INSTRUCTOR:
ROBERT A. MCLAUGHLIN
ZAILI THEO ZHAO
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MACHINERY ALIGNMENT &
VIBRATION ANALYSIS
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POWER
EQUIPMENT
LEARNING OBJECTIVES
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Understanding of the importance of accurate
alignment and benefits of vibration analysis on
rotating equipment
Identify the factors that must be considered prior to
any alignment job.
Identify the tools necessary for proper alignment.
Examine various power transmission couplings and
determine their applications and limitations.
Identify the types of misalignment found in rotating
machinery.
Identify allowable misalignment tolerance associated
with good alignment practices.
Examine the dial indicator method of alignment and
explain the “validity rule” and “repeatability”.
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COUPLINGS
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Couplings connect two shafts, end-to-end in the
same line, for two main purposes.
 Transmit power (torque) from one shaft to the
other, causing both to rotate in unison, at the
same RPM.
 Compensate for minor amounts of
misalignment.
 Are also sacrificial elements in some cases,
and are much less expensive to replace than a
crank shaft or rotor assembly.
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COUPLINGS - TWO TYPE OF COUPLINGS
Solid couplings
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Solid coupling have no tolerance for misalignment,
strictly for transmitting torque.
 Torque is transmitted by the friction between the
faces of the couplings
 Coupling bolts are torqued to 40,000 lb/in2 – this
elongates the bolt 1 ½ mils.
 The proper bolt torque is necessary to create the
necessary face friction.
 No lubrication is required
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COUPLINGS - TWO TYPE OF COUPLINGS
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Flexible couplings
Allow for flexible, random movement axial
movement, thermal expansion, and slight
misalignment between two shafts.
Flexible couplings are
classified as
Mechanical-Flexing
has components that move or
slide in relation to each other
to accommodate shaft
misalignment.
 Mechanical flexing couplings
require lubrication.
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COUPLINGS - TWO TYPE OF COUPLINGS
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Flexible couplings
Types include:
Chain, gear, grid and
pin type couplings
gear
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grid
disc
Chain
pin
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COUPLINGS
Diaphragm
Material Flexing
 uses a flexible material between the coupling
halves to accommodate misalignment.
 Common materials include metal, rubber, plastic, or
composite material.
 Material flexing couplings do not require lubrication.
 Types include:
 Spring
 Diaphragm
 flexible disc-ring
 Elastomer
Spring
Elastomer
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disc
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ELASTOMER COUPLING
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FUNCTIONS OF COUPLING
Connect/ disconnect
driver to driven
component.
 Allow slight
misalignment only
flexing type.
 Absorb shake - sacrificial
element.
 Torque transmission.
 Absorb vibration.
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WHY ALIGNMENT IS IMPORTANT
Proper alignment between the driver and the
driven equipment serves to:
 Reduce noise
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Misaligned equipment creates noise as it is running.
Vibration reduction
Prolong equipment life
Misalignment and vibration decreases bearing life
 It also reduces coupling life
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Reduces costs
It takes more power to drive misaligned equipment.
 it can increase energy cost by up to 12%
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POOR ALIGNMENT
Poor Alignment means:
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Premature bearing, seal, shaft and coupling failures
High Bearing and coupling temperatures
Excessive vibration
Looseness of foundation bolts.
The breaking (or cracking) of
shafts at, or
close to the
inboard
High power
consumption
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FACTORS TO CONSIDER PRIOR DOING
ALIGNMENT:
Consider the two components – which is easier
to move
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Driver – Motors, turbines, etc.
 Driven – Pumps, generators, etc.
 Jacking bolts may be welded to the foundations to assist
with the movement of the equipment.
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FACTORS TO CONSIDER PRIOR DOING
ALIGNMENT:
Stress Elimination – Piping must not create
any stress on the equipment.
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To test, disconnect pump suction and discharge piping.
 If the piping springs away from the pump when
disconnected, stress exists and can cause misalignment
when reconnected.
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FACTORS
Soft Foot – A condition that occurs when one
or more machinery feet do not make complete
contact with the base.
Soft foot can exist when the mounting plate is uneven from
rust or the plate is warped, or the machinery foot is warped
or rusted, or both.
 To correct, clean all surfaces, fasten the equipment solidly
with three mounting bolts, and then use a feeler gauge to
measure under the fourth foot.
 To level the equipment, you must put shims equal to the
feeler gauge thickness under this foot, or alternatively, you
can put an amount of shims equal to half the feeler gauge
thickness under the measured foot, and half under the foot
that is diagonally opposite the measured foot.
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FACTORS
Coupling Speed – Must be
known to determine the
allowable tolerance.
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As the speed of the machinery increases, the
acceptable misalignment decreases
Shaft thrust – you need to know if either of the
rotating components has thrust in order to
maintain the proper air gap
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Air gap - the space between the face of the couplings.
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FACTORS
Run out
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Before couplings can
be aligned, you must check both
shafts and couplings for run out.
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Shaft and coupling run out means that the motor or
pump shaft and coupling hub centerlines do not
lineup properly or the shaft and coupling centerlines
are non-colinear.
 Shaft and coupling run out
exceeding
.003˝ must be corrected
before couplings
can be aligned.
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FACTORS TO CONSIDER PRIOR DOING
ALIGNMENT:
Run out condition can be caused by:
Bent shafts
 Bad coupling bores- angular or parallel
offset bores
 Damaged coupling hubs or egg shaped hubs
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Note: Bad bearings may look like run out
but are simply bad bearing and will also
need replacement prior to doing an
alignment job.
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Feeler
TOOLS OF ALIGNMENT
Tools of alignment include anything that
will measure accurately to .001” or 1 mil.
Dial Indicators
 Feeler gauges
 Taper gauges
Taper
 Straight edge
 Dial Indicators
 Optical scopes
 Lasar units
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THREE TYPES OF
MISALIGNMENT:
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Parallel – the shafts
are parallel but the
centerlines are offset,
either vertically or
horizontal.
Angular – the faces are
uneven but the
centerlines intersect.
Combination of
parallel and angular –
this is the most common
situation that must be
corrected.
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TYPES OF
MISALIGNMENT
Place a straight edge firmly against the rim of one coupling
half
 Use feeler gauges to determine the gap between the
straight edge and the other coupling half rim.
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To correct parallel misalignment, you use what is known as the rim
method.
 The rim method consists of using the outer rim of
the coupling to correct the misalignment.
 Three ways of accomplishing:
 Straight edge and feeler gauges – a
straight edge can be use to for rough
alignment, then an indicator or laser can be
used to complete the alignment process.
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TYPES OF
MISALIGNMENT
Dial indicator
Clamp the dial indicator base to the shaft of the equipment
that will not be moved.
 Use dial indicator extension arms to allow the indicator to
measure the amount of misalignment. Be aware that if
extension arms are two long they can sag, which can lead to
inaccurate readings.
 Set the indicator at 0 in the 12 o’clock position.
 Take reading at the 3, 6, and 9 o’clock positions.
 For top to bottom parallel misalignment, determine how
many thousands the shafts are out of alignment. The actual
offset is equal to ½ the sum of the indicator readings.
 Same thing is done for up and down parallel
misalignment.
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TYPES OF MISALIGNMENT
Lasers – very accurate
alignment tool.
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TYPES OF MISALIGNMENT
Validity Rule
You should always rotate the indicator a full 360o of
rotation when taking readings.
 In some installations this may be difficult to achieve.
 The validity rule states that the sum of the right side
readings plus the left side readings should equal the
bottom reading (+-10%).
(left) + (right) = bottom + 0 (top)
 This is to check the accuracy of your indicator setup
and to also insure there is no excessive shaft or
coupling run out.
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TYPES OF MISALIGNMENT
To correct angular
misalignment-
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If the air gap is big enough,
the dial indicators can be
use as shown.
 If not, feeler gauges can be
used between the faces.
 With either method, the
readings and correction are
taken like the ones for
parallel misalignment.
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--- use Face--24
TYPES OF MISALIGNMENT
Repeatability
It is when you set up the
dial indicator to take reading at the 12 o’clock, 3
o’clock, 6 o’clock & 9 o’clock positions and you want to
insure the accuracy of your setup by rotating the
indicator around and repeating the zero reading on
the dial indicator at the top of the coupling.
 There is no point in trying to do the alignment process
if you have not eliminated soft foot or if you cannot
repeat zero at the top of the coupling.
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To correct parallel misalignment--- use Rim ---
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FIVE STEPS TO PROPER ALIGNMENT
2)
3)
4)
5)
Check and correct
for coupling ‘run out’.
Check and correct
for soft foot.
Check and fix
angular.
Check and fix
parallel vertically
Check and fix
parallel horizontal
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1)
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SUGGESTED ANGULAR ALIGNMENT
GUIDE
Excellent
mils per inch
Acceptable
mils per inch
600
1.5
2.5
900
1.
1.5
1200
.7
1.0
1800
.5
.7
3600
.3
.5
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RPM
1 mil = .001 in
Consult machinery manufacturer
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THREE THINGS
YOU NEED TO KNOW
When aligning rotating machinery there are 3
things you need to know
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Where is the machinery at when the equipment is
not running?
 What position will the machinery move to when
operating?
 If the machinery moves from off-line to running
conditions, what acceptable range of positions could
the machinery shafts be in when the machinery is
aligned off-line and still maintain acceptable
alignment tolerance during operation?
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Or simply… Where are they? Where will they go?
Where should they be?
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ALIGNMENT TOOL
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IMPORTANT
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Proper alignment takes time and patience to
accomplish but the results will be worth the
effort.
 Equipment will run quieter with less vibration
and operating budgets will be reduced.
 Equipment life expectancy can be significantly
increased and energy consumption can show a
significant decrease.
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THANK YOU
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