Gene Vogel
EASA Pump & Vibration Specialist

It happens to just about every EASA service center. A machine shows up for repair; it has leads, and there’s a motor, but the machine is a pump. Most often, it’s a close-coupled pump or a submersible pump. If your response is, “We don’t work on those here,” because you’re thinking, “We don’t know anything about repairing pumps,” you may be turning your back on some very profitable work.

As I detailed in my February Currents article, pump repair can be a very profitable expansion area for service centers that specialize in electric motor repair only. If you agree that pump repair would be a good fit for your business, the next step is to evaluate what changes your facility needs to accommodate repairing pumps. You will find that you have much of the necessary equipment from repairing electric motors. The mechanical characteristics of motors and centrifugal pumps are very similar. Depending on the type of pump, there may be very little additional that you need.

End Suction Pumps
The simplest pumps to repair are end suction pumps. They come in two general configurations: free-standing and close-coupled. Most often, a free-standing end suction pump is mounted on a metal base and direct-coupled to an electric motor. A close-coupled pump is simply an electric motor with an impeller mounted on the motor shaft and the pump housing bolted to the motor C-face or D-flange. No special equipment is needed for the repair of close-coupled style pumps. For stand-alone end suction pumps, the same would be true unless the bearing housing in the frame needs to be repaired (bore and sleeve). For smaller units, it may be possible to chuck the pump frame in a lathe and turn it to accomplish the machine work. For larger pump frames, a boring mill is the right tool for the job. A boring mill is not a tool commonly found in electric motor repair facilities, and it is something that should be considered when evaluating what’s needed for pump repair.  

Submersible Pumps

Submersible pumps are another machine that electric motor repair centers are likely to encounter. Submersible pumps are close-coupled pumps – a motor with the impeller mounted on the motor shaft. These are specially built machines. The motor is integrated into the pump frame rather than the pump being mounted on the motor. Additionally, submersible pumps have dual seals with an oil-filled seal housing between the motor and the impeller and housing. While submersible pumps are more complex than common close-coupled pumps, tools and machining capability found in most electric motor repair centers will handle most repairs. The exceptions include purpose-built tools for removing stators cores from their housings and a few manufacturers’ special seal installation tools (See Figure 1). Service centers generally make these items on an as-needed basis.

For larger pumps, especially split case pumps (the impeller mounted between bearings), a boring mill becomes a necessity for repairs requiring machine work to the pump housing (See Figure 2). While some service centers outsource this machine work to other machine shops, having an in-house boring mill available to control quality, scheduling and inspection of the dimensional integrity of a pump frame is an advantage. A standard engine lathe will handle repair machine work for components other than the pump housing.

Vertical Turbine Pumps  

Vertical turbine pumps (VTPs) are common in water, wastewater, agriculture and manufacturing applications. They can be a profitable part of service center’s pump repair business. They are not complicated machines to repair, but they do present some unique challenges. These pumps can be mounted to depths of 100 feet (30 meters) or more. Individual pump and column sections can be 20 to 30 feet (6 to 9 meters) in length. The service center will require adequate workspace for disassembly (more on workspace requirements later). An important part of VTP repair is ensuring the dimensional integrity of the pump bowl and column section flanges and the bowl and line shaft bearings (See Figure 3). A lathe with sufficient length and swing can be used for flange run out measurement and machining. For line boring VTP bearings, once again, a boring mill is the right tool for the job.

At this point, it may seem that a boring mill is an essential piece of equipment for pump repair. It is important to have that capability available for larger pumps. For smaller pumps, all necessary machine work can be completed in a lathe. What constitutes a large or small pump depends somewhat on the swing limits of your lathe.  

Workspace

Another consideration for setting up a service center for pump repair is providing appropriate workspace. Many pumps come into the service center containing significant amounts of pumpage. Submersible pumps will have a seal chamber filled with oil, glycol or similar barrier fluid. Spillage of these fluids is inevitable during disassembly (See Figure 4). In some pump shops for smaller submersible pumps, each workbench is set in a catch tray with a drain. Anticipating a spill is the best way to control one. The pump disassembly area must have adequate drainage and wash down accommodations. Further, sewage pumps may be affectionately referred to as “stinkers,” and adequate ventilation and a convenient area for the initial washdown will be appreciated by all.

A related concern is the handling of and protection from septic, toxic and flammable hazardous materials associated with pump applications. If pumps are from petrochemical industries, U.S. EPA restrictions (or equivalents in other countries) may apply. In all cases, service technicians must be required to wear proper personal protection equipment (PPE). Until all pump components have been thoroughly cleaned, they should be considered contaminated, and PPE is required.  While EASA cannot make specific recommendations, it is generally agreed that PPE for pump disassembly would include rubber gloves and apron, safety glasses and a face shield. 

Repairing electric motors and repairing pumps have a lot in common. Both electric motors and pumps are ubiquitous in industrial applications. The information here should be helpful to those who may consider pump repair as a natural expansion of their electric motor repair business.

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Categories: Technical topics, Pumps, Repair procedures & tips, Safety, Service center equipment

Tags: Personal protective equipment (PPE) Pump repairs

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