U.S. patent application number 15/631564 was filed with the patent office on 2017-12-28 for large bore plug valve.
The applicant listed for this patent is S.P.M. FLOW CONTROL, INC.. Invention is credited to Nuder Said, Duc Thanh Tran, Brian C. Witkowski.
Application Number | 20170370480 15/631564 |
Document ID | / |
Family ID | 60675036 |
Filed Date | 2017-12-28 |
United States Patent
Application |
20170370480 |
Kind Code |
A1 |
Witkowski; Brian C. ; et
al. |
December 28, 2017 |
LARGE BORE PLUG VALVE
Abstract
A plug valve including a valve body defining an internal cavity,
a first passage, and a second passage, a plug defining a third
passage and being rotatable within the internal cavity, and an
insert extending within the internal cavity between the valve body
and the plug. The insert defines an interior surface and an opening
aligned with the first passage of the valve body. The insert may
also define a sealing surface extending around the opening and
standing in relief against the interior surface to sealingly engage
the plug. In addition to, or instead of, the sealing surface, the
insert may define a projection at least partially defining the
interior surface. In addition, a boot may be connected to the valve
body and interlocked with the projection to prevent, or at least
reduce, rotation of the insert relative to the valve body when the
plug rotates within the internal cavity.
Inventors: |
Witkowski; Brian C.; (Fort
Worth, TX) ; Said; Nuder; (Fort Worth, TX) ;
Tran; Duc Thanh; (Spring, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
S.P.M. FLOW CONTROL, INC. |
FORT WORTH |
TX |
US |
|
|
Family ID: |
60675036 |
Appl. No.: |
15/631564 |
Filed: |
June 23, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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62354101 |
Jun 23, 2016 |
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62393990 |
Sep 13, 2016 |
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62412230 |
Oct 24, 2016 |
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62421019 |
Nov 11, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01F 3/0853 20130101;
F04B 23/06 20130101; B01F 2215/0081 20130101; E21B 43/26 20130101;
F16K 11/00 20130101; E21B 33/038 20130101; F04B 15/02 20130101;
F16K 5/00 20130101; F16K 5/04 20130101; F04B 23/04 20130101; F16K
11/048 20130101; F16K 31/126 20130101; F16L 41/03 20130101; B01F
7/00008 20130101; F04B 47/00 20130101; E21B 33/068 20130101 |
International
Class: |
F16K 5/04 20060101
F16K005/04; F16K 31/126 20060101 F16K031/126; F16K 11/048 20060101
F16K011/048 |
Claims
1. An apparatus, comprising: a valve body defining an internal
cavity, a first passage, and a second passage; a plug defining a
third passage and being rotatable within the internal cavity to
selectively permit communication of a fluid between the first and
second passages via the third passage; and an insert extending
within the internal cavity between the valve body and the plug, the
insert defining a first opening aligned with the first passage of
the valve body, a first interior surface, and a first sealing
surface extending around the first opening and standing in relief
against the first interior surface to sealingly engage the plug;
wherein migration of the fluid into an annular region between the
insert and the plug is prevented, or at least reduced, by the
sealing engagement of the first sealing surface with the plug.
2. The apparatus of claim 1, wherein the insert comprises a first
segment including the first interior surface, the first opening,
and the first sealing surface.
3. The apparatus of claim 1, wherein the insert further defines a
second opening aligned with the second passage of the valve body, a
second interior surface, and a second sealing surface extending
around the second opening and standing in relief against the second
interior surface to sealingly engage the plug.
4. The apparatus of claim 3, wherein migration of the fluid into
the annular region between the insert and the plug is prevented, or
at least reduced, by the respective sealing engagements of the
first and second sealing surfaces with the plug.
5. The apparatus of claim 3, wherein the insert comprises a first
segment including the first interior surface, the first opening,
and the first sealing surface, and a second segment including the
second interior surface, the second opening, and the second sealing
surface.
6. The apparatus of claim 5, wherein the insert further comprises
third and fourth segments interconnecting the first and second
segments so that, in combination, the first, second, third, and
fourth segments surround the plug.
7. The apparatus of claim 1, further comprising: a flow iron
section adapted to be positioned between a hydraulic fracturing
pump and a wellhead, the flow iron section comprising one or more
of a pressurization manifold connected to the hydraulic fracturing
pump, a hydraulic fracturing tree connected to the wellhead, and a
distribution manifold connected between the pressurization manifold
and the hydraulic fracturing tree; wherein the valve body is
connected to the flow iron section so that the plug is rotatable
within the valve body to selectively permit communication of a
hydraulic fracturing fluid from the hydraulic fracturing pump to
the wellhead via at least the flow iron section and the third
passage.
8. An apparatus, comprising: a valve body defining an internal
cavity, a first passage, and a second passage; a plug defining a
third passage and being rotatable within the internal cavity to
selectively permit communication of a fluid between the first and
second passages via the third passage; an insert extending within
the internal cavity between the valve body and the plug, the insert
defining a first opening aligned with the first passage of the
valve body, a first interior surface, and a first projection at
least partially defining the first interior surface; and a boot
connected to the valve body and interlocked with the first
projection of the insert to prevent, or at least reduce, rotation
of the insert relative to the valve body when the plug rotates
within the internal cavity.
9. The apparatus of claim 8, wherein the first projection includes
first and second side surfaces, and the boot includes first and
second edge portions extending adjacent the first and second side
surfaces, respectively, of the first projection.
10. The apparatus of claim 9, wherein the boot further includes a
third edge portion extending between the first and second edge
portions and adjacent the first interior surface of the insert.
11. The apparatus of claim 8, wherein: the insert further defines a
second opening aligned with the second passage of the valve body, a
second interior surface, and a second projection at least partially
defining the second interior surface; and the boot is interlocked
with the second projection of the insert to prevent, or at least
reduce, rotation of the insert relative to the valve body when the
plug rotates within the internal cavity.
12. The apparatus of claim 11, wherein: the first projection
includes first and second side surfaces, and the boot includes
first and second edge portions extending adjacent the first and
second side surfaces, respectively, of the first projection; and
the second projection includes third and fourth side surfaces, and
the boot includes third and fourth edge portions extending adjacent
the third and fourth side surfaces, respectively, of the second
projection.
13. The apparatus of claim 12, wherein the boot further includes: a
fifth edge portion extending between the first and second edge
portions and adjacent the first interior surface of the insert; and
a sixth edge portion extending between the third and fourth edge
portions and adjacent the second interior surface of the
insert.
14. The apparatus of claim 11, wherein the insert comprises a first
segment including the first interior surface, the first projection,
and the first opening, and a second segment including the second
interior surface, the second projection, and the second
opening.
15. The apparatus of claim 14, wherein the insert further comprises
third and fourth segments interconnecting the first and second
segments so that, in combination, the first, second, third, and
fourth segments surround the plug.
16. The apparatus of claim 8, further comprising: a flow iron
section adapted to be positioned between a hydraulic fracturing
pump and a wellhead, the flow iron section comprising one or more
of a pressurization manifold connected to the hydraulic fracturing
pump, a hydraulic fracturing tree connected to the wellhead, and a
distribution manifold connected between the pressurization manifold
and the hydraulic fracturing tree; and wherein the valve body is
connected to the flow iron section so that the plug is rotatable
within the valve body to selectively permit communication of a
hydraulic fracturing fluid from the hydraulic fracturing pump to
the wellhead via at least the flow iron section and the third
passage.
17. An apparatus, comprising: a flow iron section adapted to be
positioned between a hydraulic fracturing pump and a wellhead, the
flow iron section comprising one or more of a pressurization
manifold connected to the hydraulic fracturing pump, a hydraulic
fracturing tree connected to the wellhead, and a distribution
manifold connected between the pressurization manifold and the
hydraulic fracturing tree; and a plug valve connected to the flow
iron section, the plug valve comprising a valve body and a plug,
the plug defining a first passage and being rotatable within the
valve body to selectively permit communication of a hydraulic
fracturing fluid from the hydraulic fracturing pump to the wellhead
via at least the flow iron section and the first passage, the first
passage having an inner diameter that is equal to, or greater than,
about 51/8 inches.
18. The apparatus of claim 17, wherein the valve body further
defines second and third passages configured to communicate with
one another via the first passage of the plug when communication of
the hydraulic fracturing fluid is selectively permitted from the
hydraulic fracturing pump to the wellhead via at least the flow
iron section and the first passage.
19. The apparatus of claim 18, wherein the plug valve further
comprises an insert extending between the valve body and the plug,
the insert defining an opening aligned with the first passage of
the valve body, an interior surface, and a sealing surface
extending around the opening and standing in relief against the
interior surface to sealingly engage the plug.
20. The apparatus of claim 18, wherein the plug valve further
comprises: an insert extending within the valve body between the
valve body and the plug, the insert defining an opening aligned
with the first passage of the valve body, an interior surface, and
a projection at least partially defining the interior surface; and
a boot connected to the valve body and interlocked with the
projection of the insert to prevent, or at least reduce, rotation
of the insert relative to the valve body when the plug rotates
within the valve body.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of the filing date of,
and priority to, U.S. Application No. 62/354,101, filed Jun. 23,
2016, the entire disclosure of which is hereby incorporated herein
by reference.
[0002] This application also claims the benefit of the filing date
of, and priority to, U.S. Application No. 62/393,990, filed Sep.
13, 2016, the entire disclosure of which is hereby incorporated
herein by reference.
[0003] This application also claims the benefit of the filing date
of, and priority to, U.S. Application No. 62/412,230, filed Oct.
24, 2016, the entire disclosure of which is hereby incorporated
herein by reference.
[0004] This application also claims the benefit of the filing date
of, and priority to, U.S. Application No. 62/421,019, filed Nov.
11, 2016, the entire disclosure of which is hereby incorporated
herein by reference.
TECHNICAL FIELD
[0005] The present disclosure relates in general to valves and, in
particular, to a "large bore" plug valve used in oil or gas
operations.
BACKGROUND
[0006] In oil or gas operations, one or more plug valves may be
used to control fluid flow; one such plug valve generally includes
a valve body defining a pair of fluid passages intersecting an
internal cavity. The internal cavity of the valve body accommodates
a plug and an insert, which insert extends within an annular space
between the plug and the valve body. The plug and the insert
include fluid passages that are adapted to be substantially aligned
with the fluid passages of the valve body. The plug is adapted to
rotate relative to the insert and the valve body to selectively
permit fluid flow through the respective fluid passages of the
valve body, the insert, and the plug. During operation, the insert
is meant to seal against the plug and the valve body to thereby
prevent migration of the fluid flow into the annular region between
the plug and the valve body. To establish a suitable seal between
the insert and the plug, contact pressure between the insert and
the plug must be maintained above a threshold level.
[0007] During rotation of the plug, friction between the plug and
the insert can cause the insert to shift, turn, or rotate relative
to the valve body. The shifting, turning, or rotation of the insert
relative to the valve body causes misalignment between the fluid
passages of the insert, the valve body, and the plug. This
misalignment typically causes wear, erosion, or complete wash-out
of the insert, the valve body, and/or the plug. In addition, the
force required to maintain the contact pressure between the insert
and the plug above the threshold level often increases the amount
of friction between the insert and the plug, thereby exacerbating
the issue(s) described above. Indeed, in some instances, excessive
friction between the insert and the plug can make rotation of the
plug relative to the insert difficult or impossible. These issues,
among others, are particularly acute for "large bore" plug valves
in which the fluid passage of the plug has a relatively large
diameter (e.g., about 51/8 inches, greater than about 51/8 inches,
etc.).
[0008] Therefore, to make possible the manufacture of an effective
and reliable "large bore" plug valve, what is needed is an
apparatus, system, or method to address one or more of the
foregoing issues, and/or one or more other issues.
SUMMARY
[0009] In a first aspect, the present disclosure introduces an
apparatus, including a valve body defining an internal cavity, a
first passage, and a second passage; a plug defining a third
passage and being rotatable within the internal cavity to
selectively permit communication of a fluid between the first and
second passages via the third passage; and an insert extending
within the internal cavity between the valve body and the plug, the
insert defining a first opening aligned with the first passage of
the valve body, a first interior surface, and a first sealing
surface extending around the first opening and standing in relief
against the first interior surface to sealingly engage the plug;
wherein migration of the fluid into an annular region between the
insert and the plug is prevented, or at least reduced, by the
sealing engagement of the first sealing surface with the plug.
[0010] In an embodiment, the insert includes a first segment
including the first interior surface, the first opening, and the
first sealing surface.
[0011] In another embodiment, the insert further defines a second
opening aligned with the second passage of the valve body, a second
interior surface, and a second sealing surface extending around the
second opening and standing in relief against the second interior
surface to sealingly engage the plug.
[0012] In yet another embodiment, migration of the fluid into the
annular region between the insert and the plug is prevented, or at
least reduced, by the respective sealing engagements of the first
and second sealing surfaces with the plug.
[0013] In certain embodiments, the insert includes a first segment
including the first interior surface, the first opening, and the
first sealing surface, and a second segment including the second
interior surface, the second opening, and the second sealing
surface.
[0014] In an embodiment, the insert further includes third and
fourth segments interconnecting the first and second segments so
that, in combination, the first, second, third, and fourth segments
surround the plug.
[0015] In another embodiment, the apparatus further comprises a
flow iron section adapted to be positioned between a hydraulic
fracturing pump and a wellhead, the flow iron section including one
or more of a pressurization manifold connected to the hydraulic
fracturing pump, a hydraulic fracturing tree connected to the
wellhead, and a distribution manifold connected between the
pressurization manifold and the hydraulic fracturing tree; wherein
the valve body is connected to the flow iron section so that the
plug is rotatable within the valve body to selectively permit
communication of a hydraulic fracturing fluid from the hydraulic
fracturing pump to the wellhead via at least the flow iron section
and the third passage.
[0016] In a second aspect, the present disclosure introduces an
apparatus, including a valve body defining an internal cavity, a
first passage, and a second passage; a plug defining a third
passage and being rotatable within the internal cavity to
selectively permit communication of a fluid between the first and
second passages via the third passage; an insert extending within
the internal cavity between the valve body and the plug, the insert
defining a first opening aligned with the first passage of the
valve body, a first interior surface, and a first projection at
least partially defining the first interior surface; and a boot
connected to the valve body and interlocked with the first
projection of the insert to prevent, or at least reduce, rotation
of the insert relative to the valve body when the plug rotates
within the internal cavity.
[0017] In an embodiment, the first projection includes first and
second side surfaces, and the boot includes first and second edge
portions extending adjacent the first and second side surfaces,
respectively, of the first projection.
[0018] In another embodiment, the boot further includes a third
edge portion extending between the first and second edge portions
and adjacent the first interior surface of the insert.
[0019] In yet another embodiment, the insert further defines a
second opening aligned with the second passage of the valve body, a
second interior surface, and a second projection at least partially
defining the second interior surface; and the boot is interlocked
with the second projection of the insert to prevent, or at least
reduce, rotation of the insert relative to the valve body when the
plug rotates within the internal cavity.
[0020] In certain embodiments, the first projection includes first
and second side surfaces, and the boot includes first and second
edge portions extending adjacent the first and second side
surfaces, respectively, of the first projection; and the second
projection includes third and fourth side surfaces, and the boot
includes third and fourth edge portions extending adjacent the
third and fourth side surfaces, respectively, of the second
projection.
[0021] In an embodiment, the boot further includes a fifth edge
portion extending between the first and second edge portions and
adjacent the first interior surface of the insert; and a sixth edge
portion extending between the third and fourth edge portions and
adjacent the second interior surface of the insert.
[0022] In another embodiment, the insert includes a first segment
including the first interior surface, the first projection, and the
first opening, and a second segment including the second interior
surface, the second projection, and the second opening.
[0023] In yet another embodiment, the insert further includes third
and fourth segments interconnecting the first and second segments
so that, in combination, the first, second, third, and fourth
segments surround the plug.
[0024] In certain embodiments, the apparatus further comprises a
flow iron section adapted to be positioned between a hydraulic
fracturing pump and a wellhead, the flow iron section including one
or more of a pressurization manifold connected to the hydraulic
fracturing pump, a hydraulic fracturing tree connected to the
wellhead, and a distribution manifold connected between the
pressurization manifold and the hydraulic fracturing tree; and
wherein the valve body is connected to the flow iron section so
that the plug is rotatable within the valve body to selectively
permit communication of a hydraulic fracturing fluid from the
hydraulic fracturing pump to the wellhead via at least the flow
iron section and the third passage.
[0025] In a third aspect, the present disclosure introduces an
apparatus, including a flow iron section adapted to be positioned
between a hydraulic fracturing pump and a wellhead, the flow iron
section including one or more of a pressurization manifold
connected to the hydraulic fracturing pump, a hydraulic fracturing
tree connected to the wellhead, and a distribution manifold
connected between the pressurization manifold and the hydraulic
fracturing tree; and a plug valve connected to the flow iron
section, the plug valve including a valve body and a plug, the plug
defining a first passage and being rotatable within the valve body
to selectively permit communication of a hydraulic fracturing fluid
from the hydraulic fracturing pump to the wellhead via at least the
flow iron section and the first passage, the first passage having
an inner diameter that is equal to, or greater than, about 51/8
inches.
[0026] In an embodiment, the valve body further defines second and
third passages configured to communicate with one another via the
first passage of the plug when communication of the hydraulic
fracturing fluid is selectively permitted from the hydraulic
fracturing pump to the wellhead via at least the flow iron section
and the first passage.
[0027] In another embodiment, the plug valve further includes an
insert extending between the valve body and the plug, the insert
defining an opening aligned with the first passage of the valve
body, an interior surface, and a sealing surface extending around
the opening and standing in relief against the interior surface to
sealingly engage the plug.
[0028] In yet another embodiment, the plug valve further includes
an insert extending within the valve body between the valve body
and the plug, the insert defining an opening aligned with the first
passage of the valve body, an interior surface, and a projection at
least partially defining the interior surface; and a boot connected
to the valve body and interlocked with the projection of the insert
to prevent, or at least reduce, rotation of the insert relative to
the valve body when the plug rotates within the valve body.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1A is a perspective view illustrating a plug valve,
according to one or more embodiments of the present disclosure.
[0030] FIG. 1B is an exploded perspective view illustrating
internal components of the plug valve of FIG. 1A, including, inter
alia, a plug, an inlet segment, an outlet segment, and a boot,
according to one or more embodiments of the present disclosure.
[0031] FIG. 2 is a cross-sectional view of the plug valve of FIG.
1A, including the plug, the inlet segment, the outlet segment, and
the boot, according to one or more embodiments of the present
disclosure.
[0032] FIG. 3 is an enlarged view of the plug valve of FIG. 2,
according to one or more embodiments of the present disclosure.
[0033] FIG. 4 is another enlarged view of the plug valve of FIG. 2,
according to one or more embodiments of the present disclosure.
[0034] FIGS. 5-8 are rear perspective, front perspective, top plan,
and bottom plan views, respectively, of the inlet segment of FIGS.
1B and 2, according to one or more embodiments of the present
disclosure.
[0035] FIGS. 9 and 10 are perspective views illustrating the plug,
the inlet segment, and the outlet segment in different stages of
assembly, according to one or more embodiments of the present
disclosure.
[0036] FIG. 11 is a perspective view of the boot of FIGS. 1A and 2,
according to one or more embodiments of the present disclosure.
[0037] FIG. 12 is an enlarged cross-sectional view of the plug
valve of FIG. 2 in a first operational configuration, according to
one or more embodiments of the present disclosure.
[0038] FIG. 13 is a sectional view of the plug valve taken along
the line 13-13 of FIG. 12, according to one or more embodiments of
the present disclosure.
[0039] FIG. 14 is a sectional view of the plug valve taken along
the line 14-14 of FIG. 12, according to one or more embodiments of
the present disclosure.
[0040] FIG. 15 is an enlarged view of the plug valve similar to
that shown in FIG. 12, except that the plug valve is in a second
operational configuration, according to one or more embodiments of
the present disclosure.
[0041] FIG. 16 is a sectional view of the plug valve taken along
the line 16-16 of FIG. 15, according to one or more embodiments of
the present disclosure.
[0042] FIG. 17 is a schematic illustration of a hydraulic
fracturing system, the hydraulic fracturing system including a
hydraulic fracturing pump, a flow iron section, and a wellhead,
according to one or more embodiments of the present disclosure.
[0043] FIG. 18 is an elevational view of the plug valve of FIGS.
1-16 connected between a pair of flow-line components, which
flow-line components are part of the flow iron section of FIG. 17,
according to one or more embodiments of the present disclosure.
DETAILED DESCRIPTION
[0044] Turning initially to FIGS. 1A and 1B, an example embodiment
of a plug valve, generally referred to by the reference numeral 10,
is illustrated. As shown in FIG. 1A, the plug valve 10 includes a
valve body 12, an actuator 14, an actuator plate 16, and a cover
plate 18. The actuator 14 is connected to the actuator plate 16 via
a plurality of fasteners 20, and the actuator plate 16 is connected
to the valve body 12. The cover plate 18 is connected to the valve
body 12 via a plurality of fasteners 22, opposite the actuator
plate 16. In some embodiments, the cover plate 18 is considered
part of the valve body 12. The plug valve 10 includes one or more
lubrication fittings 24 connected to the valve body 12 to
facilitate lubrication of internal component(s) of the plug valve
10. The actuator 14 is adapted to actuate the plug valve 10 between
an open configuration in which fluid flow is permitted through the
plug valve 10 and a closed configuration in which fluid flow
through the plug valve 10 is prevented, or at least reduced.
[0045] The valve body 12, the actuator 14, the actuator plate 16,
and the cover plate 18 are omitted from view in FIG. 1B to more
clearly illustrate the internal components of the plug valve 10.
Turning to FIG. 1B, the plug valve 10 further includes a plug 26
and an insert 28, which plug 26 defines an exterior surface 30 and
a fluid passage 32 extending transversely therethrough. The insert
28 is adapted to extend about and sealingly engage the exterior
surface 30 of the plug 26. The insert 28 includes an inlet segment
34, an outlet segment 36, and side segments 38a and 38b. The inlet
segment 34 includes an inlet opening 40 and is adapted to
accommodate an inlet seal 42 around the inlet opening 40. The inlet
seal 42 is adapted to engage the valve body 12. The outlet segment
36 includes an outlet opening 44 and is adapted to accommodate an
outlet seal 46 around the outlet opening 44. The outlet seal 46 is
adapted to engage the valve body 12. The side segments 38a and 38b
are adapted to connect the inlet segment 34 to the outlet segment
36 to thereby place a compressive load on the plug 26. The plug
valve 10 includes alignment dowels 48a and 48b to facilitate the
alignment of the inlet and outlet openings 40 and 44 within the
valve body 12.
[0046] The plug valve 10 also includes a drive gear 50 and an
adapter 52 via which the actuator 14 is adapted to be operably
coupled to the plug 26. The adapter 52 is adapted to be supported
within the valve body 12 via a bearing 54 and a spacer 56. The
spacer 56 is adapted to accommodate an outer seal 58 and an outer
backup ring 60 so that the outer seal 58 engages the spacer 56 and
the valve body 12. The spacer 56 is further adapted to accommodate
an inner seal 62 and an inner backup ring 64 so that the inner seal
62 engages the spacer 56 and the adapter 52. The valve body 12 is
adapted to accommodate a wiper seal 66 so that the wiper seal 66
engages the adapter 52 and the valve body 12 to prevent drainage of
fluid (e.g., lubricating fluid) from the actuator 14 into the valve
body 12. The cover plate 18 is adapted to accommodate a seal 68 and
a backup ring 70 so that the seal 68 engages the cover plate 18 and
the valve body 12. The plug valve 10 includes a boot 72 adapted to
be connected to the cover plate 18 via a plurality of fasteners 74.
Thus, the boot 72 is adapted to be connected to the valve body 12
in those embodiments in which the cover plate 18 is considered part
of the valve body 12. The boot 72 is adapted to interlock with the
insert 28 to thereby prevent, or at least reduce, rotation of the
insert 28 relative to the valve body 12 when the plug 26
rotated.
[0047] Turning to FIG. 2, with continuing reference to FIGS. 1A and
1B, it can be seen that the valve body 12 defines an internal
cavity 76, an inlet passage 78, an outlet passage 80, an actuator
bore 82, and an access port 84. The inlet passage 78 permits fluid
communication between the valve body 12 and an adjacent flow-line
component such as, for example, the flow-line component 134 shown
in FIGS. 18A and 18B, which will be discussed in further detail
below. The valve body 12 includes a flange 86 around the inlet
passage 78 to facilitate connection of the valve body 12 to the
adjacent flow-line component. The flange 86 includes a through-hole
pattern (visible in FIG. 1A; or a threaded-hole pattern). The
outlet passage 80 permits fluid communication between the valve
body 12 and another adjacent flow-line component such as, for
example, the flow-line component 136 shown in FIGS. 18A and 18B,
which will be discussed in further detail below. The valve body 12
includes a flange 88 around the outlet passage 80 to facilitate
connection of the plug valve 10 to the another adjacent flow-line
component. The flange 88 includes a through-hole pattern (visible
in FIG. 1A; or a threaded-hole pattern). In some embodiments, one
or both of the flanges 86 and 88 are omitted and replaced with
another type of fluid-line connector such as, for example, the male
half of a hammer union, the female half of a hammer union, a
hammerless union, another fluid-line connector, or any combination
thereof.
[0048] The plug 26 extends within the internal cavity 76 of the
valve body 12 and is coupled to the actuator 14 via the drive gear
50 and the adapter 52. The adapter 52 is supported within the
actuator bore 82 via the bearing 54 and the spacer 56. The wiper
seal 66 seals against the adapter 52 and the valve body 12 to
thereby prevent drainage of fluid (e.g., lubricating fluid) from
the actuator 14 into the valve body 12. The insert 28 extends about
and seals against the exterior surface 30 of the plug 26. The inlet
and outlet openings 40 and 44 are aligned with the inlet and outlet
passages 78 and 80, respectively, of the valve body 12. The
actuator 14 is operable to rotate the drive gear 50, the adapter
52, and the plug 26 relative to the valve body 12 to thereby
actuate the plug 26 between the open configuration and the closed
configuration. As shown in FIG. 2, the fluid passage 32 of the plug
26 is adapted to be aligned with the inlet and outlet openings 40
and 44 of the insert 28 and the inlet and outlet passages 78 and 80
of the valve body 12 when the plug valve 10 is in the open
configuration. In some embodiments, the fluid passage 32 has an
inner diameter of about 51/8 inches, of about 7 1/16 inches, or
ranging from about 51/8 inches to about 7 1/16 inches.
[0049] Turning to FIG. 3, with continuing reference to FIG. 2, it
can be seen that the inlet segment 34 accommodates the inlet seal
42 around the inlet opening 40 in a manner that seals the inlet
seal 42 against the valve body 12 around the inlet passage 78.
Likewise, the outlet segment 36 accommodates the outlet seal 46
around the outlet opening 44 in a manner that seals the outlet seal
46 against the valve body 12 around the outlet passage 80 (visible
in FIG. 2). The cover plate 18 extends into the access port 84 and
accommodates the seal 68 and the backup ring 70 so that the seal 68
seals against the valve body 12. The boot 72 is connected to the
cover plate 18 via the plurality of fasteners 74 in a manner that
permits interlocking of the insert 28 with the boot 72. Thus, the
boot 72 is connected to the valve body 12 in those embodiments in
which the cover plate 18 is considered part of the valve body 12.
Alternatively, although described herein as being connected to the
cover plate 18, the boot 72 may instead be connected directly to
the valve body 12.
[0050] Turning to FIG. 4, with continuing reference to FIG. 2, the
spacer 56 accommodates the outer seal 58 and the outer backup ring
60 so that the outer seal 58 seals against the valve body 12. The
spacer 56 also accommodates the inner seal 62 and the inner backup
ring 64 so that the inner seal 62 seals against the adapter 52.
[0051] The outlet segment 36 is substantially identical to the
inlet segment 34 and, therefore, in connection with FIGS. 5-8, only
the inlet segment 34 will be described in detail below; however,
the description below also applies to the outlet segment 36.
Turning to FIGS. 5-8, the inlet segment 34 includes a concave
interior surface 90 and a convex exterior surface 92. The inlet
opening 40 extends through the concave interior surface 90 and the
convex exterior surface 92. The inlet segment 34 includes a concave
sealing surface 94 formed around the inlet opening 40. The concave
sealing surface 94 stands in relief against the concave interior
surface 90 to seal against the exterior surface 30 of the plug 26.
The inlet segment 34 includes a sealing groove 96 formed in the
convex exterior surface 92 and around the inlet opening 40. The
sealing groove 96 accommodates the inlet seal 42. The convex
exterior surface 92 also includes longitudinally-extending grooves
98a and 98b formed therein to facilitate connection of the inlet
segment 34 to the side segments 38a and 38b, respectively. The
inlet segment 34 includes an alignment notch 100 to accommodate the
dowel 92a when the plug valve 10 is assembled. The inlet segment 34
also includes a projection 102 opposite the alignment notch 100.
The projection 102 includes side surfaces 104a and 104b. In some
embodiments, the side surfaces 104a and 104b are spaced in a
parallel relation. The projection 102 is adapted to interlock with
the boot 72 to thereby prevent, or at least reduce, rotation of the
insert 28 relative to the valve body 12 when the plug 26 is
actuated between the open configuration and the closed
configuration, as will be discussed in further detail below.
[0052] Turning to FIGS. 9 and 10, with continuing reference to
FIGS. 5-8, an example embodiment of the manner in which the
compressive load is placed on the plug 26 by the insert 28 is
illustrated. To begin with, the inlet and outlet segments 34 and 36
are engaged with the exterior surface 30 of the plug 26.
Subsequently, the side segment 38a is adapted to be connected to
the longitudinally-extending groove 98a of the inlet segment 34 and
a longitudinally-extending groove of the outlet segment 36 (which
is analogous to the longitudinally-extending groove 98b of the
inlet segment 34). Moreover, the side segment 38b is adapted to be
connected to the longitudinally-extending groove 98b of the inlet
segment 34 and a longitudinally-extending groove of the outlet
segment 36 (which is analogous to the longitudinally-extending
groove 98a of the inlet segment 34). The connection of the side
segments 38a and 38b with the inlet and outlet segments 34 and 36
is adapted to place the side segments 38a and 38b in tension
between the inlet and outlet segments 34 and 36 so that the
compressive load is placed on the plug 26 by the inlet and outlet
segments 34 and 36. The tensioning of the side segments 38a and 38b
between the inlet and outlet segments 34 and 36 is adapted to seal
the concave sealing surface 94 of the inlet segment 34 against the
exterior surface 30 of the plug 26, and to seal a concave sealing
surface of the outlet segment 36 (which is analogous to the concave
sealing surface 94 of the inlet segment 34) against the exterior
surface 30 of the plug 26, opposite the inlet segment 34. During
operation, the sealing of the inlet and outlet segments 34 and 36
against the plug 26 is aided by a lubricating fluid (not shown)
provided at the interface between the plug 26 and the inlet and
outlet segments 34 and 36 via, for example, the lubrication
fitting(s) 24 (FIG. 1A). The side segments 38a and 38b are spaced
apart from the plug 26 when the side segments 38a and 38b are
tensioned between the inlet and outlet segments 34 and 36 (i.e.,
such that the side segments 38a and 38b do not contact the plug
26).
[0053] Although the side segments 38a and 38b have been described
herein as being connected to the inlet segment 34's
longitudinally-extending grooves 98a and 98b and the outlet segment
36's longitudinally-extending grooves (which are analogous to the
inlet segment 34's longitudinally-extending grooves 98a and 98b),
the side segments 38a and 38b may be connected to the side segments
38a and 38b in another suitable manner. Moreover, although the
compressive load applied to the plug 26 by the inlet and outlet
segments 34 and 36 has been described herein as being provided by
tensioning of the side segments 38a and 38b between the inlet and
outlet segments 34 and 36, the side segments 38a and 38b may
alternatively be omitted and the compressive load applied to the
plug 26 by the inlet and outlet segments 34 and 36 may be provided
by another suitable structure or mechanism.
[0054] Turning to FIG. 11, with continuing reference to FIGS. 5-10,
an example embodiment of the boot 72 is illustrated. The boot 72
includes edge portions 106a and 106b and edge portions 108a-d. In
some embodiments, the edge portions 106a and 106b are convex. In
some embodiments, the edge portions 108a-d are straight. In some
embodiments, the edge portions 106a and 106b are convex and the
edge portions 108a-d are straight. The boot 72 includes a
through-hole pattern 110 (e.g., including countersunk
through-holes) to facilitate connection of the boot 72 to the cover
plate 18.
[0055] The edge portions 108a and 108b of the boot 72 are adapted
to extend adjacent the side surfaces 104a and 104b, respectively,
of the inlet segment 34. In some embodiments, the edge portions
108a and 108b are spaced in a parallel relation. Moreover, the edge
portion 106a is adapted to extend adjacent the concave interior
surface 90 of the inlet segment 34 when the edge portions 108a and
108b of the boot 72 extend adjacent the side surfaces 104a and
104b, respectively, of the inlet segment 34. In this manner, the
boot 72 is adapted to interlock with the projection 102 of the
inlet segment 34.
[0056] The edge portions 108c and 108d of the boot 72 are adapted
to extend adjacent surfaces, respectively, of the outlet segment
36. In some embodiments, the edge portions 108c and 108d are spaced
in a parallel relation. The surfaces of the outlet segment 36 with
which the edge portions 108c and 108d of the boot 72 are adapted to
extend adjacent are analogous to the side surfaces 104a and 104b of
the inlet segment 34. Moreover, the edge portion 106b of the boot
72 is adapted to extend adjacent a concave interior surface of the
outlet segment 36 when the edge portions 108c and 108d extend
adjacent the surfaces of the outlet segment 36. The concave
interior surface of the outlet segment 36 with which the edge
portion 106b of the boot 72 is adapted to extend adjacent is
analogous to the concave interior surface 90 of the inlet segment
34. In this manner, the boot 72 is adapted to interlock with a
projection of the outlet segment 36 that is analogous to the
projection 102 of the inlet segment 34.
[0057] Turning to FIGS. 12-16, in operation, the plug valve 10 is
actuable between the open configuration (shown in FIGS. 12-14) and
the closed configuration (shown in FIGS. 15 and 16). Turning to
FIGS. 12 and 13, in the open configuration, the fluid passage 32 of
the plug 26 is aligned with the inlet and outlet openings 40 and 44
of the insert 28 and the inlet and outlet passages 78 and 80 of the
valve body 12 so that fluid flow is permitted through the plug
valve 10, as indicated by arrow(s) 112. The inlet seal 42 engages
the valve body 12 around the inlet passage 78 to thereby prevent
migration of the fluid 112 into an annular region between the
insert 28 and the valve body 12 as the fluid 112 enters the fluid
passage 32 via the inlet passage 78 and the inlet opening 40. To
prevent migration of the fluid 112 into an annular region between
the insert 28 and the plug 26, the concave sealing surface 94 of
the inlet segment 34 seals against the exterior surface 30 of the
plug 26 around the fluid passage 32. In addition, the outlet seal
46 engages the valve body 12 around the outlet passage 80 to
thereby prevent migration of the fluid 112 into the annular region
between the insert 28 and the valve body 12 as the fluid 112 exits
the fluid passage 32 via the outlet opening 44 and the outlet
passage 80. To prevent migration of the fluid 112 into the annular
region between the insert 28 and the plug 26, the concave sealing
surface of the outlet segment 36 (which is analogous to the concave
sealing surface 94 of the inlet segment 34) seals against the
exterior surface 30 of the plug 26 around the fluid passage 32. The
sealing of the inlet and outlet segments 34 and 36 against the plug
26 is aided by the lubricating fluid (not shown) provided at the
interface between the plug 26 and the inlet and outlet segments 34
and 36 via, for example, the lubrication fitting(s) 24 (FIG.
1A).
[0058] Turning to FIG. 14, it can be seen that the projection 102
of the inlet segment 34 and the projection of the outlet segment 36
(which is analogous to the projection 102 of the inlet segment 34)
each interlock with the boot 72 to thereby prevent, or at least
reduce, rotation of the insert 28 relative to the valve body 12.
More particularly, the edge portions 108a and 108b of the boot 72
extend adjacent the side surfaces 104a and 104b, respectively, of
the inlet segment 34, and the edge portion 106a of the boot 72
extends adjacent the concave interior surface 90 of the inlet
segment 34. In this manner, the boot 72 interlocks with the
projection 102 of the inlet segment 34. In addition, the edge
portions 108c and 108d of the boot 72 extend adjacent the surfaces,
respectively, of the outlet segment 36 (which are analogous to the
side surfaces 104a and 104b of the inlet segment 34), and the edge
portion 106b of the boot 72 extends adjacent the concave interior
surface of the outlet segment 36 (which is analogous to the concave
interior surface 90 of the inlet segment 34). In this manner, the
boot 72 interlocks with the projection of the outlet segment 36
(which is analogous to the projection 102 of the inlet segment 34)
to prevent, or at least reduce, rotation of the insert 28 relative
to the valve body 12. As a result, the substantial alignment
between the inlet and outlet openings 40 and 44 of the insert 28
and the inlet and outlet passages 78 and 80, respectively, of the
valve body 12 is maintained during the actuation of the plug valve
10 between the open and closed configurations.
[0059] Turning to FIGS. 15 and 16, in the closed configuration, the
plug 26 is rotated to prevent, or at least reduce, communication of
the fluid 112 from the inlet passage 78 to the outlet passage 80 of
the valve body 12. To actuate the plug 26 from the open
configuration to the closed configuration, the actuator 14 rotates
the plug 26 (via the drive gear 50 and the adapter 52) so that the
fluid passage 32 of the plug 26 is no longer aligned with the inlet
and outlet openings 40 and 44 of the insert 28 or the inlet and
outlet passages 78 and 80 of the valve body 12. Instead, the
exterior surface 30 of the plug 26 is substantially aligned with
the inlet and outlet openings 40 and 44 of the insert 28 and the
inlet and outlet passages 78 and 80 of the valve body 12 to thereby
block communication of the fluid 112 from the inlet passage 78 to
the outlet passage 80 of the valve body 12. The fluid 112 within
the inlet passage 78 and the inlet opening 40 is prevented from
migrating into the annular region between the insert 28 and the
valve body 12 by the sealing engagement of the inlet seal 42
against the valve body 12 around the inlet passage 78. More
particularly, to prevent migration of the fluid 112 into the
annular region between the insert 28 and the plug 26, the concave
sealing surface 94 of the inlet segment 34 seals against the
exterior surface 30 of the plug 26. The lubricating fluid (not
shown) provided at the interface between the plug 26 and the inlet
segment 34 (via, for example, the lubrication fitting(s) 24 (FIG.
1A)) aids with the sealing engagement of the inlet segment 34
against the plug 26. The tensioning of the side segments 38a and
38b between the inlet and outlet segments 34 and 36 prevents the
fluid 112 in the inlet passage 78 from unsealing the concave
sealing surface 94 of the inlet segment 34 from the exterior
surface 30 of the plug 26.
[0060] The manner in which the concave sealing surface 94 stands in
relief against the concave interior surface 90 of the inlet segment
34 reduces the contact area between the insert 28 and the plug 26.
Similarly, the manner in which the outlet segment 36's concave
sealing surface (which is analogous to the concave sealing surface
94 of the inlet segment 34) stands in relief against the concave
interior surface (which is analogous to the concave interior
surface 90 of the inlet segment 34) reduces the contact area
between the insert 28 and the plug 26. In addition, the spacing
apart of the side segments 38a and 38b from the plug 26 when the
side segments 38a and 38b are tensioned between the inlet and
outlet segments 34 and 36 reduces the contact area between the
insert 28 and the plug 26.
[0061] In some embodiments, reducing the contact area between the
insert 28 and the plug 26 increases the contact pressure between
the insert 28 and the plug 26. In some embodiments, reducing the
contact area between the insert 28 and the plug 26 decreases the
amount of force required to maintain the contact pressure between
the insert 28 and the plug 26 above the minimum threshold required
to establish a suitable seal with the plug 26. In some embodiments,
reducing the contact area between the insert 28 and the plug 26
enables the side segments 38a and 38b (or another suitable
structure or mechanism) to maintain the contact pressure between
the insert 28 and the plug 26 above the minimum threshold required
to establish a suitable seal with the plug 26.
[0062] In some embodiments, reducing the contact area between the
insert 28 and the plug 26 decreases the amount of friction between
the plug 26 and the insert 28. In some embodiments, reducing the
contact area between the insert 28 and the plug 26 mitigates any
shifting, turning, or rotation of the insert 28 relative to the
valve body 12. In some embodiments, reducing the contact area
between the insert 28 and the plug 26 prevents, or at least
reduces, misalignment between the inlet and outlet openings 40 and
44 of the insert 28 and the inlet and outlet passages 78 and 80 of
the valve body 12. In some embodiments, reducing the contact area
between the insert 28 and the plug 26 prevents, or at least
reduces, wear, erosion, or complete wash-out of the plug 26, the
insert 28, and/or the valve body 12.
[0063] In some embodiments, the reduced contact area between the
insert 28 and the plug 26 makes possible the manufacture of an
effective and reliable "large bore" plug valve 10 in which the
fluid passage 32 of the plug 26 has an inner diameter of: about
51/8 inches, greater than about 51/8 inches, ranging from about
51/8 inches to about 7 1/16 inches, about 7 1/16 inches, or greater
than about 7 1/16 inches. In some embodiments, the reduced contact
area between the insert 28 and the plug 26 permits relaxed
tolerances during the manufacture of the insert 28 while
maintaining the insert 28's capability to matingly engage the plug
26 so that an effective seal is maintained therebetween.
[0064] In some embodiments, the engagement of the boot 72 with the
inlet segment 34's projection 102 and/or the outlet segment 36's
projection (which is analogous to the projection 102) mitigates any
shifting, turning, or rotation of the insert 28 relative to the
valve body 12. In some embodiments, the engagement of the boot 72
with the inlet segment 34's projection 102 and/or the outlet
segment 36's projection (which is analogous to the projection 102)
prevents, or at least reduces, misalignment between the inlet and
outlet openings 40 and 44 of the insert 28 and the inlet and outlet
passages 78 and 80 of the valve body 12. In some embodiments, the
engagement of the boot 72 with the inlet segment 34's projection
102 and/or the outlet segment 36's projection (which is analogous
to the projection 102) prevents, or at least reduces, wear,
erosion, or complete wash-out of the plug 26, the insert 28, and/or
the valve body 12.
[0065] In some embodiments, the engagement of the boot 72 with the
inlet segment 34's projection 102 and/or the outlet segment 36's
projection (which is analogous to the projection 102) makes
possible the manufacture of an effective and reliable "large bore"
plug valve 10 in which the fluid passage 32 of the plug 26 has an
inner diameter of: about 51/8 inches, greater than about 51/8
inches, ranging from about 51/8 inches to about 7 1/16 inches,
about 7 1/16 inches, or greater than about 7 1/16 inches.
[0066] Turning to FIG. 17, with continuing reference to FIGS. 1-16,
a hydraulic fracturing system, generally referred to by the
reference numeral 114, is illustrated. The hydraulic fracturing
system 114 includes a flow iron section 116 positioned between a
hydraulic fracturing pump 118 and a wellhead 120. The flow iron
section 116 includes one or more of: a pressurization manifold 122
connected to the hydraulic fracturing pump 118, a hydraulic
fracturing tree 124 connected to the wellhead 120, and a
distribution manifold 126 connected between the pressurization
manifold 122 and the hydraulic fracturing tree 124. The
pressurization manifold 122 includes a low pressure section 128
connected between a fluid source 130 and the hydraulic fracturing
pump 118, and a high pressure section 132 connected between the
hydraulic fracturing pump 118 and the distribution manifold 126. In
addition to, or instead of, the hydraulic fracturing pump 118, the
hydraulic fracturing system 114 may include other hydraulic
fracturing pump(s) (not shown) to facilitate pressurization of the
hydraulic fracturing fluid from the low pressure section 128 and
communication of the pressurized hydraulic fracturing fluid to the
high pressure section 132. The wellhead 120 is located at the top
or head of an oil and gas wellbore (not shown), which penetrates
one or more subterranean formations (not shown). In addition to, or
instead of the, wellhead to which the fracturing tree is connected,
the hydraulic fracturing system 114 may also include one or more
wellheads (not shown) to which fracturing trees (not shown) are
connected; the distribution manifold 126 facilitates communication
of the pressurized hydraulic fracturing fluid to such wellhead(s)
via the corresponding fracturing tree(s).
[0067] In operation, the hydraulic fracturing fluid is communicated
from the hydraulic fracturing pump 118 to the wellhead 120 via at
least the flow iron section 116 to thereby facilitate hydraulic
fracturing of the subterranean formation(s). More particularly, the
hydraulic fracturing fluid is communicated from the fluid source
130 to the low pressure section 128 of the pressurization manifold
122. The hydraulic fracturing pump 118 receives the hydraulic
fracturing fluid from the low pressure section 128, pressurizes the
hydraulic fracturing fluid, and communicates the pressurized
hydraulic fracturing fluid to the high pressure section 132. The
high pressure section 132 communicates the pressurized hydraulic
fracturing fluid from the hydraulic fracturing pump 118 to the
distribution manifold 126. The distribution manifold 126
communicates the pressurized hydraulic fracturing fluid from the
high pressure section 132 of the pressurization manifold 122 to the
hydraulic fracturing tree 124 connected to the wellhead 120.
[0068] Turning to FIG. 18, with continuing reference to FIG. 17, it
can be seen that the flange 86 of the valve body 12 is connected to
the flow-line component 134, and the flange 88 of the valve body 12
is connected to the flow-line component 136. The flow-line
component 134 is connected to, or part of, the flow iron section
116, including one or more of the pressurization manifold 122
connected to the hydraulic fracturing pump 118, the hydraulic
fracturing tree 124 connected to the wellhead 120, and the
distribution manifold 126 connected between the pressurization
manifold 122 and the hydraulic fracturing tree 124. Likewise, the
flow-line component 134 is connected to, or part of, the flow iron
section 116, including one or more of the pressurization manifold
122, the hydraulic fracturing tree 124, and the distribution
manifold 126. The connection of the valve body 12 between the
flow-line components 134 and 136 incorporates the plug valve 10
into the hydraulic fracturing system 114 so that, during the
operation of the hydraulic fracturing system 114 to facilitate
hydraulic fracturing of the subterranean formation(s), the plug 26
is rotatable within the valve body 12 to selectively permit
communication of the hydraulic fracturing fluid from the hydraulic
fracturing pump 118 to the wellhead 120 via at least the flow iron
section 116 and the fluid passage 32 of the plug 26.
[0069] The flow-line components 134 and 136 to which the plug valve
10 is connected are illustrated in FIG. 18 as a pair of spools;
however, the flow-line components 134 and 136 may each be, include,
or be part of, a variety of flow-line components including, but not
limited to, a valve, a spool, a flow block, a swivel block, another
flow-line component, or any combination thereof. In addition,
depending upon the particular characteristics of the flow iron
section 116 to which the plug valve 10 is connected, the flow-line
components 134 and 136 and the plug valve 10 may be oriented
differently than the orientation illustrated in FIG. 18 (i.e.,
horizontally, vertically, diagonally, etc.).
[0070] It is understood that variations may be made in the
foregoing without departing from the scope of the present
disclosure.
[0071] In some embodiments, the elements and teachings of the
various embodiments may be combined in whole or in part in some or
all of the embodiments. In addition, one or more of the elements
and teachings of the various embodiments may be omitted, at least
in part, and/or combined, at least in part, with one or more of the
other elements and teachings of the various embodiments.
[0072] In some embodiments, while different steps, processes, and
procedures are described as appearing as distinct acts, one or more
of the steps, one or more of the processes, and/or one or more of
the procedures may also be performed in different orders,
simultaneously and/or sequentially. In some embodiments, the steps,
processes and/or procedures may be merged into one or more steps,
processes and/or procedures.
[0073] In some embodiments, one or more of the operational steps in
each embodiment may be omitted. Moreover, in some instances, some
features of the present disclosure may be employed without a
corresponding use of the other features. Moreover, one or more of
the above-described embodiments and/or variations may be combined
in whole or in part with any one or more of the other
above-described embodiments and/or variations.
[0074] In the foregoing description of certain embodiments,
specific terminology has been resorted to for the sake of clarity.
However, the disclosure is not intended to be limited to the
specific terms so selected, and it is to be understood that each
specific term includes other technical equivalents which operate in
a similar manner to accomplish a similar technical purpose. Terms
such as "left" and right", "front" and "rear", "above" and "below"
and the like are used as words of convenience to provide reference
points and are not to be construed as limiting terms.
[0075] In this specification, the word "comprising" is to be
understood in its "open" sense, that is, in the sense of
"including", and thus not limited to its "closed" sense, that is
the sense of "consisting only of". A corresponding meaning is to be
attributed to the corresponding words "comprise", "comprised" and
"comprises" where they appear.
[0076] Although some embodiments have been described in detail
above, the embodiments described are illustrative only and are not
limiting, and those skilled in the art will readily appreciate that
many other modifications, changes and/or substitutions are possible
in the embodiments without materially departing from the novel
teachings and advantages of the present disclosure. Accordingly,
all such modifications, changes, and/or substitutions are intended
to be included within the scope of this disclosure as defined in
the following claims. In the claims, any means-plus-function
clauses are intended to cover the structures described herein as
performing the recited function and not only structural
equivalents, but also equivalent structures. Moreover, it is the
express intention of the applicant not to invoke 35 U.S.C.
.sctn.112, paragraph 6 for any limitations of any of the claims
herein, except for those in which the claim expressly uses the word
"means" together with an associated function.
* * * * *