Flowserve 1878 Double-Disc Gate Valve User Manual
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9.0
MAINTENANCE INSTRUCTIONS
9.1
The following instructions cover the disassembly and reassembly of a gate valve.
Typical valve configuration is shown in Figure 1 (see Section 12.0).
CAUTION
CHECK LINE PRESSURE: IF LINE IS STILL UNDER PRESSURE,
VENT BEFORE VALVE DISASSEMBLY IS STARTED
9.1.1
Disassembly
Extreme care should be taken to ensure that the stem and disc do not
separate when removed as one unit, until both are adequately supported.
Failure to do so may cause damage to the disc.
After removal from the valve, care should be taken to protect the seating
surface of the discs from damage. The discs should be placed in a clean
area until they are ready to be replaced in the valve. THE SLIGHTEST
NICK OR SCRATCH ON A SEATING SURFACE MAY PREVENT
COMPLETE SHUT-OFF AND NECESSITATE EXTENSIVE REWORK OR
REPLACEMENT.
(a)
Remove the Gland Stud Nut (234) from the Gland Bolt (210) which
will permit the Gland Bolt to be removed.
(b)
Lift the Gland Flange (133) upward from the stuffing box area, thus
exposing the Packing (110 & 112).
(c)
Remove the Packing (110 & 112). This is best accomplished with a
packing hook or similar device.
(d)
Remove the Bonnet Studs and Nuts (200 & 230) and remove the
Bonnet (002) from the Stem (025) by turning the Handwheel (136) in
a clockwise direction. Be careful not to damage the stem threads.
The Gland Flange (133) will come off with the removal of the Bonnet.
Be careful not to scratch the bonnet's gasket seating surface.
(e)
Remove the Gasket (100) from its groove. This operation may
require the use of a screwdriver or similar tool to pry the Gasket from
the groove. Be careful not to scratch the gasket seating surfaces.
(f)
The Stem (025) and Disc Package (004, 069, 071 & 269) can now
be removed as one unit. Support the Discs (004) so they do not fall
off and become damaged. The "T" head of the Stem (025)
separates from the "T" slot of the Upper Wedge (069) by sliding.