Page 23 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

List of Lessons Learned
3.4: Failure to limit piston speed in non-lube reciprocating 4.3: Avoid the use of three bearing systems in high torque
applications results in low MTBFs. reduction gears.
3.5: Failure to address pulsation problems has resulted in 4.4: Gears can experience high vibration during start-up.
safety and reliability issues. 4.5: Integral gear compressor bearings are highly loaded and
3.6: Using high speed reciprocating applications has resulted require centerline shaft position monitoring.
in $MM in lost revenue and maintenance costs. 4.6: Oil lubricated gear couplings can require yearly PM
3.7: Do not use lubricated screw compressor types in sour checks if PDM is not practiced.
gas services. 4.7: The majority of hydraulic coupling slip incidents are
3.8: Horizontal split centrifugal compressors with top caused by liquid accumulation.
nozzles extend maintenance times. 4.8: High vibration has occurred due to shaft end thermal
3.9: Failure to review for impeller/blade experience reduces axial growth calculation errors.
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reliability and revenue. 4.9: / 4 " per foot tapers have caused catastrophic coupling
3.10: Failure to limit head per impeller reduces safety, failures.
reliability and revenue. 4.10: Installing a hydraulic coupling with ‘O’ rings installed
3.11: Avoid the flat centrifugal (low head rise) compressor can cause coupling slippage.
characteristic curves.
3.12: Avoid operating individual impellers more than 20% Chapter 5 Steam Turbine Lessons
greater than their rated flow. Learned
3.13: Require new curves if gas density changes more than
+/- 20% from specified values. 5.1: Failure to properly specify steam conditions has led to
3.14: When performance and phase angle are not monitored, low power output and erosion.
fouling cannot be detected. 5.2: Fouling and steam conditions which are lower than
3.15: The use of low solidity diffusers (LSD) has resulted in anticipated can result in lost revenue.
severe production reductions. 5.3: The use of prototype blading has resulted in costly blade
3.16: Integral geared compressors have lower reliability than failures.
between bearing compressors. 5.4: Failure to trend ‘after first stage’ pressure will result
3.17: Integral geared failures can result from intercooler reduced power and vibration.
performance deterioration. 5.5: Failure to screen for shaft stiffness has resulted reduced
3.18: Sub-sync vibration and critical speed issues occur when
field reliability.
the shaft stiffness ratio > 10. 5.6: Lemon bore or offset sleeve bearings have caused
3.19: The use of lemon bore or offset sleeve type bearings has
extended FAT test periods.
caused vibration issues. 5.7: Many impulse steam turbines have encountered high
3.20: Increase displacement alarm/ trip settings if the bearing thrust bearing pad temperatures.
pad temperature <108 C. 5.8: Failure to monitor gland condenser vacuum has caused

3.21: Check balance device conditions before changing thrust contamination of oil systems.
bearing assemblies. 5.9: Most special purpose turbine gland sealing systems fail
3.22: Require bushing seals with ‘flow through’ feature in high and cannot be repaired on-line.
pressure applications. 5.10: Specific machinery unit field testing is not cost effective
3.23: Dry gas seal reliability issues result from end user lack of and should not be accepted.
proactiveness.
5.11: Uncoupled overspeed trip checks expose personnel to
3.24: Low solidity diffusers (LSDs) can reduce product injury.
revenue.
5.12: Failure to exercise trip valves has resulted in
3.25: Vacuum shop tests do not completely confirm catastrophic machinery failure.
centrifugal compressor acceptability. 5.13: Efficiency calculations will be erroneous when
3.26: Using the aftercooler for recycle gas heat removal torquemeters are not installed.
reduces surge system response. 5.14: Single stage turbine steam seal systems are ineffective
3.27: 80% of component failure root causes are contained in and contaminate oil systems.
process changes. 5.15: Single stage, turbine, lube oil pump drive governor
3.28: Failure to consider sufficient drive system capability linkage has caused unit tips.
reduces revenue and reliability.
5.16: Keeping hand valves closed in critical services has
resulted in process unit ESDs.
5.17: Failure to exercise single valve steam turbines has led to
Chapter 4 Gear and Couplings critical train trips.
Lessons Learned
Chapter 6 Gas Turbine Lessons
4.1: Planetary gears require many additional gears and Learned
bearings which lowers reliability.
4.2: Damaging gearbox flooding can occur at pitch line 6.1: Aero-derivative types now have reliabilities equal to or
velocities > 6,000 meters/min. greater than industrial types.

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