Flowserve PHL - Manual (Page 15)

PHL USER INSTRUCTIONS ENGLISH 00079593 – 10/10
Page 15 of 31
d) Piping Installed - Correct Vent, Gauge, Valve,
Suction Strainer Locations?
e) All Flange Bolting Correctly Torqued with
appropriate gaskets in place?
f) Check Shaft/Coupling Alignment again.
g) Coupling guard correctly installed?
Complete piping as below.
4.6 Piping
Protective covers are fitted to the pipe
connections to prevent foreign bodies entering during
transportation and installation. Ensure that these
covers are removed from the pump before connecting
any pipes.
4.6.1 Suction and discharge pipework
In order to minimize friction losses and hydraulic noise
in the pipework it is good practice to choose pipework
that is one or two sizes larger than the pump suction
and discharge. Typically, main pipework velocities
should not exceed 2 m/s (6 ft/sec) suction and 3 m/s
(9 ft/sec) on the discharge.
Take into account the available NPSH which shall be
higher than the required NPSH of the pump.
Never use the pump as a support for
piping.
Maximum allowable forces and moments on the pump
flanges vary with the pump size and type. To minimize
these forces and moments, which, if excessive, cause
misalignment, hot bearings, vibration and the possible
failure of the pump casing, the following points should
be strictly followed:

Prevent excessive external pipe load

Never bring piping into place by applying forces to
the pump flange connections

Do not mount expansion joints so that their force,
due to internal pressure, acts on the pump flange
The table on the general arrangement drawing
summarizes the maximum allowable forces and
moments on the pump casing. The allowable forces
and moments are also listed in the addendum (Tab 1).
Refer to Flowserve for other configurations.
Mount the flanges of the pipes and pump so that they
are parallel with a tolerance of 0.1 mm. Make sure that
the centrelines of the flanges are in line with each
other.
Ensure piping and fittings are flushed
before use.
Ensure piping for hazardous liquids is arranged
to allow pump flushing before removal of the pump.
4.6.2 Suction piping
a) The inlet pipe should be one or two sizes larger
than the pump inlet bore and pipe bends
should be of a radius as large as possible.
b) Pipework reducers should have a maximum
total angle of divergence of 15 degrees.
c) Keep the total length of the suction pipe as
short as possible.
d) A bend in the suction pipe should be located at
a distance of at least 5 times the pipe bore from
the suction flange
e) Install as few bends as possible in the suction
pipe and select the largest possible radius
f) On suction lift the piping should be inclined up
towards the pump inlet with eccentric reducers
incorporated to prevent air locks.
g) On positive suction, the inlet piping must have
a constant fall towards the pump.
h) Inlet strainers, when used, should have a net
`free area' of at least three times the inlet pipe
area.
i) Do not install elbows at an angle other than
perpendicular to the shaft axis. Elbows parallel
to the shaft axis will cause uneven flow.
j) In the case of contaminated liquids, install a
suction strainer or dirt trap with a bore which
matches the bore of the pump.
k) Fitting an isolation valve will allow easier
maintenance.
l) Never throttle pump on suction side and never
place a valve directly on the pump inlet nozzle.
4.6.3
Maximum allowable forces and
moments on PHL pump flanges
Refer to the General Arrangement drawing (tab 1)
4.6.4 Discharge piping
A non-return valve should be located in the
discharge pipework to protect the pump from
excessive back pressure and hence reverse
rotation when the unit is stopped.
Pipework reducers should have a maximum total
angle of divergence of 9 degrees.
Fitting an isolation valve will allow easier
maintenance.
4.6.5 Auxiliary piping
4.6.5.1 Drains
Pipe casing drains and gland leakage to a
convenient disposal point.
4.6.5.2 Pumps fitted with gland packing
When suction pressure is below atmospheric
pressure, it is necessary to feed the gland packing
with liquid to provide lubrication and prevent the
ingress of air. This is normally achieved with a
supply from the pump discharge volute to the
stuffing box. A control valve or orifice plate may
have been fitted into the supply line to control the
pressure to the gland / stuffing box.