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 & A • 3. Discussion of Vibration Parameters and M easurement Locations (8 minutes) Q & A
Vanguard Vibration M onitoring Presentation
T. C. Rathbone?
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!
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. M achine Running Overall Vibration Condition 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
Fast Forward to…
The Vibration Spectrum
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.
“ Standard” M ethodology Determine YES YES Defect Acquire Vibration at Vibration Frequencies / defect Severe? Data frequencies? Acquire spectrum NO NO Vibration Diagnosis Severe? NO YES Recommend Action
Questions and Answers
Proposed Program - The Extra M ile
How do we determine Machine Condition? n 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? n 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.
Vanguard M ethodology Determine Defect Set Inspect YES Acquire Frequencies for Vibration and Repair all machines / Severe? Data levels Acquire Baseline Spectra NO The Extra M ile Inspect / Repair Dates predicted? NO YES NO YES Fault and Recommend condition Diagnosis confirmed Action ?
Implementation Example
Program Setup Baseline (Baseline Survey) Spectrum Red cursors M easured amounts correspond to of vibration at each specific defect defect frequency. frequencies Inspect and Repair levels calculated as 2.5X and 10.0X baseline.
Reporting 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 of personnel - from high level management to engineering and maintenance staff.
Executive Summary Customer: Sample Customer VANGUARD ENGINEERING, INC. VIBRATION MONITORING REPORT EXECUTIVE SUMMARY Data Taken: 12/1/2010 Report Date: 12/4/2010 Measurement Point Comment Recomm endation CCW Fan #6A M.P. 331 – 334 Not running. No action needed at this time. CCW Fan #6BM.P. 335 – 338 Not running. No action needed at this time. CCW Fan #5B M.P. 339 – 342 Not running. No action needed at this time. CCW Fan #4B M.P. 343 – 346 No problems noted. No action needed at this time . CCW Fan #3B M.P. 347 – 350 No problems noted. No action needed at this time. CCW Fan #2B M.P. 351 – 354 W e note an increasing trend in Front Fan Bearing Since we are in the range between Inspect and FTF (Cage Defect frequency) vibration. We have Repair, we will conduct some diagnostics to verify a June, 2011 Repair Date with 90% Prediction the prediction. Although the vibration level is Confidence. “Low” (0.02 ips), the trend is significant, and you should begin planning to replace this bearing during the April outage. CCW Fan #1B M.P. 355 – 358 Accelerometers have been removed from the We will reinstall these at our next opportunity. fan. Nitrogen Gen. Air Compressor #1 M.P. 359 – 362 No problems noted. No action needed at this time. Nitrogen Gen. Air Compressor #2 M.P. 363 – 366 Not running. No action needed at this time. 6
Overall Summary
Trend Summary
M easurement Point Report n The current spectrum can be visually compared to the baseline.
M easurement Point Report n Trends of individual trouble spots and time to maintenance estimates can be examined ...
M easurement Point Report n … and displayed. VANGUARD ENGINEERING, INC. PREDICTIVE MAINTENANCE REPORT Customer: Measurement Point No.: 353 Report Date: 12/01/10 Description: CCW Fan 2B - Front 2x10 -3 a c Fan FTF 1.79 Hz. c Prediction Confidence = 90 % e l REPAIR e r 06/08/11 1x10 -3 a t i o n g INSPECT 09/21/10 05/10 08/10 11/10 02/11 05/11 08/11 11/11 02/12 05/12
Diagnosis n Use the existing M achine M odel to aid diagnosis
Summary
Vanguard Engineering Will … 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.
Vanguard Support Services 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.
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