Flowserve MNV - Manual (Page 17)

MNV & MNZ USER INSTRUCTIONS ENGLISH 71569188 11/04
Page 17 of 47
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The foundation should be of sufficient strength to
absorb vibration (i.e., at least five times the weight of
the pump unit) and to form a permanent, rigid support
for the suction nozzle/steel frame support. This is
important in maintaining the alignment of a close
coupled unit. A concrete foundation on a solid base
should be satisfactory.
4.3.1 Pump and structural natural frequency
Pump manufacturers can calculate or determine the
natural frequency of the pump assembly, including
the driver. However, in a field installation, the
vibrating structure comprises, in addition to the pump
assembly, the foundation, the mounting, the piping,
and supports. The natural frequency of the vibrating
structure is determined by the stiffness of the total
structure and by its equivalent mass. The natural
frequency of the structure may therefore differ
significantly from the natural frequency of the pump.
In the absence of any specific information, the pump
manufacturer will assume that the piping is installed
rigidly and anchored close to the pump connections.
It will also be assumed that the hold down bolts are
securely embedded in a concrete foundation of
infinite mass and rigidity.
The system designer must give proper consideration
and must ensure that the natural frequency of the
vibrating structure, as defined above, does not fall
within the pump operating speed range. That person
also must be aware of the much lower stiffness of
fabricated system structures, relative to concrete,
and the problems associated with calculating
stiffness of unconventional and composite structures.
4.4 Grouting
The pump and motor must be aligned
on the base prior to grouting the base in place (see
alignment). To do otherwise will negate the factory
pre-alignment and may result in alignment difficulties
at the expense of others. Where applicable, grout in
the foundation bolts.
Grouting provides solid contact between the pump
unit and foundation, prevents lateral movement of
running equipment and dampens resonant vibrations.
4.4.1 Typical foundation bolt arrangement
Foundation bolts of the specified size should be
embedded in concrete and located according to the
Elevation drawing. Each bolt should be surrounded
by a pipe sleeve at least two times the diameter of
the bolt. The sleeve should be held rigidly yet
allowing the bolts to be moved to conform to the
holes in the baseplate as shown in the detail under
this section.
PUMP FOOT
(IF SOLE PLATE IS USED)
PUMP FOOT
OR SOLE PLATE
FOUNDATION
BOLT
SHIMS
FOUNDATION
GROUT
SLEEVE
Foundation bolts should only be fully tightened when
the grout has cured.
Only non-shrinking grout with a 41.4 Mpa (6000 psi)
compressive strength in 72 hours should be used.
Flowserve recommends the following procedure for
grouting.
4.4.2 Recommended procedure for grouting
a) Build a wooden form around the outside of the
base to contain the grout. In some cases the form
is placed tightly against the lower edge of the base
and in other cases it is placed a slight distance
from the edge of the pump base.
b) Saturate the top of the rough concrete foundation
with water, if required before grouting. Add grout
until the entire area under the pump base is filled,
including the space between the foundation bolt
and pipe sleeve. A stiff wire should be used to
work the grout and release any air pockets.
c) After the grout is poured, the exposed surfaces
should be covered with wet burlap to effect slow
curing and prevent cracking. When the grout is
set (about 48 hours) remove the forms and
smooth the exposed surfaces if desired. The
grout should be allowed to cure at least 72 hours
before dynamically loaded.
If leveling nuts are used on the
foundation bolts to level the base, they must be
backed off as far as possible prior to grouting the
base in place. Shim near the foundation bolts, back
off the leveling nuts, and tighten the foundation bolts.
To do otherwise will significantly lower the structural
natural frequency and result in separation of the base
from the grout.