Managers facing repair-or-replace decisions for pumps must take into account both in-house maintenance capabilities and company policy. Some managers opt to repair as long as the pump casing remains in good condition, which can be decades. Technicians simply replace rotating or worn parts as needed, and if the in-house maintenance shop has cutoff machines, drills, lathes, milling machines and shapers, technicians can make many of the needed parts.
One alternative approach is to follow the policy that optimum service life occurs when cumulative maintenance labor and material costs equal a pump's replacement cost. Managers can use a formula to calculate a pump's optimum service life in hours and can compare optimum hours to actual operating hours.
An hour meter or service-hours recorder attached to the pump can help accurately determine actual hours. The service recorder is the best option because it accumulates operating hours and sorts them into idling hours and hours under load — valuable data for evaluating the effectiveness of the pump design. When actual hours exceed optimum hours, the unit is replaced.
Company financial policy also affects the repair-or-replace decision. Managers must expense parts for rebuilding in the year purchased, but they can capitalize and depreciate replacement pumps over several years. With either option, managers need to watch for upgrade possibilities to newer, more energy-efficient designs, such as VFDs to replace throttling valves. Upgrading the design of a pump or drive can help defray the upfront costs through energy and reliability savings.
Thomas A. Westerkamp is a maintenance and engineering management consultant and president of the work management division of Westerkamp Group LLC.
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