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6.5 Assembly of Bonnet
Check that the packing ring (6), the spacer (5) and the guide
bushing (22) have been removed from the bonnet.
Position the bonnet (7) above the valve, so that the packing
flange studs (2) are perpendicular to the flow direction of the
valve.
Lower the bonnet (7) onto the valve stem (1) and push it
down carefully until it goes into the valve body studs (21) and
takes up its correct position.
Grease the threads of the valve body studs (21) and the
bearing surfaces of the body stud nuts (8).
Screw on the body stud nuts by hand. Tighten the nuts
lightly and evenly so that the internal parts are held in place.
The face of the bonnet should be parallel to the upper face
of the body.
Slide the guide bushing (22) onto the valve plug stem and let
it drop to the bottom of the packing box housing.
6.6 Tightening of Body Stud Nuts
Alignment of internal parts
In order to achieve perfect alignment of the seat ring and the
valve plug, a force must be applied to the plug stem during
tightening of the bonnet which results in correct relative
positioning of the two parts.
The force can be applied with the pneumatic actuator
as follows:
Place the actuator on the valve bonnet (7) by means of the
yoke nut (33) or attachment screws and connect the valve
plug stem to the actuator stem. See chapter on actuators for
installation instructions.
During this operation, make sure that the plug
does not turn when it is seated. If the plug travel
is very small and there is a large amount of plug
stem inside the actuator, it may be necessary to
remove the yoke nut and lift the actuator so that
the plug is not touching the seat.
Align the internal parts as follows:
In the case of air-to-extend actuators, supply air to the
actuator at the maximum pressure indicated on the serial
plate and in the case of spring-to-extend actuators, do not
supply air to the actuator, so that the optimum positioning of
the valve plug and seat can be obtained.
Single bolting circle:
Evenly tighten the nuts (8) by applying the torque indicated
in table 2 up to 5 and the tightening sequence in Figure 6.
Double bolting circle:
Beginning by the internal nuts, manually screw all the bolts.
Screw the internal nuts in order indicated by the Figure 6
and screw them by successive, uniform and progressive
levels. During the tightening, make sure that the bonnet face
stays parallel at that of the body. When the torque values
given in the following table are reached, the bonnet face
must be in contact with that of the body. Screw the external
nuts in order indicated by the Figure 6 and screw them by
successive, uniform and progressive levels until the torque
values given in the tables on next pages.
To the direction of assembly of spring washer:
• ND 150 (6”) to 450 (18”) valves, the concave face
is upwards,
• ND 500 (20”), and 600 (24”), the concave face is
downwards and the tapped holes are visible.
Summary of Contents for Masoneilan 41005 Series
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