Flowserve S-series PolyChem - Manual (Page 41)

USER INSTRUCTIONS POLYCHEM S-SERIES ENGLISH 71569207 11-08
Page 41 of 52
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6.10 Assembly of pump and seal
It is important that all pipe threads be
sealed properly. PTFE tape provides a very reliable
seal over a wide range of fluids, but it has a serious
shortcoming if not installed properly. If, during
application to the threads, the tape is wrapped over the
end of the male thread, strings of the tape will be
formed when threaded into the female fitting. These
strings can then tear away and lodge in the piping
system. If this occurs in the seal flush system, small
orifices can become blocked effectively shutting off
flow. For this reason, Flowserve does not recommend
the use of PTFE tape as a thread sealant.
Flowserve has investigated and tested alternate
sealants and has identified two that provide an
effective seal, have the same chemical resistance as
the tape, and will not plug flush systems. These are
La-co Slic-Tite and Bakerseal. Both products contain
finely ground PTFE particles in an oil based carrier.
They are supplied in a paste form which is brushed
onto the male pipe threads. Flowserve recommends
using one of these paste sealants.
Full thread length engagement is required for all
fasteners.
Refer to Figure 6-2 for recommended bolt
torques.
6.10.1 Power end assembly
The Mark 3A design has an optional oil slinger. If the
slinger was removed during disassembly, install a
new slinger [2541]. (See Figure 6-16.)
Figure 6-16
6.10.1.1 Bearing installation
Mounting of bearings on shafts must be done in a clean
environment. Bearing and power end life can be
drastically reduced if even very small foreign particles
work their way into the bearings. Wear clean gloves.
Bearings should be removed from their protective
packaging only immediately before assembly to limit
exposure to possible contamination. After removing
the packaging they should only come in contact with
clean hands, fixtures, tools and work surfaces.
The chart shown in Figure 6-19 gives the SKF part
numbers for bearings in Flowserve PolyChem pumps.
The term “inboard bearing” refers to the
bearing nearest to the casing. “Outboard bearing” refers
to the bearing nearest to the motor. (See Figure 6-16.)
Both bearings have a slight interference
fit which requires that they be pressed on the shaft with
an arbor or hydraulic press. Figure 6-14 identifies the
bearing fits. Even force should be applied to only the
inner race. Never press on the outer race, as the force
will damage the balls and races.
An alternate method of installing bearings is to heat
the bearings to 93 °C (200 °F) by means of an oven
or induction heater. With this approach the bearing
must be quickly positioned on the shaft.
Never heat the bearings above 110 °C (230 °F). To
do so will likely cause the bearing fits to permanently
change, leading to early failure.
a) Install the inboard bearing [3011] on the shaft
[2100] the bearing must be positioned against the
shoulder as shown in Figure 6-16. (If the power
end is equipped with single shielded regreasable
bearings, see Figure 5-8 for proper orientation of
the shields.)
b) Install the outboard bearing retaining device onto
the shaft.
Double row bearings. Place the snap ring [2530]
onto the outboard end of the shaft and slide down
to the inboard bearing. (Note: the proper orientation
of the snap ring must be assured in this step. The
flat side of the snap ring must face away from the
inboard bearing.)
Duplex angular contact bearings. Place the bearing
retainer [2530.1] onto the outboard end of the shaft
and slide down to the inboard bearing. Note: the
proper orientation of the bearing retainer must be
assured in this step. The small side of the retainer
must face away from the inboard bearing.
c) Install the outboard bearing.
Double row bearings. Install the outboard bearing
[3013] firmly against the shoulder as shown in
Figure 6-16. If hot bearing mounting techniques are
used, steps must be taken to ensure the outboard
bearing is firmly positioned against the shaft
shoulder. The outboard bearing, while still hot, is to
be positioned against the shaft shoulder.
Duplex angular contact bearings. Duplex angular
contact bearings must be mounted back-to-back with
the wider thrust sides of the outer races in contact
with each other as shown in Figure 6-17. Only
bearings designed for universal mounting should be
used. SKF’s designation is “BECB”. NTN’s
designation is “G”. (Note: a special shaft is required
when using duplex angular contact bearings.)