Why Predictive and Preventative Maintenance for South Africa’s Wastewater Treatment Plants are so Important

The key to a long-lasting, reliable operation of motors and pumps is a well-planned preventive maintenance programme. For South Africa’s wastewater treatment plants, unscheduled stoppage of operations, or long repair shutdowns, are intolerable.

In the world of pumps, generators, and motors, it is widely agreed that reactive maintenance is not the best strategy when it comes to pump-reliability. Waiting for equipment to fail first before scheduling maintenance can result in unplanned downtime, emergencies, rushed jobs, unscheduled overtime, and replacement of expensive parts with little to no budget put aside for it.

The best pump reliability strategy that procurement professionals in municipalities can deploy is a combination of preventive and predictive maintenance.

First, what is Predictive and Preventative Maintenance?

Preventive and predictive maintenance initiatives prolong the overall life of pumps and motors and can lead to fewer unplanned breakdowns. With each of these maintenance types, maintenance work is scheduled well in advance of when the work is actually carried out, making them both a form of scheduled maintenance.

What is Preventative Maintenance

Preventative maintenance to pumps or motors or other equipment can be likened to going to the doctor for a general check-up. Maintenance tasks such as equipment calibration, greasing, oil change, and analysis, are carried out by technicians while everything is in good working order. This is done to prevent future mechanical or electrical failures or emergency issues.

One of the bigger root causes of damage to rotating machinery can be traced back to misalignment issues. Misalignment causes increased vibration, premature seal and bearing failure, and higher energy consumption. An unbalanced pump causes similar issues. All of this can easily be avoided with the right preventative maintenance measures.

Preventative maintenance helps municipalities keep operational costs down, and productivity up.

What is Covered in Preventative Maintenance

Electrical

Scheduled maintenance could include checking the electrical aspects of the plant, such as the state of the control panel – inspecting and testing its operation, checking and tightening all terminations, testing telemetry/alarms, checking TVSS/voltage monitor, phase monitor, properly-sized breakers, recording voltage, and identifying and correcting any electrical issues.

Pump

Preventative maintenance could include pump maintenance and inspection, such as taking amp readings on the pumps, motor winding resistance, megger readings, and overtemp/leakage sensors.

Mechanical

Scheduled maintenance ensures oil or coolant is regularly changed and inspected for evidence of sewage, that the motor chamber is checked for evidence of sewage, and if so – where it is coming from. Mechanical maintenance technicians will also check cable entry, look for failed seals – both physically damaged and separated faces – and inspect the impeller to see if it is worn or unbalanced, if there is cavitation or suction recirculation. Additionally, motor maintenance technicians should check for any physical damage or excessive wear, and adjust clearance to OEM specs (if adjustable).

What is Predictive Maintenance?

Predictive maintenance is where the condition of equipment is monitored and analysed over time. For example, vibration analysis measures the vibration of the equipment while in use. This data allows the technician to see the change in vibrations over time to forecast or predict when a problem may occur, and why.

Predictive maintenance is imperative for pumps and rotating equipment that absolutely can not afford to fail. Predictive maintenance gives operators and maintenance managers a glimpse into the future life of the pump as it’s running today, allowing them to plan effectively for upcoming repairs, and mitigate the risk of unexpected downtime.

How Municipalities Can Successfully Launch a Preventative and Predictive Maintenance Programme

Motivate

While it is well known that scheduled maintenance is essential for increased productivity and reduced costs, the first step to your maintenance programme is to show that it pays dividends. You may need to illustrate the advantages gained by deploying a motor maintenance programme. Start by researching case studies of motor breakdowns and the cost of resultant lost productivity. Show how budgeted predictive maintenance costs are much lower than the cost of breakdowns, operational interruption, and emergency repairs.

Categorise

Not all pumps are equally important in a wastewater treatment plant. Therefore, not all pumps should receive the same maintenance plan. Before creating a scheduled maintenance plan, divide the pumps into categories based on importance, such as critical (catastrophic for the plant if this pump fails), priority (parts of the pump are difficult to replace), and low-priority (the pump has a backup, or is non-essential). This will guide you in determining how much time and money to invest in each one.

Plan

Planning is an essential part of scheduled maintenance. You will need to select the best motor-maintenance techniques and methods for your pumps and motors. For example, is the best way to check for possible bearing trouble on a motor by feeling components for over temperature and listening for unusual sounds, or would it be better to install temperature monitoring devices and make inspections using a stethoscope or an infrared scanner?

If you are unsure, reach out to specialists in the industry who know the ins and outs of electromechanical intricacies.

Maintenance checklist

Here is a general checklist for scheduled maintenance. Reference the O&M manual for items specific to each machine.

Check the electrical condition of insulation on power cables and on all phases of the motor (in MegOhms).
Check for any loose or faulty electrical connections within the control panel.
Measure resistance between stator windings (in Ohms).
Check voltage supply between all phases of the electrical control panel.
Check voltage balance between all phases on the load side of the pump / mixer control panel with pump / mixer running (VAC).
Check amperage draw on all phases of the motor (in Amps).
Check condition and operation of the motor thermal protection control system (if equipped).
Removal of pump / mixer from the lift station for physical inspection.
Check condition of upper and lower shaft seals (inspect condition of motor / stator housing, if applicable).
Check condition and operation of leakage and bearing sensors (if equipped).
Drain oil from oil housing and replace with new oil.
Check for worn or loose impellers or propellers.
Check impeller wear rings (rotating and stationary). Note wear rings are a wear item and are not included in the cost of this contract.
Adjust clearances as needed for optimal operation.
Check for any unusual noise in the upper and lower bearings.
Clean, reset and check operation of the level control system (if equipped).
Check for physical damage of power and control cables.
Check for correct shaft rotation.
Reinstall the pump / mixer and check operation (if liquid level in the station permits).
Test the pump / mixer operating cycle, under load (if liquid level in the station permits).
Perform drawdown tests on pumps to establish GPM being produced (when possible).
Perform shut off head test on pumps to establish pressure being produced (when possible).
Check operation of valves and associated equipment.

What if My Pump Needs Repair?

If your pump is faulty, it is important to differentiate between needing a repair and needing an overhaul. A repair simply means that the component that failed gets replaced, where an overhaul begins with a complete inspection of the machine, followed by restoring it back to OEM standards, or better.

Sustainable repairs

The motor would need to be analyzed through comprehensive motor testing, such as a surge test, megger test, winding resistance test, visual inspection, and the stator baked to remove any moisture.

All wear parts will then be replaced with new parts, such as seals, bearings, o-rings, impeller/wear ring (if required). Damaged components can be restored by welding, coating, plate machining, grinding, etc. Rotating assembly is constructed with all components, the total indicator runout is verified to <.003”. It is certified balanced to 4W/N, and then the entire pump is assembled and pressure tested. A test run is carried out for amp draw, phase balance, vibration testing, and then the pump is painted and ready to go.

Precision rebuilds

A precision rebuild or precision maintenance is where the pump is rebuilt as close to OEM standards as possible. Attention to detail, experience, equipment, and expertise are required for precision rebuilds.

Precision rebuilds are effective in reducing failures and should be a central component of a pump reliability strategy. If the municipality lacks capacity, tools, or expertise to rebuild pumps to OEM standards, look to local, experienced, trusted experts in water and sanitation repair and maintenance.

A properly refurbished pump will perform as new, and give you many more years of trouble-free operation.

Vibration monitoring

Vibration monitoring and testing is a very useful tool to accurately predict pump failures. Testing requires expensive equipment and a great deal of expertise. Unless the wastewater plant has a large population of critical equipment, this is a service best hired out. CAW’s field service and motor testing takes care of this at your premises.

Conclusion

Preventative maintenance extends the life of your pumps and motors, and makes your plant more sustainable, productive, and cost-effective. Preventative maintenance and predictive maintenance Identifies potential problems before the point of catastrophic failure. This protects your investment and keeps you operational for longer.

When choosing a partner for scheduled maintenance, look for one that has all the necessary tools, procedures, qualifications, and experience.

CAW is the trusted name in electromechanical solutions, taking the stress out of the maintenance and repair of the pumps and motors of municipalities in the Western Cape.