How
Qualified are You to Detect and Correct Shaft Alignment? |
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by
John Piotrowski |
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Purchasing an alignment
measurement system does not necessarily qualify you as an alignment 'expert'.
What is the best method to measure misalignment under different
circumstances? What effect does excessive 'soft foot', runout, and
piping stress have on rotating machinery? What are the different levels
of testing that can be performed at your plant to determine the skill
level of the people responsible for alignment? What sort of training is
required to become proficient in this area? The effectiveness of written
or oral exams, simulated misalignment test, and actual on the job skills
testing on process machinery is discussed. |
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Why do certification testing? |
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Perhaps several true life
examples will illustrate the need for certification testing in shaft
alignment. |
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- A maintenance technician at a
chemical plant was asked to align a motor and a pump with a newly
purchased laser shaft alignment system. Shaft position measurements were
captured with the instrument and the alignment corrections required to
align the motor (assigned as the movable machine) to the pump indicated
that the outboard end of the motor had to be lowered 85 mils and the
inboard end of the motor had to be lowered 37 mils and there was no shim
stock under any of the motor feet. After completely removing the motor,
the technician began grinding the baseplate away. The motor was place
back on the base and shaft position measurements were captured again.
The technician then added shims under the motor since too much metal had
been ground away and several side to side moves were made to bring the
equipment into alignment. |
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- A company who manufactures gas
turbines was in the process of installing several large air compressors
to expand the capacity of the compressed air system used to test their
jet engines. Requests for bids were sent out to several general
contractors to install the 11,000 hp motors, gearboxes, and compressors.
Very detailed specifications were sent to each of the general
contractors including very specific instructions on installation of the
foundations, sole plates, correcting 'soft foot' conditions, rough
alignment procedures, final 'cold' alignment procedures, and 'hot'
alignment procedures. The general contractor was told to sub-contract
the alignment work to companies who specialize in machinery alignment.
When the alignment specifications were sent to the 'alignment' sub-contractors,
several of the contractors did not understand many of the detailed
specifications for the required work but submitted bids anyway believing
that no one would check their work. The contract awards were dispensed
and toward the completion of the project the company discovered that the
alignment work was not performed to the written specifications and
withheld payment to the contractors who performed the work (or lack
thereof). |
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- A company who was in the process
of becoming ISO 9000, 9001, and 9002 compliant, requested information on
who administers certification testing for their maintenance personnel
for shaft alignment. Several of their people had been certified in
vibration analysis and thermography and they wanted to show
documentation that their personnel were adept at not only finding
problems but also adept at fixing them. |
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- A petroleum company decided to
sell one of their facilities and several of the prospective buyers were
interested in retaining as many employees as possible. However they only
wanted to hire the people who were adequately trained and were certified
to do certain tasks. When asked to provide information on task
certification of their employees, the petroleum company was unable to
provide the information. |
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- A steel company was having some
problems with a fairly complex, multiple element drive train where
misalignment was found to be the root cause of the failures. No one in
the plant knew how to align the drive system. An alignment service
company was contacted and the technician said that they could align the
drive system in less than 4 hours. When the work was actually done, the
job took several days to complete. |
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- An electric utility company had
experienced several failures on a critical pump. The in-house
maintenance personnel had been using a laser shaft alignment system to
measure the positions of the shafts. The pump was being driven by a
variable speed hydraulic clutch and the manufacturer of the clutch
stated in the instruction manual that the clutch would raise upward 15
mils once it attained normal operating conditions. The maintenance
personnel henceforth set the clutch 15 mils lower than the pump shaft
assuming that the pump would not move from off-line to running
conditions. A survey was conducted that showed that the pump shaft
raised upward far greater than the clutch did forcing the unit to run
under severe misalignment conditions. |
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Twenty years ago, there were
so few people doing vibration analysis, IR thermography, and oil
analysis compared to today that companies we delighted to have anyone
taking vibration or thermography data. With a couple thousand dollars,
anyone could buy a hand held vibration meter, an oscilloscope, or a
swept frequency analyzer (FFT analyzers and computers weren't readily
available back then). Today, the equipment available to us for vibration
and thermography is far superior to the instruments of twenty years ago
and the number of people working in these areas has increased
substantially. With a couple thousand dollars, anyone can buy a personal
computer and a vibration data collector and a good IR camera and be in
business. |
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Most of us are keenly aware
that purchasing this equipment does mean that we know how to use it.
Buying a vibration analyzer does not make one a vibration analyst, nor
does and IR camera qualify someone as knowledgeable in thermography, or
a scalpel magically transform someone into a surgeon. The learning curve
for this equipment and the knowledge to use it properly is long and
steep. Determining what buttons to push, how to operate the software
program that came with the instrument as well as learn how to use a
computer can consume several months of time. Once you've figured out how
to operate the equipment and begin to collect data, the next task is to
ascertain what the data is telling you so some sort of judgement on the
condition of our machinery can be made. This part can take years to
become proficient at since the equipment being monitored at your plant
doesn't necessarily follow generic equipment deterioration 'patterns'
and proper condition assessment can only be realized with
experimentation and experience. During its infancy, many CBM programs
have turned people off because one or two bad 'calls' were made
assessing the condition of the machinery. People get really mad after
tearing down a machine to find that nothing or very little was wrong
when you made it sound like the machine was about to catastrophically
fail. |
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So it became apparent that
these CBM/Predictive Maintenance programs only worked effectively after
the people have received adequate training. Consequentially the people
went to the training courses. Some people learned a lot, some learned a
little, and some had their minds occupied elsewhere during the training
courses. Those who worked hard and learned a lot started wondering how
they could prove that they knew more than those who didn't. |
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Henceforth came the 'certification'
testing along with the arguments and disagreements on who had the
authority to dispense 'certification' in the first place. Over the past
five years, there has been a lot of effort put into determining the
skill level of people working in vibration analysis and infrared
thermography through qualification/certification testing by several
companies and/or institutions. Some people may disagree with the need
for testing, but it has become a way of life and many companies are
requiring their employees to become certified in these areas. In fact,
this made people begin thinking about certification for several other
kinds of 'tasks' performed in the industrial work place. If
certification is desirable for methods to detect problems with rotating
machinery, then certification should also be desirable for correcting
problems with rotating machinery such as balancing, shaft alignment, and
tribology for example. |
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How qualified are people in
finding and correcting shaft misalignment however? As more companies are
turning to 'Task Based Training' and 'Task Based Testing', what is the
best way to determine if people are suitably qualified to do shaft
alignment? Another facet that should be addressed is ... how qualified
in shaft alignment are the contractors who are installing new rotating
machinery? |
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Before qualification testing
begins, you should have a fairly good idea of how knowledgeable you and
your coworkers (or the contractors you hire) are in the field of shaft
alignment already so unnecessary training isn't done. Assessing what you
and your coworkers know about shaft alignment can be done by soliciting
the employees through an Experience Evaluation Form that queries their
knowledge and experience on specific types of machinery and specific
types of tasks performed on this machinery. The next step is to test
each individual on the tasks that they said they were adept at to
determine if they are truly capable of performing that task and if not,
what supplementary training would be required to elevate their level of
proficiency. In summary, what do you think you know, what do you
actually know, and what do you need training in? |
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Who needs to needs to be trained and/or qualified in
shaft alignment? |
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Many organizations feel that
the full responsibility for shaft alignment rests solely in the hands of
the trades people (e.g. mechanics, millwrights, pipefitters,
electricians). Ask yourself these questions. Is it the responsibility of
a trades person to: - Pick training courses they feel they need and send
themselves to the course(s)? - Research all of the available types of
shaft alignment measurement systems and purchase a system that best fits
the needs of their organization? - Tell a contractor that they are not
installing new rotating machinery correctly? - Hire some new people or a
contractor to help with the work overload? - Rebuild a piece of rotating
machinery due to excessive runout conditions? - Determine that a
rotating machinery foundation or baseplate has be removed and
reinstalled if it has deteriorated excessively or been installed
improperly? - Redesign and rework improperly installed piping that is
putting and excessive strain on the rotating machinery itÕs attached to?
- Purchase and install piping supports or design a custom piping anchor
on a CAD system, purchase the materials, and install the anchor? -
Select a new flexible coupling design to replace one that doesn't work
well or fails often? - Pick a pump to be the 'moveable' machine and
leave the motor as the 'stationary' machine? - Issue work orders to
check the alignment of all the rotating machinery every year? - Shut a
machine down based on vibration and temperature data that indicates a
misalignment or 'soft foot' condition? - Determine which machinery might
need to have the 'hot' alignment checked, select an off-line to running
machinery movement measurement technique, install the equipment on the
machinery, measure and analyze the data, and alter the 'cold' alignment
position based on the data collected? - Maintain records of the
alignment work that was performed and save it in the equipment files or
computer data base? - Install X-Y proximity probes on a machine
supported in sliding type bearings to analyze the Lissajous orbit for
signs of running misalignment? |
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I wouldn't be
surprised if a lot of managers, engineers, front line supervisors, and
trades people felt that some, if not several of the above items are not
their responsibility (let alone what some of them mean). Well then, if
the trades people aren't responsible for some of the above items, then
who is? |
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Shaft alignment training
should be for managers (who can't understand why alignment takes longer
than 45 minutes), engineers (who were never taught this in school and
are rarely allowed to do 'hands-on' work), technicians (who are asked to
identify it through CBM programs but don't know how to correct it),
front line supervisors (who need to help the trades people if they get
stuck or need a special tool for the work), and trades people (who are
the ones ultimately responsible for the final outcome) to give them the
minimum working knowledge to achieve accurate alignment and to let them
know what's involved in the overall alignment process. Since it is
apparent that trades personnel should not be accountable for every facet
of shaft alignment, several people need to be trained and qualified in
whatever tasks they are responsible for. Engineering and maintenance
managers, rotating equipment and maintenance engineers, maintenance
technicians, vibration specialists, foremen and front line supervisors,
as well as the trades personnel all should be trained and qualified to
do their respective tasks. |
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Assessing a persons knowledge and experience level in
shaft alignment |
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Field Experience Evaluation
forms (shown at the end of this article) which could be used for your
in-house personnel or for contractors working at your plant site. Part 1
identifies the person and what their job titles are (or have been). Part
2 gives you an indication of what type of rotating machinery a person
has worked on in the past. Part 3 gives you some idea of the training a
person has received in different shaft alignment measurement tools and
techniques. Part 4 lists the amount of actual filed experience a person
has in measuring shaft alignment when the equipment is off-line. Part 5
lists the amount of actual filed experience a person has in measuring
off-line to running machinery movement (aka thermal movement or 'hot'
and 'cold' alignment). |
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Alignment qualification / certification testing |
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The Experience Evaluation
Form can be used to determine what training is required for personnel
installing, maintaining, or aligning rotating machinery. However anyone
could fill out the form and say they were proficient and experienced
working with every type of rotating machine and alignment method listed
but how can they verify what they say they know? Written or oral
examinations are one mechanism to verify a persons knowledge level for
each item in the Experience Evaluation Form. There could be one
comprehensive test administered that encompasses every facet of shaft
alignment or there could be a series of tests given for discrete blocks
of information. By breaking down the overall body of information into
separate blocks, the people with little or no experience could be tested
incrementally as their level of knowledge grew. |
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A Basic or Level 1
examination would test the individuals knowledge on the following blocks
of information : |
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¥ the detrimental
consequences of poor alignment on rotating machinery - detecting
misalignment on running rotating machinery (i.e. vibration, IR methods)
- use and care of measuring tools and instruments (feeler gauges, dial
indicators, optical encoders, laser/detector system, proximity probes,
etc.) - finding and correcting excessive runout conditions - finding and
correcting 'soft foot' problems - finding and correcting excessive
piping strain - foundation and baseplate design, installation, and care
- concrete and grouting installation - alignment tolerances - rigid and
flexible coupling design, installation, and care - how to perform the
Reverse Indicator method - basic mathematical or graphical/modeling
principles for re-alignment - how to determine effective alignment
corrections using the Reverse Indicator technique - keeping records of
alignment work |
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An Intermediate or Level 2
examination would test the individuals knowledge on the following blocks
of information : |
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- how to perform the Face & Rim
method - how to determine effective alignment corrections using the Face
& Rim technique - how to perform the Shaft to Coupling Spool method
- how to determine effective alignment corrections using the Shaft to
Coupling Spool technique - how to perform the Double Radial method - how
to determine effective alignment corrections using the Double Radial
technique - how to perform the Face-Face method - how to determine
effective alignment corrections using the Face-Face technique -
mathematical or graphical/modeling principles for all of the above
methods |
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An Advanced or Level 3
examination would test the individuals knowledge on the following blocks
of information : |
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- how to align multiple element
drive trains - how to align right angle drives - the four general
categories for measuring off-line to running (OL2R) machinery movement
(aka 'hot' and 'cold' alignment) - calculating machine case thermal
expansion - inside micrometer-tooling ball-angle measurement methods -
proximity probes with water cooled stands technique - using optical
alignment tooling for OL2R machinery movement - alignment bars with
proximity probes OL2R method - using laser-detector systems to measure
OL2R machinery movement - using the Ball-Rod-Tubing Connector system to
measure OL2R machinery movement - using the Vernier-Strobe system to
measure OL2R machinery movement - mathematical or graphical/modeling
principles for all of the above methods - how to align rotating
machinery to compensate for OL2R machinery movement |
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Written or oral exams can
test a persons knowledge on a subject but is somewhat inadequate in
determining a persons skill level in performing specific tasks. Shaft
alignment is a 'hands on' task. Someone can understand how the Reverse
Indicator alignment method works but not be able to perform the method
correctly. |
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Perhaps the most effective
means of verify a persons knowledge and skill level is to have the
person perform the task on a simulation machine or directly on a
operating rotating equipment drive system at the plant site. However
using process machinery as a test platform may not be possible. What if
the equipment canÕt be shut down for a schedule test time, or what if
the person being tested misaligns the machine and no one checks to see
that itÕs not correct? By having simulation equipment available,
testing can occur at virtually any time without impacting on production
or maintenance schedules. For accurate skills assessment, it is
important to insure that the test equipment simulate 'real life'
circumstances. |
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Conclusions |
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In todays society,
specialized jobs in many different areas require some sort of
certification to verify that an individual is proficient in that task.
In the health, education, and finance industries for example, doctors,
nurses, teachers, and accountants must show that they are certified in
those areas before they are even considered for employment. In industry,
welders must be certified before they can work on pressure vessels and
HVAC technicians must be certified to work with freon refrigerants. You
can't even drive a car or fly a plane without a license! The need for
qualification / certification testing in specialized tasks such as
vibration analysis, thermography, and shaft alignment is justifiable.
Establishing the requirements for qualification or certification can be
accomplished by appraising the experience level of personnel through an
evaluation form that addresses all of the aspects of the task. Skill
requirements for each individual can then be assessed and appropriate
training can be administered. Written/oral exams and/or task simulation
tests can then be conducted to determine the true proficiency of the
individual. Although most of us don't like to be tested on what we know
(or think we know), appraising our skill level is beneficial to the
companies or customers we all work for. Certification / qualification /
licensing examinations can be used as an effective tool in verifying an
individuals level of proficiency in any specific task and a viable
mechanism to let someone know where they need additional training. |
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References |
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Guidebook for Maintenance Proficiency Testing,
Electric Power Research Institute, December 1989, EPRI NP-6679. |
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Handbook for Evaluating the Proficiency of
Maintenance Personnel, Electric Power Research Institute, March 1988,
EPRI NP-5710. |
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Experience Evaluation forms |
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This
article is provided courtesy of Turvac
Incorporated. |
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Return
to the Alignment / Balancing Reference Articles Index |
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