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.
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
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.
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,
The engineer relayed more information and asked several
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
suns 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?
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
lifein oil-lubricated pumps equipped with loose oil rings
dipping in the oil sumpwill 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.
1. High shaft misalignment vs.
expected trouble-free operating
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
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 readers 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.
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 componentsdown 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
1 Journal of the International Society of
Automation, January 2009.
2 Bloch, H. P. and A. R. Budris, Pump
Users HandbookLife 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.
Heinz P. Bloch resides in
Westminster, Colorado. His professional career
commenced in 1962 and included long-term assignments
as Exxon Chemicals 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.