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VSG/VSSG • Installation, Operation and Maintenance Manual •Vilter/Emerson • 35391STG
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Section 3 • Installation
Piping
The ideal load applied to
fl
anges of the compressor unit
is zero. However, it’s not practical to expect that no loads
will be applied to unit connections. Thermal, dead, live,
wind & seismic loads must be considered and even toler-
ated. Well supported external piping connected to the
compressor will still result in some loads applying forces
and moments in three axes to unit
fl
anges.
The most important issue is the motor-compressor mis-
alignment caused by external forces (F in lbf) and mo-
ments (M in ft-lbf) imposed by plant piping. In Figure
3-9 and Table 3-2, are the maximum allowable forces
and moments that can be applied to compressor
fl
anges
when the compressor is mounted on an oil separator.
It must be noted that it is necessary to check for com-
pressor shaft movement when the job is complete. In
no case shall the attached piping be allowed to cause
more than 0.002” movement at the compressor shaft.
If more than 0.002” movement is detected the piping
must be adjusted to reduce the compressor shaft move-
ment to less than 0.002”. For example, the compressor
shaft should not move more than 0.002” when piping is
removed or connected to the compressor.
IMPORTANT – piping elements shall be supported per
the requirements of ASME B31.5 / B31.3 as applicable.
See guidelines below, particularly with concern to mini-
mizing loads on check valves.
Header Piping and Drains
Header drains should also be installed to allow drainage
of liquids from the discharge and suction headers. See
Appendices for Recommended Header Piping.
CAUTION
Accumulated liquid in the suction header can damage
the compressor if not drained. Always drain headers
(suction and discharge headers) prior to start-ups.
Failure to comply may result in damage to equipment.
Remote Air Cooled Oil Cooler Piping
If equipped with a remote air cooled oil cooler, it is im-
portant that the piping be installed correctly to and from
the compressor unit and remote air cooled oil cooler.
See Appendices for Recommended Air Cooled Oil Cooler
Piping.
