Bearing Fault, Inner Race
Keystone Foods, North Baltimore, OH
BACKGROUND
Vibration surveys at this facility
are routinely performed at 6 month intervals on the
equipment. The compressor is a FES Model 800GL with a
1000 HP Siemens Motor. Baseline data was recorded on
this compressor in February 2002. The vibration data
collected on September 27, 2005 indicated a sharp
increase on the compressor bearing vibration.
RESULTS AND CONCLUSIONS
The detailed analysis of the data indicated a fault
had developed on the outer and inner race of the male
thrust bearing. Although the extent of the fault was not
known for certain, the increase suggested that a bearing
failure was pending. Due to the importance of this
machine to production, a field bearing replacement was
scheduled for December.
The photograph above was taken
of the bearing in question during the compressor
rebuild. The defects, in this case pitting and flaking,
can be clearly seen.
RECOMMENDATIONS
Proactively follow recommendations
on the report. This report recommended that a compressor
bearing replacement should be performed during an
up-coming convenient opportunity. This was completed in
December and although the defects increased, a
catastrophic bearing failure was avoided, thus reducing
downtime and repair cost.
Perform vibration surveys at 4-6
month intervals. If possible, start with a baseline
where the compressor is known to be in good condition.
Trending the data will improve the reliability of the
report. The more critical the machine is to plant
production, the more often it should be monitored.
Below is
the actual report filed on the #012 compressor. It
contains an explanation of the fault identified and
recommendations. The spectra plot is a comparison of the
same compressor just 7 months earlier.
The BPFO “Ball Pass
Frequency Outer Race” defect is appearing in the
spectrum with harmonics. Running speed harmonics
have also increased in the spectrum. This
indicates a fault on the thrust bearing and
possible wear on the sleeve bearings. The thrust
bearing is starting stage 3 of the 4-part
bearing failure scenario.
Recommendation:
Monitor closely for any
changes in noise or vibration. Consider
scheduling the compressor for bearing
replacement or overhaul during an up-coming
convenient opportunity. Perform an oil sample
analysis to determine if the looseness is coming
from the sleeve bearings. High tin and/or lead
levels indicate sleeve bearing wear. Perform
another vibration survey in 3-4 months to
determine rate of thrust bearing degradation.
