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7/30/2019 Failure Analysis Case Studies by Using Vibration Analysis T~
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Failure Analysis Case Studies by using Vibration Analysis
Technique
1- Bearing Premature Fatigue
Problem Initiation and definition :
The problem was initiated by the operator. He noticed that high vibration
level was sensed by human sense. Vibration measurements were carried out
by condition monitoring engineer as he received the order.
Measuring procedures and used instrumentations :
The condition monitoring engineer select the measuring point which is near
to the expected fault. An axial vibration data ware collected using
piezoelectric accelerometer mounted with magnet. The accelerometer have
the following characteristics ( natural frequency F= 200 order 0f the
machine rotational speed, the accelerometer sensitivity = 100 mV/g) The
accelerometer signal was sent to the CSI model 2120 equipped condition
monitoring and diagnosis programs.
Analysis:Bearing outer race defect was detected in the 4th mode as indicated from
the time signal and FFT plot where BPFO was presented at 12.21 order
according the bearing type and it needs to be changed As Soon As possible.
This defect resulted from
excessive axial load causes edge loading and overstressing of the raceway
and result in premature fatigue. This is easily recognized as the damage is
clearly restricted to one side..
Follow Up:After changing the bearing and revising the assembly . the problem was
disappeared where vibration measurements identical to that described in
Measuring procedures and used instrumentations were carried out.
7/30/2019 Failure Analysis Case Studies by Using Vibration Analysis T~
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WAVEFORM DISPLAY15-Jul-99 10:03:42RMS = 4.89
PK(+) = 14.75PK(-) = 18.71CRESTF= 3.83
0 100 200 300 400 500 600
-25
-20
-15
-10
-5
0
5
10
1520
Time in mSecs
AccelerationinG-s
CF ALARM
CF ALARM
PK ALARMPK ALARM
SPIN - FINISHING HOLDER
HOLDER#16 -IHA INNER BRG.HOLDER AXIAL (HIGH FRQ)
Label: Befor e changing the bearing
ROUTE SPECTRUM15-Jul-99 10:03:42
OVRALL= 36.75 V-DGPK = 36.51LOAD = 100.0RPM = 507.RPS = 8.44
0 100 200 300 400 500 600 700 800
0
2
4
6
8
10
12
14
1618
Frequency in Hz
PKV
elocityinmm/Sec
Freq:
Ordr:Spec:
103.13
12.213.648
>SKF 61836M AE=BPFO : 102.5
E E E E E E E
WAVEFORM DISPLAY
22-Jul-99 08:49:03RMS = .3284PK(+) = 1.39PK(-) = 1.16CRESTF= 4.23
0 100 200 300 400 500 600 700
-2.0
-1.5
-1.0
-0.5
0
0.5
1.0
1.5
2.0
Time in mSecs
AccelerationinG-s
CFALARM
CF ALARM
PK ALARM
PK ALARM
SPIN - FINISHING HOLDER
HOLDER#16 -IHA INNER BRG.HOLDER AXIAL(HIGH FRQ)
Label: After changing the bearing
ROUTESPECTRUM22-Jul-99 08:49:03
OVRALL= 6.73 V-DGPK = 6.70LOAD = 100.0RPM = 430.RPS = 7.16
0 100 200 300 400 500 600
0
2
4
6
8
10
12
14
1618
Frequency in Hz
PKVelocityinmm/Sec
Freq:Ordr:Spec:
7.125.9955.086
7/30/2019 Failure Analysis Case Studies by Using Vibration Analysis T~
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2- Bearing Fatigue
Problem Initiation and definition :
The problem was initiated by the PM Craw. They noticed that high vibration
level was sensed by human sense. Vibration measurements were carried out
by condition monitoring engineer as he received the order.
Measuring procedures and used instrumentations :The condition monitoring engineer select the measuring point which is near
to the expected fault. An axial vibration data ware collected usingpiezoelectric accelerometer mounted with magnet. The accelerometer have
the following characteristics ( natural frequency F= 200 order 0f the
machine rotational speed, the accelerometer sensitivity = 100 mV/g) The
accelerometer signal was sent to the CSI model 2120 equipped condition
monitoring and diagnosis programs.
Analysis:Bearing outer race defect was detected in the 4th mode as indicated from
the time signal and FFT plot where BPFO was presented at 12.1order
according the bearing type and it needs to be changed As Soon As possible.
This defect resulted from
excessive axial load due to severe looseness causes general outer race
annular damage.
..
Follow Up:After changing the bearing and revising the assembly . the problem was
disappeared where vibration measurements identical to that described in
Measuring procedures and used instrumentations were carried out.
7/30/2019 Failure Analysis Case Studies by Using Vibration Analysis T~
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WAVEFORM DISPLAY15-Jul-99 10:03:42RMS = 4.89
PK(+) = 14.75PK(-) = 18.71CRESTF= 3.83
0 100 200 300 400 500 600
-25
-20
-15
-10
-5
0
5
10
1520
Time in mSecs
AccelerationinG-s
CF ALARM
CF ALARM
PK ALARMPK ALARM
SPIN - FINISHING HOLDER
HOLDER#16 -IHA INNER BRG.HOLDER AXIAL (HIGH FRQ)
Label: Befor e changing the bearing
ROUTE SPECTRUM15-Jul-99 10:03:42
OVRALL= 36.75 V-DGPK = 36.51LOAD = 100.0RPM = 507.RPS = 8.44
0 100 200 300 400 500 600 700 800
0
2
4
6
8
10
12
14
1618
Frequency in Hz
PKV
elocityinmm/Sec
Freq:
Ordr:Spec:
103.13
12.213.648
>SKF 61836M AE=BPFO : 102.5
E E E E E E E
WAVEFORM DISPLAY
29-Jun-02 11:51:45
RMS = 7.27
PK(+) = 19.50
PK(-) = 20.49
CRESTF= 2.82
0 50 100 150 200 250 300 350 400
-25
-20-15
-10
-5
0
5
10
15
20
Time in m Secs
A
ccelerationinG-s
CF ALARM
CF ALARM
PK ALARMPK ALARM
Spin - FINSHING HOLDER
HOLDER#17 -UOA UPPER BRG.HOLDER AXIAL(HIGH FRQ)
Lab el: BEFORE CHANGING THE BEARING
ROUTE SPECTRUM
29-Jun-02 11:51:45
OVRALL= 38.49 V-DG
PK = 38.38
LOAD = 100.0
RPM = 626.
RPS = 10.44
0 200 400 600 800 1000
0
3
6
9
12
15
18
21
24
27
30
Frequency in Hz
PK
Velocityinmm/Sec
Freq:
Ordr:
Spec:
126.25
12.10
4.069
>SKF 61836MA
E=BPFO : 126.6
E E E E E E E
7/30/2019 Failure Analysis Case Studies by Using Vibration Analysis T~
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WAVEFORM DISPLAY
30-Jun-02 16:13:32RMS = 1.11PK(+) = 6.42
PK(-) = 6.42CRESTF= 5.77
0 100 200 300 400 500 600
-8
-6
-4
-2
0
2
4
6
8
Time in mSecs
Acce
lerationinG-s
CF ALARM
CF ALARM
PK ALARM
PK ALARM
Spin - FINSHING HOLDER
HOLDER#17 -UOA UPPER BRG.HOLDER AXIAL(HIGH FRQ)
Labe l: AFTER CHANGING THE BEARING
ROUTE SPECTRUM30-Jun-02 16:13:32
OVRALL= 20.01 V- DG
PK = 19.92LOAD = 100.0RPM = 565.
RPS = 9.42
0 100 200 300 400 500 600 700 800
0
3
6
9
12
15
18
21
24
27
Frequen cy in Hz
PKVeloci
tyinmm/Sec
Freq:Ordr:Spec:
9.375.9955.998
B=1X HARMONIC
: 9.42
BBBBBBBBBBBB
7/30/2019 Failure Analysis Case Studies by Using Vibration Analysis T~
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3- Coupling Fatigue
Problem Initiation and definition :
The problem was initiated by the maintenance groupe. They noticed that
high vibration level was sensed by human sense. Vibration measurements
were carried out by condition monitoring engineer as he received the order.
Measuring procedures and used instrumentations :The condition monitoring engineer select the measuring point which is near
to the expected fault. An axial vibration data ware collected using
piezoelectric accelerometer mounted with magnet. The accelerometer havethe following characteristics ( natural frequency F= 200 order 0f the
machine rotational speed, the accelerometer sensitivity = 100 mV/g) The
accelerometer signal was sent to the CSI model 2120 equipped condition
monitoring and diagnosis programs.
Analysis:Coupling defect was detected in the 4th mode as indicated from the time
signal and FFT plot where it was presented at 8order and 1 order in the axial
direction in the radial direction according the coupling type where the
coupling have 8 jaws and it needs to be changed As Soon As possible. This
defect can be attributed to misalignment of coupling jaws causes edge
loading and overstressing of the coupling jaws and result in premature
fatigue. Coupling defect frequency exists with rotating speed modulation
due to coupling excessive wear. Action must be taken is to adjust the
alignment and change the coupling.
Follow Up:
After adjusting the alignment and changing the coupling . the problem wasdisappeared .
7/30/2019 Failure Analysis Case Studies by Using Vibration Analysis T~
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VWP - VERTICAL WATER PUMP
PUMP#B -P1V INPUT SHAFT INB.BRG.VER.
Label: Before changing the coupling
Route Spectrum29-Jan-03 14:17:35
OVRALL= 12.70 V-DGPK = 12.65LOAD = 100.0RPM = 1488.RPS = 24.79
0 400 800 1200 1600 2000
0
1
2
3
4
5
6
7
8
Frequency in Hz
PKVelocityinmm/Sec
Freq:Ordr:Spec:
198.368.0006.221
L=Coupling frq: 198.3
L L L L L L
VWP - VERTICAL WATER PUMP
PUMP#B -P1V INPUT SHAFT INB.BRG.VER.
Label: After changing the coupling
Route Spectrum05-Feb-03 11:45:27
OVRALL= 5.80 V-DGPK = 5.80LOAD = 100.0RPM = 1493.RPS = 24.89
0 400 800 1200 1600 2000
0
1
2
3
4
5
6
7
8
Frequency in Hz
PKVelocityinm
m/Sec
Freq:Ordr:
Spec:
199.118.000
.275
L=Coupling frq: 199.1
L L L L L L
7/30/2019 Failure Analysis Case Studies by Using Vibration Analysis T~
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7/30/2019 Failure Analysis Case Studies by Using Vibration Analysis T~
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4- Impeller Wear
Problem Initiation and definition :The problem was initiated by the operator and from the pump performance.
They noticed that high vibration level was sensed by human sense. Vibration
measurements were carried out by condition monitoring engineer as he
received the order.
Measuring procedures and used instrumentations :
The condition monitoring engineer select the measuring point which is nearto the expected fault. An radial vibration data ware collected using
piezoelectric accelerometer mounted with magnet. The accelerometer have
the following characteristics ( natural frequency F= 200 order 0f the
machine rotational speed, the accelerometer sensitivity = 100 mV/g) The
accelerometer signal was sent to the CSI model 2120 equipped condition
monitoring and diagnosis programs.
.
Analysis:The defect was detected in the 4th mode as indicated from the time signal
and FFT plot . It was presented at 1order in the radial direction and it needsto be changed As Soon As possible. This defect can be attributed to Severe
pitting on the pump impeller due to corrosion erosion and chemical water
effect. Action must be taken is to adjust the alignment and change the
coupling. Sub-synchronous vibrations due to impeller wear which exits
structure resonance. Change the pump impeller and recoat it with the
ceramic coating.
Follow Up:The lifetime of the impeller was extended and the Sub-synchronous
vibration was disappeared after changing the impeller.
7/30/2019 Failure Analysis Case Studies by Using Vibration Analysis T~
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VWP - VERTICAL WATER PUMP
PUMP#A -MOH AC MOTOR OUTB.BRG.HO .
Label: Before changing the impeller
Route Spectru m18-Oct-01 12:08:35
OVRALL= 15.59 V-DGPK = 15.56LOAD = 100.0RPM = 1493.RPS = 24.88
0 50 100 150 200 250 300 350 400
0
2
4
6
8
10
12
Frequency in Hz
PKVelocityinmm/Sec
Freq:Ordr:Spec:
25.001.0058.558