U.S. patent application number 09/836019 was filed with the patent office on 2001-09-20 for valve with secondary load bearing surface.
This patent application is currently assigned to Halliburton Enrgy Services, Inc.. Invention is credited to Davis, Glenn Ray, Dennistoun, Stuart Morton.
Application Number | 20010022194 09/836019 |
Document ID | / |
Family ID | 26976970 |
Filed Date | 2001-09-20 |
United States Patent
Application |
20010022194 |
Kind Code |
A1 |
Davis, Glenn Ray ; et
al. |
September 20, 2001 |
Valve with secondary load bearing surface
Abstract
A valve (120) for controlling fluid flow therethrough in
downhole applications is disclosed. The valve (120) comprises a
valve housing having a valve closure mechanism (122) and a valve
seat (124) disposed therein. The valve closure mechanism (122) has
sealing surface (128) and a secondary load bearing surface (142).
The valve seat (124) has a valve seat sealing surface (126) that
mates with the sealing surface (128) of the valve closure mechanism
(122). The secondary load bearing surface (142) of the valve
closure mechanism (122) mates with a valve secondary load bearing
surface (134) which may be supported by the valve seat (124).
Inventors: |
Davis, Glenn Ray; (Euless,
TX) ; Dennistoun, Stuart Morton; (Carrollton,
TX) |
Correspondence
Address: |
Lawrence R. Youst
Smith, Danamraj & Youst, P.C
LB-15, Suite 1200
12900 Preston Road
Dallas
TX
75230-1328
US
|
Assignee: |
Halliburton Enrgy Services,
Inc.
|
Family ID: |
26976970 |
Appl. No.: |
09/836019 |
Filed: |
April 17, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09836019 |
Apr 17, 2001 |
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09483355 |
Jan 14, 2000 |
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6263910 |
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09483355 |
Jan 14, 2000 |
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09309716 |
May 11, 1999 |
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6196261 |
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Current U.S.
Class: |
137/527 ;
137/516.27; 166/325; 166/332.8 |
Current CPC
Class: |
Y10T 137/7898 20150401;
E21B 2200/05 20200501; E21B 34/10 20130101; F16K 1/2057 20130101;
Y10T 137/7867 20150401; F16K 1/2014 20130101; E21B 34/06 20130101;
Y10T 137/7866 20150401 |
Class at
Publication: |
137/527 ;
137/516.27; 166/325; 166/332.8 |
International
Class: |
F16K 015/00; E21B
034/10 |
Claims
What is claimed is:
1. A valve comprising: a valve housing; a valve closure mechanism
disposed within the valve housing having a valve closure mechanism
sealing surface and a valve closure mechanism secondary load
bearing surface; a valve seat disposed within the valve housing
having a valve seat sealing surface; and a valve secondary load
bearing surface for receiving the valve closure mechanism secondary
load bearing surface.
2. The valve as recited in claim 1 wherein the valve secondary load
bearing surface is supported by the valve seat.
3. The valve as recited in claim 1 wherein the valve secondary load
bearing surface is supported by the valve housing.
4. The valve as recited in claim 1 wherein the valve secondary load
bearing surface further comprises an internal load bearing
shoulder.
5. The valve as recited in claim 1 wherein the valve secondary load
bearing surface further comprises an external load bearing
surface.
6. The valve as recited in claim 1 wherein the valve secondary load
bearing surface further comprises an internal support member.
7. The valve as recited in claim 1 wherein the valve secondary load
bearing surface further comprises first and second internal support
members.
8. The valve as recited in claim 1 wherein the valve secondary load
bearing surface further comprises an internal support member and an
internal load bearing shoulder.
9. The valve as recited in claim 1 wherein the valve secondary load
bearing surface further comprises first and second internal support
members and an internal load bearing shoulder.
10. The valve as recited in claim 1 wherein the valve secondary
load bearing surface further comprises an internal support member
and an external load bearing surface.
11. The valve as recited in claim 1 wherein the valve secondary
load bearing surface further comprises first and second internal
support members and an external load bearing surface.
12. The valve as recited in claim 1 wherein the valve secondary
load bearing surface further comprises a seal ring insert within
the valve seat.
13. The valve as recited in claim 12 wherein the seal ring insert
further comprises a solid ring.
14. The valve as recited in claim 12 wherein the seal ring insert
further comprises a machined weld bead.
15. A valve comprising: a valve housing having a valve chamber; a
valve seat mounted within the housing having a valve seat sealing
surface, the valve seat defining a flow passage therethrough; and a
flapper closure plate rotatably disposed within the valve chamber
rotatable between a valve open position in which the flapper
closure plate is removed from the valve seat and a valve closed
position in which a sealing surface of the flapper closure plate
sealingly engages the valve seat sealing surface for preventing
flow through the flow passage, a valve secondary load bearing
surface receiving a flapper closure plate secondary load bearing
surface to define the maximum travel of the flapper closure plate
in the closed position.
16. The valve as recited in claim 15 wherein the valve secondary
load bearing surface is supported by the valve seat.
17. The valve as recited in claim 15 wherein the valve secondary
load bearing surface is supported by the valve housing.
18. The valve as recited in claim 15 wherein the secondary load
bearing surface further comprises an internal load bearing
shoulder.
19. The valve as recited in claim 15 wherein the valve secondary
load bearing surface further comprises an external load bearing
surface.
20. The valve as recited in claim 19 wherein the flapper closure
plate further comprises a ballast member and wherein the external
load bearing surface of the valve seat and the ballast member of
the flapper closure plate define the maximum travel of the flapper
closure plate in the closed position.
21. The valve as recited in claim 15 wherein the valve secondary
load bearing surface further comprises an internal support
member.
22. The valve as recited in claim 15 wherein the valve secondary
load bearing surface further comprises first and second internal
support members.
23. The valve as recited in claim 15 wherein the valve secondary
load bearing surface further comprises an internal support member
and an internal load bearing shoulder.
24. The valve as recited in claim 15 wherein the valve secondary
load bearing surface further comprises first and second internal
support members and an internal load bearing shoulder.
25. The valve as recited in claim 15 wherein the valve secondary
load bearing surface further comprises an internal support member
and an external load bearing surface.
26. The valve as recited in claim 15 wherein the valve secondary
load bearing surface further comprises first and second internal
support members and an external load bearing surface.
27. The valve as recited in claim 15 further comprising a seal ring
insert within the valve seat.
28. The valve as recited in claim 27 wherein the seal ring insert
further comprises a solid ring.
29. The valve as recited in claim 27 wherein the seal ring insert
further comprises a machined weld bead.
30. The valve as recited in claim 15 wherein the sealing surface of
the flapper closure plate forms a convex spherical segment having
radius of curvature and wherein the valve seat sealing surface
forms a concave spherical segment having a radius of curvature that
is substantially matched with the radius of curvature of the convex
spherical segment of the flapper closure plate to permit nesting
engagement of the convex spherical segment of the flapper closure
plate against the concave spherical segment of the valve seat.
31. A subsurface safety valve adapted to be placed in a well tubing
string to control flow therethrough comprising: a valve housing
having a bore therethrough; a flapper closure plate mounted within
the bore of the housing and movable between a valve open position
and a valve closed position, the flapper closure plate having a
sealing surface and a secondary load bearing surface; an operator
movably disposed within the bore of the housing for controlling
movement of the flapper closure plate between the valve open
position and the valve closed position; a valve seat disposed
within the valve housing, the valve seat having a flow passage bore
and a sealing surface, in the valve closed position, the sealing
surface of the flapper closure plate sealingly engaging the sealing
surface of the valve seat; a valve secondary load bearing surface
receiving the secondary load bearing surface of the flapper closure
plate to define the maximum travel of the flapper closure
plate.
32. The subsurface safety valve as recited in claim 31 wherein the
valve secondary load bearing surface is supported by the valve
seat.
33. The subsurface safety valve as recited in claim 31 wherein the
valve secondary load bearing surface is supported by the valve
housing.
34. The subsurface safety valve as recited in claim 31 wherein the
valve secondary load bearing surface further comprises an internal
load bearing shoulder.
35. The subsurface safety valve as recited in claim 31 wherein the
valve secondary load bearing surface further comprises an external
load bearing surface.
36. The subsurface safety valve as recited in claim 35 wherein the
flapper closure plate further comprises a ballast member and
wherein the external load bearing surface of the valve seat and the
ballast member of the flapper closure plate defining the maximum
travel of the flapper closure plate in the closed position.
37. The subsurface safety valve as recited in claim 31 wherein the
valve secondary load bearing surface further comprises an internal
support member.
38. The subsurface safety valve as recited in claim 31 wherein the
valve secondary load bearing surface further comprises first and
second internal support members.
39. The subsurface safety valve as recited in claim 31 wherein the
valve secondary load bearing surface further comprises an internal
support member and an internal load bearing shoulder.
40. The subsurface safety valve as recited in claim 31 wherein the
valve secondary load bearing surface further comprises first and
second internal support members and an internal load bearing
shoulder.
41. The subsurface safety valve as recited in claim 31 wherein the
valve secondary load bearing surface further comprises an internal
support member and an external load bearing surface.
42. The subsurface safety valve as recited in claim 31 wherein the
valve secondary load bearing surface further comprises first and
second internal support members and an external load bearing
surface.
43. The subsurface safety valve as recited in claim 31 further
comprising a seal ring insert within the valve seat.
44. The subsurface safety valve as recited in claim 42 wherein the
seal ring insert further comprises a solid ring.
45. The subsurface safety valve as recited in claim 42 wherein the
seal ring insert further comprises a machined weld bead.
46. The subsurface safety valve as recited in claim 31 wherein the
sealing surface of the flapper closure plate forms a convex
spherical segment having radius of curvature and wherein the valve
seat sealing surface forms a concave spherical segment having a
radius of curvature that is substantially matched with the radius
of curvature of the convex spherical segment of the flapper closure
plate to permit nesting engagement of the convex spherical segment
of the flapper closure plate against the concave spherical segment
of the valve seat.
Description
RELATED APPLICATION
[0001] This application is a continuation-in-part of pending
application Ser. No. 09/309,716 filed on May 11, 1999.
TECHNICAL FIELD OF THE INVENTION
[0002] This invention relates in general to subsurface safety
valves and, in particular, to a subsurface safety valve that
includes a valve sealing surface and a secondary load bearing
surface.
BACKGROUND OF THE INVENTION
[0003] Without limiting the scope of the invention, the background
will describe surface controlled, subsurface safety valves, as an
example.
[0004] Surface controlled, subsurface safety valves are commonly
used to shut in oil and gas wells in the event of a failure or
hazardous condition at the well surface. Such safety valves are
typically fitted into the production tubing and operate to block
the flow of formation fluid upwardly therethrough. The subsurface
safety valve provides automatic shutoff of production flow in
response to a variety of out of range safety conditions that can be
sensed or indicated at the surface. For example, the safety
conditions include a fire on the platform, a high or low flow line
temperature or pressure condition or operator override.
[0005] During production, the subsurface safety valve is typically
held open by the application of hydraulic fluid pressure conducted
to the subsurface safety valve through an auxiliary control conduit
which extends along the tubing string within the annulus between
the tubing and the well casing. Flapper type subsurface safety
valves utilize a closure plate which is actuated by longitudinal
movement of a hydraulically actuated, tubular piston. The flapper
valve closure plate is maintained in the valve open position by an
operator tube which is extended by the application of hydraulic
pressure onto the piston. A pump at the surface pressurizes a
reservoir which delivers regulated hydraulic control pressure
through the control conduit. Hydraulic fluid is pumped into a
variable volume pressure chamber and acts against the crown of the
piston. When, for example, the production fluid pressure rises
above or falls below a preset level, the control pressure is
relieved such that the piston and operator tube are retracted to
the valve closed position by a return spring. The flapper plate is
then rotated to the valve closed position by a torsion spring or
tension member.
[0006] In conventional subsurface safety valves of the type
utilizing an upwardly closing flapper plate, the flapper plate is
seated against an annular sealing face, either in metal-to-metal
contact or metal against an annular elastomeric seal. In one
design, the flapper closure plate has a flat, annular sealing face
which is engageable against a flat, annular valve seat ring, with
sealing engagement being enhanced by an elastomeric seal ring which
is mounted on the valve seat. In another design, the valve seat
includes a downwardly facing, conical segment having a sloping
sealing surface and the flapper closure plate has a complementary,
sloping annular sealing surface which is adapted for
surface-to-surface engagement against the conical valve seat
surface.
[0007] Typically, the flapper closure plate is supported for
rotational movement by a hinge assembly which includes a hinge pin
and a torsion spring or tension member. It will be appreciated that
structural distortion of the flapper valve closure plate, or damage
to the hinge assembly which supports the flapper closure plate, can
cause misalignment of the respective sealing surfaces, thereby
producing a leakage path through the safety valve.
[0008] Such misalignment will prevent correct seating and sealing
of the flapper closure plate, and formation fluid may escape
through the damaged valve, causing waste and pollution. During
situations involving damage to the wellhead, the well flow must be
shut off completely before repairs can be made and production
resumed. Even a small leak through the flapper safety valve in a
gas well can cause catastrophic damage.
[0009] Attempts have been made to overcome this misalignment
problem. For example, one design involves the use of a valve seat
and an upwardly closing flapper plate each having a sealing surface
with a matched spherical radius of curvature. That is, the valve
seat is a concave spherical segment and the sealing surface of the
flapper plate is a convex spherical segment. In this arrangement,
the spherical radius of curvature of the concave valve seat
spherical segment is matched with the spherical radius of curvature
of the convex spherical segment which defines the sealing surface
on the flapper plate. The matching spherical surfaces are lapped
together to provide a metal-to-metal seal along the interface
between the nested convex and concave sealing surfaces.
[0010] As such, the convex spherical sealing segment of the flapper
plate is received in nesting engagement within the concave
spherical segment surface of the valve seat, which allows some
angular displacement of the flapper plate relative to the valve
seat without interrupting surface-to-surface engagement
therebetween. Thus, the concave spherical seating surface of the
safety valve seat will tolerate a limited amount of misalignment of
the flapper plate which might be caused by structural distortion of
the closure plate or warping of the hinge assembly.
[0011] It has been found, however, the even when using spherical
sealing surfaces leakage may occur. Specifically, applications
using large diameter tubing and having a low ratio between the
outer diameter and the inner diameter of the sealing surfaces,
distortion of the flapper closure plate caused by increased loads
on the flapper closure plate may result in a loss of the seal.
These increased loads are developed as a consequence of using
larger safety valves having larger flapper closure plates in larger
tubing.
[0012] Therefore, a need has arisen for a flapper valve that
maintains a seal in a well requiring a large diameter flapper valve
having a low ratio between the outer diameter and the inner
diameter of the sealing surfaces. A need has also arisen for such a
flapper valve that does not experience a loss of the seal in
response to distortion of the flapper closure plate caused by the
increased loads associated with such designs.
SUMMARY OF THE INVENTION
[0013] The present invention disclosed herein is a valve comprising
a valve closure mechanism that mates with a valve seat, where the
valve has enhanced load-bearing capability. The valve of the
present invention has separate sealing and load bearing surfaces,
and can thus be deployed in a well requiring a large diameter valve
having a low ratio between the outer diameter and the inner
diameter of the sealing surfaces. The enhanced load-bearing
capability of the valve of the present invention is particularly
applicable in high pressure situations. Furthermore, the valve of
the present invention does not experience a loss of the seal in
response to distortion of the valve closure mechanism due to the
increased loads on the valve that are associated with such
applications.
[0014] The valve of the present invention comprises a valve
housing, a valve closure member having a sealing surface and a
secondary load bearing surface, a valve seat having a valve seat
sealing surface, and a secondary load bearing surface that is
located on either the valve seat or as part of the valve housing or
on both the valve seat and the valve housing. The valve closure
mechanism includes a secondary load bearing surface that may be
located anywhere on, or formed as an integral part of, the valve
closure mechanism. The valve closure mechanism secondary load
bearing surface may be either an internal or external shoulder, or
one or more internal or external support members, or any
combination thereof. The load bearing surface of the valve closure
mechanism will mate or engage with a load bearing surface found
either on the valve seat or the valve housing, or both.
[0015] Should the valve seat include a secondary load bearing
surface, the secondary load bearing surface may be either an
internal load bearing surface of the valve seat or an external load
bearing surface of the valve seat. The secondary load bearing
surface of the valve seat may be either an internal or external
shoulder, or one or more internal support members, or any
combination thereof. A secondary load bearing surface may
alternatively be coupled to the valve housing or integrally formed
thereon. Should the valve housing include a secondary load bearing
surface, the secondary load bearing surface of the valve housing
may, for example, be an internal shoulder or one or more internal
support members, or any combination thereof.
[0016] The valve of the present invention may be a flapper valve.
Alternatively, the valve of the present invention may be a gate
valve, a ball valve, a poppit, a valve having sliding members, a
valve having sleeves, and any other types of valves known in the
art. Accordingly, the valve closure member of the valve may be a
flapper closure plate, a gate, a ball, a sleeve, a sliding member,
or any other structure that forms a seal when mated to or engaged
with a corresponding valve seat. Furthermore, a flapper closure
plate may be flat or contoured.
[0017] In one embodiment, the valve includes a tubular valve
housing having a valve chamber. A valve seat is mounted within a
housing. The valve seat has a sealing surface and a secondary load
bearing surface. A valve closure mechanism is provided as a flapper
closure plate having a sealing surface and a secondary load bearing
surface. The flapper closure plate is disposed within the valve
chamber and rotates between a valve open position, in which the
flapper closure plate is removed from the valve seat, and a valve
closed position, in which the sealing surface of the flapper
closure plate sealingly engages the valve seat sealing surface for
preventing flow therethrough. When the flapper closure plate is in
the valve closed position, the secondary load bearing surface of
the valve seat defines the maximum travel of the flapper closure
plate.
[0018] In one embodiment of the present invention, the secondary
load bearing surface of a valve seat is an internal load bearing
shoulder that may be machined as an integral part of the valve
seat. In another embodiment, the valve seat may include a seal ring
insert that comprises a material having a hardness greater than
that of the valve seat. The seal ring insert may be a solid ring.
Alternatively, the seal ring may be a machined weld bead. In either
case, the seal ring insert forms a portion of the valve seat
sealing surface and may serve as an internal load bearing
shoulder.
[0019] In another embodiment, the secondary load bearing surface of
the valve seat is an external load bearing shoulder. In this
embodiment, the flapper closure plate includes a ballast member
extending from the end of the flapper closure plate opposite the
pivot pin, such that the external load bearing shoulder of the
valve seat and the ballast member of the flapper closure plate
define the maximum travel of the flapper closure plate. The
external load bearing shoulder may be used alone or in combination
with an internal load bearing shoulder or internal support members,
each serving as secondary load bearing surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] For a more complete understanding of the present invention,
including its features and advantages, reference is now made to the
detailed description of the invention, taken in conjunction with
the accompanying drawings of which:
[0021] FIG. 1 is a schematic illustration of an offshore oil or gas
production platform operating a subsurface safety valve of the
present invention;
[0022] FIGS. 2A-2B are half sectional views of a subsurface safety
valve of the present invention in the valve open position;
[0023] FIGS. 3A-3B are half sectional views of a subsurface safety
valve of the present invention in the valve closed position;
[0024] FIG. 4 is a cross sectional view of a valve of the present
invention in the valve closed position;
[0025] FIG. 5 is a perspective view of a flapper closure plate of a
valve of the present invention;
[0026] FIG. 6 is a cross sectional view of a valve of the present
invention in the valve closed position under typical load
conditions;
[0027] FIG. 7 is a cross sectional view of a valve of the present
invention in the valve closed position under high load
conditions;
[0028] FIG. 8 is a cross sectional view of a valve of the present
invention in the valve closed position under typical load
conditions;
[0029] FIG. 9 is a cross sectional view of a valve of the present
invention in the valve closed position;
[0030] FIG. 10 is a perspective view of a flapper closure plate of
a valve of the present invention;
[0031] FIG. 11 is a cross sectional view of a valve of the present
invention in the valve closed position;
[0032] FIG. 12 is a perspective view of a flapper closure plate
positioned against a support member of a valve of the present
invention;
[0033] FIG. 13 is a cross sectional view of a valve of the present
invention in the valve closed position; and
[0034] FIG. 14 is a perspective view of a flapper closure plate
positioned against a pair of support members of a valve of the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0035] While the making and using of various embodiments of the
present invention is discussed in detail below, it should be
appreciated that the present invention provides many applicable
inventive concepts which can be embodied in a wide variety of
specific contexts. The specific embodiments discussed herein are
merely illustrative of specific ways to make and use the invention,
and do not delimit the scope of the invention.
[0036] Referring to FIG. 1, a subsurface safety valve in use with
an offshore oil and gas production platform is schematically
illustrated and generally designated 10. A semi-submersible
platform 12 is centered over a submerged oil and gas formation 14
located below sea floor 16. Wellhead 18 is located on deck 20 of
platform 12. Well 22 extends through the sea 24 and penetrates the
various earth strata including formation 14 to form wellbore 26.
Disposed within wellbore 26 is casing 28. Disposed within casing 28
and extending from wellhead 18 is production tubing 30. A pair of
seal assemblies 32, 34 provide a seal between tubing 30 and casing
28 to prevent the flow of production fluids therebetween. During
production, formation fluids enter wellbore 26 through perforations
36 of casing 28 and travel into tubing 30 through sand control
device 38 to wellhead 18. Subsurface safety valve 40 is located
within the production tubing 30 and seals the wellhead 18 from the
well formation 14 in the event of abnormal conditions. Subsurface
safety valve 40 includes a valve closure mechanism that, during
production from formation 14, is maintained in the valve open
position by hydraulic control pressure received from a surface
control system 42 through a control conduit 44.
[0037] Referring now to FIGS. 2A, 2B, 3A and 3B, a subsurface
safety valve 50 is illustrated. Safety valve 50 has a relatively
larger production bore and is, therefore, intended for use in high
flow rate wells. Safety valve 50 is connected directly in series
with production tubing 30. Hydraulic control pressure is conducted
in communication with a longitudinal bore 52 formed in the sidewall
of the top connector sub 54. Pressurized hydraulic fluid is
delivered through the longitudinal bore 52 into an annular chamber
56 defined by a counterbore 58 which is in communication with an
annular undercut 60 formed in the sidewall of the top connector sub
54. An inner housing mandrel 62 is slidably coupled and sealed to
the top connector sub 54 by a slip union 64 and seal 66, with the
undercut 60 defining an annulus between inner mandrel 62 and the
sidewall of top connector sub 54.
[0038] A piston 68 is received in slidable, sealed engagement
against the internal bore of inner mandrel 62. The undercut annulus
60 opens into a piston chamber 70 in the annulus between the
internal bore of a connector sub 72 and the external surface of
piston 68. The external radius of an upper sidewall piston section
74 is machined and reduced to define a radial clearance between
piston 68 and connector sub 72. An annular sloping surface 76 of
piston 68 is acted against by the pressurized hydraulic fluid
delivered through control conduit 44. In FIGS. 2A-2B, piston 68 is
fully extended with the piston shoulder 78 engaging the top annular
face 80 of an operator tube 82. In this valve open position, a
return spring 84 is fully compressed.
[0039] In the illustrated embodiment, a flapper plate 86 is
pivotally mounted onto a hinge sub 88 which is threadably connected
to the lower end of spring housing 90. A valve seat 92 is confined
within a counterbore formed on hinge sub 88. The lower end of
safety valve 50 is connected to production tubing 30 by a bottom
sub connector 94. The bottom sub connector 94 has a counterbore 96
which defines a valve chamber 98. Thus, the bottom sub connector 94
forms a part of the valve housing enclosure. Flapper plate 86
pivots about pivot pin 100 and is biased to the valve closed
position as shown in FIGS. 3A-3B by coil spring 102. In the valve
open position as shown in FIGS. 2A-2B, the spring bias force is
overcome and flapper plate 86 is retained in the valve open
position by operator tube 82 to permit formation fluid flow up
through tubing 30.
[0040] When an out of range condition occurs and subsurface safety
valve 50 must be operated from the valve open position to the valve
closed position, hydraulic pressure is released from conduit 44
such that return spring 84 acts on the lower end of piston 68 which
retracts operator tube 82 longitudinally through valve chamber 98.
Flapper closure plate 86 will then rotate through chamber 98. As
flapper closure plate 86 nears the valve closed position within
valve chamber 98 where significant throttling of fluid flow occurs,
the high magnitude reaction forces may distort the operator tube
82, flapper closure plate 86 or pivot pin 100. Moreover, the
alignment of flapper plate 86 relative to valve seat 92 may be
disturbed in response to slamming impact of flapper closure plate
86 against valve seat 92.
[0041] Referring now to FIG. 4, a valve is depicted and generally
designated 120. Valve 120 includes a valve closure mechanism which
is depicted as flapper closure plate 122. Valve 120 also includes a
valve seat 124. In the illustrated embodiment, the sealing surfaces
of flapper closure plate 122 and valve seat 124 have mating
segments which are matched in curvature to provide a metal-to-metal
seal. Sealing surface 126 of valve seat 124 is a concave spherical
segment. Sealing surface 128 of flapper closure plate 122 is a
convex spherical segment. Convex flapper closure plate sealing
surface 128 and concave valve seat sealing surface 126 are both
generally a surface of revolution produced by revolving a
semi-circular arc having an arc length 130 and radius of curvature
132. As shown in FIG. 4, the radius of curvature of convex flapper
closure plate sealing surface 128 is substantially equal to the
radius of curvature of concave valve seat sealing surface 126.
[0042] Specifically, the spherical radius of curvature of the
concave valve seat sealing surface 126 is matched with the
spherical radius of curvature of the convex flapper closure plate
sealing surface 128. As used herein, "matched radius of curvature"
means that the radius of curvature of the flapper plate convex
sealing surface 128 is substantially the same as, but not greater
than, the radius of curvature of the concave valve seat sealing
surface 126. Preferably, the convex and concave surfaces are
matched in curvature to provide smooth, non-binding surface
engagement of convex flapper closure plate sealing surface 128
against concave valve seat sealing surface 126. The matching convex
and concave spherical surfaces 128, 126 are lapped together to
permit close nesting engagement of flapper closure plate 122 within
valve seat 124. This arrangement permits smooth angular
displacement of flapper closure plate 122 relative to valve seat
124 without interrupting surface-to-surface engagement
therebetween.
[0043] Valve seat 124 includes a secondary load bearing surface
which, in the illustrated embodiment, is an internal load bearing
shoulder 134 extending generally radially inwardly from concave
valve seat sealing surface 126. As explained in more detail below,
internal load bearing shoulder 134 defines the maximum travel of
flapper closure plate 122 relative to valve seat 124.
[0044] Referring now to FIG. 5, flapper closure plate 122 has a
convex spherical sealing surface 128 and a semi-cylindrical channel
136 across the top of flapper closure plate 122 in alignment with
its longitudinal axis 138. The radial projection of flapper closure
plate 122 is minimized, so that in the valve open position as shown
in FIGS. 2A-2B, operator tube 82 is received within
semi-cylindrical channel 136, with convex spherical sealing surface
128 projecting into the annulus between operator tube 82 and bottom
sub connector 94. Flapper closure plate 122 has a secondary load
bearing surface depicted as shoulders 142.
[0045] Referring now to FIGS. 6 and 7, valve 120 is depicted in a
view that is rotated 90 degrees from that in FIG. 4. Valve 120
includes flapper closure plate 122 and valve seat 124. As explained
above with reference to FIG. 4, sealing surface 126 of valve seat
124 is a concave spherical segment and sealing surface 128 of
flapper closure plate 122 is a convex spherical segment. Concave
sealing surface 126 of valve seat 124 has a radius of curvature
that is substantially equal to that of convex flapper closure plate
sealing surface 128. Valve seat 124 includes an internal load
bearing shoulder 134 extending generally radially inwardly from
concave valve seat sealing surface 126 which defines the maximum
travel of flapper closure plate 122 relative to valve seat 124.
[0046] Under typical flow rate regimes, the matching convex and
concave spherical surfaces 128, 126 are lapped together to permit
close nesting engagement of flapper closure plate 122 within valve
seat 124 as shown in FIG. 6 wherein a gap 140 exists between
shoulders 142 of flapper closure plate 122 and internal load
bearing shoulder 134 of valve seat 124. In applications where large
diameter tubing and large diameter flapper closure plates are
necessary and where the ratio of the outer and inner diameters of
the sealing surfaces are low, the loads on flapper closure plate
122 tend to deform flapper closure plate 122 about axis 138 which
may result in a loss of seal. Specifically, as flapper closure
plate 122 deforms about axis 138, the seal area between flapper
closure plate 122 and valve seat 124 could be reduced. As best seen
in FIG. 7, internal load bearing shoulder 134 of valve seat 124
defines the maximum travel of flapper closure plate 122 such that
any deformation of flapper closure plate 122 about axis 138 that
closes gap 140 between shoulders 142 of flapper closure plate and
internal load bearing shoulder 134 of valve seat 124 will not
reduce the seal area between flapper closure plate 122 and valve
seat 124 and will not interrupt surface-to-surface engagement
between the nested spherical segments, but will merely shift the
region of overlapping engagement. Consequently, a continuous,
positive metal-to-metal seal is maintained completely around the
spherical segment interface.
[0047] Referring next to FIG. 8, therein is depicted another
embodiment of a valve of the present invention that is generally
designated 150. Valve 150 has valve closure member shown as a
flapper closure plate 122 and valve seat 152. As with valve 120 of
FIGS. 6 and 7, valve seat 152 has concave valve seat sealing
surface 126 and flapper closure plate 122 has a convex flapper
closure plate sealing surface 128. Concave sealing surface 126 of
valve seat 152 has a radius of curvature that is substantially
equal to that of convex flapper closure plate sealing surface
128.
[0048] Valve seat 152 includes a seal ring insert 154. Seal ring
insert 154 forms a portion of concave sealing surface 126 and forms
the secondary load bearing surface illustrated as internal load
bearing shoulder 134 that extends generally radially inwardly from
concave valve seat sealing surface 126. Internal load bearing
shoulder 134 defines the maximum travel of flapper closure plate
122 relative to valve seat 152. Preferably, seal ring insert 154
comprises a material that has a higher hardness than valve seat
152. As seal ring insert 154 must withstand extreme loads exerted
by shoulders 142 of flapper closure plate 122, the hardness of seal
ring insert 154 is an important feature of the present invention.
For example, seal ring insert 154 may be formed by machining out a
section of valve seat 152 and laying a weld bead therein. The weld
bead is then machined smooth to form a portion of concave sealing
surface 126 and internal load bearing shoulder 134. Alternatively,
seal ring insert 154 may be a solid ring that is welded in place
within valve seat 152 then machined smooth to form a portion of
concave sealing surface 126 and internal load bearing shoulder
134.
[0049] Referring now to FIG. 9, a valve is depicted and generally
designated 160. Valve 160 includes a valve closure member shown as
a flapper closure plate 162 and a valve seat 164. In the
illustrated embodiment, the sealing surfaces of flapper closure
plate 162 and valve seat 164 have mating segments which are matched
in curvature to provide a metal-to-metal seal. Sealing surface 166
of valve seat 164 is a concave spherical segment. Sealing surface
168 of flapper closure plate 162 is a convex spherical segment. The
radius of curvature 170 of convex flapper closure plate sealing
surface 168 is substantially equal to the radius of curvature of
concave valve seat sealing surface 166.
[0050] Specifically, the radius of curvature of the flapper plate
convex sealing surface 168 is substantially the same as, but not
greater than, the radius of curvature of the concave valve seat
sealing surface 166. Preferably, the convex and concave surfaces
are matched in curvature to provide smooth, non-binding surface
engagement of convex flapper closure plate sealing surface 168
against concave valve seat sealing surface 166. The matching convex
and concave spherical surfaces 168, 166 are lapped together to
permit close nesting engagement of flapper closure plate 162 within
valve seat 164. This arrangement permits smooth angular
displacement of flapper closure plate 162 relative to valve seat
164 without interrupting surface-to-surface engagement
therebetween.
[0051] Valve seat 164 includes two secondary load bearing surfaces,
specifically an internal load bearing shoulder 172 extending
generally radially inwardly from concave valve seat sealing surface
166 and an external load bearing shoulder 174 extending generally
radially outwardly from concave valve seat sealing surface 166.
Flapper closure plate 162 also includes two secondary load bearing
surfaces depicted as shoulders 188 and ballast member 176. External
load bearing shoulder 174 is axially aligned with ballast member
176 of flapper closure plate 162. Ballast member 176 is integral
with flapper closure plate 162 and is disposed opposite of pivot
pin support member 178. Together, these secondary load bearing
surfaces, internal load bearing shoulder 172 and external load
bearing shoulder 174, define the maximum travel of flapper closure
plate 162 relative to valve seat 164. It should be noted by those
skilled in the art that even though ballast member 176 is depicted
as integral with flapper closure plate 162, a ballast member could
be attached to flapper closure plate 162 using a variety of methods
including, but not limited to, welding or bolting.
[0052] In application where large diameter tubing and large
diameter flapper closure plates are necessary and wherein the ratio
between the outer and inner diameters of the sealing surfaces is
low, the loads on flapper closure plate 162 tend to deform flapper
closure plate 162 about both axis 180 and axis 182, as best seen in
FIG. 10. As flapper closure plate 162 deforms about axis 180 and
gap 184 is closed, internal load bearing shoulder 172 of valve seat
164 defines the maximum travel of shoulders 188 of flapper closure
plate 162. Likewise, as flapper closure plate 162 deforms about
axis 182 and gap 186 is closed, external load bearing shoulder 174
of valve seat 162 defines the maximum travel of ballast member 176
of flapper closure plate 162. As such, any deformation of flapper
closure plate 162 about axis 180 or axis 182 will not reduce the
seal area between flapper closure plate 162 and valve seat 164 and
will not interrupt surface-to-surface engagement between the nested
spherical segments, but will merely shift the region of overlapping
engagement. Consequently, a continuous, positive metal-to-metal
seal is maintained completely around the spherical segment
interface.
[0053] Even though FIG. 9 depicts two secondary loads bearings
surfaces, internal load bearing shoulder 172 and external load
bearing shoulder 174, it should be understood that by those skilled
in the art that a single secondary load bearing surface may
alternatively be utilized such as internal load bearing shoulder
172, as explained above with reference to FIGS. 4-8, or external
load bearing shoulder 174.
[0054] Referring now to FIG. 11, a valve is depicted and generally
designated 200. Valve 200 includes a valve closure mechanism
depicted as a flapper closure plate 202 and a valve seat 204. In
the illustrated embodiment, the sealing surfaces of flapper closure
plate 202 and valve seat 204 have mating segments which are matched
in curvature to provide a metal-to-metal seal. Sealing surface 206
of valve seat 204 is a concave spherical segment. Sealing surface
208 of flapper closure plate 202 is a convex spherical segment.
Convex flapper closure plate sealing surface 208 and concave valve
seat sealing surface 206 are both generally a surface of revolution
produced by revolving a semi-circular arc having an arc length 210
and radius of curvature 212. As shown in FIG. 11, the radius of
curvature of convex flapper closure plate sealing surface 208 is
substantially equal to the radius of curvature of concave valve
seat sealing surface 206.
[0055] Preferably, the convex and concave surfaces are matched in
curvature to provide smooth, non-binding surface engagement of
convex flapper closure plate sealing surface 208 against concave
valve seat sealing surface 206. The matching convex and concave
spherical surfaces 208, 206 are lapped together to permit close
nesting engagement of flapper closure plate 202 within valve seat
204. This arrangement permits smooth angular displacement of
flapper closure plate 202 relative to valve seat 204 without
interrupting surface-to-surface engagement therebetween.
[0056] Valve seat 204 includes a secondary load bearing surface
depicted as internal support member 214 extending generally
radially inwardly about a portion of the circumference of concave
valve seat sealing surface 206 on the side opposite hinge 216.
Internal support member 214 is positioned within a pocket 218 cut
in concave valve sealing surface 206 of valve seat 204. Internal
support member 214 is securably attached within pocket 218 using
suitable means of such a one or more bolts 220. Internal support
member 214 is properly aligned within pocket 218 using pin 222 that
extends into hole 224 of internal support member 214 and hole 226
of valve seat 204. Internal support member 214 defines the maximum
travel of flapper closure plate 202 relative to valve seat 204.
[0057] Under typical flow rate regimes, the matching convex and
concave spherical surfaces 208, 206 are lapped together to permit
close nesting engagement of flapper closure plate 202 within valve
seat 204 as shown in FIG. 11 wherein a gap 228 exists between a
secondary load bearing surface 230 of flapper closure plate 202 and
surface 232 of internal support member 214. In applications where
large diameter tubing and large diameter flapper closure plates are
necessary and where the ratio of the outer and inner diameters of
the sealing surfaces are low, the loads on flapper closure plate
202 tend to deform flapper closure plate 202 about both axis 234
and axis 236, as best seen in FIG. 12, which may result in a loss
of seal. Specifically, as flapper closure plate 202 deforms about
axes 234, 236, the seal area between flapper closure plate 202 and
valve seat 204 could be reduced. Internal support member 214
defines the maximum travel of flapper closure plate 202 such that
any deformation of flapper closure plate 202 closes gap 228 but
will not reduce the seal area between flapper closure plate 202 and
valve seat 204 and will not interrupt surface-to-surface engagement
between the nested spherical segments, merely shifting the region
of overlapping engagement. Consequently, a continuous, positive
metal-to-metal seal is maintained completely around the spherical
segment interface.
[0058] While FIG. 11 has been described with reference to a single
secondary load bearing surface, i.e., support member 214, it should
be understood by those skilled in the art that support member 214
may be used in conjunction with an internal load bearing shoulder
134 as described above with reference to FIGS. 4-7 or an external
load bearing shoulder 174 as described above with reference to
FIGS. 9-10 or both.
[0059] Alternatively, it should be noted that internal support
member 214 may be secured to flapper closure plate 202 such that
when flapper closure plate 214 is in the closed position, internal
support member 214 is received within pocket 218 which serves as
the secondary load bearing surface of valve seat 204. In another
alternative, internal support member 214 may be received within or
against a secondary load bearing surface of the valve housing as
opposed to the valve seat 214.
[0060] Referring now to FIG. 13, a valve is depicted and generally
designated 240. Valve 240 includes a valve closure member depicted
as a flapper closure plate 242 and a valve seat 244. In the
illustrated embodiment, the sealing surfaces of flapper closure
plate 242 and valve seat 244 have mating segments which are matched
in curvature to provide a metal-to-metal seal. Sealing surface 246
of valve seat 244 is a concave spherical segment. Sealing surface
248 of flapper closure plate 242 is a convex spherical segment.
Preferably, the convex and concave surfaces are matched in
curvature to provide smooth, non-binding surface engagement of
convex flapper closure plate sealing surface 248 against concave
valve seat sealing surface 246. The matching convex and concave
spherical surfaces 248, 246 are lapped together to permit close
nesting engagement of flapper closure plate 242 within valve seat
244. This arrangement permits smooth angular displacement of
flapper closure plate 242 relative to valve seat 244 without
interrupting surface-to-surface engagement therebetween.
[0061] Valve seat 244 includes a secondary load bearing surface
depicted as a pair of internal support members 250, 252 extending
generally radially inwardly about portions of the circumference of
concave valve seat sealing surface 246. Internal support members
250, 252 are positioned within pockets 254, 256 cut in concave
valve sealing surface 246 of valve seat 244. Internal support
members 250, 252 are secured within pockets 254, 256 using by
suitable means such as one or more bolts 258. Internal support
member 250 is aligned within pocket 254 using a pin 260 that
extends between hole 262 of valve seat 244 and hole 264 at internal
support member 250. Internal support member 252 is aligned within
pocket 256 using a pin 266 that extends between hole 268 of valve
seat 244 and hole 270 of internal support member 252.
[0062] Internal support members 250, 252 define the maximum travel
of flapper closure plate 242 relative to valve seat 244. Under
typical flow rate regimes, the matching convex and concave
spherical surfaces 248, 246 are lapped together to permit close
nesting engagement of flapper closure plate 242 within valve seat
244, as shown in FIG. 13, wherein gaps 272, 274 exists between
secondary load bearing surface 280 of flapper closure plate 242 and
internal support members 250, 252. In applications where large
diameter tubing and large diameter flapper closure plates are
necessary and where the ratio of the outer and inner diameters of
the sealing surfaces are low, the loads on flapper closure plate
242 tend to deform flapper closure plate 242 about both axis 276
and axis 278, as best seen in FIG. 14, which may result in a loss
of seal. Specifically, as flapper closure plate 242 deforms about
axes 276, 278, the seal area between flapper closure plate 242 and
valve seat 244 could be reduced. Internal support members 250, 252
defines the maximum travel of flapper closure plate 242 such that
any deformation of flapper closure plate 242 closes gaps 272, 274
but will not reduce the seal area between flapper closure plate 242
and valve seat 244 and will not interrupt surface-to-surface
engagement between the nested spherical segments, merely shifting
the region of overlapping engagement. Consequently, a continuous,
positive metal-to-metal seal is maintained completely around the
spherical segment interface.
[0063] Even though FIG. 13 has depicted the secondary load bearing
surface as consisting of a pair of internal support members 250,
252, it should be understood by those skilled in the art that these
secondary load bearing surfaces may be used in conjunction with the
other secondary load bearing surfaces described above including
internal load bearing shoulder 134 of FIG. 4 and external load
bearing shoulder 174 of FIG. 9.
[0064] Alternatively, it should be noted that internal support
members 250, 252 may be secured to flapper closure plate 242 such
that when flapper closure plate 242 is in the closed position,
internal support members 250, 252 are received within pockets 254,
256 which serve as the secondary load bearing surface of valve seat
244. In another alternative, internal support members 250, 252 may
be received within or against a secondary load bearing surface of
the valve housing as opposed to the valve seat 244.
[0065] While this invention has been described with a reference to
illustrative embodiments, this description is not intended to be
construed in a limiting sense. Various modifications and
combinations of the illustrative embodiments as well as other
embodiments of the invention, will be apparent to persons skilled
in the art upon reference to the description. It is, therefore,
intended that the appended claims encompass any such modifications
or embodiments.
* * * * *