Post on 09-Jan-2016
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WEB DEFLECTION ANALYSIS
AND
THE USE OF WEBMAPSOFTWARE
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OUTLINE
A WEB DEFLECTION SURVEY IS.. WHY RUN WEB DEFLECTIONS TOOLS AND TECHNIQUES WEBMAP DEVELOPMENT CASE HISTORIES DEMONSTRATIONS: SOFTWARE
and HARDWARE
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A WEB DEFLECTIONSURVEY IS:
MEASURING CRANKSHAFT WEBFLEXURE AS A FUNCTION OFCRANK ROTATION
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WHY CONDUCT A SURVEY
REALIGNMENT / MAJOR REPAIR ROUTINE MECHANICAL
INSPECTION
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Repairing Block Separation
Courtesy: Adhesive Services
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CRANKSHAFT BEHAVIOR
Large crankshafts are flexible Can sag 60+ mils from gravity Crankshaft assumes frame shape
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Courtesy: Clark Bros Co.
FACTORY ASSEMBLY: TCV-16
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FINAL GRIND
Courtesy: Fusion, Inc.
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CRANKSHAFT BEHAVIOR Bending takes
place primarilyin the webs!
Web acts like ahinge
Max stressesoccur at thefillets
Apparent hinge points
Location of max stress
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WEB DEFLECTION MECHANICS If the bearings in a machine are not precisely
aligned, the crankshaft webs will move fartherapart or closer together as the crankshaft isrotated.
Bearings alignedweb deflection zero
Bearings misalignedwebs closer togetherwith pin up
Bearings misalignedwebs farther apartwith pin down
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Courtesy: Philadelphia Resins
GAS PLANT COMPRESSOR
DONT
I
WISH!
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KING RANCH GAS PLANT TLA-8
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Clark Cross-section
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DISTORTION GAGE BETWEEN WEBS
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THE WEB DEFLECTION ISOVER THE LIMIT !!
TheSuperintendentis going to killme!
Easy, Now,Dont Panic.
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GET AN ACTION PLAN !
Check tools/ Rerun survey. Suspect bad bearings before
suspecting distorted frame. Check bearing clearances. Replace bearings as necessary. A bent crankshaft is rarely the
cause of excessive deflections.
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The Web Deflection Survey
Tools Techniques Recording the data (Forms to use) Units (Inches, Mils, MM, Whatever) Maximum Limits
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TOOLS FOR THE SURVEY
INSIDE MICROMETER STARRETT DISTORTION GAUGE INDIKON ELECTRONIC GAUGE LASER ALIGNMENT KIT
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INSIDE MICROMETER
USED BY DRESSER-RAND CAN REACH BETWEEN VEE RODS SLOWER AND MORE DIFFICULT
THAN USING A DISTORTIONGAUGE
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STARRETT DISTORTIONGAUGE
TRADITIONALLY RECOMMENDED SUBJECT TO SOME UNCERTAINTY FULLY ADEQUATE
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DISTORTION GAGE AND EXTENSIONS IN BOX
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STARRETT TECHNIQUES
USE FACTORY POINTS AVOID BENT EXTENSIONS REVIEW ACCURACY
PERIODICALLY USE CARE REGARDING PUNCH
MARK INDENTIONS
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INDIKON ELECTRONIC
VERY HIGH RESOLUTION SOMEWHAT COMPLICATED PROVIDES ANGULAR DATA RECOMMENDED, BUT IS NOT
NECESSARY WHEN USINGWEBMAP
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LASER ALIGNMENT KIT
THEORETICALLY EXCELLENT NOT YET DEVELOPED AS AN
APPLICATION DETECTS OFFSET AS WELL AS
ANGULAR MISALIGNMENT
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FACTORS AFFECTING DATA Condition of the Tools Positioning of the Tool Temperature of the Engine Temperature of the Instrument Condition of the Punch Marks Extensions: Bolts or
Counterweights
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EXTENSIONS
RECORD EXTENSION LENGTHS DO NOT RECORD CORRECTED
READINGS AS DATA CORRECT FOR EXTENSION LATER WEBMAP CORRECTS READINGS
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Maximum Deflection Limits Three mils is about the number
you will hear for most largeengines (10 to 20 inches of stroke)
It is best considered a function ofthe stroke length
Traditional formula 0.18 mils /inch of stroke (Courtesy: CooperEnergy Services)
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Recording the Data
Do not use inches Make written marks in Mils Use a form for recording data Employ circles for the data, not a
table Show approximate angle for data
points
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This Many Inches Deflection?This Many WHAT?
0.00025 Inches, You say? 0.0025 Or was it this many? Uh...Well. It was about a quarter
of a mil. I was looking at it!
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INCIDENTAL DATA
DATE AND TIME ENGINE SUMP TEMPERATURE MECHANICAL CONSIDERATIONS COMPLETE IDENTIFICATION
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Typical Deflection Readings
As Viewed From Oil Pump End
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FILE The DATA
Keep a good file on location or atthe nearest field office.
Send a copy to the area engineer.
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WEBMAP DEVELOPMENT
EXXONS KING RANCH GASPLANT
ALIGNMENT PROBLEMS GROUT CREEP ASSISTED BY RAY JAMES CONVERTED TO PC BY GMRC
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Courtesy: Cooper Bessemer
THE QUESTION WEBMAP ANSWERS
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MATHEMATICAL BASIS
ASSUME A HARMONIC FUNCTION DEVELOP A SIMPLE ANALOGY INCLUDE ENGINE GEOMETRY THE RESULTS APPLY DIRECTLY
TO THE SHAFT, BUTINDIRECTLY TO THE FRAME
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APPLYING THE THEORY
CHOOSE A ZERO REFERENCE FIT WEB DEFLECTION DATA TO A
SINE FUNCTION FORMULA FOR CORRECTIONS FOR
EXTENSIONS RELATES ENTIRE SURVEY FOR
VERTICAL AND HORZ. PROFILES
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WEBMAP ANALYSIS
SCREENS FIELD DATA CORRECTS FOR EXTENSIONS EXTRAPOLATES FOR 360 DEGREES GENERATES A LONGITUDINAL
PROFILE OF THE INFERREDFRAME POSTURE
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EXAMPLES OF WEBMAP
KVR CASE CONFIRMS CRUCIALDATA
HRA CASE ILLUSTRATES HEATEFFECTS
OFFSHORE GMVA DATACONFIRMS FRAME DISTORTIONMEASUREMENTS
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INGERSOLL-RAND 3400 HP KVR
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CRANKSHAFT ALIGNMENTAND WEB DEFLECTIONS
WHY RUN A WEB SURVEY DOING SURVEYS RIGHT WHAT WEB SURVEYS REVEAL THEY WILL ALWAYS BE
NECESSARY
BUT...
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BUT...THE WEB SURVEY
IS ONLY AN INDIRECTINDICATOR OF FRAME ALIGNMENT
BEST PRACTICES CALL FORDIRECT MEASUREMENTS OFFRAME SETTING POSTURE ANDPOSITION?
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NEW SPLIT STEEL CHOCKS
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