Sample Vibration Assessment Analysis Report.pdf

7/28/2019 Sample Vibration Assessment Analysis Report.pdf

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Sample Predictive Maintenance Report

Vibration Assessment Analysis

12857 E. Independence Blvd., Suite F

Matthews, North Carolina 28105

800-532-0415

www.ISIservesYOU.com


2/10

August 17, 2006

ABC Company123 Street

Anywhere, USA

Dear Sir:

Subject: Baseline vibration testing of both Gypsum Bleed Pumps and both Mist Eliminator Pumps.

Part 1: Gypsum Bleed Pumps

Abstract

ISI was contacted to perform baseline vibration testing on the Gypsum Bleed Pumps (AB-P4031A/B)under full load conditions on August 15

thand 16

th. It should be noted that both pumps were using

water as process fluid vice slurry, as would be during normal operation. While no condemning

problems were recorded on either machine, the A unit has a very early stage defect on both of themotor bearings while the B unit has an early-to-mid stage race defect on the pump non-drive end

(NDE) bearing.

Data and Analysis

I Gypsum Bleed Pump A (AB-P4031A)

A Motor Condition

1) Baseline vibration data collected on the motor test points indicates a very early stage outer

race defect on both of the motor bearings. The levels of impacting are so low that thedefect is probably not yet visible to the naked eye (FIGURE 1). One possible cause may

be false brinnelling, a condition caused by ambient vibration on a stationary ball bearing

which leaves impressions of the rolling elements on the outer raceway. False brinnelling

typically occurs, for example, when a motor is shipped on a tractor trailer or stored in a

warehouse without adequate vibration isolation or without the shaft being rotated by hand.

2) Belt condition and pulley alignment appears to be satisfactory.

B Pump Condition

1) No significant bearing defects, imbalance, cavitation, or other hydraulic problems werenoted. There was an anomaly with the discharge pipe expansion joint that was causing a

loud noise and elevated broadband vibration which transmitted back to the pump bearing

housing. This may be due to air trapped in the system causing pressure pulsationscombined with the fact that the process fluid used for the test was water vice slurry.

12857 E. Independence Blvd, Suite FMatthews, NC 28105

(800) 532-0415Fax: (704) 893-0173

www.ISIservesYOU.com


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z Page 2 August 17, 2006

Regardless, no immediate corrective actions are required until data can actually be

collected with slurry being pumped. Discharge pressure was 16 psig +/- 1 psig.

II Gypsum Bleed Pump B (AB-P4031B)

A Motor Condition

1) No significant vibration problems were observed on any of the motor test points. No

corrective actions are required.

2) Belt condition and pulley alignment appears to be satisfactory.

B Pump Condition

1) Noted a moderate amount of metallic impacting occurring on the pump bearing housing,particularly on the NDE bearing (FIGURE 2). Levels appear to be about 4 times higher

than those recorded on the A pump. The pump was run for an hour and bearing

temperature did not exceed 128 F, which is well within specification (temperatures

greater than 180 F would have been considered problematic and indicative of alubrication issue). A stethoscope was used to listen to both pump bearings and an

unmistakable, though muffled, mechanical clicking sound could be detected from the

NDE bearing. The actual confirmation of this suspected bearing defect as well as theseverity requires knowledge of the bearing manufacturer name and model number.

Discharge pressure was 16 psig +/- 1 psig.

Recommendations

Gypsum Bleed Pump A: Continue monitoring the bearing defects on the motor with

vibration spectrum trending. No immediate corrective action is required.

Gypsum Bleed Pump B: Provide ISI with the pump bearing manufacturer and model

number to verify the defect on the NDE bearing. Perform additional vibration trending todetermine if the fault is worsening. Also, check bearing preload and endplay to ensure the

bearing is not slightly bound or cocked.


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R

outeWaveform

15-Aug-0609:02:14

RMS=.3422

PK(+/-)=1.11/1.15

CRESTF=3.37

0

100

200

300

400

500

600

700

-1.5

-1.0

-0.50

0.5

1.0

1.5

T i m e

i n m S e c s

AccelerationinG-s

ABP4031A

MOH

MotorOutbrdHoriz

R

outeSpectrum

15-Aug-0609:02:14

O

VERALL=.0379V-AN

PK

=.0394

LOAD=100.0

RPM=1796.(29.94Hz)

0

500

1000

15

00

2000

0

0.005

0.010

0.015

0.020

0.025

0.030

Frequ

encyinHz

PKVelocityinIn/Sec

Freq:

Ordr:

S p e c :

91.87

3.069

0 0 2 7 5


5/10

R

outeWaveform

16-Aug-0610:56:37

(PkVue-HP1000Hz)

RMS=2.33

PK(+)=6.98

CRESTF=3.00

DCoff=0.0

0

0.4

0.8

1.2

1.6

012345678

T i m e

i n S e c o n d s

AccelerationinG-s

ABP4031B

POPPumpOutbrdHoriz(PKVUE)

R

outeSpectrum

16-Aug-0610:56:37

(PkVue-HP1000Hz)

O

VERALL=1.17A-AN

RMS=.9621

LOAD=100.0

RPM=1075.(17.92Hz)

0

100

200

300

400

500

00.1

0.2

0.3

0.4

0.5

Frequ

encyinHz

RMSAccelerationinG-s

Freq:

Ordr:

S p e c :

135.67

7.572

3 6 7


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Part 2: Mist Eliminator Pumps

Abstract

ISI was contacted to perform baseline vibration testing on the Mist Eliminator Pumps (MW-P4001A/B) under full load conditions on August 15

thand 16

th. Both units have similar problems with

excessive vibration on the motor due to softfoot amplified by natural frequency problems with thebaseplate support. The pumps themselves appeared fine.

Data and Analysis

III Mist Eliminator Pump A (MW-4001A)

A Motor Condition

1) Baseline vibration testing indicated excessive amplitudes of a vibration occurring at 120

Hz on several motor test points (FIGURE 3). While the motor was running, one of the

motor foot hold down bolts was slightly loosened and a significant decrease was observed

in overall vibration level. This is indicative of a softfoot condition due to either a defectwit the motor feet or the baseplate being warped or twisted slightly. When the hold down

bolt is tightened, it smashes the motor foot flat on the base and contorts the stator frame,

resulting in an uneven air gap between the rotor and stator. This uneven air gap causes avibration to occur at twice line frequency, or 120 Hz. The highest reading observed was

0.47 inches/second (IPS) on the motor DE bearing, axial plane. Efforts to check the

alignment of the unit and shim the softfoot were unsuccessful, sometimes resulting in evenhigher levels. The alignment itself was ruled out as a problem when the motor was run

uncoupled and no change was observed in the motor vibration. Furthermore, a bump

test was performed on the motor to determine where the system natural frequencies were.

It was discovered the natural frequency of the motor was within 10% of 120 Hz in all 3

test planes (FIGURE 4). This means that if a forcing function (such as softfoot) causes avibration to appear within 10 15% of the observed natural frequency, this vibration can

become significantly amplified in the manner of a tuning fork being struck. A bump testwas also performed on the motor with the inboard left hold down bolt loose. Not only did

vibration levels decrease by half, but the natural frequency shifted left and away from thesoftfoot vibration at 120 Hz (FIGURE 5). That is to say, the amplification factor was

removed by changing the stiffness of the system. Long term operation in this condition

without corrective action may result in excessive motor operating temperatures and

premature failure of the motor bearings.

B Pump Condition

1) No significant bearing defects, imbalance, cavitation, or other hydraulic problems were

noted. Discharge pressure was 88 psig.


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IV Mist Eliminator Pump B (MW-4001B)

A Motor Condition

1) The baseline vibration condition and analysis of this unit is nearly identical to the Apump, except for the high vibration being located only in the horizontal plane instead of

the vertical and axial as well (as with the A motor). The highest reading recorded was0.41 IPS on the motor NDE bearing, horizontal plane.

B Pump Condition

1) No significant bearing defects, imbalance, cavitation, or other hydraulic problems were

noted. Discharge pressure was 88 psig.

Recommendations

Recommend using a machinists level to ensure the baseplate is flat in width and length,

particularly where the motor feet sit. Flatness should be within 0.002 inches/foot. Machine

the surface as necessary to achieve this standard.

Fill the baseplate in with non-shrinking grout and allow to cure before making any further

adjustments. Contact the pump vendor for further assistance on this, or consult a foundation

specialist. Additional modifications to the foundation may be necessary to have the desired

effect on the natural frequency and ultimately the overall vibration level.

Verify the motor feet sit flat on the baseplate and use a dial indicator mounted to the baseplate

and contacting the motor shaft to determine if softfoot exists. Repair as necessary.

Perform vibration acceptance testing on the motors both uncoupled and coupled to determine

the effectiveness of the repair.

Please feel free to call if there are any questions regarding this analysis and thank you for letting ISI

service your facility.

Respectfully,

Frank T. Vereb

Predictive Maintenance EngineerInstrumentation Services, Inc.


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R

outeWaveform

16-Aug-0614:18:14

RMS=.5299

PK(+/-)=1.08/1.07

CRESTF=2.03

0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

-1.2

-0.8

-0.4

0.0

0.4

0.8

1.2

T i m e

i n S e c o n d s

AccelerationinG-s

MW

P4001A

EL1

Mot

orInbrdHoriz(ELECTRICA

L)

R

outeSpectrum

16-Aug-0614:18:14

O

VERALL=.3762V-AN

PK

=.3566

LOAD=100.0

RPM=3574.(59.56Hz)

60

80

100

120

140

160

180

00.1

0.2

0.3

0.4

0.5

Frequ

encyinHz

PKVelocityinIn/Sec

Freq:

Ordr:

S p e c :

119.98

2.014

3 5 6


9/10

A

nalyzeWaveform

16-Aug-0614:31:12

RMS=.0233

PK(+/-)=.1921/.1634

CRESTF=8.24

0

100

200

300

400

500

600

700

800

-0.24

-0.16

-0.08

00.08

0.16

0.24

T i m e

i n m S e c s

AccelerationinG-s

MW

P4001AM

IA

MotorInbrdAxial

A

nalyzeSpectrum

16-Aug-0614:31:12

(PeakHold)

PK

=.0384

LOAD=100.0

RPM=3565.(59.42Hz)

0

100

200

300

400

500

0

0.005

0.010

0.015

0.020

Frequ

encyinHz

PKVelocityinIn/Sec

Freq:

Ordr:

S p e c :

111.83

1.882

0 2 0 5 8


10/10

A

nalyzeWaveform

16-Aug-0614:48:10

RMS=.0591

PK(+/-)=.3639/.3180

CRESTF=6.16

0

100

200

300

400

500

600

700

800

-0.4

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

0.4

T i m e

i n m S e c s

AccelerationinG-s

MW

P4001AM

IA

MotorInbrdAxial

A

nalyzeSpectrum

16-Aug-0614:48:10

(PeakHold)

PK

=.0521

LOAD=100.0

RPM=3565.(59.42Hz)

0

100

200

300

400

500

0

0.005

0.010

0.015

0.020

0.025

0.030

Frequ

encyinHz

Freq:

Ordr:

S p e c :

96.91

1.631

0 3 3 6 8

Documents

Sample Vibration Assessment Analysis Report.pdf