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6. Valve Reassembly
6.1 Pinning the Valve Plug Stem
The valve plug (15) and stem (1) assembly consists of a
rod threaded into the valve plug and pinned in place.
If the valve plug (15) [or the auxiliary pilot plug (20)
in the case of a 41405 valve] needs to be replaced,
it is recommended using a new stem. The hole of the
original pin in an old stem often prevents satisfactory
results being obtained and can seriously impair the
mechanical strength of the stem-valve assembly.
Assembly is carried out as follows:
6.1.1 Reference marking on the
valve plug stem
Make a reference mark on the valve plug stem at a
distance "X" (Figures 7 and 8), equivalent to the stem
recess in the valve plug.
Note: For shouldered plug stems with two flats, the
above marking is unnecessary.
Valve
Diameter
plug stem
A
diameter B
mm (in.)
mm (in.)
12.7 (1/2)
20 (.79)
15.87 (5/8)
25.5 (.98)
19.05 (3/4)
35 (1.38)
25.4 (1.0) 44.5 (1.66)
31.75 (1 1/4)
58 (2.28)
38.1 (1 1/2)
70 (2.76)
Two flats of wrench size "E"
Shouldered stem
X
Standard stem
12 | GE Oil & Gas
Metric
Anglo-
pin,
Saxon
diameter
pin dia.
C
C
mm
In.
mm (in.)
3.5
0.14
18 (.70)
5.0
0.2
24 (.95)
5.0
0.2
30 (1.2)
8.0
5/16
40 (1.58) 47.5 (1.88)
8.0
5/16
55 (2.20)
10.0
-
65 (2.56)
Plug shank
D
B
X
A
B
Dia. C
6.1.2 Tightening of the plug stem
To carry out this operation, the valve plug must be
prevented from moving by holding the plug shank with an
appropriate tool.
Screw two nuts on to the end of the new plug stem and
lock them together. Screw the valve plug stem solidly into
the plug, checking that the reference mark is level with
the end of the plug shank.
If the stem has flats, apply a torque "T" using a wrench of
dimension "E" (see Figure 7).
6.1.3 Drilling the pin hole (Figures 7 and 8)
Note: For this operation, it is recommended clamping
the valve plug-stem assembly by the plug shank to avoid
damaging the guiding surfaces; particular care must be
taken so that the pin hole goes through the valve plug axis.
If the valve plug is new, drill a hole of diameter "C" at a
distance "D" from the end of the valve plug; choose the
diameter "C" from the table according to the type of pin
used (metric or Anglo Saxon pin).
If the hole is already drilled in the valve plug, use the hole
as a guide to drill through the valve plug stem.
Distance
F
D
X
mm (in.)
mm (in.)
18.5 (.73)
6 (.24) 17 (11/16)
28 (1.1)
8 (.30)
45 (1.77)
19 (.75) 27 (11/16)
25 (.98)
70 (2.76) 31.5 (1.24) 40 (1 5/8)
90 (3.54)
33 (1.30)
Figure 7
Shouldered
F
Stem pin
Figure 8
Torque T
Non-
E
Shouldered
stem
mm (in.)
N.m (Ft.lbs)
50 (37)
22 (7/8)
50 (37)
160 (118)
30 (11/4)
160 (118)
-
50 (2)
-
stem
© 2015 General Electric Company. All rights reserved.
Shouldered
stem
N.m (Ft.lbs)
60 (44)
160 (118)
160 (118)
250 (184)
800 (590)
1 500 (1100)
Standard
stem
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