1. Introduction
The water treatment and desalination sector operates under highly demanding conditions. Reverse osmosis (RO) systems, high-pressure pump stations, and pretreatment equipment must operate continuously to meet supply demand. The reliability of maintenance, repair and operations (MRO) assets is critical to ensuring operational availability and quality of processed water.
Bearings, as critical elements in the power transmission of pumps and motors, are subject to dynamic loads, corrosive environments and variable temperature conditions. Proper management of these components, from technical selection to condition monitoring, determines the life cycle of rotating equipment.
2. Critical Components: The Case of SKF 62032Z
The SKF 62032Z deep groove ball bearing is a standard component in small to medium scale electric motors and pumps within water treatment plants. With standardized dimensions under ISO 15 (17 mm internal diameter, 40 mm external diameter, 12 mm wide), this bearing incorporates two metal protection plates (2Z) that prevent the entry of solid contaminants, extending its useful life in industrial environments.
This component must work in conjunction with other critical elements to maintain system integrity:
- Mechanical seals: Made of silicon carbide or ceramic to resist abrasive media.
- Elastic couplings: Absorb angular misalignments and vibrations between the motor and the pump.
- Axle sleeves (Sleeves): They protect the axle against wear caused by contact with the seals.
- Vibration sensors (accelerometers): Allow continuous monitoring in accordance with the guidelines of the standard ISO 13373.
3. Plant Typology and Process Flow
In a typical reverse osmosis desalination plant, the process is structured as:
- Capture and Pretreatment: Large volume centrifugal pumps transport seawater through granular media filters and cartridge filters.
- High Pressure: Multistage piston or centrifugal pumps raise the pressure to 60-80 bar to overcome the osmotic pressure. Here, axle support and alignment are critical.
- Reverse Osmosis Trains: Where the separation of salts occurs through semipermeable membranes.
- Posttreatment and Distribution: pH adjustment and remineralization before supply.
The SKF 62032Z bearing is primarily found in direct-coupled motors that drive auxiliary pumps, chemical dosing systems and cooling fans.
4. Failure Modes and Economic Impact
Premature bearing failure in this sector is mainly associated with:
- Corrosion: Due to moisture or leaks in mechanical seals, even in protected components (2Z).
- Excessive load fatigue: Operation outside the pump's best efficiency point (BEP).
- Lubrication failure: Degradation of the base lubricant due to the entry of contaminants or elevated temperature.
The economic impact of an unscheduled shutdown is significant. In large-scale desalination plants, the costs per hour of shutdown, considering the loss of production, specialized personnel and emergency services, range between €5,000 and €15,000 per hour, depending on the installed capacity and supply contracts.
5. Maintenance Strategies: Preventive vs. Predictive
An approach based exclusively on preventive maintenance (changing bearings based on hours of operation) is often inefficient, resulting in unnecessary changes or unforeseen failures. The EN 13306 standard defines the principles for asset management.
- Preventive Maintenance: Useful for scheduled lubrication tasks and cleaning of metal protections in type 2Z bearings.
- Predictive Maintenance: It is the current standard through vibration spectral analysis. An increase in vibratory speed levels at rolling element passing frequencies (BPFO/BPFI) is a clear technical indicator of incipient damage, allowing replacement during scheduled stops.
6. Case Study: Dosing System Failure
In a seawater desalination plant, a failure rate of more than 15% per year was detected in antiscalant dosing pumps. Following the root cause analysis (RCA), it was identified that the ingress of salt vapor degraded the metal protection (2Z) of the SKF 62032Z. The solution was to change to a bearing specification with contact seals (2RS) and improve the sealing of the motor housing. This action reduced the failure rate to <2% annually, extending the MTBF (Mean Time Between Failures) from 4,000 to 12,000 hours.
7. Spare Parts Management
Inventory management for critical components such as bearings should be based on a criticality analysis (ABC-XYZ Matrix):
- Class A components (High criticality/High consumption): Permanent security stock in warehouse.
- Technical strategy: Since SKF 62032Z is a common component, a minimum stock must be maintained determined by the supplier's delivery time and historical consumption. Avoid prolonged storage of factory-lubricated bearings, as the grease may degrade; rotate inventory (FIFO - First In, First Out).
8. Conclusion
Operational reliability in desalination plants depends on attention to technical detail in each rotating component. The correct selection of bearings according to the environment, continuous monitoring of their condition and data-based spare parts management are the pillars to optimize efficiency and reduce high downtime costs. For the acquisition of certified components and technical advice on bearings and transmission components, consult our technical catalog in the UNITEC-D E-Catalog.
9. References
- ISO 15: Bearings - Radial bearings - Limit dimensions.
- ISO 281: Bearings - Nominal dynamic load and nominal life.
- ISO 13373: Condition monitoring and machine diagnosis.
- UNE-EN 13306: Maintenance terminology.
