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Reasonable Pump Life Assessed in “Petrochemical Machinery Insights”

By: , Posted on: December 16, 2016

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Recently published Petrochemical Machinery Insights allows readers to review and understand hundreds of interwoven reliability improvement details. Among these reliability improvement details are the determination of pump Mean-Times- Between-Failure (MTBF) and highly accurate explanations of how Best-of-Competition plants have systematically eliminated repeat failures from their process pump failure inventories. An API-style process pump is shown in Figure 1; notice oil mist lubricant supply lines connected to bearing housings.

Examining pump repair records and MTBF

Pump failure statistics are often translated into MTBF. For what it’s worth and so as not to get enmeshed in arguments, many of the best practices plants simply take all their installed pumps and divide this number by the repair incidents in a particular time period being observed. Taking, as an example, a well-managed and reasonably reliability-focused U.S. refinery with 1,200 installed pumps and 156 repair incidents in one year, the MTBF would be (1,200/156) =7.7 years. The refinery would count as a repair incident the replacement of parts—any parts—regardless of cost. In this case, a drain plug worth $3.70 or an impeller costing $7,000 would show up the same way on the MTBF statistics. Only the replacement or replenishment of lube oil would not be counted as a repair.

A best-practices plant’s total repair cost for pumps would include all direct labor, materials, indirect labor and overhead, administration cost, the cost of labor to procure parts, and even the prorated cost of pump-related fire incidents. The average cost of repairing API-style process pumps in the U.S Gulf Coast region was given as $ 10,287 in 1984 and $ 11,000 in 2005. Newer estimates (in 2016) remain in the range of $11,000 to $12,000 and the normally expected inflation multipliers seem to cancel because earlier detection of flaws limits the extent of damage. Earlier detection of component deficiencies has recently been made possible through refinements in Predictive Maintenance (PdM) instruments and analyzers.

It has been reasoned that predictive maintenance and similar monitoring strategies have led to corrective maintenance interventions taking place before failures became too severe. Quality control and systematic upgrading are now practiced by Best-of Class Companies; these user-owners understand the importance of seeking out and predefining competent pump repair shops.

Using the same bare-bones metrics and from published data and observations made in the course of performing maintenance effectiveness studies and reliability audits in the late 1990’s and early 2000’s, the mean-times-between-failure shown in Table 1 have been estimated.  As of 2016, they were still considered reasonably accurate.

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Target pump and component lifetimes

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Significant asset life extensions were achieved by the implementation measures documented in “Petrochemical Machinery Insights.” As just one more example, the target mechanical seal lifetimes in Table 2 have been re-validated and should be considered readily achievable in 2017 and the coming years. If your plant does not meet these expectations, closely following “Petrochemical Machinery Insights” will save you much money. The text explains the work procedures and component upgrade measures which propelled plants to considerably greater profitability.

Want to read more? Petrochemical Machinery Insights is a priceless collection of solutions and advice from Heinz Bloch on a broad range of equipment management themes, from wear to warranty issues, organizational problems and oil mist lubrication, and professional growth and pre-purchase of machinery.

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The author draws on his industry experience to hone in on important problems that do not get addressed in other books, providing actionable details that engineers can use. Mechanical, reliability, and process engineers will find this book the next best thing to having Heinz Bloch on speed dial.

The book is available now on the Elsevier store. Enter STC215 at the checkout for 30% discount!

About the Author

heinz-blochHeinz P Bloch is the owner and principal of Process Machinery Consulting Co, and has been the reliability editor of Hydrocarbon Processing Magazine since 1990. He is the author or co-author of over 650 technical papers or articles, and 19 full text books. He was a founding member of Texas A&M University’s International Pump Users Symposium.

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