Installation and operating instructions Wilo
–
SCPV pumps
23
9.3 Disassembling the pump
9.3.1 Disassembling the top casing
(Refer Annexure-1)
Isolate the pump system by closing suction
and delivery valve.
Drain the pump and open the upper air
vent.
Remove the Bottom Bearing
Isolate the top and bottom half casing
Hold the top casing to the trolley / crane by
fixing screws and rest the top half.
Remove nuts of split gland from both ends
and slide away the gland. Remove gland
packing as well as logging ring.
Remove all split flange nuts and the two
dowel pins.
Connect suitable lifting tackle to the
eyebolts provided on the top half casing.
Remove the casing joint gasket. Withdraw
the casing top.
Note:
If the pump set is installed with a goal post
arrangement please refer Annexure 4
9.3.2 Dismantling the rotating element
(Gland pack version pump)
To completely dismantle the rotating element
proceed as follows :
Remove the coupling screws /nuts, for
coupling dismantling procedure refers
Support the rotor on jackscrew and clamps.
Stripping of rotating element
Take off the neck rings.
Remove sleeve nut & sleeve from Non-
driving end.
Remove the impellers. It may be necessary
to apply heat to the impeller for removal.
Apply heat uniformly from the shrouds
inwards towards the hub. Before removing
the impeller put a reference mark on the
shaft for ease of reassembly at correct
centre position.
Remove the drive end ball bearing using
some form of extractor or puller. This must
act directly on the inner race of the bearing
to be removed. Never try to remove the
inner race of the bearing by applying force
to the outer race.
Pull the mechanical seal carefully over the shaft
followed by removal of adjusting ring
Rest procedure is same as explained for gland
pack version pump
9.4 Examination of Internal Components
With the disassembled rotating element, the
internal components and clearances can be
checked
9.4.1 Casing neck ring
Use an internal micrometer to measure the bore of
casing neck ring, taking measurements at intervals
around the circumference to check for uneven wear.
A comparison between this dimension and that of
the impeller neck, will indicate the amount of
diametrical clearance between the casing neck ring
and the impeller neck.
9.4.2 Shaft Sleeves
The shaft sleeve should be examined to see if it is
grooved or generally worn. The outside diameter of
the sleeve should be measured and a comparison
made with the bore of the
stuffing box bush through which the sleeve passes.
The amount of clearance between the two can
thus be checked to determine whether or not it is
within acceptable limits.
9.4.3 Impeller
Inspect the impeller as follows:
Examine the impeller for damage.
For corrosive /erosion pitting.
Cavitations pitting.
Bent or cracked vanes, inlet and outlet vane end
wear.
If damage is extensive, impeller may need
replacement.
Further information should be sought from Wilo
before any decision on repair work is undertaken.
Around the eye, wearing rings protects the
impeller. Examine around the eye at neck portion
for grooving in alignment with spindle axis; slight
grooving is acceptable but deep or profuse
grooving must be remedied by machining the
impeller by taking a polish cut on wearing ring.
Spare wear rings are supplied with excess outside
diameter to facilitate machining after fitting. The
wear rings are shrink fitted on impeller neck and are
screwed.
9.3.3 Dismantling the rotating element
(Mechanical seal version pump)
The only difference between disassembly of
gland pack and mechanical seat version pump
is the disassembly of the mechanical seal
The procedure up to water thrower removal is
same as per gland pack version.
Disassembly of mechanical seal is as follows:
Slide out the gland plate(2421) carefully
over the shaft.
Now mark the position of mechanical seal
on the shaft to ease the position while
reassembling
Unscrew the grub screw of the seal
adjusting ring
NOTE:
Impeller wearing rings are an optional feature to
enhance the protection for impeller eye. In standard
case pump is supplied with neck ring only.
To check wear around the impeller neck, use
precision instruments such as outside micrometer
to accurately measure the outside diameter.
Measurements should be taken at intervals around
the circumference to check the uneven wear.
Differences between the neck OD and the neck ring
ID measured will give us the clearance between the
two. Clearance thus obtained should not be more
than 150% of maximum designed clearance.
