Introduction to Basic Alignment

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INTRODUCTIONto

BASIC ALIGNMENT


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What is Machinery Alignment?

Collinear shaft centerlines undernormal operating conditions

Normal load, temperatures , pressures, flow


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Types of Misalignment

Offset(parallel)

Angular


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Types of Misalignment

Combination (Parallel and Angular)

Axial (couplinggap incorrect)


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Offset (Parallel) Misalignment

Vertical Plane


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Offset (Parallel) Misalignment

Horizontal Plane


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Angular Misalignment

Vertical Plane


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Angular Misalignment

Horizontal Plane


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Combined Misalignment

Vertical Plane


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Problems Caused ByMisalignment

High Axial / Radial Vibration

High Bearing TemperaturesBearing and Seal Wear / Failure

Coupling Wear / Failure


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Problems Caused ByMisalignment

Axial Misalignment

Coupling Gap Must Be Correct OrFlexible Element Will Fail

Shaft Cracks

Other (rubs, instability, etc.)


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High Axial / Radial Vibration

Vibration Behavior Depends On:

Amount and Type of MisalignmentCoupling TypeFoundation and Grouting ConditionSoft Foot and Casing Distortion


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High Bearing Temperatures

Preload: A Uni-directional Steady State F orce

Misalignment Can Significantly Increase

Bearing PreloadHigher PSI loading on Babbit Surface

Increased Friction

Heavily loaded bearings may exhibithigher than normal metal temperatures


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Bearing and Seal Wear /Failure

Fluid Film Bearings: Polishing Wiping

Rolling Element Bearings: Shortened Life Span


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Fluid Film Bearing Failure

Tilt-Pad Bearing With Localized Wiping


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Rolling Element BearingLife Calculation

L 10 =16,700 dynamic capacity x load rating

rpm FORCE

Hours of lifefor 10% failure rate

L 10 =

3


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Coupling Wear / Failure

Gear-Type Coupling

Problems Caused By Misalignment

Gear Tooth Failure


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Shaft Cracks


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Other Problems Cause ByMisalignment

High Unbalance Response Unloaded Bearing

Mechanical Looseness


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Misalignment Detection

Vibration Data

Shaft Average Centerline

PositionBearing Metal Temperatures


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Casing Expansion

Trend Data

Hot Alignment MonitoringInfrared Thermography


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Machinery Inspection

Maintenance History

Mechanical / MetallurgicalInspection of Components


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Misalignment Detection Contd

Axial and Radial Vibration (1X, 2X)

Orbits with High Degree ofPreloading

Abnormal Shaft Average Centerline

Position


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Vibration Data

High Axial Casing Vibration


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Vibration Data

Orbits With Increasing Preload From Misalignment

Figure 8 mayoccur at 1/2 ofany resonance


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Shaft Average Centerline Position

Preloaded Orbit and Corresponding Shaft Average Centerline Plot


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Bearing Metal Temperatures

RTD / ThermocoupleTypical Babbit Bearing Metal Temperature:

160 F to 180 F

A M etal Temperature Approachi ng 220 F M ayCause F ailure Of The Bearing (babbit melts at

260 F , but will move at 240 F )


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Use Trend Data During Loading Following A Cold Startup

Thermal Growth Changes Occur Vs. Time

Vibration Vs. Time Bearing Metal Temperatures Vs. Time


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Casing Expansion Unbound Axial and Radial Growth Dual Casing Expansion

Infrared Thermography Determine Local Temperatures


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Piping Hangers Should Not Oppose Thermal Growth Of

PipingExpansion Joints

Allow Relief For Thermal Expansion

Flange Bolts Check For Loose Or Broken Bolts


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Shims No More Than 3-4 Check For Rust, Paint, Looseness

Dowel Pins

Check For Loose, Damaged,Missing Pins


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Maintenance History Machine Reliability Repeated Failure of Components?

Alignment Readings Changes to Alignment


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Mechanical / MetallurgicalInspection Of Worn Components

Couplings

Bearings Seals


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Use and cor relate all information


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Introduction to Basic Alignment

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