When it comes to repairing axial-flow line shaft pumps, size doesn’t matter. The approach is the same whether it’s a small or large-volume pump. But the first step, according to MWI pump repair expert Tom Hyde, is implementing a proper preventive maintenance program to try and avoid failures.
MWI Pumps builds large-volume axial-flow line shaft pumps that have a lifespan of 20 to 30 years, or more, if properly maintained. “I recently saw an MWI pump that was built in 1957 that is still pumping pure clean water for bell peppers in Georgia,” Hyde said. “We have pumps in Busch Gardens that run 12 hours a day, seven days a week. that we just recently replaced. The original pumps were installed in 1981.”
However, to improve the possibility of this kind of longevity, Hyde recommends the following preventive maintenance best practices:
- The pumps should be visually inspected daily. “It doesn’t matter if the pump is in a sugar cane field, an orange grove, or in a refinery, someone should visually check the pumps every day,” Hyde said. The daily inspection should include:
• Check oil levels
• Grease the bearings.
• If the pump is driven by belts, these should be inspected.
- Hyde said that MWI Pumps recommends pulling the pump out every five to seven years to have it serviced. At that time, the following best practices are ideal:
• Replace the seals.
• Replace the lubricants during this scheduled maintenance.
• Have the pump sandblasted and painted while it’s out of service for maintenance.
• Replace the bearings.
• Check for rust and corrosion
Hyde emphasized that these best practices relate only to the pumps and do not include maintenance that may be required for the engines, motors, and other ancillary equipment connected to the pumping system.
Unplanned failures regarding large-volume axial-flow line shaft pumps can happen for many reasons, Hyde explained.
“Our pumps have a propeller just like a boat motor. If you were out in the middle of the ocean and hit a piece of debris, it is possible you could rip the propeller off. The same type of thing can happen with a pump. If something hits it or gets stuck in the propeller, it could rip a blade from the propeller causing the pump to be out of balance. This unbalanced movement could be damaging to the pump as it turns.”
Every failure is unique, Hyde said. For example, water could get inside the pump and displace the oil. With thousands of different types of scenarios, there are some common types of failures. Aside from unique, uncontrolled instances like the ones described above, failures can be caused simply by the pump not being well maintained.
Each scenario creates a specific approach to repair. However, these are some general, broad, standard recommendations and procedures when repairing large-volume axial-flow lineshaft pumps:
- Many customers are educated and have experienced pump failures in the past. When they first determine that a pump is failing, they call MWI for a professional opinion about whether the pump should be pulled out of service for evaluation. (For preventive purposes, MWI Repair conducts site visits during the year to remind customers that pulling the pump out every five to seven years is a good practice in order to eliminate catastrophic pump repairs.)
- When the customer calls with the inquiry (for example, the pump may be making an unfamiliar noise, shaking, or vibrating), MWI arranges a time to meet the customer at the pump station to evaluate.
- If the customer is advised that a repair is needed, the pump is removed and transported to the MWI repair facility.
- An estimate is presented to the customer for the repair after the pump is completely disassembled and inspected.
- All components (including gear drive, electric motor, sheaves, belts, drive shafts, etc.) are inspected.
- Bearings, seals, lubricants, etc. are replaced if/when necessary.
- The pump will be sandblasting, or an epoxy coat applied.
- The impeller may need to be rebalanced, repaired, or replaced.
- The shaft may need to be straightened, repaired, or replaced.
- The pump column may need to be repaired, patched, or replaced. Sections of the column may also need to be replaced.
- The oil enclosing tube may need to be repaired, patched, or replaced.
Hyde emphasized that each pump repair is unique and must be evaluated separately based on the materials and application for the best possible recommendations. And most important, proper preventative maintenance can help to avoid unexpected repairs.