Improvements to make your equipment better than new.
by Kurt Schumann
March 23, 2018

Upgrades for circulating water pumps include:

  1. An inner column stop on pullout style pumps to hold down the pump element during starting, stopping, unit trips, and other transients.
  2. A flanged inner column with rabbet fits replaces screwed inner columns, resulting in better bearing alignment and easier disassembly.
  3. Bearing spiders provide stiffer bearing support.
  4. Shroud metallurgy upgraded in high-velocity areas eliminates erosion and corrosion damage.
  5. Inlet bell modifications lower the required submergence and reduce vortexing.
  6. Modified impellers optimize cooling water flow, increase plant output, or save pumping horsepower.
  7. Erosion in iron casing vanes can be repaired. Coatings can be applied to extend casing life.
  8. Keyed shaft coupling improves shaft alignment and eliminates problems associated with removing threaded couplings. Shafts can usually be re-machined and re-used.
  9. Rabbet-fit drive couplings replace body-bound bolt couplings and improve alignment repeatability.

Boiler Circulating Pumps

Boiler circulating pumps (BCPs) are in a particularly sever duty, handling 600 F water at over 3,000 psig.

Many of the original pumps supplied in the 1950s and 1960s exhibited less-than-desirable life spans. In light of this, an upgrade program was developed that:

  • adds a graphite-impregnated bearing
  • improves the primary sealing device
  • incorporates other reliability “lesson learned”

To date, more than 200 BCPs have been upgraded to this new design, and the resulting MTBF is typically two to three times that of the pumps before upgrading.

API Process Pumps

Process pumps may handle hazardous materials, and as a result seal leakage is critical. Industry standards (API 610 7th Edition), as well as federal legislation like the Clean Air Act, address mechanical seal reliability and pump maintenance.

There are upgrades available for process pumps to improve seal reliability and reduce emissions, including:

  • using a heavy-duty rotor (shaft and bearings)
  • enlarging the stuffing box bore for better seal cooling
  • using a heavy-duty cartridge seal (single, double, or tandem)

Summary

These descriptions cover some typical upgrades. This article focused on specific types of pumps, but upgrades are available for most models and sizes. Pump companies are useful resources for aid in problem solving. They are usually anxious to apply new technology and gain field experience with new designs and materials. Most upgrade suppliers can customize upgrades for individual users. Review your maintenance problems and discuss them with your pump supplier.

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