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POSITIONAL CHANGE MONITORING (i.e. distortion/displacement)
The fact that machinery moves
during operation is established and well documented. Many manufacturers of rotating
equipment provide expansion data for their products derived from theoretical calculations.
It is Bengal Resources position that no matter how painstakingly careful one is in
approaching these calculations, and no matter how sophisticated the mathematical approach,
unavoidable limitations are encountered when applying pure theory to field situations.
Further, thermal growth is not the only contributor to positional change of on-line
machinery.
Some variables posing problems to
theoretical growth calculations for alignment are:
- Piping size and length
- Downstream temperature variations ( and their effect on piping)
- Variations in load
- Machine frame distortion due to torque
- Non-homogeneous materials composition
- Non-uniform machinery cross-sections
- Uneven heating of material
- Foundation problems
- Frequent and significant changes in ambient temperature
- Process effects (changes in operating pressure, temperature)
- Mechanical looseness
- Oil film thickness
- Sole Plate Instability
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A good alignment target takes all
significant factors into account. The objective is to deliberately misalign the machine
assembly off-line so that it runs into a "straight line" when activated.
Occasionally, the solution to thermal growth problems requires expansion joints or
additional securing of pipes. Nevertheless, the problem with on-line monitoring is:
"How do I get realistic data"?
The approach to positional change measurement employed by Bengal Resources
is to apply several methods of measurement (i.e. laser, optical,
and theoretical calculations of temperature gradients) at a reasonable cost. Our goal is to learn more about the
physical behavior of a machine assembly so that we may intelligently
recommend a course of action to eliminate poor machinery performance.
Frequently, that course of action is a recommended cold alignment target.
Sometimes a change in piping may be required. On occasion, the source of
alignment problems is foundation movement. Regardless of the causal nature
of a movement problem, Bengal Resources has the necessary equipment and
expertise to confirm positional change.
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CLICK ON IMAGES BELOW FOR A LARGER VIEW.
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Permalign and Rotalign
Pro M3 system measuring thermal growth;
Agricultural Products Manufacturer in Nebraska. |
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Optical and Laser Measurement;
Compressor Thermal
Growth;
Gas Transition Facility, Minnesota |
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Optical measurement axial movement of a
crossover pipe, using a jig transit
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Laser and Strain gauge measurement of
steam turbine
foundation pedestal movement in Ohio. |
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Casing Distortion Measurement on Steam Turbine |
Click on images for larger view
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Copyright © 2000-2003, Bengal Resources, Inc.. All Rights Reserved.
107 Walter Payton Drive Ste 102, Columbia MS 39429
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