Oil
pipelines are reassembled after acid cleaning is over.
Oil
tank and duplex filters are clean.
Oil
tank is filled to the required level with recommended oil. Oil should be filled
through filter
/centrifuge.
Oils of different quality / make should never be mixed. Follow OEM
Recommendation.
Oil
pipelines are disconnected from the bearings. The bearings are bypassed by
temporarily
interconnecting
the inlet and outlet lines of bearings using temporary loops.
Oil
lines are properly supported and all temporary supports are cut and removed.
Temporary
line filter of stainless steel mesh is provided in the return line before entry
to the tank to
avoid
entry of dirt into MOT of Hydraulic coupling.
Working
oil lines to working oil coolers disconnected at hydraulic coupling end and
temporary loops
made
as shown in the flushing scheme.
Temporary
connections, preferably of transparent hose which can withstand temperature as
high as
800 C, are made across the bearings.
Portable
centrifuge / electrostatic filtration unit is connected to the MOT of the
Hydraulic coupling.
Suction
of the unit is connected to the drain of MOT of Hydraulic coupling through
suitable hose and
discharge is left inside
the Hydraulic Coupling tank through inspection cover.
Required
instruments such as pressure and temperature gauges are calibrated and mounted
in the
system.
Temperature
of 65-750C to be
reached during oil flushing through centrifuge heaters.
With
MOT of Hydraulic tank already filled with recommended oil, AOP is bump started
to check the
direction
of rotation of the pump.
After
ensuring correct direction of rotation the AOP is run continuously and the
system is filled
gradually.
Oil
level in the tank is watched till oil flow is established throughout the
system. Oil is topped up, if
required.
The
system is checked for oil leakages and the leakages, if any, are attended.
Temperature
of oil is raised to 65-70 deg Celsius by using the heaters of centrifuge or by
external
heaters.
After
attaining the elevated oil temperature, heater is switched off and cooling
water is admitted in
the
cooler to suddenly bring down the oil temperature to get an effect of thermal
shock. Oil pipelines
are
also tapped with wooden hammers during the period of thermal shock.
Oil
temperature is again raised and thermal shock is given. Thermal shocks are
repeated till oil
flushing
is declared complete as per completion criteria.
The
working oil and lub oil circuits are flushed separately by making suitable
temporary connections.
Flushing
of lub oil circuit is done in sub stages by grouping lines of two to three
bearings ( to be
decided
at site ) by suitable isolation of lub oil supply lines to other bearings to
have adequate
velocity
in the pipelines for effective flushing .
The
filters are cleaned whenever there is an increase in differential pressure
across the filter beyond
0.5
kg/cm2 over the
normal value.
Periodicity
of oil sampling and filter inspection is mutually decided at site.
Oil
flushing of oil lines bypassing the bearings is declared complete based on
completion criteria.
Hydraulic
test of the pipelines is carried out at a pressure 1.5 times the working
pressure with the
help
of an external pump or the AOP itself. There should be NO leakage.
Temporary
bypass connections / blanks / dummies / are removed and the pipeline connections
with
the
bearings are normalized.
Flushing
of lub oil circuit with bearings included in the flushing circuit is started.
Flushing
through bearings is declared complete based on completion criteria.
The
oil used for flushing is drained and kept in safe custody. This oil can be used
for flushing in
other
units if the oil quality is found suitable. While using this used oil for
flushing in other units,
filling
should be done through centrifuge.
All
the bearings are inspected and cleaned.
Fresh
oil is filled in the system. Oil pump is run, flow through each bearing
adjusted and flow of
return
oil through each bearing ensured.
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COMPLETION
CRITERIA
The
flushed components are considered clean when the DP across the filter
stabilizes and does
not
rise more than 0.2 to 0.3 ksc over the normal value after eight hours of
continuous flushing.
Also
there should be NO deposition of hard particles in oil filters.
Mechanical
impurities ( through 0.45 micron filter ) and moisture content in the sample
collected
from
flushing oil should be each less than 100 ppm in three consecutive samples
taken at
intervals
of four hours.
Continued to last part BFP commissioning
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