Flowserve MN - Manual (Page 33)

MN USER INSTRUCTIONS ENGLISH 71569189 11/04
Page 33 of 49
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6.1.6.1 Measuring wearing ring gap
There are two methods for checking wearing ring
clearance on pumps equipped with axial wearing ring
construction. The simplest is to remove the suction
head hand hole cover and check with a feeler gauge
around the gap perimeter. The second method
follows but is difficult to perform on horizontal pumps:
The bearing frame support bolts must be
loosened to allow movement of the bearing frame
during adjustment. Be sure to re-tighten the bolts
when the wearing ring gap adjustment is completed.
a) Disconnect pump-coupling halves if required.
b) Back off the bearing frame retaining screws
between the bearing frame and the stuffing box
approximately 1.5 mm (0.06 in.). Do Not
Remove.
c) Tighten the two exterior jacking bolts to break the
shim joint, then remove all shims.
d) Back off the two jacking bolts until they are even
with the bottom of the bearing frame flange.
Tighten the bearing frame retaining screws until
the impeller wearing ring seats against the casing
wearing ring. Ensure that the gap between the
bearing frame and stuffing box flange is even all
the way around the perimeter.
e) Measure the gap between the bearing frame
flange and the stuffing box head flange. Add the
desired amount of wearing ring gap to the
measurement. This is the required amount of
shims to be added between the bearing frame
and the stuffing box head
6.1.6.2 Adjusting wearing ring gap
After the actual ring gap has been determined, adjust
the shim pack as required to obtain the desired ring
gap. If the desired ring gap cannot be obtained
because of having reached the limit of axial
adjustment, one or both of the wearing surfaces will
have to be restored or replaced.
a) Loosen the bearing frame retaining screws and
then tighten the two jacking bolts to allow the
placement of the proper shim pack.
b) After the shims are in place, back off the two
jacking bolts until they are even with the bottom
of the bearing frame flange.
c) Tighten the four bearing frame retaining screws.
Ensure that the gap between the bearing frame
and stuffing box flange is even all the way around
the perimeter.
d) Rotate the pump shaft by hand to check for free
rotation. Recheck the gap and repeat steps (a)
thru (b) as necessary.
e) Recheck the coupling alignment and then replace
the coupling bolts.
Shim stock identification
Light Brown = 0.76 mm (.030 in.)
Yellow. = 0.51 mm (.020 in.)
Brown = 0.25 mm (.010 in.)
Blue = 0.12 mm (.005 in.)
Each shim set consists of two halves, permitting easy
removal. Each half must be the same thickness.
6.1.6.3 Removal of wearing rings
The impeller and suction head wearing rings are held
in place by screws locked in place using Loctite 271
or equivalent. They may require heating to 200 o C
(400 o F) to allow removal.
6.1.6.4 Mounting of wearing rings
Clean the screw threads and taps. Clean the ring
and the area where the ring is to be mounted. Mount
the ring and secure it using screws with Loctite 271
or equivalent applied to the threads.
New tapped holes may be required to
facilitate installation of a new wearing ring. Use the
wearing ring as a template.
6.1.7 Maintenance of shaft and shaft sleeve
When the pump is dismantled, examine the shaft
carefully. Its condition should be checked at the
impeller hub fit, under the shaft sleeve (if sleeve is
removed), at the bearings, and under the coupling
flange (if flange is removed). The shaft may become
damaged by rusting or pitting due to leakage along
the shaft at the impeller or shaft sleeve, excessive
exposure to moisture, or mishandling.
Anti-friction bearings improperly fitted to the pump
shaft may result in the bearing cone rotating on the
shaft, thus causing undue damage. Check the shaft
keyways for distortion. Excessive thermal stresses
or corrosion may loosen the impeller on the shaft and
damage the keyway. Replace a shaft that is bent or
distorted. If wear on the shaft is slight, it may be
possible to rebuild it by metal spraying or plating and
re-grinding. This repair should be carried out by
trained and competent personnel.
After a shaft has been repaired, check it for possible
runout, maximum 0.051 mm (0.002 in.) T.I.R.
Recheck the runout after the bearing frame is
completely assembled.
When the sleeve has become worn appreciably, it
becomes difficult to adjust the packing to prevent
leakage and it should be replaced. Excessively
grooved and scored sleeves will tear new packing as
soon as it is inserted into the stuffing box.