Perfect is the Enemy of Good - Pumps & Systems Magazine - The Resource for Pump Users Worldwide

Perfect is the Enemy of Good

Written by Robert X. Perez

Page 2 of 2

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This example illustrates that as custodians of our equipment we should strive for the optimum repair-not the maximum MTBR point. What if you asked one of your rolling element bearing manufacturers for a set of bearings with tolerances that approached those of the Gravity Probe B?

While the manufacturer would fall short they could probably provide a set of bearings that were 10 times more exact in tolerance for about 100 times the cost. Would this make economic sense? It certainly would not, because we would be well to the right of the optimum MTBR point. (Note: This analysis is purely hypothetical. Your optimum MTBR will depend on your organization and actual overall repair costs.)

The End-Users' Responsibility

It is the responsibility of the final end-user to select the standards that make the most economical sense and stick to them faithfully. This philosophy will result in the most profitable return from your working pump population. With that being said, I propose the following modification to the adage of discussion:

"Perfection is the Enemy of Good Enough"

In the business world, providing quality beyond what is required is equivalent to giving money away.

So with this slight modification, I am willing to accept this adage as sound business acumen. I recommend readers consider adopting this viewpoint. I have seen pump users who have hurt their careers by insisting on quality beyond what was required by their standards. Here a few examples of what I call "over-specification":

Your standard allows 0.002-in of shaft runout, but you insist on 0.001-in
Your standard allows 4W/N ounce-inches of residual imbalance, but you insist on W/N ounce-inches of residual imbalance.
Your standard allows 0.002-in of offset per inch between shaft ends of misalignment, but you insist in 0.001-in of offset per inch between shaft ends of misalignment.

The credo of all end-users should be:

"Fight for your standards, but nothing more"

End-users who consistently abide by this philosophy will help ensure company profits and earn a solid reputation as a business savvy engineer.

Robert X. Perez, the website editor for PumpCalcs.com, has more than 25 years of rotating equipment experience in the petro-chemical industry. He holds a BSME from Texas A&M University in College Station, a MSME degree from the University of Texas at Austin, a Texas PE license, and is an adjunct professor at Texas A&M University-Corpus Christi, teaching the Engineering Technology Rotating Equipment Course.

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