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8 | Baker Hughes
• Install packing, positioning the skive cut of each packing
ring 120˚ away from the cut of an adjacent ring. Slightly
push down rings one after another using a tube 1/2”
schedule 160 size. Install packing follower (9) on the plug
stem.
•
Hold actuator above body S/A. Before that actuator stem
contacts the plug stem, screw two nuts (8a) on the two
studs (7), slide packing flange (10) on the stem and the
studs and screw the two nuts (27) to the threaded end of
plug stem.
•
While holding the plug in “Open” position, slowly pull down
the actuator and screw the plug stem into the actuator stem.
Note:
This operation will be facilitated turning the plug by
means of a wrench applied on the nuts (27) tightened one
against the other.
Carefully avoid that seating surface of the plug contacts
the seat ring during the plug screwing.
Pulling down motion of the actuator and plug stem screwing
must be simultaneously performed : carry on until the lower
part of actuator yoke con- tacts the body flange (13).
•
Screw and tighten the two screws (16). Tighten also the two
nuts (8a). Finger tight the two packing flange nuts (8b).
• Unscrew the plug stem until the plug is seated.
•
Screw one nut (27) against the lower part of the actuator
stem while placing a 2,5 mm shim between nut and stem
(see Figure 5).
•
Tighten second nut (27) against the first in this position.
Remove the shim and screw the plug stem into the actuator
stem, until the nuts contact the actuator stem. Lock by
means of a wrench applied on the nuts.
• Connect the controlled pressure line(s) to diaphragm case.
• Place back in service and tighten the nuts (8b), only as
much as is necessary to stop any leakage.
Packing box
Adding Packings
To add a ring of packing, depressurize the regulator, back off
packing flange nuts (8b) all the way, lift the packing flange and
follower and insert one ring of packing. Tighten nuts (8b) finger
tight plus one full turn.
Packing Quick Change Method
(For regulators Cv 0.6 to 3.8 only)
The fastest and simplest way to replace packing is to remove
the entire actuator without disturbing actuator parts or
calibration. However, this is not recommended for regulators
with a small C
v
(C
v
< 0.6), due to the very fineness of their
plug. In this event, disassemble the regulator to replace the
packing (See under “Disassembly”, page 5).
• Remove safety pin (11) from body. The safety pin engages
the packing spacer (5). The function of safety pin and
spacer is to prevent the plug from being pushed out if the
actuator is removed while the regulator is still pressurized.
The regulator internal parts cannot be removed unless the
safety pin is removed first. Remove two packing flange
nuts (8b) and two mounting nuts (8a). Remove also two
mounting screws (16).
•
Remove the actuator-plug assembly off the regulator.
• Clean the packing box and plug stem and carefully place
new rings of packing around the stem. Position the skive cut
of each packing ring 120˚ from that of the adjacent ring.
• Reassemble the actuator-plug assembly to the regulator
body, taking care : (a) to align hole in spacer (5) with safety
pin hole ; (b) to replace two mounting nuts (8a) before nuts
(8b) ; (c) to take extra care in guiding each ring into the
packing box.
• Tighten two nuts (8a) and two screws (16) on the actuator
yoke.
•
Wrap the safety pin (11) with two turns of PTFE tape
(Teflon). Screw it into the bonnet five and a half to six turns
from where threads engagement starts.
Note:
To find start of threads engagement, proceed as follows:
a.
Screw safety pin about one turn,
b. Pull safety pin outwards while unscrewing it.
•
Replace packing follower, packing flange and flange nuts
(8b). Tighten nuts finger tight plus one full turn. Place back
in service.
Regulator must be isolated and pressure vented
before disassembly.
Figure 5 - Plug-stem
adjustment
