Flowserve Valtek FlowTop V726 User Instructions page 43

Valtek FlowTop
Bonnet Tightening
The bonnet seal plays a special role in valves. On the one
hand, the axial alignment of valve seat / plug / stem and bon-
net is intentional for the internal valve tightness and wear; on
the other hand, it guarantees external tightness in addition
to the stuffing box packing. Misalignments must therefore be
avoided.
Cleanliness and optimal seal compression are the corner-
stones of the service life of a bonnet seal.
Use only calibrated torque wrenches for
NOTICE
tightening. Striking tools and extension
tubes are unsuitable tools !
1. Remove all seal residues from the gasket chamber and
clean carefully.
A standard brass scraper is suitable as a
NOTICE
tool.
2. Check surfaces for damage such as grooves and warp-
age.
3. Use only original replacement gaskets. Never reuse
used gaskets !
4. Lubricate the thread and underside of the nuts / screw
heads sparingly with a suitable, approved lubricant.
Under no circumstances apply lubricant to the sealing
surfaces !
5. Carefully insert a new gasket and attach the bonnet.
6. Tighten nuts / bolts according to pattern - torque see
section 14.2: Torque Requirements, page 60.
Step Methode
1
2
3
4
5
Check the freedom of movement of the plug by lifting
(~ 10mm) between step 2 to 5. If it is hard to move,
loose the bolted connection and start again !
7. Check the bonnet bolting after first pressurization in a de-
pressurized and cooled state and retighten if necessary.
Gasket settling, the phenomenon intensi-
NOTICE
fies under increased temperatures!
FCD VLEEIMFTOP-03 (EN/A4) June 2023
Tightening torque
by hand
30 %
crosswise
60 %
100 %
all around 100 %
Cross-dress pattern
1 5
8 3
4 7
6 2
8 screws, 45 ° angular distance
1 5
12
9
8
4
10 11
6 2
12 screws, 30 ° angular distance
1 9
16 5
8
12
4
14
15
6
10
2
16 screws, 22,5 ° angular distance
1 13
12 5
20
8
16
4
10
18
6 11
14 2
20 screws, 18 ° angular distance
3
7
13
3
11
7
17
9
3
15
7
19
43
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