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As part of our precision
alignment philosophy, we offer Optical Alignment services to precisely
measure the movement and placement of machinery components. And we are one
of the only vendors providing quality Optical Alignment measurement services
in the rotating machinery industry.
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Our field experience has repeatedly
proven the value of measuring the machine movements that occur from
offline-to-running conditions on larger, more critical machines such as
turbine generators, boiler feed pumps, and high speed compressors and
gearboxes.
For a more detailed
discussion, you can view our on-line presentation "Optical
Alignment, Thermal Growth and Machinery Movement" on our
Downloads page, or get a
PDF version.
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Accurate measurement of the
machinery and bearing movements that occur from ambient, off-line conditions
to full-load operating conditions (offline-to-running, or 'OL2R') is critical
to achieving accurate machinery
alignment while operating. There is little point in setting a cold
shaft alignment within 0.002" if adjacent bearing housings move 10 or more
times that amount in different directions.
M&B engineers have
extensive optical measurement and alignment experience. By utilizing specialized
tooling & techniques, we can perform a variety of
measurements to quantify thermal, torsion, and strain-related movements.
Once measured, the machinery cold alignment can be offset accordingly
to produce excellent alignment while operating.
Would you have correctly anticipated this Boiler Feed
Pump's Movement? 
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Many customers
ask us: "Shouldn't we just use the OEM
thermal growth numbers?"
While these provide a
starting point, our experience
repeatedly proves
that machines demonstrate unique responses. Until a
particular machine or class of machines is actually measured, you cannot be
sure of its response. We have repeatedly found that the true "thermal growth" of most
machinery does not accurately match OEM calculated values, and can run
counter to what would seem intuitively obvious. These discrepancies between
'calculated' or OEM offsets, and the true required machinery offsets, create misalignment
while operating and add mechanical stresses that reduce
reliability and increase maintenance costs.
The discrepancies arise
for two primary reasons. First, OEM thermal growth values typically rely
on an estimated delta-T across a bearing
or
support structure to calculate a thermal expansion for each affected
material. Any difference between estimated and actual material temperatures
results in calculation errors. Also, even if temperatures are checked with a
pyrometer, they are only the 'skin' temperatures of the components, not the
core temperatures, which can be significantly different. Second, and perhaps
more significantly, calculated values cannot accurately account for the
deflections incurred in the bearing housings, supports, casings, etc., that
occur when a machine is under full operating torque, all of which directly
affect the operating alignment of the machinery. |
How can we provide you
with accurate measurement of data that even the OEMs don't seem to have?
We have the knowledge, equipment, and 20 years of
experience to specialize in optical measurements. By
utilizing precision optical instrumentation from makers such as Brunson
Instruments, Keuffel & Esser, and others, we can provide measurement
accuracy and repeatability within +/- 0.001".
Our typical 'thermal
growth study' measures the vertical and horizontal deflections of each
bearing housing in a machine train. All measurements are referenced to
common benchmarks mounted in the machinery foundation. Thus all bearings can
be cross-referenced, ensuring an accurate overall alignment. This becomes
particularly important on large turbo-machinery with several machine cases
and long bearing spans.
In addition to factoring the thermal / deflection data into
the cold shaft offsets, we have the experience and
equipment to measure
shaft movements within journal bearings during operation. This allows us to
further refine the cold alignment offsets to ensure accurate operating
alignment. This aspect of alignment adjustment can be particularly important
on high-speed machinery, and on gear boxes where gear to pinion reactionary
forces atypically displace shaft centers and affect the shaft alignment. |
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If you are installing
new or refurbished machinery, or undergoing significant repairs, M&B
engineers can assist you with a variety of tasks to get your work done on
time and with a focus on ensuring long-term machinery reliability and
operability.
Utilizing the
optical tooling and techniques mentioned above, we can help you:
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Inspect / level machinery
soleplates within
+/- 0.001"
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Inspect / level machine
casings within +/- 0.001"
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Monitor long-term
elevations of installed foundations for settling
We also
have standard construction / surveying instrumentation and experience, to
assist you with:
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