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Demand specifics in designing your asset management programs

12.01.2013  |  Bloch, H. P.,  Hydrocarbon Processing Staff, 

Keywords: [asset management] [predictive maintenance] [preventive maintenance] [wireless] [alrams] [equipment monitoring]

In 2009, an automation journal commissioned an online survey asking industry observers and practitioners to rank technology trends in 2009 and beyond.1 Table 1 summarizes the respondents’ preferences on technologies that would be adopted or installed in operating facilities over the next five years.

While this particular survey was restricted to the automation and instrumentation segments of modern industry, the results are probably applicable to the mechanical and maintenance segments. All industrial segments anticipate, and will apply, some or possibly all or similar versions of the automation/monitoring/communication equipment and systems listed in Table 1.

Seasoned reliability professionals should welcome these trends. However, successful implementation of automation/monitoring/alarm equipment requires tremendous planning and action. Specific training is needed early in the process to translate any of the existing or future trends (Table 1) into safe and profitable uptime for the industrial/manufacturing facilities.

 



User beware

Engineering teams involved in automation/monitoring programs should be fully aware of “consultant-conceived generalities.” Such generalities add no value unless there is action on relevant specifics. Technology implementation requires knowledge-based action even on minor items. Getting the “big picture” and embracing the concept of asset management (AM) is commendable, but more is needed for sustainable success.

Asset management by definition

AM is a systematic and highly detailed process of operating, maintaining, upgrading and disposing of assets cost-effectively. The AM process is aimed at achieving the greatest return on plant assets and equipment. It includes predictive maintenance (PdM) and preventive maintenance (PM) in facilities to provide the best possible service to all users. This is a very general guideline; however, the importance and urgency of pursuing and implementing specifics is best illustrated by an example.

Example

An equipment alignment problem indicates needed upgrades. Earlier this year, a machinery engineer on temporary assignment overseas struggled with equipment alignment issues. While shaft alignment may seem to be a very “low technology” issue, the engineer realized that alignment problems could have a demonstrable impact on the availability and reliability of equipment and possibly processing units. The engineer summarized the situation and wrote:2

“Suppose you have very precisely aligned the shafts of pump and driver; nevertheless, the shims placed under the equipment feet to achieve this precise alignment caused the shaft system to slant 0.005 in. or 0.01 in. per foot of shaft length. As a consequence, the brass or bronze oil ring (slinger ring) will now exhibit a strong tendency to run ‘downhill.’ While bumping into other pump components thousands of times per day, the oil ring gradually degrades and sheds numerous tiny specks of the alloy material. These metal specks cause progressive oil deterioration and, ultimately, bearing distress.”

The engineer relayed more information and asked several questions:3

“We are currently installing a couple of hundred motor-driven pumps on steel modules. The modules are being built in a Pacific Rim country and will be shipped to another continent when completed. I have a concern now, after reading your book. The pumps are all installed on skids from different manufacturers. After setting the flatness of the skids’ machined surfaces to the requirements spelled out in an applicable standard (API-686, 0.25 mm/m), we came back the next day or week and found the surfaces out-of-tolerance due to the sun’s orientation and changes in ambient temperature. The equipment stayed in a common plane, but not within the guidelines of API-686.

Do you have any recommendations? Can you shed more light on the expected equipment or component life reduction if the pump orientation is out-of-flatness? Are pumps used on ships different from API-compliant pumps?”

Answer

In short, this author may not have all of the answers, but shaft misalignment reduces the expected trouble-free operating time, as shown in Fig. 1. Pumps on shipboard are often grease-lubricated, and the re-greasing frequencies on well-managed ships are better than those practiced on land. Regardless of where equipment is installed, bearing life—in oil-lubricated pumps equipped with loose oil rings dipping in the oil sump—will be influenced by oil replacement (per PM) frequency. Factors influencing the bearing service life include oil cleanliness, degree of immersion in the oil, variation of oil viscosity from an as-designed value, bore roughness of the oil rings, and the degree of horizontality of the shaft system.

 
  Fig. 1. High shaft misalignment vs.
  expected trouble-free operating time.4


The out-of-roundness of loose oil rings is very important, and some researchers have asked for concentricity within 0.002 in./0.05 mm.5 In 2009, at a facility in South Texas, we measured malfunctioning oil rings that were over 0.06 in./1.5 mm out-of-round. For loose oil rings, remaining within the asked-for concentricity is difficult. Therefore, flinger discs clamped to the shaft are preferred over loose oil rings. However, if the loose oil rings are required, then these rings should be manufactured with stress relieving as a required fabrication step.

Garbage in, garbage out

Reliability professionals must fully advise their owners, employers, project managers and superintendents on what may appear to be a small matter. Cheap equipment will require more maintenance, and reliability professionals must bring these facts to the attention of decision-makers and purchasing teams. If it is too late for the overseas reader to insist on flinger discs, they could now lay much groundwork for upgrading via suitable retrofits.

Upgrading is part of the definition for AM. So, whenever the first one of the reader’s many skid-mounted pumps fails and is taken to the shop, the needed flinger disc adaptations would be retrofitted.2 A designated responsible implementer would be involved in this follow-up. Carrying out such upgrades is rarely optional at reliability-focused facilities. For them, upgrading is mandatory because only the reliability-focused plants will operate safely and profitably. Using oil rings and expecting the highest possible equipment reliability are contradictions. Attempts to live with contradictions will ultimately cost more than implementing best-available technology during the inception stage of the project.

The message

Effective AM deals with specifics. Not understanding, acknowledging these specifics and implementing suitable upgrades will be an expensive process. Experience shows that “average” facilities will run, but they will get locked in a never-ending cycle of repeat failures or random repairs. From the start, these facilities will be repair-focused and notably less profitable than their reliability-focused competition. Ideally, an owner-operator should work with design contractors who know, specify and insist on obtaining the lowest failure risk components—down to parts such as flinger discs in locations where “average” users will accept loose oil rings. If the design contractor does not have these insights, the timely and consistent application of machinery quality assessment is even more important. HP

LITERATURE CITED

1 Journal of the International Society of Automation, January 2009.
2 Bloch, H. P. and A. R. Budris, Pump User’s Handbook—Life Extension, 4th Ed., Fairmont Publishing, Lilburn, Georgia, 2013.
3 Bloch, H. P., Pump Wisdom: Problem Solving for Operators and Specialists, John Wiley & Sons, Hoboken, New Jersey, 2011.
4 Piotrowski, J., Shaft Alignment Handbook, 3rd Ed., Marcel Dekker, New York, New York, 2006.
5 Wilcock, D. F. and E. R. Booser, Bearing Design and Application, McGraw-Hill Publishing Co., New York, New York, 1957.


The author

Heinz P. Bloch resides in Westminster, Colorado. His professional career commenced in 1962 and included long-term assignments as Exxon Chemical’s regional machinery specialist for the US. He has authored over 500 publications, among them 18 comprehensive books on practical machinery management, failure analysis, failure avoidance, compressors, steam turbines, pumps, oil-mist lubrication and practical lubrication for industry. Mr. Bloch holds BS and MS degrees in mechanical engineering. He is an ASME Life Fellow and maintains registration as a Professional Engineer in New Jersey and Texas. 




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Barry Snider
12.05.2013

Once again, Heinz Bloch has demonstrated the need for precision and due diligence when applying the concepts of Asset Management. the timing could not be better as the new standards ISO 55000, 55001, 55002, and 55003 are about to be published. these standards do not emphasize detail and precision but only the attributes for a management system. The lesson is to learn how to manage your assets before setting up a management system and placing a certificate on the wall that announces compliance to a standard established by some far away committee.

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