Note: Descriptions are shown in the official language in which they were submitted.
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PATENT APPLICATION
DUAL SEAL FIRE SAFE STEM PACKING ORIENTATION
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation in part, and claims priority to and
the benefit of, co-
pending U.S. Application Serial No. 14/090,026, now U.S. Patent No. 9,347,585
filed November
26, 2013, titled "Dual Seal Fire Safe Stem Packing Orientation," the full
disclosure of which is
hereby incorporated herein by reference in its entirety for all purposes.
BACKGROUND
1. Field of the Disclosure
[0001] The present disclosure relates in general to valve bonnets and more
particularly, to valve
bonnet seals for use with oil, gas and other fluids.
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2. Description of Related Art
[0002] A gate valve has a body with a central chamber that is intersected by a
flow passage. A
gate moves within the chamber between the open and closed positions. The gate
has a hole
through it that aligns with the flow passage while in the open position. A
stem extends into
engagement with the gate for moving the gate between open and closed
positions. In one type,
the stem has a first end that extends through a bonnet of the valve body
assembly and a second
end that extends into rotatable engagement with a threaded nut or sleeve
secured to the gate.
Rotating the stem causes the gate to move linearly. In another type, the stem
does not rotate.
Instead a threaded nut or sleeve mounted in the bonnet engages the stem, and
when rotated,
causes the stem to move linearly.
[0003] In gate valves, and in other valves with stems that rotate or move
linearly, a stem packing
is typically located in the bonnet and engages the stem to seal pressure
within the chamber.
Valves which are designed to work within a defined fire envelope must be
capable of providing
both high integrity normal operation well control and emergency pressure
containment in the
event of a fire. A single metal to metal seal that can meet both of these
demands can require
special coatings and can be very expensive and technically difficult to design
and implement,
especially on rotary valves. In addition, a single seal does not provide
redundancy in the case of
the failure of the seal.
SUMMARY OF THE DISCLOSURE
[0004] Embodiments of the current disclosure provide a system and method
relating to a stem
packing with seal redundancy that is capable of providing both a high
integrity seal during
normal operation well control and also emergency pressure containment in the
event of a fire or
other type of packing failure. Embodiments of the current disclosure have
robust capabilities for
both normal operations and for emergency pressure containment in the event of
a fire without
significantly increasing the overall height of the valve body assembly and
without significantly
increasing the cost of the stem packing components, compared to a stem packing
that is only
capable of functioning during normal operations.
[0005] In an embodiment of this disclosure, a valve having a packing assembly
can include a
valve body assembly defining a flow passage and a body cavity perpendicular to
the flow
passage. The valve body assembly further defines a bore extending from an
exterior of the valve
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body assembly into the body cavity, the bore having a second bore portion with
an enlarged
diameter defined by an inner surface of the bore. A valve stem extends from
the body cavity to
an exterior of the valve body assembly through the bore for moving a valve
member from the
closed position to an open position, the valve stem having an axis. A first
stem packing
circumscribes a first portion of the valve stem, forming a seal between the
valve stem and the
valve body assembly, and being located in the second bore portion. A first
packing retainer has
a collar that limits axial movement of the first stem packing, and has a first
retainer body
defining an inner cavity. A second stem packing circumscribes a second portion
of the valve
stem and is located in the inner cavity of the first packing retainer. A
second packing retainer
limits axial movement of the second stem packing. A piston member is located
axially between
the first stem packing and the second stem packing, the piston member being
moveable to apply
axial force to one of the first stem packing and the second stem packing.
[0006] In another embodiment of the current disclosure, a packing assembly for
sealing an
annular space between a valve stem with an axis and a valve body assembly
includes a first
packing retainer having a collar with a first end surface, and a first
retainer body defining an
inner cavity with a bottom surface, the collar having a smaller outer diameter
than the first
retainer body. A first stem packing is located axially between the first end
surface of the collar
of the first packing retainer and the valve body assembly, forming a seal
between the valve stem
and the valve body assembly. A fire resistant stem packing is located in the
inner cavity of the
first packing retainer. A second packing retainer limits axial movement of the
fire resistant stem
packing. A piston member is located axially between the first stem packing and
the second stem
packing, the piston member being moveable to apply axial force to one of the
first stem packing
and the second stem packing.
[0007] In yet another embodiment of the current application, a method of
sealing a valve with a
packing assembly includes providing a valve having: a valve body assembly
defining a flow
passage and a body cavity perpendicular to the flow passage, the valve body
assembly further
defining a bore extending from an exterior of the valve body assembly into the
body cavity, the
bore having an second bore portion with an enlarged diameter defined by an
inner surface of the
bore; and a valve stem extending from the body cavity to an exterior of the
valve body assembly
through the bore for moving a valve member from the closed position to an open
position, the
valve stem having an axis. A first portion of the valve stem is circumscribed
with a first stem
packing, forming a seal between the valve stem and the valve body assembly in
the second bore
portion. Axial movement of the first stem packing is limited with a first
packing retainer having
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a collar and having a first retainer body defining an inner cavity. A second
portion of the valve
stem is circumscribed with a second stem packing located in the inner cavity
of the first packing
retainer. Axial movement of the second stem packing is limited with a second
packing retainer.
A piston member is located axially between the first stem packing and the
second stem packing,
the piston member being moveable to apply axial force to one of the first stem
packing and the
second stem packing.
BRIEF DESCRIPTION OF DRAWINGS
[0008] Some of the features and benefits of the present disclosure having been
stated, others will
become apparent as the description proceeds when taken in conjunction with the
accompanying
drawings, in which:
[0009] Figure 1 is a partial sectional view of a gate valve with a packing
assembly in accordance
with an embodiment of the present disclosure.
[0010] Figure 2 is a sectional view of a bonnet of a valve body assembly with
a packing
assembly in accordance with an embodiment of the present disclosure.
[0011] Figure 3 is a sectional view of a bonnet of a valve body assembly with
a packing
assembly in accordance with an alternate embodiment of the present disclosure.
[0012] Figure 4 is a sectional view of a bonnet of a valve body assembly with
a packing
assembly in accordance with an alternate embodiment of the present disclosure.
[0013] While the disclosure will be described in connection with the preferred
embodiments, it
will be understood that it is not intended to limit the disclosure to that
embodiment. On the
contrary, it is intended to cover all alternatives, modifications, and
equivalents, as may be
included within the spirit and scope of the disclosure as defined by the
appended claims.
DETAILED DESCRIPTION OF DISCLOSURE
[0014] The method and system of the present disclosure will now be described
more fully
hereinafter with reference to the accompanying drawings in which embodiments
are shown. The
method and system of the present disclosure may be in many different forms and
should not be
construed as limited to the illustrated embodiments set forth herein; rather,
these embodiments
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are provided so that this disclosure will be thorough and complete, and will
fully convey its
scope to those skilled in the art. Like numbers refer to like elements
throughout.
[0015] It is to be further understood that the scope of the present disclosure
is not limited to the
exact details of construction, operation, exact materials, or embodiments
shown and described,
as modifications and equivalents will be apparent to one skilled in the art.
In the drawings and
specification, there have been disclosed illustrative embodiments and,
although specific terms
are employed, they are used in a generic and descriptive sense only and not
for the purpose of
limitation.
[0016] Referring to Figure 1, valve 11 is a gate valve with a valve body
assembly 12. Valve
body assembly 12 includes a bonnet 14 that is coupled to a valve body 13. A
flow passage 15
extends transversely through valve body 13. Valve 11 has a valve member or
gate 17 with hole
19 therethrough. Gate 17 is shown in the closed position in Figure 1. Valve 11
shown in Figure
1 is a rising-stem type valve; however, embodiments of this disclosure can
similarly be used on
non-rising-stem type valves. When gate 17 is in the open position, hole 19 of
gate 17 registers
with flow passage 15 of valve body 13 thereby allowing flow through valve 11.
When gate 17 is
closed as shown, hole 19 no longer registers with flow passage 15, blocking
flow of fluid
through flow passage 15 and valve 11. Flow passage 15 intersects a body cavity
21 located in
valve body 13. Body cavity 21 is generally perpendicular to flow passage 15.
[0017] Valve 11 also includes a valve stem 23 coupled to gate 17. Valve stem
23 has an axis 25
passing through a center of valve stem 23. Valve stem 23 is linearly moveable
without rotation
along axis 25 to move gate 17 between the open and closed positions. In
alternative
embodiments, valve stem 23 extends into rotatable engagement with a threaded
nut or sleeve
(not shown) secured to gate 17 and rotating valve stem 23 will cause the gate
to move linearly.
In the illustrated embodiment, a valve actuator 27 couples to the bonnet 14 of
valve body
assembly 12, and circumscribes and is co-axially aligned with valve stem 23.
As illustrated,
valve 11 is hydraulically actuated. Valve 11 may be actuated by alternative
means such as by an
electrical or pneumatic actuator, using a remote operating system or by
turning a hand wheel.
Valve stem 23 extends from the body cavity 21 to the exterior of the valve
body assembly 12
through the bore 31 of bonnet 14. A packing assembly 29 provides a fluid
barrier or seal for
valve stem 23 where valve stem 23 passes through bore 31 of bonnet 14.
[0018] A person skilled in the art will understand that valve 11, which is
shown as a
hydraulically actuated gate valve, is an exemplary valve. The disclosed
embodiments
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contemplate and include any valve having a stem passing through a valve body
to operate a
valve member located within the body. Valve 11 can be, for example associated
with a wellhead
assembly that is disposed over a well. The wellhead assembly can include a
wellhead housing, a
production tree over the housing and flow lines connected to the tree or the
wellhead assembly
(not shown). The flow lines and wellhead assembly can include embodiments of
valve 11
described herein. Valve 11 can also be used for regulating fluids, such as a
fracturing fluid, that
are designated for entry into the wellhead assembly. The wellhead assembly can
be at surface or
can be subsea.
[0019] Referring to Figure 2, packing assembly 29 is shown in more detail.
Bore 31 has a first
or lower bore portion 31a of smaller diameter than second or upper bore
portion 31b which has
an enlarged diameter, creating an annular space between the valve stem 23 and
the upper bore
portion 31b. Bonnet 14 has an upward facing bonnet shoulder 35. A first or
lower stem packing
37 is axially limited by the upward facing bonnet shoulder 35. Lower stem
packing 37 is located
within the upper bore portion 3 lb and circumscribes a first portion of the
valve stem 23. Lower
stem packing 37 is a ring or tubular shaped member with a height 39. Lower
stem packing 37
creates a fluid seal between the valve stem 23 and the bonnet 14. Lower stem
packing 37 can be
formed from any material suitable for use with a valve stem packing and can
be, for example, a
floating stem packing, an elastomeric stem packing, and other known type of
stem packing.
[0020] The packing assembly 29 also includes a first or lower packing retainer
41. Lower
packing retainer 41 is located in the upper bore portion 31b, has a stepped
ring or tubular shape
and circumscribes a portion of the valve stem 23. Lower packing retainer 41
can be metal and
has a collar 43 and a first retainer body such as lower retainer body 45.
Collar 43 has a smaller
outer diameter than lower retainer body 45 and extends downwards from lower
retainer body 45.
[0021] Collar 43 has a lower end surface 47 that can provide an upper limit
for axial movement
of lower stem packing 37. In the example embodiment of Figure 4, lower end
surface 47
directly provides an upper limit for axial movement of lower stem packing 37.
In such an
example embodiment, an inner circumferential surface of the collar 43
slidingly engages valve
stem 23. In alternate embodiment of Figures 2-3, lower end surface 47 can
indirectly provide an
upper limit for axial movement of lower stem packing 37 by way of piston
member 50.
[0022] In certain embodiments, height 39 of lower stem packing 37 can be less
than the distance
between the upward facing bonnet shoulder 35 and the lower end surface 47 of
collar 43 or
piston member 50, as applicable. In such embodiments there is a gap 49 between
the upper end
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of lower stem packing 37 and the lower end surface 47 of collar 43 or piston
member 50, as
applicable. Or there is a gap between the lower end of lower stem packing 37
and the upward
facing bonnet shoulder 35. Or there is some combination thereof of such
locations of the gap,
depending on the axial location of lower stem packing 37. This gap 49 results
in lower stem
packing 37 being axially uncompressed and lower stem packing 37 is able to
float between the
upward facing bonnet shoulder 35 and the lower end surface 47 of collar 43.
Lower stem
packing 37 can therefore float separate from lower packing retainer 41 so that
lower stem
packing 37 is free of energization by lower packing retainer 41.
[0023] The lower retainer body 45 extends upwards from collar 43 and extends
radially outward
from collar 43. Lower retainer body 45 has an inner circumferential surface
defining an inner
cavity 51. Inner cavity 51 is an annular recess adjacent to valve stem 23 with
an inner annular
surface 53. Inner cavity 51 can be open in a downward facing direction
(Figures 2-3) or in an
upward facing direction (Figure 4). An outer circumferential surface 55 of
lower retainer body
45 is in non rotating contact with a part of upper bore portion 3 lb of bonnet
14 of valve body
assembly 12. A second packing, such as fire safe or fire resistant stem
packing 57 is located
within inner cavity 51. Fire resistant stem packing 57 is a ring or other
shaped member that
circumscribes a second portion of the valve stem 23. Fire resistant stem
packing 57 creates a
fluid seal between the valve stem 23 and the lower packing retainer 41. Fire
resistant stem
packing 57 can be formed of any material capable of continued seal performance
under
emergency fire conditions. Fire resistant stem packing 57 can be, for example,
a compressed
graphite packing or other known type of stem packing.
[0024] Lower packing retainer 41 also has a nose or tapered seal portion 59.
Tapered seal
portion 59 is located adjacent to the collar 43 and has a sloped downward
facing seal surface.
Tapered seal portion 59 has a circumferential recess 63 which is elongated and
opens downward
and separates the tapered seal portion 59 from collar 43. The downward facing
seal surface
mates with a sloped upward facing seal surface of the bonnet 14 of the valve
body assembly 12.
Recess 63 allows the tapered seal portion 59 to deflect inward, applying an
outward force to the
upward facing seal surface and creating a metal to metal fluid seal between
the lower packing
retainer 41 and the bonnet 14 when the downward facing seal surface is pushed
downward into
engagement with the upward facing seal surface. This metal to metal seal
prevents pressurized
fluids from escaping between the lower packing retainer 41 and the bonnet 14
in an emergency
fire condition. Lower end surface 47 of collar 43 is located axial past
tapered seal portion 59 in
a first direction and the and the entire lower stem packing 37 is located
axially past lower
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packing retainer 41 in the first direction. Therefore, fluids that are
traveling through flow
passage 15 would first have to leak past lower stem packing 37 before reaching
tapered seal
portion 59.
[0025] Packing assembly 29 further includes a second packing retainer, such as
upper packing
retainer 67. Upper packing retainer 67 is located in the upper bore portion 3
lb and is a ring or
tubular shaped member that circumscribes a portion of the valve stem 23. Upper
packing
retainer 67 has a downward facing retainer shoulder 70. An inner
circumferential surface of
upper packing retainer 67 surrounds the valve stem 23 and an outer
circumferential surface of
upper packing retainer 67 is surrounded by the bonnet 14 of valve body
assembly 12, and is in
contact with upper bore portion 31b.
[0026] In the example embodiments of Figures 2-3, upper packing retainer 67 is
an integral part
of lower packing retainer 41. In the alternate example of Figure 4, upper
packing retainer 67 is a
separate member from lower packing retainer 41. In the example embodiment of
Figure 4, upper
packing retainer 67 has a lower portion with a reduced outer diameter to
define a downward
protruding neck 68.
[0027] Downward facing retainer shoulder 70 of upper packing retainer 67 can
limit axial
movement of fire resistant stem packing 57 within inner cavity 51. In certain
embodiments, fire
resistant stem packing 57 can be axially compressed between downward facing
retainer shoulder
70 and the inner annular surface 53 of inner cavity 51.
[0028] Looking at the right side of Figure 4, upper packing retainer 67 can
engage lower retainer
body 45 of lower packing retainer 41 and can apply downward force to lower
packing retainer
41, causing lower packing retainer 41 to move downward to set the metal to
metal seal between
the lower packing retainer 41 and the bonnet 14 of valve body assembly 12 by
engaging the
downward facing seal surface of lower packing retainer 41 with the upward
facing seal surface
of bonnet 14. However, looking at the left side of Figure 4, because upper
packing retainer 67 is
threaded directly to bonnet 14, upper packing retainer 67 of such an
embodiment would not
cause lower packing retainer 41 to move downward.
[0029] Packing assembly 29 includes retaining assembly 84. Retaining assembly
84 provides a
means for retaining the components of packing assembly 29 with bonnet 14.
Looking at the
example embodiment of Figures 2-3, retaining assembly 84 includes threads on
an outer
diameter of upper packing retainer 67 (which is shown as is an integral part
of lower packing
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retainer 41). The threads of upper packing retainer 67 mate directly with
threads of bonnet 14 to
releasably secure upper packing retainer 67 to bonnet 14. Looking at the
example of Figure 4,
retaining assembly 84 is a separate threaded member that is located within the
upper bore portion
31b, retains the upper packing retainer 67 within upper bore portion 31b of
bore 31, and can
provide axial downward force to the upper packing retainer 67.
[0030] Looking at the example embodiment of the right side of Figure 4, as
retaining assembly
84 is screwed into bonnet 14, retaining assembly 84 applies downward axial
force on upper
packing retainer 67, pushing upper packing retainer 67 downwards, which in
turn causes both
the downward protruding neck 68 of the upper packing retainer 67 to axially
compress the fire
resistant stem packing 57 and the upper packing retainer 67 to push the lower
packing retainer
41 downward.
[0031] Looking at the alternate example embodiment of the left side of Figure
4, as retaining
assembly 84 is screwed into bonnet 14, retaining assembly 84 applies downward
axial force on
upper packing retainer 67, pushing upper packing retainer 67 downwards, which
in turn causes
downward protruding neck 68 of the upper packing retainer 67 to axially
compress the fire
resistant stem packing 57. Because lower retainer body 45 is also threaded
directly to bonnet 14,
in such an embodiment, retaining assembly 84 would not cause lower retainer
body to move
downward. Instead, lower stem packing 37 is axially restrained by the
threading of lower
packing retainer 41 directly into bonnet 14 and fire resistant stem packing 57
is separately
axially restrained by the threading of retaining assembly 84 directly into
bonnet 4.
[0032] Shims 98 can be located within inner cavity 51 at one or both ends of
fire resistant stem
packing 57. Shims 98 correct for any misalignments generated by the cumulative
tolerances of
the valve actuator 27, valve body assembly 12, packing assembly 29, valve stem
23, and gate 17,
in order for the hole 19 of gate 17 to correctly align with flow passage 15 of
valve body 13 of
valve body assembly 12. Shims 98 are selected to set to position the retaining
assembly 84 a
selected distance from the flow passage 15 for limiting a down stroke of the
valve stem 23 and
set the appropriate stroke of valve actuator 27. The upper end 100 of
retaining assembly 84 will
set the lower limit of the stroke of valve actuator 27. If larger shims 98 are
selected, the overall
height of packing assembly 29 will increase, and the lower limit of the stroke
of valve actuator
27 will be higher. Conversely if smaller shims 98 are selected, the overall
height of packing
assembly 29 will decrease and the lower limit of the stroke of valve actuator
27 will be lower.
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[0033] Shims 98 also make up the required space within inner cavity 51 to
allow fire resistant
stem packing 57 to be energized by downward facing retainer shoulder 70, if
desired.
Alternately, shims 98 can be made smaller than required for fire resistant
stem packing 57 to be
energized by downward facing retainer shoulder 70. Instead, fire resistant
stem packing 57 can
be energized by alternate source.
[0034] Looking at the example embodiment of Figure 2, during the initial
assembly of packing
assembly 29 within bonnet 14 of valve body assembly 12 fire resistant stem
packing 57 may or
may not be energized. The sealing capacity of packing assembly 29 may need to
be increased
during operation of valve 11, as an example due to the deterioration of the
seal members, leaks,
or a fire or overheating event. In order to energize fire resistant stem
packing 57, or in order to
provide an increase in sealing capability packing assembly 29 injection
material can be injected
into injection port 69. As an example, if during operation, wear on the fire
resistant stem
packing 57 causes the size of fire resistant stem packing 57 to be reduced,
there may no longer
be sufficient axial compression on fire resistant stem packing 57 to provide a
fluid seal during
emergency fire conditions. In such a case, an injection material can provide
additional sealing
capability to fire resistant stem packing 57.
[0035] Injection port 69 extends from the exterior of valve body assembly 12
to upper bore
portion 31b. Injection port 69 provides a flow path for the injection material
to either first stem
packing 37 (left side of Figure 4) or to fire resistant stem packing 57
(Figures 2-3). The injection
material can be, for example a plastic material, a sealant material compatible
with graphite, or
other known seal injection material. The injection material injected through
injection port 69
can alternately or concurrently apply an axial force on piston member 50. In
the example
embodiment of Figures 2-3, injection port 69 extends to a region of inner
cavity 51 that is axially
above piston member 50. In such embodiments, injecting injection material into
injection port
69 can cause piston member 50 to move downward and apply an energizing force
on first stem
packing 37. In the example embodiment of the left side of Figure 4, injection
port 69 extends to
a region of inner cavity 51 that is axially below piston member 50. In such
embodiments,
injection material injected into injection port 69 can pass through retainer
port 73 and cause
piston member 50 to move upward and apply an energizing force on second stem
packing 57.
[0036] In the example embodiment of Figure 3, the injection material can also
energize
secondary tapered seal portion 74. Secondary tapered seal portion 74 is an
integral part of lower
packing retainer 41 and can be fluid pressure energized or can have an
increased sealing
capability when injection material is injected through injection port 69.
Secondary tapered seal
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portion 74 is radially deflectable and can form a fluid seal between lower
packing retainer 41
and valve stem 23 when energized.
[0037] In the example embodiment of the right side of Figure 4, injection port
69 extends
radially inward of tapered seal portion 59 and radially outward of collar 43.
In such an
embodiment, collar seal 71 can form a seal between an outer diameter of collar
43 and an inner
surface of bonnet 14 so that injection material is forced upward towards fire
resistant stem
packing 57 and prevented from flowing downward towards first stem packing 37.
Retainer port
73 can provide a fluid flow path from injection port 69 through lower packing
retainer 41 and to
inner cavity 51. The injection material will pass through retainer port 73 and
apply a force on
piston member 50. Piston member 50 is an annular member that sealingly
circumscribes valve
stem 23 and is in sealing engagement with an inner diameter surface of lower
packing retainer
41. Piston member 50 will move axially upward and apply an axial force on fire
resistant stem
packing 57 so that fire resistant stem packing 57 is energized or so that the
sealing capability of
fire resistant stem packing 57 is increased. In such embodiment, the injection
material can
alternately be a hydraulic, pneumatic, or other pressure media.
[0038] Embodiments described herein also provide automatic internal
energization so that upon
a leak, failure, or other deterioration of packing assembly 29, operating
fluids traveling through
valve 11 can act to increase the sealing capacity of packing assembly 29.
Operating fluid that
flows from body cavity 21 to piston member 50 can apply an axial force to
piston member 50.
Looking at the example embodiments of Figures 2-3, if during operation, lower
stem packing 37
begins to leak, operating fluid from body cavity 21 can travel along
energizing fluid flow path 83
to reach piston member 50. Energizing fluid flow path extends from body cavity
21 to first stem
packing 37 and from first stem packing 37 to piston member 50. Energizing
fluid flow path 83
can follow an annular space between the outer dimeter of valve stem 23 and
inner diameter of
lower bore portion 31a. Energizing fluid flow path 83 can then pass by leaking
first stem
packing 37 to reach piston member 50. By applying an axial force on piston
member 50, Piston
member 50 will move axially upward and apply an axial force on fire resistant
stem packing 57
so that fire resistant stem packing 57 is energized or so that the sealing
capability of fire resistant
stem packing 57 is increased. In the example embodiment of Figures 2-3, piston
member 50 is
an annular member that sealingly circumscribes valve stem 23 and is in sealing
engagement with
an inner diameter surface of bonnet 14.
[0039] Looking at the example embodiment of the left side of Figure 4, if
during operation,
lower stem packing 37 begins to leak, operating fluid from body cavity 21 can
travel along
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energizing fluid flow path 83 to reach piston member 50. Energizing fluid flow
path extends
from body cavity 21 to first stem packing 37 and from first stem packing 37 to
piston member
50. Energizing fluid flow path 83 can follow an annular space between the
outer dimeter of
valve stem 23 and inner diameter of lower bore portion 31a. Energizing fluid
flow path 83 can
then pass by leaking first stem packing 37. Energizing fluid flow path then
extends through the
portion of 69 that extends through lower packing retainer 41 and to inner
cavity 51 to piston
member 50. By applying an axial force on piston member 50, piston member 50
will move
axially upward and apply an axial force on fire resistant stem packing 57 so
that fire resistant
stem packing 57 is energized or so that the sealing capability of fire
resistant stem packing 57 is
increased. In such an embodiment there may be no collar seal 71.
[0040] Embodiments of the current application can include a number of sealing
members 80
located within circumferential grooves of the components of packing assembly
29. For example,
looking at the example embodiments of Figures 2-3, sealing members 80 can from
a dynamic
seal between the outer diameter of valve stem 23 and the inner diameter of
lower packing
retainer 41 as well as form a static seal between the outer diameter of lower
packing retainer 41
and the inner diameter of bonnet 14. Sealing members 80 can be, for example,
elastomeric o-
rings and prevent any fluids from exiting the upper end of the valve body
assembly 12 if the
lower stem packing 37, lower packing retainer 41 or fire resistant stem
packing 57 leaks and
allow fluid to reach sealing members 80.
[0041] The terms "vertical", "horizontal", "upward", "downward", "above", and
"below" and
similar spatial relation terminology are used herein only for convenience
because valve 11 may
be installed in various positions, other than with the valve stem 23 pointing
upward.
[0042] The present disclosure described herein, therefore, is well adapted to
carry out the objects
and attain the ends and advantages mentioned, as well as others inherent
therein. While a
presently preferred embodiment of the disclosure has been given for purposes
of disclosure,
numerous changes exist in the details of procedures for accomplishing the
desired results. These
and other similar modifications will readily suggest themselves to those
skilled in the art, and are
intended to be encompassed within the spirit of the present disclosure
disclosed herein and the
scope of the appended claims.
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