24 | BHGE
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XVII. Assembly of Main Valve (Contd.)
1. Install both the Lower Backing Ring (9), and “U”
Ring Guide Seal (13) in the Guide (8) as indicated in
Figure 17.
Note: Seal Orientation is the hollow side face upward.
CAUTION
Backing rings must be heated to approximately
130° to properly seat in backing ring groove.
Lubricate the guide lightly with silicone. Install the
guide assembly tool, Figure 12b in Section XV, and
lower the guide into the valve body until it seats solidly
within the body. Remove the assembly tool. Install the
Upper Backing Ring (9).
2. Using slings on the Center Post of the Disc (7), lower the
disc into the guide. Using the assembly tool shown in
Figure 12a in Section XV, force the disc down onto the
seat bushing. Remove the tool after the disc is firmly
installed.
3. Install the Disc Spring Ring (57) and Spring (56) on the
disc.
4. Install a new Gasket (18) in the groove provided on the
top of the guide.
5. Using slings through the eyebolts, lower the Main
Bonnet (19) onto the base.
6. Install all Stud Nuts (23) and draw down bonnet evenly.
Tighten securely all bonnet stud nuts. See Figures 18a
and 18b with Table 6 for torque values.
Table 6: Required Bonnet Nut Torque
Stud Size
10% / -0%
Round 1
Round 2
Round 3
in.
mm
ft-lb.
N-m
ft-lb.
N-m
ft-lb.
N-m
.625
15.88
15
20.3
30
40.7
60
81.3
.750
19.05
25
33.9
50
67.8
110
149.1
1.125 28.58
95
128.8
185
250.8
375
508.4
1.250 31.75
125
169.5
250
339.0
525
711.8
1
4
10
16
6
18
14
8
20
12
2
15
5
17
9
3
13
7
19
11
Figure 18: Bonnet Nuts Tightening Sequences
Procedure:
1. Refer to table for torque valve for applicable round.
2. Torque each nut in sequence shown.
3. Repeat for each round.
11
11
7
14
4
10
6
16
2
12
8
13
3
9
5
15
Figure 18a: 20 Bolt Sequence
Figure 18b: 16 Bolt Sequence
