragm)
  
  

III. Maintenance and Repair Operation Cases

(1) Standard Operation Guide for Dredging Pump Impeller Replacement

1. Preparatory Work

Cut off the pump power supply, close the water inlet and outlet valves, and completely cut off the power and medium channels; Clean the pump surface, suction port, and discharge port to prevent sand and debris from entering the pump chamber; Hang safety warning signs and take measures to prevent mis-start to ensure maintenance safety.

2. Disassembly Safety Requirements

3. Impeller Disassembly and Replacement Steps

4. Impeller Maintenance Suggestions

It is recommended to clean the impeller with warm water + weak alkaline detergent to protect the surface integrity; Regularly inspect the impeller for wear, scratches, and defects, and replace it in time if abnormal; For pump units with high-frequency use and high-load operation, increase the inspection and vulnerable parts replacement cycle; When impeller damage is found, synchronously investigate the root causes such as sand entry, hard object impact, and cavitation.

(2) Case Analysis of Pump Shell Crack in Submersible Pump of Cutter Suction Dredger

1. Basic Information of Faulty Equipment

Equipment Type: Single-shell submersible centrifugal pump of cutter suction dredger; Key Parameters: Rotational speed 331rpm, power 1700KW, head 35m, efficiency 84.78%, impeller diameter 172cm; Fault Phenomenon: Cracks repeatedly appear at the transition of the diffuser pipe in the pump shell flow channel and the discharge flange; the new pump shell cracks only 6 hours after operation, accompanied by water leakage, mud leakage, increased vibration, and construction interruption.

2. Analysis of Pump Shell Crack Causes

• Installation Structure Defects: Cantilever installation, no support at the bottom of the pump shell, resulting in vibration and stress concentration; Rigid connection of the discharge pipeline, unable to release the thermal deformation and vibration of the pump shell, intensifying stress cracking; Uneven stress on connecting bolts, leading to loosening and fracture, further expanding pump shell damage.

• Influence of Operating Conditions: High-pressure water hammer impact caused by pump blockage, instantaneous pressure exceeding the standard; Severe vibration caused by cavitation and impeller imbalance; Large fluctuation of suction vacuum degree, poor equipment stress.

• Material and Structure Problems: The original pump shell is made of high wear-resistant material with insufficient toughness and poor impact resistance; The discharge flange is too thin and has a small transition angle, resulting in obvious stress concentration; The flow channel water cutting channel is too small, prone to pump blockage and stone jamming.
  
  

3. Fault Rectification and Solution

Optimize Installation and Fixing: Only keep the connection between the shaft cover plate and the bracket to reduce the stress concentration of the pump shell; Pipeline Transformation: Replace the discharge steel pipe with a rubber reducer to release vibration and installation stress; Material Upgrade: Replace the pump shell with GS47A material to improve toughness and crack resistance; Structural Strengthening: Thickened discharge flange and increased transition angle to reduce stress accumulation; Standard Assembly: Use standard bolts and fasten them evenly according to the specified torque; Working Condition Monitoring: Real-time monitor vacuum degree, pressure, and vibration to avoid pump blockage and cavitation; Add Protection: Install a stone-proof ring on the cutter to prevent large hard objects from entering the pump body.

4. Case Conclusion

After the above rectification, the equipment has been running continuously for nearly a year without pump shell cracks, and the fault has been completely solved. Submersible pump shell cracks are mostly caused by installation stress, vibration impact, insufficient material toughness, and water hammer effect, which can be solved for a long time through structural optimization, material upgrading, and standard operation.

IV. Standard Operation and Maintenance of Dredging Mud Pump

(1) Standard Operation Requirements

1. Installation

The foundation is flat and stable, and the pump body is placed horizontally; The coupling is accurately aligned, and the pipeline connection is tight.

2. Commissioning

3. Dredging Operation

4. Operating Environment

Place in a ventilated and dry position; Prevent mud blocks, stones, and hard objects from entering the pump body.

(2) Daily Maintenance Specifications

1. Daily Inspection

Check for seal leakage, pressure, flow, vibration, noise, and oil level.

2. Regular Maintenance

Clean the pump body, valve group, and suction/discharge pipeline; Replace vulnerable parts such as valve seat, piston, and seal; Adjust the clearance of bearings, bearing bushes, and gears; Fasten all connecting bolts.

3. Lubrication Management

The oil level is moderate, kept between the oil gauge scales; The oil is clean, free of mud, water, and impurities; For forced lubrication models, ensure the oil circuit is sealed without air leakage.

4. Shutdown Storage

Drain the mud and flush the pump chamber with clean water; Do a good job in rust prevention and store in a dry place.

V. Equipment Healthy Operation and Safety Guidelines

(1) Healthy Operation Standards

Three Moderates: Medium power, medium pump pressure, medium speed operation; Three Noes: No loose fasteners, no seal leakage, no pump pressure fluctuation; Two Normals: Normal temperature, normal noise.

(2) Safety Operation Guidelines

• Before maintenance, must cut off power, close valves, and hang warning signs; strictly prohibit live operation.

• Prohibit violent knocking on precision parts such as pump body, impeller, and pump shell with heavy hammers.

• Replace vulnerable parts with original or same-specification, same-material accessories to avoid adaptability problems.

• If abnormal noise, leakage, vibration, or excessive temperature rise occurs during operation, stop the machine immediately for inspection and restart only after troubleshooting.

• Submersible equipment must be well sealed and anti-corrosive to avoid leakage and electrochemical corrosion.