8 | Baker Hughes
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B.
Carefully place plug sub-assembly into a soft jaw vise,
holding the plug by the flats provided on the upper end of
the shank.
CAUTION
CAUTION
WARNING
DANGER
When using a vise to hold the plug, extreme care
must be taken not to damage the plug shank.
C.
Using the appropriate tool, unscrew plug tip (counter-
clockwise) from the shank sub - assembly.
D.
Remove insert O-ring (for valve sizes 3"- 8" only) and insert
retainer. Discard existing insert and O-ring.
E.
Thoroughly clean all remaining metallic components
and install new insert and O-ring as follows (according to
valve size):
For 3/4"- 2" valves :
a
. Place new insert on shank and insert retainer as
shown in Figure 3.
b
. lnstall plug tip into shank sub-assembly. Hand tighten
and ensure plug tip seats evenly against insert.
For 3" – 8" valves:
a
. Apply a light coat of lubricant to the O-ring and install on
insert retainer.
CAUTION
CAUTION
WARNING
DANGER
Ensure any lubricant used is compatible with service
conditions.
b
. Install new insert on insert retainer and assemble as
shown in Figure 3.
c
. Install plug tip into insert retainer sub-assembly insuring
the plug tip seats evenly on the insert.
F.
Carefully place the plug sub-assembly into a soft jaw vise,
holding the plug by the flats provided on the upper end of the
shank.
CAUTION
CAUTION
WARNING
DANGER
When using a vise to hold the plug, extreme care
must be taken not to damage the plug shank.
G.
Using the appropriate tool used during disassembly, firmly
tighten the plug tip.
CAUTION
CAUTION
WARNING
DANGER
The plug tip must be tightened, allowed to set for
approximately 4 hours, re-tightened, allowed to set
another 4 hours, then tightened one more time. The
purpose of this tightening sequence is to allow the
insert material to “cold flow” into place on the plug
sub-assembly.
H.
Following the above tightening sequence, securely tighten
the set screw down into the plug. Plug is ready for assembly
into the valve.
7.6.3.2 Packing Installation
a.
The packing must be lubricated with Krytox
®
fluori-
nated grease prior to installation (Krytox GPL206 or
equivalent).
b
. Packing should be lubricated as a set (
not
individually
) to minimize getting lubricant between
the rings.
c
. Packing should be lubricated with a generous application
to the O.D. and I.D. of the packing set.
Note:
All exposed surfaces of the packing set must
be covered with the lubricant.
d
. PFE/PTFE is to be installed as a set. Carefully slide the
packing set down the stem. Do not cock or force the
packing on the threads.
If the packing set separates while on the stem, do not
remove. Continue installing the remaining pieces to put
the set back together.
e
. Gently press the packing into the packing box. Do not
tap the packing down into the box.
f
. The spring loaded follower is installed on top of the
packing. This follower is installed as an assembly held
together by tape. This tape should be removed after
assembly. Proper assembly of the packing box will leave
the top of the Lower Follower 0.25 – 0.50 inches (6 to
13 mm) above the bonnet.
A groove is scribed into the O.D. of the upper follower.
The packing flange is tightened evenly until the top of
the Lower Follower aligns with the scribe mark (groove)
in the Upper Follower.
Note:
This is the optimum loading for this packing.
Further tightening will shorten life of the packing.
Thread locking compound can be used on packing
nuts.
g
. The packing should be checked for leakage.
h
. Packing load should be checked after the valve has
cycled approximately 500 times. Adjust if necessary. No
further adjustment should be required for the life of the
packing.
7.7 Soft Seat Plug (Figure 3)
The soft seat plug used in the 21000 Series valve has a
replaceable insert. To remove and replace the insert, proceed
as follows.
CAUTION
CAUTION
WARNING
DANGER
The shank OD is the plug guide. Extreme care must
be taken to prevent scoring or marring this surface.
Failure to do so could result in damage to the guide
bushing and destruction of the plug. Two flats are
provided for holding.
A.
Loosen set screw until the head of the set screw is flush with
the OD of the shank.
Note:
On 3/4"‑ 2" size valves, the plug tip has a machined
slot into which a bar can be inserted for removal. On
3"‑ 6" size valves, the plug tip has two machined holes
into which a tool (fabricated with appropriate size pins)
can be inserted for removal.