Restoring Corrosion and Erosion Damage in Split Case Pumps
For many demanding applications, split case pump components inevitably suffer from corrosion and erosion damage. Severely damaged pumps might appear unsalvageable, but advanced restoration techniques can often return them to—or even exceed—their original performance standards. This damage affects both stationary casings/housings and rotating impellers in pumps.
Note: Cavitation is a specific, aggressive form of erosion damage common in pumps.
1. Coating Repair (Surface Restoration)
Coating repair is often the simplest and quickest fix for metal damage on split case pump parts. Specialized polymeric, epoxy, or metallic coatings from numerous suppliers are designed to rebuild eroded surfaces, restore hydraulic profiles, and protect against further corrosion or abrasion. This method is frequently combined with machining or welding for comprehensive pump overhauls.
2. Machining Repair (Restoring Critical Fits)
Machining is vital for restoring damaged split surfaces on pump casings and component faces. Precision is paramount:
- Split Surfaces: Maintaining flatness, perpendicularity, and concentricity between halves is critical for proper reassembly and pump alignment. Careful machining recreates the necessary sealing surface.
- Axial Impacts: Machining spigot joints or mating faces alters axial clearances (e.g., for bearings, seals, wear rings).
- Compensation: While thicker gaskets can compensate for minor material removal on standard pump case fits, this is unacceptable for high-energy split case pumps, necessitating precision realignment of components.
- Critical Parts: Restoring impeller hub faces or volute surfaces may require shaft modifications (e.g., relocating shoulder positions or ring keyways) to maintain correct clearances.
3. Welding Repair (Complex Restorations)
Welding repair is the most complex option for pump components, particularly cast items (impellers, casings):
- Challenges: Cast materials are prone to cracking and distortion during welding.
- Techniques: Pre/post-heating and specialized processes like brazing may be required, but distortion remains a significant risk.
- Post-Welding: Extensive weld repairs usually necessitate machining all critical surfaces post-weld to correct distortion and restore dimensional tolerances and hydraulic profiles.
Why Repairing Split Case Pump Damage is Essential
Neglecting corrosion or erosion damage in a split case pump accelerates the degradation process. Rough surfaces increase turbulence and hydraulic inefficiency, rapidly worsening the damage. Proactive restoration using the appropriate combination of coating, machining, and welding techniques is crucial for restoring performance, reliability, and extending the service life of valuable pump assets.
