Page 595 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

Best Practice 1 1.2
Preventive and Predictive Maintenance Best Practices Best Practice 1 1.3
must be aware of the reliability program philosophy and must be significantly increase the reliability of general purpose (spared)
able to implement it. Having operators and machinists equipped equipment through the implementation of an effective pre-
and trained in the use of simple vibration instruments (vibration dictive maintenance program.
pens), oil condition monitors and laser temperature guns will

Best
Best Practice 11.2Practice 11.2
Maximize pump unit bearing bracket oil change intervals expose the plant to additional maintenance, shutdowns
by using the principles of component condition monitoring and do not increase reliability.
(CCM) to extend pump bearing bracket oil change intervals Comparison of pump MTBFs before and after bearing bracket oil
from 13 weeks to as much as 104 weeks. change intervals were increased from 13 weeks to over 100 weeks
The principle of component condition monitoring addresses the five shows higher MTBFs for the extended interval pumps.
major components of any type of machinery to completely monitor its
condition. (See B.P. 10.11 supporting material for details.) Benchmarks
Using these principles to trend rotor performance, bearing, seal and This best practice has been recommended since the late 1990s,
auxiliary system conditions, clients have extended the previous 13 following experience with a number of refinery machinery reliability
week oil change out time in 13 week intervals from 13 to 104 weeks! audits. Since that time, this best practice has produced pump MTBFs
The savings in manpower and materials was tremendous and the in excess of 100 months where they were less than 48 months prior to
exposure to reliability issues was significantly reduced. the extension of oil change intervals.
Lessons Learned
13 or 26 week pump unit bearing bracket oil change
intervals, when all component parameters are acceptable,

B.P. 11.2. Supporting Material
See B.P:11.1 for supporting material.

Best
Best Practice 11.3Practice 11.3
Optimize pump unit component MTBFs by changing over ‘New spare’ philosophy e operate started pump for four hours and
pumps every 3 to 6 months to minimize pump start-ups ‘CCM’ this pump unit
while ensuring stand-by pump unit availability.
Excessive pump start-ups expose components (especially me- Lessons Learned
chanical seals) to reduced MTBFs.
Most plants do not have or follow a specified pump changeover Plants that do not have an active and monitored pump
program. Many plants change over pumps frequently (as often as once changeover program experience significantly lower
per week) while other plants do not change over pumps on a regular MTBFs.
basis. I have never visited a plant where I was not asked my opinion of
We recommend that a pump changeover program be developed, pump changeover philosophy.
based on site pump wear experience. With the exception of firewater Discussion always resulted in a recommendation consistent with
(mandatory weekly operation) and seawater (frequent operation to the information in this B.P.
control corrosion) we recommend: Unfortunately, follow-up usually has shown mixed results in
The program initially require three month interval changeover implementation of the recommendations.
The three month interval be extended month by month based on
pump CCM (see B.P.10.11) Benchmarks
The length of operation of the started pump be determined by: This best practice has been recommended to all plants visited
Pump driver e if the main pump is steam turbine driven to prevent since the late 1980s. Where it has been followed, plant pump MTBFs
electrical shutdowns and the started pump is motor driven e have increased. There is an example of pump MTBFs being increased
operate for four hours and ‘CCM’ this pump unit from less than 36 months to over 70 months in a process unit where
Plant spare pump philosophy: the changeover program results are continuously monitored and
Equal wear philosophy e operate started pump for changeover implemented.
interval

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