Goulds Pumps 3910 11th ed. - IOM - Manual (Page 19)

PIPING
Guidelines for piping are given in the “Hydraulic Institute
Standards,” available from:
Hydraulic Institute
9 Sylvan Way
Parsippany, NJ 07054
and in API RP 686, and must be reviewed prior to pump
installation.
s
! WARNING
Never draw piping into place by forcing at the flanged
connections of the pump. This may impose dangerous
strains on the unit and cause misalignment between
pump and driver. Pipe strain will adversely affect the
operation of the pump resulting in physical injury and
damage to the equipment.
!
Flange loads from the piping system, including
those from thermal expansion of the piping, must
not exceed the limits of the pump. Casing deforma-
tion can result in contact with rotating parts which
can result in excess heat generation, sparks and
premature failure.
1. Piping runs should be as short as possible to minimize
friction losses.
2. It is suggested that expansion loops be properly
designed and installed in suction and/or discharge lines
when handling liquids at elevated tempera- tures, so
thermal expansion of piping will not draw pump out of
alignment.
3. The piping should be arranged to allow pump flushing
prior to removal of the unit on services handling
hazardous liquids.
4. Carefully clean all pipe parts, valves and fittings, and
pump branches prior to assembly.
5. All piping must be supported independently of, and
line up naturally with, the pump flanges. Table 2
shows piping flange alignment criteria.
Table 4
Piping Flange Alignment
Type Criteria
Axial Flange gasket thickness
± 0.8 mm (.03 in.).
Parallel
0.001 mm/mm (.001 in./in.) of flange diameter
to a maximum of 0.8 mm (.03 in.).
Concentric Flange bolts should easily install by hand.
In no case should loads on the pump flanges exceed the
limits stated in API Standard 610,
11th Edition (ISO
13709).
6. Bottom of casing should be supported by a solid
foundation or casing feet should be used.
SUCTION PIPING
$
CAUTION
NPSH
A
must always exceed NPSH
R
as shown on
Goulds performance curves received with order.
(Reference Hydraulic Institute for NPSH and pipe
friction values needed to evaluate suction piping).
Properly designed and installed suction piping is a necessity for
trouble-free pump operation. Suction piping should be flushed
BEFORE connection to the pump.
1. Use of elbows close to the pump suction flange should
be avoided. There should be a minimum of two (2)
pipe diameters of straight pipe [five (5) pipe diameters
is preferred] between the elbow and suction inlet.
Where used, elbows should be long radius.
2. Use suction pipe one (1) or two (2) sizes larger than
the pump suction, with a reducer at the suction flange.
Suction piping should never be of smaller diameter
than the pump suction.
3. Reducers, if used, should be eccentric and located at
the pump suction flange with sloping side down.
$
CAUTION
Pump must never be throttled on suction side.
4. A suction screen should be installed prior to initial
start-up and when suction system has been opened for
work. The screen should be of the cone type with a
net area equal to at least three (3) times the cross
sectional area of the suction pipe. The mesh of the
screen should be sized to prevent particles larger than
1.6 mm (1/16 in.) from entering the pump and should
be installed in a spool piece to allow removal for
cleaning. The screen should remain in the system until
periodic inspection shows system is clean.
5. Separate suction lines are recommended when more
than one pump is operating from the same source of
supply.
Suction Lift Conditions
1. Suction pipe must be free from air pockets.
2. Suction piping must slope upwards to pump.
3. All joints must be air tight.
4. A means of priming the pump must be provided.
3910-1
1th IOM 5/08
19
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