Section 5 - Standard Options - Emerson VANESSA 30,000 Series Installation, Operation And Maintenance Manual

VANESSA SERIES 30,000 TRIPLE OFFSET VALVE (TOV)
INSTALLATION, OPERATION AND MAINTENANCE MANUAL

SECTION 5 - STANDARD OPTIONS

This section is referred only to Vanessa
products configured with the following options:
- bearing and packing flushing,
- live loaded packing.
Disc
side
FIGURE 9
FIGURE 10
5.1 Bearing and packing flushing
Bearing flushing
The bearing flushing option is obtained
by adding two tapped holes, one in the
bottom flange and one in the neck of the
valve (see figure 9). This option includes the
introduction of a lantern ring at the bottom
of the valve packing. Bearing flushing is
recommended when the valve is installed in
a service where the particles present in the
fluid or the line fluid itself can migrate into
the shaft/bearing area causing problems.
A typical example is sulphur recovery services,
where the sulphur in a liquid or gaseous
state may enter this area and crystallize as a
consequence of the plant shutdown.
Bearing flushing inlet
Flush pressure = P + 5%
Shaft
side
Bearing flushing inlet
The bearing protector
minimizes the consumption
of the clean fluid
FIGURE 9A
This crystallisation may result in an increase
in the torque requirement of the valve. Another
example may be a fluid that contains particles
(e.g. catalyst) that may cause similar problems
to those highlighted above.
In these types of situations the bearing
flushing may be used to introduce an inert fluid
compatible with the process via the bearing
flush taps (see figure 10) to create a pressure
barrier which prevents the introduction of the
unwanted product from the line into the shaft/
bearing area. The pressure of the flushing fluid
must be slightly higher than the line pressure
(i.e. P1 + approx 5%). This acts as a safety
measure and a positive contribution to increase
the life expectancy of the valve, as well as
maintaining the constant torque requirement
and hence operability of the valve.
The bearings may be continuously flushed, this
is recommended for critical services such as
described above. Periodic flushing may be used
for less critical services in order to clean the
bearing/shaft interface or in order to prepare
the valve for a shutdown of the process.
The bearing flush taps may also be used to
introduce a lubricant compatible with the
process to the bearing areas for high cycle or
dry gas service. The presence of the bearing
protector drastically reduces the consumption
of the flushing or lubricant by reducing the
amount of fluid required to give efficient service
(see figure 9A).
Contact your nearest Emerson sales office for
further information.
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