16 | GE Oil & Gas
- VariPak valves with C
v
max. 3.8 do not have seatring
gaskets (2).
5.4 REASSEMBLY (Figures 5, 15, 19, 20, 24, 25, 26, 27,
28 and 29)
Before reassembly, thoroughly clean the inside of the
valve body and parts, paying particular attention to
gasket seating surfaces and contact surfaces. Make
sure to use a new seat-ring gasket (2) and new packing
(6) during reassembly.
A. Insert a new seat-ring gasket (2) into valve body (13),
then fit seat ring (3), making sure that the gasket is
correctly centered on the seat-ring shoulder. Turn it
so that one of its ports is lined up with the valve body
outlet orifice.
Note: If the maximum C
v
is less than 0.10, first fit the
seat ring (3e) on the new gasket (2), taking the same
precautions as above. Then fit the spacer (3f), turning it
so that one of its ports is turned towards the body outlet
orifice.
VariPak valves with a maximum C
v
of 3.8 do not include
a seat-ring gasket (2).
B. Carefully apply Never Seez grease or equivalent to
the threads and bottom of the seat-ring retainer
(4). Using a 9/16" or 14 mm piece of hex stock and a
wrench, torque the retainer to 59 ftlb or 8 daN.m for
stainless-steel reinforced graphite gaskets or 40 ft-lb
or 5.5 daN.m for glass-filled PTFE gaskets (see figure
19).
Note: Torque the retainer to 30 ft-lb or 4 daN.m for
valves with a maximum C
v
of 3.8.
C. Insert the plug and stem assembly into the seat
ring. For valves with a maximum C
v
< 0.10, check
that there are no friction points in the plug stroke.
If a friction point is detected, loosen retainer (4)
and reposition seat ring (3e) until the stem slides
smoothly. Fit spacer (5), turning it so that one of its
holes is aligned with safety pin (11) hole in the valve
body.
Note: For valves with a maximum C
v
less than 0.10,
check that the retaining ring (182) is fitted on the plug
before fitting the plug in the spacer (3f). If the retaining
ring is worn or damaged, replace it.
Figure 19 - Tightening the seat-ring retainer (4)
D. Wind two layers of PTFE tape around the safety pin
(11). Screw the pin into the bonnet five and a half to
six turns as from the thread engagement point.
Note: To determine the thread engagement point:
- Screw the safety pin about one turn.
- Pull the safety pin out while unscrewing it.
E. Fit the packing, making sure that the skive cut of
each packing ring is located 120° away from the that
of the adjacent ring. Push the rings down slightly
using a 1/2" sch., size 160 tube. Fit the packing
follower (9) onto the plug stem.
F. Fit actuator bracket (108) and secure it with two
nuts (8a). Slip packing flange (10) onto plug stem.
Handtighten the two packing flange nuts and add
one full turn with the wrench.
G. Fit, in the following order, grommet plate (101),
conical compression spring (106) and its spring
button (102) (see position in figure 26 and 27). Screw
nut (103) and clevis (104a) on the plug stem.
Adjust the nut and clevis without locking them together
until the clevis holes are positioned approximately:
- 2.3 mm below the alignment of the pin holes in
the actuator bracket (108) for the VariPak 28001
single-lever valve (see figure 15).
- 1.5 mm above the alignment of the pin holes in
the actuator bracket (108) for the VariPak 28002
adjustable-C
v
valve (see figure 20).
Note: Measuring this distance can be simplified by fitting
pins (105), (184) and (18) into their holes.
(24 pages)
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