Note: Descriptions are shown in the official language in which they were submitted.
~3.~
1 BACKGROUND OF THE INVENTION
2 Field of the Invention
3 The present inven~ion concerns hydraulically
4 operated actuators which use ~ul~iple metal~to-metal
static seals and, more particularly, such actuators em-
6 ployed as external operators for subsea valves.
7 D_~cription of the P_ior Art
8 Conventional elastomer type seals have been used
9 heretof~re on hydraulically operated type actuators to pre-
lQ vent contamination of the po~er fluid in subsea and/or well
11 environments. Those environments are corrosive and degrad-
12 ing to most elastomeric ~resilient) materials and, conse-
13 quently, such seals are of questionable reliability. The
14 metal-to-metal static seals of the present invention have
greater reliability than the elastomer seals~ The metals
16 (alloys) which ~orm the metallic static seals are much less
17 susceptible to deterioration and failure from chemical at-
18 tack and high temperatures than elastomer compounds cur-
19 rently being used for actuator seals. Further, the
actua~or-safety valve design of the present invention
21 is more reliable than known conventional actuator safety
22 valve designs and achieves full through-bore capability re-
23 quired for wire line and pump-down tool work. Also, metal-
24 to-metal seals are not contained in such conventional de-
signs. In addition, conventional downhole safety valves
26 are subject to seal leakage due to transfer of loads
27 through the hydraulic components whereas in the present
28 invention, axial loads in the ~ubing string do not affect
29 operation of the hydraulic system.
SUMMARY ~F T~ I~VENTION
31 In accordance with the ~eachings of the invention,
32 an improved hydraulically operated ac~uator for use subsea
~ 3 - ~
.~ 3~
1 and/or in wells for producing oil and~or gas includes a
2 housing containing at least two linearly spaced apart
3 chambers. I~ one Df the chambers - a hydraulic chamber - a
4 piston reciprocates f~om ~ retracted position to an extended
~ position in a power stroke and from the extended position
6 to the retracted position in a return stroke. The piston
7 sepaxates the hydraulic chamber into high and low pressure
8 sections. A first metal seal ring unit effects a seal only
9 at the completion of the power stroke of ~he piston to
isolate the ~ow pressure section from external ambient
11 fluids which may be at a higher pressure. A second metal
12 seal ring unit effects a seal only at the completion of the
13 return stroke of the piston to isolate ~he low pressure
14 section from such external ambient fluids. The force
needed to energize the second metal seal ring unit is sup-
16 plied by return springs, with pressure from the surrounding
17 (contaminating fluid) environment contributing some biasing
18 force when ambient pressure is higher than the pressure of
19 the power fluid. Means are provided in the housing on
opposite sides of the piston for supplying operating or
21 power fluid to and for exhausting fluid from the hydraulic
22 chamber when the piston reciprocates in its power and re-
23 turn strokes. A third metal seal ring unit, which, al-
~4 ternatively, may be a knife-edqe type metal-to-metal seal
or a resilient type seal, is provided to isolate the high
26 pressure section from the low pressure section of the hy-
27 draulic chamber at the completion of the power stroke of
28 the piston. To ensure that the third metal seal ring
29 unit effects a se~l afterthe first seal means effects its
seal, deformable travel compensation means is positioned
31 adj acent the first metal seal ring unit. A further
32 feature of the invention is employing the actuar-~r to
r. ~
1 operate a s~bsurface safety ~alve used to control flow of
2 fluids through a well tubing and locating the actuator ex-
3 terna7 ~f the w~1~ tu~ing. ~eans are provided to compen
4 sate for difex~nces in trav~l between the piston and a
5 valve operator in opening and maintaining open the valve.
6 The compensating means may be arranged on the linkage be-
7 tween the piston and the valve operator or on the valve
8 operator.
9 BRIEF DESCRIPTION OF THE DRAWINGS
.
~igs. lA and lB are vertical views of the actuator
11 of the invention, partly in section, illustrating the com-
12 ponents thereof at the ~tart of the power stroke of the
13 piston;
14 Figs. 2A and 2B are ~ertical ~iews ~f the actuator
of the invention~ partly in section, illustrating the com-
16 ponents thereof at the completion of the power stroke of
17 the piston;
18 Fig. 3 is a vertical, partly sec~ional, view il-
19 lustrating a portion of the actuator apparatus of Fig. lA
in greater detail;
21 Fig. 4 is a vertical view, partly in section,
22 illustrating another portion of the actuator apparatus of
23 Fig. lA in greater detail;
24 Fig. 5 is an enlarged view of a portion of the
apparatus shown in Fig. lA;
26 Fig. 6 is an enlarged view of a portion of the
27 apparatus shown in Fig. 5;
28 Fig. 7 is a vertical, partly sectional, view of
29 the actuator of the invention connected to a ball type sub-
surface ~afety val~e used in well operations with the
31 safety valve in its open position;
1 Fig. 8 is a similar view of a portion of the
2 actuator and subsurface safety valve illustrated in Fig. 7
3 wi~h ~he safety v~lve in it~ closed position;
4 Fig. 9 is a more detailed v:iew ~f the connection
between the actu~or and safety valve of Figs. 7 and 8;
6 Fig. 10 is a vertical, partly sectional, view of
7 the actuator of the invention connec~ed to a ga~e valve;
8 Fig. 11 is a view of the actuator of the inven-
9 tion connected t~ a ball valve which requires rotat:ion to
operate;
11 Figs. 12 and 13 are vertical, partly sectional,
12 views of the actuator of the invention connected to a flap-
13 per type safet~ ~alve us~d in well operations in its open
14 and closed positlons, respactively;
Fig. 14 is a view taken along line 14-14 of Fig.
16 12;
17 Fig. lS is a view taken along line 15-lS of Fig.
18 12;
19 Fig. 16 is another vertical, partly sectional
view of the flapper typ~ subsurface safety valve of Figs.
21 12 and 13 showing the flapper valve closed and the load
22 limiter spring compressed;
23 Figs. 17 and 18 are ver~ical views, partly in
24 section, of another e~bodiment of the actuator of the in-
vention illustrating the components thereof at the begin-
26 ning and at ~he oompletion of the power s~roke, respec-
27 tively;
28 Fig. 19 is a view of still another embodiment of
29 the actuator of the invention illustrating the u~e of a
re~ilient type sta~ic ~eal for sealing off the pistGn;
31 Fi~. 20 is a vertical, partly sectional, view of
32 a modified valve shroud;
--6--
1 Fig. 21 is a ~ertical, partly sectional, view o
2 a modified return spring arrangement.
3 ~ig. 22 is a ~e~tical, partly sectional view, of
4 a modified val~e ~hroud; and
Fig. 23 is a ~ertical, part:ly sectional, ~iew of
6 another modification o the va~ve shroud.
7 DESCRIPTION Q~ THE PREFERRED EMBODIMENTS
, . .,.
8 Referring to Figs. lA, lB, 2A and 2B there is
9 shown a hydraulically ~perated actuator, generally desig-
nated 10, for use in operating valves and ~he like, partic-
11 ularly in subsea and/or well environments.
12 The actuator includes a housing 11 having a
13 closed upper end 12 ~nd containing threP chambers, upper
14 chamber 13, middle (hydraulic) chamber 14 and lower chamber
15. An upper piston rod 16 reciprocates in ch~bexs 13 and
16 14 through a bushing 17 formed in a nipple 18 ~part of
17 housing 11). The upper end of piston rod 16 contains a
18 wrench backup head 20 and a threaded portion 21 on which
19 is threaded a pre-load nut 22 provided with an interior
vertical keyway 23. Threaded portion 21 is provided with
21 an exterior vertical keyway 25. A wedge~shaped key ~4
22 positioned in keyway 23 and keyway 25 prevents rotation of
23 nut 22 on piston rod 16. A return compression spring,
24 designated 26, surrounds piston rod 16 between nut 22 and
nipple lB and includes two coiled springs 26a and 26b
26 separated by a spacer ring 27. Chamber 13 contains hy-
27 draulic fluid indicated by numeral 28.
28 Hydxaulic chamber 14 has a large diameter por-
~9 tion 50 in which a pi~ton 30, connected to piston rod lfi,
reciproca~es in power and return strokes and upper and
31 l~weT smaller diameter portions 51 and 52, respectively.
32 Chamber 14 contains hydraulic power fluid which is
¢~
1 introduced from a hydraulic power fluid sys~em, which may be
2 a closed system, into a high pressure section of chamber 14
3 above pist~n 3~ thro~gh an inlet 55 formed in housing 18
4 and exhaus~s from a ~ow pre~sure section of chamber 14 be-
low piston 30 through an exit opening 56. High pressure
6 fluid is introduced into chamber 14 above piston 30 to
7 drive piston 30 downwardly in i~s power stroke. The posi-
8 tion of piston 30 a~d the other components connected to it
9 are shown in Figs. lA and lB at the start or beginning of
the power stroke (or completion of the return stroke) of
11 the piston. The position of piston 30 and the other com-
12 ponents connected to it are shown in ~igs. 2~ and 2B at the
13 completion of the power stroke of piston 30. Piston 30 i5
14 provided with a metal piston ring 31 which serves as a dy-
namic seal for the power fluid. A lower piston rod 33,
16 slightly less in diameter than the diameter of portion 52,
17 is formed on the lower end of piston 30. Piston rod 33 may
18 be a separate component connected to piston 30 or it may
19 be made integral with piston 30, as shown. A metal seal
ring unit 32 surrounds and is retained on piston rod 33
21 against the underside of piston 30 by a snap ring 34. A
22 connector rod 36 is connected to the lower end of piston
23 rod 33 or it may be an integral part of piston rod 33. A
24 metal seal ring unit 35 is arranged on the upper end of
connector rod 36. A crushable keeper ring 37 is also ar-
26 ranged on oonnector rod 36 below seal ring unit 35. Keeper
27 ring 37 and seal ring unit 35 are maintained on connector
28 rod 36 by a snap ring 38. Connector rod 36 extends ~hrough
29 a wall member 39 containing a press fit slee~e bushing 39a
and into lower chamber 15. The lower end of connector rod
31 36 is pro~ided with an enlarged cylindrical portion 40
32 which is of slightly less diameter than the diameter of
-- 8 --
,3~
1 chamber 15. A metal seal ring unit 42 is a~ranged on con-
2 nectox rod 36 above cylindrical portion 40. Seal ring
3 unit 42 i5 main~ained in position ~y a snap ring 43. ~n
4 actuator rod 4~ is connected to the lower end of connector
rod portion 40 and extends through an opening in the lower
6 end 45 of housing 11. A unidirectional resilient seal 41
7 on that lower end seals off the space between housina 11
8 and actuator rod 44 in that opening. Seal 41 permits fluid
9 to exit at venting port 46 if the volume change in chamber
15 is significant during energization of the metal seal
11 ring unit 35. A 1ower flange 47 on housing 11 contains
12 bolt holes 47a for fastening ~he actuator ~o equipment to
13 be opexated and a venting port 46 is provided in the hous-
14 ing between seal 41 and flange 47.
Referring now to Figs. 3, 4, 5 and 6 in which
16 the actuator components are shown in grea~er detail, a by-
17 pass 60 is formed in piston 30 and fluidly communicates
18 chamber 14 above and below piston ring 31. Bypass 60 is
19 provided with a threaded portion 60a for locating a threaded
orifice member (not shown) for controlling the rate of up-
21 ward movement (return stroke) of piston 30. The ori~ice
22 size is small enough so that sufficient differential pres-
23 sure can be developed across piston 30 to permit the power
24 stroke of the actuator. Metal seal ring unit 32 includes
two chamfered spacer rings 32a and 32b between which are
26 positioned two frusto conical me~al seal rings 32c. The
27 seal rings are similar in shape to Bellville springs.
28 Such metal rings, because of their resilient character-
29 istics, can be seated and unseated with a high degree of
reliability and yet permit loading forces to be developed.
l 31 The materials fo~ming the metal rings may suitably be
~,~ ., ~
32 nickel-chromium-molybdenum alloys such as Inconel 625 and
~r~
_ g _
~ ~3~
`-` 1 Hastelloy C or cobalt-nickel-chromium-molybd2num alloys
2 such as MP 35 N an~ Elgiloy. The Yealing principle is
3 based on changiny o~ the outer and inner diameters of the
4 F,eal ~ings as they are ~lattened under loading. In un-
5 loaded position as shown in Fig. 3 the outer edges or
6 pexipheries of rings 32c are aligned or nearly aligned
7 with the outer peripheries of spacer rings 32a and 32b.
8 When loaded, as shown in Fig. 4, seal rings 32c are com-
9 pressed ~o seal against the bore wall of the portion 50 of
chamber 14 and against the outer periphery of piston rod
11 33.
12 Metal seal ring unit 35 is similar to m~tal seal
13 ring unit 32 and is provided with chamfered spacer rings
14 35a and 35b between which are positioned two frusto conical
metal seal rings 35c. As shown in Fig. 3, in unloaded
16 position the outer edges or peripheries of rinys 35c are
17 aligned or approximately aligned with ~he outer peripheries
18 of spacer rings 35a and 35b and when loaded seal rin~s 35c
19 are compressed to ~eal against the bore wall of the portion
52 of chamber 14 and against ~he outer periphery of con-
21 nector rod 36, as shown in F'ig. 4.
22 As shown in Fig. 1, length Dl is slightly greater
23 than length D2. Dl represents the downward travel (power
24 stroke of piston 30) of seal unit 32 un~il its lower end
engages the lower end wall, shoulder 50a, of chamber 50.
26 Similarly, D2 represents the downward travel of the crush-
27 able keeper ring 37 until its lower end engages, the lower
28 end wall, 52a, of chamber ~2. It i5 desirable to have
29 both sea~ ring units 32 and 3~ seal off at the same time.
As shown in Fig. 4, keeper ring 37 has deformed slightly to
31 ensure precise spacing for seal ring units 32 and 35 when
32 in their seali~g positions. Keeper ring 37 deforms, if at
-- 10 --
1 sll, only on ~ompletion of the initial power stroke of
2 pis~n 30 and, thereafter, retain~ its plastically deformed
3 ~hape. Such deform~ty ~nsures pxecise spacing for the
4 metal seal ring units 32 and 35 in ~he sealing position.
ln Figs. 5 and 6 me~al seal ring unit 42 is shown
6 in sea}ing position against the wall of chamher 15 and con-
7 nector rod 36. Seal ring unit 42 is also similar to seal
8 ring units 32 and 35 in that frusto conical metal seal
9 rings 42c are p~itioned between chamfered spacer rings
42a and 42b. Metal rings 42c seal on the inner wall of
11 chamber 15 when piston 30 is at the end of its return
12 stroke (ox at the start of its power stroke). Seal ring
13 unit 42 is energized in its sealing position by return
14 spring 26 in chamber 13 and ambient fluid pressure that
may act on the area o~ actuator rod 44. At the completion
16 of the power stroke, seal units 32 and 35 are in sealing
17 position as shown in Fig. 4 and seal unit 42 in non-sealing
18 position. As shown, the inwardly directed taper of frusto
19 conical metal rings 32c, 35c or 42c are in the direction
of the movement of the rings which causes release of the
21 seal. The apices of the conically shaped metal rings 32c,
22 35c or 42c are in the direction of their mo~ement which
23 causes release of the seal. In this manner a more eE-
24 ficient release of the seal rings is achieved and jamming
of the seal rings against the chamber wall on which the
26 seal rings seal is prevented.
27 In Fig. 7, actuator 10 is shown mounted by bolts
28 48 on a safety val~e housing 8Q which is connected into a
29 well pipe string 81. A ~luid supply conduit 82 connects
a closed hydra~lic power system fluid supply to opening
31 55 in actuator 10 and exhaust conduit 83 connects port 56
32 of actuator 10 into the closed hydraulic system. Actuator
11 -
1 rod 44 is connected to a drive rod 84 through linkage 85.
2 Rod 8~ is connected to a rack B6 which engages a pinion
3 gear ~7 axranged in a c~amber 91 of housing 80. Pinion
4 gear B7 is oonnected to a ~all valve 88 which is mounted
for rotation in valve housing 80. The rack and pinion
6 arrang~ment may be suitably lubri~ated by oil or other lu~
7 bricant 92 contained in chamber 91. An adjustable stop
8 member, indicated at ~3, is connected ~o the lower end o~
9 rack 86 and extends through the lower end of chamber 91 of
housing 80. The stop member 93 limits the downward travel
11 of the rack when opening ball valve 88. This permits the
12 ball valve to assume its full open position as shown in
13 Fi~, 7. The ~ull open position is desired when producing
14 or circulating fluids and when running downhole tools
through the safety valve to perform operations in the well
16 bore below the safety valve.
17 Fig. 8 shows ball valve 88 in closed position.
18 In that position of the valvP, piston 30 of actuator 1~ is
19 in its retracted position. ~eal ring unit 42 is energized
20~ at this time.
21 As shown in Fig. 9 a compression spring 94 is
22 positioned in a chamber 95 in linkage 85. Spring 94
23 functions as a load limiter to allow the piston to stroke
24 fully, and the metal rings to obtain a seal, in the event
the valve is stuck in the closed position (pressure trapped
26 below the ball). Spring 94 also permits overtravel of
27 actuator rod 44 so that the ball valve may be moved to its
28 full open position and thereafter allow sealing movement
29 of metal seal ring units 32 and 35. This assures full
seating o~ the mRta~ seals when the valve is in its closed
31 positionO Thus, it allows further stroke of rod 44 after
32 rack 86 abuts stop 93.
- 12 -
~l3~
1 Fig. 10 illustrates the use of actuator 10 with
a gate-type valve 96 positioned in a valve housing 97 which
3 may be i~2~ted in a flow line, not shown.
4 Fig. 11 illu~t~ates the use of actuator 10, which
is mounted as at 98 ~n a flow line 99, with a xotatable
6 ball valve or stopcock type valve 100. Actuator rod 44 is
7 connected to suitable linkage 101 for causing rotation of
8 the ball valve.
9 ~e~esring tv ~igs. 12 through 16, ac~uator 10 is
connected to a shroud 110 which is welded to (or made inte-
11 gral with) a housing 111 through which a 10w tube 112 ex-
12 tends. Actuator rod 44 extends through the upper end of
13 shroud 110 and is sealed by a resilient bidirectional type
14 seal 113 and is bolted to a clevis 11~ within shroud 110.
The lower end of shroud 110 is closed by a bull plug 115
16 which permits access to the interior of the shroud so that
17 the clevis can be installed on the clevis ring 120 surround-
18 ing flow tube 112. Shroud 110 is also provided with access
19 openings 121 which are shown plugged. Above clevis ring
120 a retainer ring 125 is attached to and surrounds flow
21 tube 112. A wiper ring 126 and a slotted wear ring (or
22 bearing) 127 are positioned on the interior wall of housing
23 111. An adjustable retainer 128 is arranged on threads
24 129 on flow tube 112. A load limiter spring 130 is posi-
tioned between clevis ring 120 and the adjustable retainer
26 128. A wiper ring 135a and slotted wear ring (ox bearing)
27 135b are located in the lower end of housing 111. Differ-
28 ential pressure will not be buil~ up across either of the
29 wiper or wear rings, so that frictional drag on the flow
tube 112 is minimized~ The well bore fluid is isolated
31 ~rom the surrounding environment by resilient seal 113. A
32 ~pring-biased flappçr val~e 136 is ~ecured to ~:he lower end
~ 13 -
1 of housing 111 to close off the pa~sage through which flow
2 tube 11 ? extends.
3 Load lim~tes spring 130 may be loaded to, for ex-
4 ampl~, ab~ut 50D p~unds 50 that under ~ormal operation on
5 opening of ~lapper valve 136 flow tube 112 is moved down by
6 actuator rod 44 without further comprlession of spring 130
7 as illustrated in Fig. 13. However, if flapper valve 136
8 will not open because of high well pr~essure below it or for
9 other ~actors actua~or rod 44 will complete its fu:Ll stroke
and compress the load limiter spring 130 as illustra~ed in
11 Fig. 16. Permitting full stroke of the actuator rod 44
12 prevents damage to the equipment, as for example, breaking
13 of cle~is 11~. As seen moxe clearly in Fig. 15 the sides
14 forming the opening between the valva body and the shroud,
lS indicated at 139, serve as a retainer guide for clevis 114.
16 Bull plug llS is contoured to streamline the shroud for
17 running into the well pipe. Access openings 121 permit
18 bolting of clevis 114 to clevis ring 120.
19 Another embodiment of the invention is illustrated
in Figs. 17 and 18. As shown in those figures an actuator
21 includes a housing 140 having three chambers as in the em-
22 bodiments of the invention described heretofore, only two
23 of which, a hydraulic chamber 141 and a lower chamber 142,
24 aTe shown. An upper piston rod 146 reciprocates in chamber
141. Hydraulic chamber 141 contains a piston 150 connected
26 to the lower end of upper piston rod 146 and to a lower
27 piston rod 147. Piston 150 includes a bypass 151 which
28 fluidly communicates chamber 147 abo~e and below a piston
29 ring 152 and is provided with ~ threaded portion 151a for
locating a thIeaded ~rifice member (not shown~ for control-
31 ling the rate of upward movement lreturn stroke) of piston
32 150. A crushable keeper ring 115 is arranged about a
- 14 -
1 connector sod 156 which is connected to piston rod 147~
2 Keeper ring 155 is attached to ~he lower end of rod 147 by
3 bc)lts 1~7~ Cr~nnector rod lSfi ex~ends through a wall member
4 160 which contains 2 metal seal ring unit 161, a press fit
~leeve bushing 162 below metal ~eal ring unit 161 and a
6 second metal seal ring unit 163 below sleeve 162. Seal ring
7 unit 161 is retained in the recess in wall member 160 by a
8 snap ring 165 and seal ring unit 163 is retained in its re-
9 cess in wall member 150 by a snap ring 166. The actuator
rod 170 is connected to a ~houlder coupling 171 through
11 which a fluid by-pass 172 is fo~med. Piston 15Q contains a
12 metallic knife-edge seal 153, which, a~ shown in Fig. 18,
13 forms a static metal-to-metal seal with a ~houldex 154 formed
14 in the inner wall of housing 140. Static seal 153 is an
annular member being tapered in cxoss-section, as shown, and
16 having a deformable reduced contact area or aage. At the
17 end of the power ætroke of piston 150 the edge contacts and
18 seals on shoulder seat 154. Under the compressi~e force of
19 piston 150 the edge yields or plastically deforms to con-
form to seat 154 to achieve intimate contact and a seal.
21 Piston 150 is preferably constructed of a soft malleable
22 steel such as an annealed American Iron and Steel ~nstitute
23 (AISI) 1015 steel with a hardness in the range of 120
24 Brinell Hardness Number (BHN). The cylinder and static
seat 154 are constructed of a harder steel such as AISI
26 4130 with a hardness in the range of 235 BHN. Preferably,
27 the seal e~ge is blunted to prevent failure of the steel
28 seal. The reduced area (edge) of the seal also facilitates
29 cutting t~rough any particles or debris which may be in the
fluid in the piston chamber and adhere to s~at 154.
31 As shown in Fig. 17, s~al ring unit 161 does not
32 seal on connector rod shaft 156 but metal seal ring unit
15 -
1 163 seals on connector rod shaft 156 in ~he position of
2 piston 150 at the beginning or ~tart o~ the power stroke
3 th~eof. ~æal ~ing unit 163 isolates chamber 141 from
4 cham~er 142 ~n~ prevents c~ntaminating fluid in chamber 142
~ from entering chamber 141. At the completion of the power
6 stroke of the piston, seal 153 seals off on surface 154 to
7 isolate the high and low pressure fluids on each side o
8 piston 15~ from each other and seal ring unit 161 seals on
9 connector rod 156. In that position seal ring unit 163
does not seal. However, contaminating fluid is prevented
11 from mixing with the l~w pressure fluid in chamber 141 by
12 seal ring unit 161.
13 Referring to Fig. 19, instead of the metal static
14 seal 153-154, a resilient type seal 153a may be arranged on
a piston 150a to seal off on a seating surface 154a formed
16 on the inner wall of a housing 140a.
17 A modification of the seal for sealing off the
18 actuator rod is illustrated in ~ig. 2~. Actuator 10 is con-
19 nected to a shroud 110' which is connected to housing 111
- 20 through which a flow tube ex~ends (not shown). An actuator
21 rod 44' extends through the upper end o~ shroud 110' and is
22 sealed by a resilient seal 113' and by a metal seal ring
23 unit 175 arranged in a recess 176 formed in the upper end of
24 shroud 110'. Metal seal ring unit 175 is similar to the
earlier described metal seal ring units and includes an
26 upper spacer ring 191, seal rings 192 and a lower spacer
27 ring 193 ha~ing an enlarged diameter portion 194. A deform-
28 able keeper slee~e 195 abuts against the enlarged portion
2g 194 of spacer sleeve 193 and is secured to rod 44' by a lock
screw lg6. An adjustable retainer ring 178 is threaded to
31 the inner wall of recess 176 for engaging the enlarged
. 3~ pcrtion 194 of spac2r ring 193 to retain m~tal seal ring
- 16
a~
1 unit 175 and limit downward movement of that unit when rod
2 44' and keeper slee~e 195 move downward ~rom their upper
3 most positions, as sh~wn. In that position of rod 44' the
4 ~alve is closed.
Reerring to ~ig. 21, there is shown a modified
6 return spring axrangement in which a tension spring is used
7 instead of a compression sping. The lower end of tension
8 ~pring 187 is connected to piston 150' by a celvis con-
9 nector 186 and threaded spring plug 185. The upp~r end of
the spring is threaded to a second spring plug 188 provided
11 with an upwardly extending threaded rod 189 which extends
12 through a plate 190 fixed in the bore of the hous.ing 11'.
13 A threaded nut 191 allows tension adjustment of ~he spring
14 187.
The valve shroud shown in Fig. 2~ illustrates a
16 metal sealing unit 175' which seals in the lowermost posi
17 tion of rod 44'' in which position the valve is open. The
18 val~e shroud of Fig. 23 illustrates the use of two metal
19 seal units, one of which seals in the lowermost position of
20~ rod 44''' (valve open) as in Fig. 22 and the other of which
21 seals in the uppermost position of rod 44''' (valve closed)
22 as in ~ig. 2~. The components of Fig. 22 include a shroud
23 110'l, rod 44 " connected to cle~is 114, a recess 176' form-
24 ed in shroud 110 which contains an adjustable retainer ring
178', metal ring seal unit 175' which includes a lower spac-
26 er ring 191', an upper spacer ring 193' having an enlarged
27 upper portion 1~4', and seal rings 192' positioned between
28 spacer rings 191' and 193'. A deformable keeper ring 195'
29 is secured to rod 44lt ~y a lock screw 196'. An annular
shoulder 1~7 is formed on rod 44'' and abuts against keeper
31 rincJ 195'. A resilient seal 113'' seals about rod 44'' in
32 t~.~ bore belcsw recess 176'.
1 The val~e shroud 110''' shown in Fig. ~3 includes
2 both the seal ring unit 175' of Fig. 22 and the seal ring
3 unit 175 ~ Fig~ 2~. In this position of rod 44''' seal ring
4 unit 17~ is in the unsealed position, i.e, rod 44''' has
completed its do~m stroke and in that po~ition ~eal ring
6 unit 175' is in sealing positi~n. The components which are
7 the same as the components of ~igs. 20 and ~2 have been
8 given the same designation in Fig. 23. A resilient seal
9 113''' seals ~b~u~ the rod 44''' in the bore between re-
cesses 176 and 176'.
11 As mentioned heretofore, seal reliabilit:y of the
12 metal-to~metal static seals described above is superior to
13 conventional elastomer or resilient type seals. Therefore,
14 the possibility of the hydraulic power fluid system used to
operate the actuator being contaminated hy sea water or by
16 production well fluids is minimized. With respect to use
17 of the actua~or of the invention as an external operator
18 for a subsurface sa~ety valve, the actuator provides iso-
19 lation of the hydraulic power fluid system from the pro-
20~ duction well fluid. In addition, the safety valve design
21 is greatly simplified and provides for full, through-bore
22 capability which is required for wire-line and p~np-down
23 tool work. Also, axial loads in the tubing strin~ in which
24 the safety valve is located do not affect operation of the
hydraulic system whereas concentric operator type safety
26 valves are subject to seal leakage caused by distortion
27 which results from the transfer of axial loads in the tubing
28 string through the hydraulic components. The metal-to-metal
29 seals are pressure energizing in that an increase is pres-
sure causes a higher contact load at the seal surfaces.
31 The actuator is compatible for use with a flapper valve,
32 ball valve or other type valves operable by an actuator.
- 18 -
3-a~
1 Changes and modifications may be made in the il-
2 lustrative embodiments of the invention shown and/or de-
3 scri~ed herein with~t. ~epar~ing from the ~cope of the in-
4 vention as defined in the appended claims.
-- 19 --
