Flowserve Mark 3 ISO Durco - Manual (Page 21)

DURCO MARK 3 ISO CLOSE COUPLED ENGLISH 26999985 02-14
Page 21 of 32
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d) Release the tension in the mechanical seal. The
seal manufacturer's instructions should be
followed for dismantling and assembling the seal.
e) Remove seal housing bolts and withdraw the seal
housing from the bracket.
6.8.3 Pumps with double mechanical seals
a) Remove the nuts retaining the seal housing to
the bracket.
b) Carefully rotate the impeller in an anti-clockwise
direction whilst supporting the impeller and seal
housing. The integral impeller and stub shaft
combined with the seal housing will release from
the unit as a sub-assembly. (Large pump sizes
have a tapped hole for fitting a lifting eye to assist
with this procedure.)
c) Remove the nuts from the seal cover to gain
access to the seals. Release the tension in the
mechanical seals.
d) The seal manufacturer's instructions should be
followed for dismantling and assembling the seal.
e) The mounting bracket can now be removed from
the motor after first removing the fixing screws.
f) The adjustment stud in the motor shaft can be
removed using two M 8 nuts.
6.9 Examination of parts
Used parts must be inspected before
assembly to ensure the pump will subsequently run
properly. In particular, fault diagnosis is essential to
enhance pump and plant reliability.
6.9.1 Casing, seal housing and integral impeller/
stub shaft assembly
Inspect for excessive wear, pitting, corrosion, erosion
or damage and any sealing surface irregularities.
Replace as necessary.
6.9.2 Integral impeller/stub shaft
Replace if the shaft is grooved or pitted or if the
impeller vanes are eroded or damaged.
6.9.3 Gaskets
After dismantling, discard and replace. (If the pump
seal arrangement has a lip seal, it should be replaced
at overhaul.)
6.9.4 Motor
Check the motor shaft for free rotation and absence
of bearing noise or shaft 'float'. If necessary, have
the motor serviced by a specialist or replace with a
Flowserve approved type.
6.10 Assembly
To assemble the pump consult the sectional
drawings. See section 8, Parts lists and drawings.
Ensure threads, gasket and O-ring mating faces are
clean. Apply thread sealant to non-face sealing pipe
thread fittings.
6.10.1 General
a) The motor shaft keyway is not used but remove
any burrs from the edge of the keyway, the motor
and pump shafts and the coupling.
b) Screw the adjustment stud into the motor shaft
and tighten with the two M 8 nuts or a stud box.
c) Locate the bracket on the motor spigot and
tighten the screws (or studs and nuts).
d) Whilst re-assembling, use new joints/gaskets and
ensure they are in their correct positions.
e) Small amounts of grease may be used to hold the
joints in position during assembly.
6.10.2 Seal housing and seal assembly
a) Extreme cleanliness is required.
b) The sealing faces and shaft surface must be free
from scratches or other damage.
c) Refer to section 6.11, Seal arrangements, for
seal diagrams.
6.10.3 Impeller assembly and setting - single seal
a) Carefully press the stationary seat into the
mechanical seal housing cover, ensuring the
seating ring is not deformed.
b) Where an anti-rotation pin is fitted, ensure that
correct engagement with the slot is achieved.
c) Refer to seal manufacturer's instructions to
position the mechanical seal rotating elements.
Tighten any drive screws in the seal drive collar.
d) Fit the seal housing into the bracket and tighten
all fasteners.
e) Apply anti-seizing compound to the adjustment
stud. Carefully, fit the stub shaft (with seal in
position) through the center of the seal housing
and locate on the adjustment stud.
f) Rotate the impeller until the back clearance is
approximately 1 mm (0.04 in.).
g) Fit the casing gasket and pump casing and
tighten all casing fasteners.
h) Refer to section 5.2, Setting impeller clearance,
for setting dimensions and coupling fitting
instructions.
i) Check that the shaft can turn freely without binding.