Anti-Corrosion and Anti-Wear Treatment Plan for Self-Priming Trailer Pump Casings-Qixiu Environmental Group

Corrosion and wear of self-priming trailer pump casings are mainly caused by scouring, chemical erosion of conveyed media (sewage, sludge, corrosive liquids) and cavitation. To address loss issues in different scenarios, targeted solutions should be formulated based on **three core dimensions: material optimization, surface protection, and working condition optimization.

Details are as follows:

I. Source Protection: Optimization of Pump Casing Material Selection

Material serves as the foundation for anti-corrosion and anti-wear performance. It is essential to select materials matching the conveyed media to fundamentally reduce loss risks.

Supplementary Recommendations**: For vulnerable parts such as impellers and pump covers, prioritize the use of materials identical to or more wear-resistant than the pump casing. For example, in sludge working conditions, impellers can be made of high-chromium alloy, which improves wear-resistant service life by 3-5 times compared with ordinary cast iron.

II. Surface Protection: Internal Coating and Hardening Treatment of Pump Casings

For in-service pump casings, improving anti-corrosion and anti-wear performance through surface protection processes is the most cost-effective modification scheme.

1. Wear-Resistant Coating Treatment (Suitable for Wear-Dominant Conditions: Sludge, Sand-Containing Water)

| Coating Type | Construction Process | Performance Characteristics | Application Parts |
|————–|———————|—————————-|——————|
| Polyurethane Wear-Resistant Coating | 1. Grind the inner wall of the pump chamber to a rough surface (roughness Ra50-80μm);
2. Clean and degrease the surface, then apply primer;
3. Scrape and apply polyurethane wear-resistant adhesive (thickness 2-3mm);
4. Cure at room temperature for 24 hours or by heating | 5-8 times more wear-resistant than cast iron, good elasticity and impact resistance | Inner wall of pump chamber, impeller surface, volute |
| Ceramic Coating (Alumina Ceramic) | 1. Sandblast for rust removal (meeting Sa2.5 standard);

2. Spray ceramic powder and sinter at high temperature (800-1000℃) | Extremely high hardness (HV1000+), strong resistance to sand scouring | Pump casing flow passage surface, impeller blades
Wear-Resistant Welding Electrode Surfacing | 1. Preheat the pump casing to 150-200℃;
2. Surface the flow passage with D212/D322 wear-resistant welding electrodes (surfacing thickness 3-5mm);

3. Keep warm and cool slowly after welding to prevent cracking | High bonding strength, resistant to severe wear | Pump chamber and impeller wear rings under high-concentration sludge conditions

2. Anti-Corrosion Coating Treatment (Suitable for Corrosion-Dominant Conditions: Acid-Alkali Wastewater)
| Coating Type | Construction Process | Performance Characteristics | Application Parts |
|————–|———————|—————————-|——————|
| Epoxy Resin Anti-Corrosion Coating | 1. Sandblast for rust removal to Sa2.5 standard, degrease and dedust;
2. Apply one coat of epoxy primer;
3. Apply 2-3 coats of epoxy topcoat (total thickness ≥200μm) | Strong adhesion, resistant to neutral and weak acid-alkali corrosion | Inner wall of cast iron pump casing, external frame |
| Polytetrafluoroethylene (PTFE) Spraying | 1. Roughen the surface by sandblasting;
2. Spray PTFE powder and bake at high temperature (380-400℃) to form a film | Resistant to strong acids and alkalis (pH 0-14), excellent chemical stability | Flow passage surface of stainless steel pump casing, impellers |
| Rubber Lining (Butyl Rubber/Neoprene Rubber) | 1. Remove rust and grind the inner wall of the pump casing;
2. Paste rubber sheets and compact with adhesive;
3. Vulcanization treatment (vulcanization temperature 140-160℃) | Dual performance of acid-alkali resistance and wear resistance, good elasticity and cavitation resistance | Pumps for transporting chemical sewage and sand-containing corrosive media

III. Structural Optimization: Reducing Local Wear and Cavitation of Pump Casings

Wear and corrosion of pump casings often concentrate in specific areas (e.g., volute outlet, impeller wear ring). Structural optimization can reduce local losses:

1. Install Wear-Resistant Liners: Add detachable wear-resistant liners (made of high-chromium cast iron or ceramic) at highly vulnerable parts of the pump chamber (e.g., volute, impeller wear ring). When worn, only the liners need to be replaced instead of the entire pump casing, reducing maintenance costs.

2. Optimize Flow Passage Design: Polish the pump casing flow passage to reduce turbulence and eddy current of media inside the flow passage, thereby lowering local scouring wear. For conditions with severe cavitation, increase the cross-sectional area of the flow passage to reduce flow velocity and mitigate cavitation damage.

3. Install Wear Ring Seals: Add wear-resistant rings between the impeller and pump cover to avoid direct friction between the impeller and pump casing, reduce medium backflow and improve pump efficiency. Wear rings can be replaced individually after wear.

IV. Working Condition Optimization: Reducing Pump Casing Losses from the Operational Perspective

1. Avoid Cavitation Operation

– Control the suction lift of the pump to ensure it does not exceed the rated self-priming height (generally ≤5m), preventing cavitation caused by excessively high suction vacuum, which may lead to honeycomb-shaped corrosion pits on the inner wall of the pump casing.

– Ensure the suction pipeline is well-sealed without air leakage; install a filter screen at the end of the suction pipeline to prevent large debris from entering the pump casing and impacting the inner wall.

2. Control Medium Temperature and Concentration

– When conveying corrosive media, control the medium temperature ≤60℃ (excessively high temperature will accelerate coating aging and metal corrosion).

– When conveying high-concentration sludge, properly dilute the medium concentration to reduce the scouring speed of solid particles on the pump casing; avoid long-term operation beyond rated flow and head to reduce pump casing load.

3. Regular Cleaning and Maintenance

– After each operation, flush the inside of the pump chamber with clean water. Especially after conveying corrosive or sand-containing media, thoroughly remove residual media to prevent local corrosion caused by media adhering to the inner wall of the pump casing.

– Regularly check whether the pump casing coating is peeling or cracking. If local damage is found, repair it in a timely manner to avoid expansion of the damaged area.

V. Maintenance and Repair: Extending the Service Life of Pump Casings

1. Daily Inspection: Inspect the pump casing for leakage, coating integrity and flexible rotation of the impeller on a weekly basis; measure the clearance between the impeller and wear ring monthly. If the clearance exceeds the standard value (generally ≥0.5mm), replace the wear ring promptly.

2. Local Repair: If small-area peeling occurs on the pump casing coating, perform local repair using **repair agents: grind the damaged area → clean and degrease → apply special wear-resistant/anti-corrosion repair agent → grind smooth after curing.

3. Overhaul and Refurbishment: After 1-2 years of service, if the coating of the pump casing suffers from large-area wear or corrosion, conduct overall refurbishment: disassemble components such as the impeller → sandblast for rust removal → re-spray coating → assemble and commission to restore pump casing performance.

VI. Notes

1. Before coating construction, ensure the pump casing surface is clean, dry and free of oil stains; otherwise, the coating adhesion will be insufficient, leading to peeling.

2. Different coatings have different curing conditions, which must be strictly implemented in accordance with the construction process (e.g., temperature, time) to avoid incomplete curing affecting the protection effect.

3. Flexible protective layers such as fluoroplastic linings and rubber linings are strictly prohibited from contacting sharp and hard objects to prevent scratching.