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NotchFlo DST
VALVE STEM DIAMETER
mm
12.7
19.1
25.4
WARNING
To avoid personal injury or property
damage caused by uncontrolled
movement of the bonnet, loosen the
bonnet by following the instructions in
the next step. Do not remove a stuck
bonnet by pulling on it with equipment
that can stretch or store energy in any
other manner. The sudden release of
stored energy can cause uncontrolled
movement of the bonnet. If the cage
sticks to the bonnet, proceed carefully
with bonnet removal and support the
cage so that it will not fall
unexpectedly from the bonnet.
The following step also provides
additional assurance that the valve
body fluid pressure has been relieved.
5. Hex nuts (key 14) attach the bonnet to the valve
body. Loosen these nuts approximately 3 mm (1/8
inch). Then loosen the body-to-bonnet gasketed joint
by either rocking the bonnet or prying between the
bonnet and valve body. Work the prying tool around
the bonnet until the bonnet loosens. If no fluid leaks
from the joint, proceed to the next step. If fluid leaks
from the joint, the process pressure was not relieved
from the valve as noted in the Warning at the
beginning of the Maintenance section in this manual.
6. Unscrew the hex nuts (key 14) and carefully lift
the bonnet off the valve stem. If the valve plug and
stem assembly starts to lift with the bonnet, use a
brass or lead hammer on the end of the stem and
tap it back down. Set the bonnet on a cardboard or
wooden surface to prevent damage to the bonnet
gasket surface.
7. Remove the valve plug (key 5), bonnet gasket
(key 11), cage (key 2), seat ring (key 4), and the
seat ring gaskets (key 12).
8
Table 7. Valve Stem Connection Torque and Hole Size for Pin
TORQUE, MINIMUM TO MAXIMUM
Inches
NSm
0.5
81-115
0.75
237-339
1
420-481
Note
LbfSft
mm
60-85
3.20 - 3.25
175-250
4.80 - 4.88
310-355
6.38 - 6.45
CAUTION
Inspect the seat ring, cage, bonnet,
and body gasket surfaces. These
surfaces must be in good condition,
with all foreign material removed.
Small burrs less than approximately
0.076 mm (0.003 inch) in height (the
thickness of a human hair) can be
ignored. Scratches or burrs that run
across the serrations are not permitted
under any conditions, since they will
prevent the gaskets from sealing
properly.
8. Clean all gasket surfaces with a good wire brush.
Clean in the same direction as the surface
serrations, not across them.
9. Cover the opening in the valve body to protect
the gasket surface and to prevent foreign material
from getting into the valve body cavity.
10. Remove the packing flange nuts (key 21),
packing flange (key 19), upper wiper (key 27), and
packing follower (key 28). Carefully push out all the
remaining packing parts from the valve side of the
bonnet using a rounded rod or other tool that will not
scratch the packing box wall.
11. Clean the packing box and the following metal
packing parts: packing follower, packing box ring
(key 26), spring or lantern ring (key 24), and, for
single arrangements of PTFE V-ring packing only,
special washer (key 25).
12. Inspect the valve stem threads for any sharp
edges that might cut the packing. A whetstone or
emery cloth may be used to smooth the threads if
necessary.
13. Remove the protective covering from the valve
body cavity, and install the seat ring and cage using
new seat ring gaskets (key 12) and bonnet gasket
(key 11). Install the plug, then slide the bonnet over
the stem and onto the studs (key 13).
The prelubricated hex nuts (key 14)
referred to in step 14 can be identified
by a black film coating on the nut
threads.
Instruction Manual
Form 5794
February 2005
HOLE SIZE
Inch
0.126 - 0.128
0.189 - 0.192
0.251 - 0.254
Note
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