8 | Baker Hughes
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7.6.3.1 Preparation
7.6.3.1.1 Stem
Inspect stem for any nicks or scratches on the surface
finish. Reject the stem for any of these reasons as they may
damage packing.
Note:
A properly etched part number on the stem in
the packing area will have no adverse effect on the
performance of the packing.
Stem finish should be 3-7 AARH (Ra 0,1/0,2).
7.6.3.1.2 Packing Box
Note:
Bonnets that have a lube hole or leak detection
port are unacceptable for use with the packing
arrangement.
CAUTION
CAUTION
WARNING
DANGER
Packing box should be clean and free of burrs, rust,
and any foreign matter. Parts can be cleaned with
denatured alcohol.
Note:
Packing box finish should be 125 AARH (Ra 3,2) or
better.
The packing box may be bored or honed oversize by up to
0.015” (0.38 mm) above the nominal diameter to improve the
finish. For instance, a nominal 0.875” (22.22 mm) packing box
may be bored or honed up to 0.890” (22.60 mm) and the LE
Packing will still seal properly.
Packing box must be finished to the bottom of the bore.
7.6.3.1.3 Packing
Inspect packing rings. DO NOT use packing if any nicks or
scratches on packing are observed. Check packing instructions
to ensure that it is in proper arrangement (different packing
materials contain arrangements specific to the design).
7.6.3.2 Packing Installation
a.
Refer to the packing instructions that were provided
with the packing for proper installation.
b
. Packing Manual Ref 34620 is also available as
an additional aid while completing the packing
installation.
c
. The packing should be checked for leakage.
Note:
All exposed surfaces of the packing set must
be covered with the lubricant.
d
. Packing load should be checked after the valve has
cycled approximately 500 times. Adjust if necessary.
Plant maintenance / operation personnel should
periodically inspect valves to spot leakage. Adjust if
necessary and per OEM recommendations. If leak is
not resolved, packing and any non-confirming hardware
part must be replaced.
7.6.2 Flexible Graphite Rings
Note: Flexible graphite packing rings replacement may require
disconnecting the plug stem from the actuator stem and
removal of the actuator if rings are not skive cut.
A.
By means of a hooked instrument, remove packing (6)
ensuring not to damage the sealing surfaces of the packing
box or plug stem.
Note:
On valves equipped with an optional lubricator
connection, the lantern ring must also be removed to
gain access to lower packing rings. Pay close attention
to the order and number of rings extracted with the
lantern ring. This will help with reassembly.
B.
Replace new packing set (6); first assemble a back-up ring
(Graphite Filament Yarn braided ring),
then the flexible
graphite rings
(smooth rings),
and finally another braided
back-up ring.
Note:
Assemble and compress rings one at a time into
packing box.
C.
Assemble packing follower (5) and packing flange (4).
D.
Assemble and tighten packing stud nuts (3).
CAUTION
CAUTION
WARNING
DANGER
Do not over-tighten.
E.
Proceed to appropriate instructions for actuator and valve
assembly adjustment.
F.
Place valve back in service and only tighten packing as
necessary to stop external leakage.
7.6.3 LE Packing
The Masoneilan Low-E (Low Emissions) Packing from Baker
Hughes is a high performance packing system capable of
containing fugitive emissions well below the specifications of the
most severe recommendations. It is also available as fire proof
configuration if required.
The packing is provided as a set of rings consisting of middle
rings and bound by end rings also referred to as anti-extrusion
rings. All of our Low-E solutions come with Live Loading which
is imperative to maintain a constant load on the packing and is
necessary for thermal cycling applications.
Applied properly, this packing exhibits below current regulations.
Consequently, it can effectively prevent fugitive emissions leaks
from a control valve. The Low-E packing system can directly
replace conventional packing, requiring no modification to the
control valve or actuator.
The packing material could vary depending on the specifications
and timing when the valve was ordered. It is important to
understand the specific packing material that is being replaced.
Installation should be performed by a qualified technician. The
following paragraphs will provide guidance while Packing Manual
Ref. 34620 is also available.
