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"Our Machinery
Analysis Team began using the PERMALIGN system two years ago to assure
that our high speed, critical rotating machinery is ‘running’ with
accurate shaft alignments. Alignment related problems with our high speed
turbomachinery have been solved using this technology. Experience with
this system has pointed out the following: 1) Conventional ‘hot checks’
do not provide an accurate measure of the actual ‘running’ alignment
condition for steam turbine applications. 2) Loads from the piping, etc.
can contribute significantly to the running alignment condition. In
summary, the PERMALIGN system provides an economical way to accurately
measure the ‘thermal growth signature’ of critical rotating
machinery."
--Brian
Miller
Eastman Chemical Company
Kingsport, TN
"I am very
pleased with the results
we achieved using PERMALIGN and OPTALIGN. I was very surprised to see how
effective these tools are when used together during heat up and cool down.
You have proven to me that a hot alignment check is virtually useless
without a means to continuously monitor equipment during operation. Thanks
again."
--Paul
Hudson
Georgia Power Co.
Waynesboro, GA
In January of 1993,
a new 900 HP
mixed gas compressor was started at Belle’s AG Products Area and so did
its vibrations. "We decided to take the bull by the horns..."
The equipment was monitored with PERMALIGN for 120 hours and we discovered
that the vibrations were due to structural changes. Since its realignment,
the compressor has been running vibration free. There was no other way to
find out what was wrong. "I would and I already have been
recommending people to give PERMALIGN a try."
--Malcohm
Colvard
E. I. Du Pont de Nemours & Co.
Belle, WV |
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"HOT" ALIGNMENT CHECKS
ONLY
TELL HALF THE STORY!
Hot alignment checks are often unsuccessful
because of delays in installing measuring devices on the equipment which has just been
shut down.
Even when good planning and
organization allowed you to take readings within minutes of shutdown, these
readings only address the so called "Thermal
Growth". Often the effects of thermal growth on alignment had been
calculated fairly accurately and the "hot alignment" check
confirmed them, but still, excessive vibration persists and continues to be
traceable to misalignment.
The problem is that machinery
moves during operation for reasons unrelated to thermal effects.
Dynamic rather than thermally
induced movements may cause machinery to operate misaligned. Since these
dynamic effects disappear before the machinery stops rotating, hot alignment
checks cannot measure them.
The non-thermal moves, both
vertical and horizontal, are often as large or larger than the thermal moves
but much more difficult to calculate. In our experience the dynamic moves
are usually ignored.
These movements can be caused
by foundation problems, by pipe strains and stresses, loose anchor bolts or
changes in the load, etc. Whatever the cause or causes, almost the only way
to determine the movements is continuous computerized monitoring of the
alignment.
When coordinated with records
from the control room it often becomes clear why and how the machinery
changed position. Proper "cold"
alignment targeting thus becomes feasible and significant operational
improvements are usually achieved.
Aside from the well known
consequences of less wear on bearings, seals, couplings, etc. it is
sometimes possible to increase the load for the equipment and last but not
least, power consumption will reduce and result in savings which are a
multiple of the cost of the monitoring equipment.
Several monitoring systems
have been on the market for many years using dial indicators or proximity
probes, etc. and now, fully automatic laser systems are available with
suitably large measuring range. PERMALIGN
using the principle of a prism reflected beam is not affected by temperature
variations and measures accurately even at very high vibration levels.
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