Vanguard Engineering Vibration M onitoring Presentation Outline - - PowerPoint PPT Presentation
Vanguard Engineering Vibration M onitoring Presentation Outline 1. Current Program ( 8 minutes) History M ethodology Q & A 2. Proposed Program (16 minutes) Theory M ethodology Implementation Q
Vanguard Engineering Vibration M onitoring Presentation Outline
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History
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M ethodology Q & A
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Theory
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M ethodology
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Implementation Q & A
Q & A
M ost attribute the beginning of the modern era of industrial vibration measurement to T.C. Rathbone. Rathbone, then Chief Engineer, Turbine and M achinery Division, for the Fidelity and Casualty Company of New York, originated the first guidelines for judging machine condition from vibration measurements in a paper published in 1939. The paper, titled “Vibration Tolerance” and published in Power Plant Engineering, provided a guide for condition assessment based on vibration velocity from approximately 60 cpm (1 Hz) to 7,200 cpm (120 Hz). The Rathbone paper introduced a number of profound ideas including a set of amplitude versus frequency severity curves that approximated constant velocity around the rotating frequencies of typical steam turbine generators. The Rathbone severity criteria were based on observations and represent the first known method for equating vibration amplitude with condition – and by implication, service life and risk of failure. It is amazing to recognize that the concepts and severity criteria developed by T. C. Rathbone continue to be the basis of many vibration monitoring programs today; seventy two years later!
M achine Running Condition Overall Vibration Velocity Very Rough 0.628 ips peak Rough 0.314 ips peak Slightly Rough 0.157 ips peak Fair 0.0785 ips peak Good 0.0392 ips peak Very Good 0.0196 ips peak Smooth 0.0098 ips peak Very smooth 0.0049 ips peak
Rathbone Chart The Rathbone Chart, devised by T. C. Rathbone in 1939, compares overall vibration velocity to varying degrees of machine smoothness. Rathbone made no inferences as to frequency content of the vibration, or to machine size. The Rathbone Chart is considered obsolete today, and is presented here only for historical interest.
Every machine or group of machine elements moves in ways that produce repetitive vibration at precisely defined frequencies. These vibration frequencies can be determined from a failure modes analysis and the geometry of the machine elements and located in the vibration spectrum. The vibration spectrum allows us to see the vibration caused by coupling inaccuracies, gear mesh, bearing faults, and many other sources.
Acquire Data
Vibration Severe?
NO YES
Determine Defect Frequencies / Acquire spectrum
Vibration at defect frequencies?
NO YES Diagnosis
Vibration Severe?
Recommend Action YES NO
Proposed Program -
How do we determine Machine Condition?
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We at Vanguard believe that the only reliable method of assessing machine health from vibration measurements is through trending, - that is, monitoring changes in a machine's vibration spectrum. And not just trending total, peak or other gross vibration parameters, but trending the amount of vibration at the specific frequencies associated with machine faults or other condition related issues.
How do we determine Machine Condition?
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Now, using special signal processing techniques and statistical analyses, we can monitor the progress of any developing machine fault that results in increasing vibration at specific frequencies. Once we determine the maximum amount of vibration we're going to allow at a fault frequency before we repair the machine, we can trend the amount of vibration caused by the particular fault and predict how much time is left before the repair should be made.
Acquire Data
Fault and condition confirmed ?
Determine Defect Frequencies for all machines / Acquire Baseline Spectra
Inspect / Repair Dates predicted?
NO YES Diagnosis
Vibration Severe?
Recommend Action YES NO Set Inspect and Repair levels NO YES The Extra M ile
Program Setup (Baseline Survey) Baseline Spectrum M easured amounts
defect frequency. Inspect and Repair levels calculated as 2.5X and 10.0X baseline. Red cursors correspond to specific defect frequencies
n Once the program is set up, Vanguard
takes the vibration measurements from the machines, processes the data and prepares the report.
n The report is designed to provide
relevant information to the entire range
management to engineering and maintenance staff.
VANGUARD ENGINEERING, INC.
VIBRATION MONITORING REPORT
EXECUTIVE SUMMARY
Data Taken: 12/1/2010 Report Date: 12/4/2010 Measurement Point Comment Recomm endation6
CCW Fan #6A M.P. 331 – 334 CCW Fan #6BM.P. 335 – 338 CCW Fan #5B M.P. 339 – 342 CCW Fan #4B M.P. 343 – 346 CCW Fan #3B M.P. 347 – 350 CCW Fan #2B M.P. 351 – 354 CCW Fan #1B M.P. 355 – 358 Nitrogen Gen. Air Compressor #1 M.P. 359 – 362 Nitrogen Gen. Air Compressor #2 M.P. 363 – 366 Not running. Not running. Not running. No problems noted. No problems noted. W e note an increasing trend in Front Fan Bearing FTF (Cage Defect frequency) vibration. We have a June, 2011 Repair Date with 90% Prediction Confidence. Accelerometers have been removed from the fan. No problems noted. Not running. No action needed at this time. No action needed at this time. No action needed at this time. No action needed at this time . No action needed at this time. Since we are in the range between Inspect and Repair, we will conduct some diagnostics to verify the prediction. Although the vibration level is “Low” (0.02 ips), the trend is significant, and you should begin planning to replace this bearing during the April outage. We will reinstall these at our next opportunity. No action needed at this time. No action needed at this time. n The
current
spectrum can be visually compared to the baseline.
n Trends of individual trouble spots and time to
maintenance estimates can be examined ...
n …
and displayed.
VANGUARD ENGINEERING, INC. PREDICTIVE MAINTENANCE REPORT
Customer: Measurement Point No.: 353 Description: CCW Fan 2B - Front Report Date: 12/01/10 a c c e l e r a t i
g 1x10 -3 2x10 -3
05/10 08/10 11/10 02/11 05/11 08/11 11/11 02/12 05/12
INSPECT 09/21/10 REPAIR 06/08/11 Fan FTF 1.79 Hz. Prediction Confidence = 90 %
n Use the existing M achine M odel to aid diagnosis
n Install measurement point mounting
pads.
n Perform Failure M odes Analysis and
determine frequencies to be monitored.
n Set up monitoring database. n Take baseline data. n Set Inspect and Repair levels. n Take periodic data. n Provide monitoring reports.
n Follow - on diagnostics. n Field Balancing. n Laser Alignment. n Infrared Thermography. n Operational Deflection Shape Analysis. n M otor Current Signature Analysis.
The Extra M ile = Value Added
n Failure modes determined by custom-
developed M achine M odels.
n M onitors defect development that might go
unnoticed by current methodology.
n M achine condition assessment based on
individual nominals, not just arbitrary absolutes.
n Time-To-M aintenance and Prediction
Confidence estimates provide optimized maintenance planning guidance.