Valve apparatus

A valve assembly comprising: a valve seat having a first end, a second end, and a valve seat passageway extending therethrough from said first end to said second end; a valve ball assembly rotatably positionable adjacent the second end of the valve seat passageway for selectively sealing the valve seat passageway; a first control arm connectable between the valve seat and the valve ball assembly, the connection between the first control arm and the valve ball assembly defining an axis of rotation for the valve ball assembly; a sealing member, reciprocatably positionable in the valve seat passageway adjacent the second end of the valve seat, for preventing fluid flow between the second end of the valve seat and the exterior of the valve ball assembly; and an urging member, positionable in the passageway, for urging the sealing member against the valve ball assembly.

FIELD OF THE INVENTION 
The present invention relates to valves useful in downhole operations. More 
particularly, but not by way of limitation, the present invention relates 
to safety valves which are leak proof in two directions. 
BACKGROUND OF THE INVENTION 
Examples of safety valves useful for downhole operations are disclosed in 
U.S. Pat. No. 5,050,839 issued to Dickson et al. The entire disclosure of 
U.S. Pat. No. 5,050,839 is incorporated herein by reference. The assignee 
of U.S. Pat. No. 5,050,839 is also the assignee of the present 
application. 
Each of the safety valves disclosed in U.S. Pat. No. 5,050,839 utilizes a 
valve assembly comprising: a valve housing; a ball assembly which is 
reciprocatably positionable in the valve housing; and a pair of ball 
assembly control arms which are held in fixed position in the valve 
housing. The ball assembly includes: a valve seat having a passageway 
extending therethrough from the top of the valve seat to the bottom of the 
valve seat; a ball valve rotatably positioned adjacent the bottom of the 
valve seat for selectively sealing the valve seat passageway; a pair of 
control arms connected between the valve seat and the ball valve such that 
(a) the control arms hold the ball valve adjacent the bottom of the valve 
seat and (b) the connections between the control arms and the ball valve 
define an axis of rotation for the ball valve; a first coupling disc 
connected to the ball valve and positioned between the ball valve and one 
of the control arms; and a second coupling disc connected to the ball 
valve and positioned between the ball valve and the other control arm. 
Each of the control frames used in the Dickson et al. valve assembly 
provides a single stationary lug member. The stationary lug member of one 
control frame projects into an aperture formed in one of the coupling 
discs while the stationary lug member of the other control frame projects 
into an aperture formed in the other coupling disc. The two stationary lug 
members are directly opposed to each other and lie outside of the axis of 
rotation of the ball valve. Consequently, when the ball assembly is 
reciprocated in the valve housing with respect to the stationary lug 
members, the stationary lug members cause the ball valve to rotate. Thus, 
by causing the ball assembly to reciprocate in the valve housing, the 
Dickson et al. safety valve can be opened and closed. 
In FIGS. 1 and 2 of U.S. Pat. No. 5,050,839, Dickson et al. disclose a 
subsurface safety valve having a design directed toward preventing the 
occurrence of galling between the valve seat and the ball valve when the 
ball valve is rotated from its closed position to its open position. As 
explained by Dickson et al., valve galling tends to occur when a ball 
valve is rotated from closed position to open position due to the fact 
that, when the ball valve is in closed position, the high relative 
formation pressure acting on the bottom of the ball valve urges the ball 
valve strongly against the valve seat. In the subsurface safety valve 
depicted by Dickson et al. in FIGS. 1 and 2, the coupling discs used in 
the Dickson et al. valve assembly are designed such that, as the ball 
valve is rotated from its closed position to its open position, the 
control discs tend to urge the ball valve away from the valve seat. 
In FIGS. 10 and 11 of U.S. Pat. No. 5,050,839, Dickson et al. disclose a 
safety valve design which is particularly well suited for use in a 
subsurface test tree. In this embodiment, the coupling discs used in the 
valve assembly are designed such that, as the ball valve is rotated about 
its axis of rotation toward its closed position, the coupling discs of the 
Dickson et al. valve assembly tend to urge the ball valve toward the valve 
seat. Consequently, as the ball valve is rotated to its closed position, 
the ball valve can readily cut a wire or reeled tubing which has been 
extended through the safety valve. 
As will be appreciated by those skilled in the art, subsurface safety 
valves of type disclosed in U.S. Pat. No. 5,050,839 have a significant 
shortcoming. This shortcoming is substantially alleviated by the present 
invention. In a safety valve of the type disclosed in U.S. Pat. No. 
5,050,839, the control arms linking the valve seat and the ball valve must 
provide sufficient play between the ball valve and the valve seat to allow 
the ball valve to be rotated. As indicated above, when the ball valve is 
closed, the formation pressure acting on the bottom of the ball valve will 
normally be substantially greater than the tubing pressure acting on the 
top of the ball valve. The resulting pressure differential urges the ball 
valve tightly against the bottom of the valve seat such that the safety 
valve is prevented from leaking. However, if the tubing pressure acting on 
the top of the closed ball valve is caused to exceed the formation 
pressure, the resulting pressure differential urges the ball valve away 
from the bottom of the valve seat such that the high pressure fluid in the 
tubing above the ball valve is allowed to flow past the ball valve and 
into the formation. 
If the tubing pressure acting on the top of the ball valve is substantially 
greater than the formation pressure, the resulting amount and rate of 
fluid leakage into the formation can be sufficient to damage the 
formation. For example, as will be understood by those skilled in the art, 
when a subsea test tree containing a safety valve of the type in question 
is "unlatched," the ocean water above the safety valve may suddenly exert 
a tremendous amount of hydrostatic pressure on the top of the ball valve. 
The hydrostatic pressure exerted on the top of the ball valve urges the 
ball valve away from the valve seat such that a large amount of ocean 
water can be allowed to flow into the formation. 
SUMMARY OF THE INVENTION 
The present invention provides a valve assembly comprising: a valve seat; a 
ball valve; at least one control arm connectable between the valve seat 
and the ball valve; a sealing means; and an urging means. The valve seat 
has a first end, a second end, and a passageway extending through the 
valve seat from said first end to said second end. The ball valve is 
rotatably positionable adjacent the second end of the passageway for 
selectively sealing the passageway. The connection between the control arm 
and the ball valve defines an axis of rotation for the ball valve. The 
sealing means is reciprocatably positionable in the passageway of the 
valve seat adjacent the second end of the valve seat and is operable for 
preventing fluid flow between the second end of the valve seat and the 
exterior of the ball valve. The urging means is also positionable in the 
passageway of the valve seat and is operable for urging the sealing means 
against the ball valve. 
The present invention also provides a valve assembly comprising: a valve 
seat having a first end and a second end and a passageway extending 
through the valve seat from said first end to said second end; a ball 
valve rotatably positionable adjacent the second end of the valve seat 
passageway for selectively sealing the passageway; a first control arm 
connectable to the valve seat and connectable to the ball valve; a second 
control arm connectable to the valve seat and connectable to the ball 
valve; a floating seat positionable in the valve seat passageway adjacent 
the second end of the valve seat; and an urging means, positionable in the 
valve seat passageway, for urging the floating seat against the ball 
valve. The connection between the first control arm and the ball valve is 
directly opposed to the connection between the second control arm and the 
ball valve such that the connection between the first control arm and the 
ball valve and the connection between the second control arm and the ball 
valve define an axis of rotation for the ball valve. 
The present invention additionally provides a valve apparatus comprising: a 
housing; an assembly positionable in the housing; and at least one 
operating lug positionable in the housing. The assembly comprises: a valve 
seat having a first end and a second end and a valve seat passageway 
extending through the valve seat from said first end to said second end; a 
ball valve which is rotatably positionable adjacent the second end of the 
valve seat passageway for selectively sealing the valve seat passageway; a 
control arm connectable between the valve seat and the ball valve; a 
floating seat positionable in the valve seat passageway adjacent the 
second end of the valve seat; and an urging means, positionable in the 
valve seat passageway, for urging the floating seat against the ball 
valve. The ball valve has a passageway extending therethrough. 
Additionally, the connection between the control arm and the ball valve 
defines an axis of rotation for the ball valve. The valve apparatus also 
comprises at least one operating lug which is positionable in the housing 
and is associatable with the ball valve. The association between the 
operating lug and the ball valve lies outside of the axis of rotation of 
the ball valve. Additionally, either the assembly or the operating lug is 
a reciprocating component which is reciprocatable in the housing while the 
other of these components is a fixed component which is positionable in 
fixed position in the housing. As a result, the ball valve can be rotated 
about its axis of rotation by reciprocating the reciprocating component in 
the housing. 
The present invention further provides a valve assembly comprising: a valve 
seat having a first end, a second end, and a valve seat passageway 
extending through the valve seat from the first end to the second end; a 
valve ball assembly rotatably positionable adjacent the second end of the 
valve seat for selectively sealing the valve seat passageway; a first 
control arm connectable between the valve seat and the valve ball 
assembly; a floating seat positionable in the valve seat passageway 
adjacent the second end of the valve seat; and urging means, positionable 
in the valve seat passageway, for urging the floating seat against the 
valve ball assembly. The connection between the control arm and the valve 
ball assembly defines an axis of rotation for the valve ball assembly. The 
valve ball assembly comprises a ball valve. The valve ball assembly 
preferably also comprises a coupling member which is connectable to the 
exterior of the ball valve and which is rotatably connectable to the 
control arm. 
The present invention also provides a valve apparatus which includes a 
housing and a valve assembly positionable in the housing. The valve 
assembly comprises: a valve seat having a first end, a second end, and a 
valve seat passageway extending through the valve seat from said first end 
to said second end; a ball assembly rotatably positionable adjacent the 
second end of the valve seat passageway for selectively sealing the valve 
seat passageway; a control arm connectable between the valve seat and the 
ball assembly; a floating seat positionable in the valve seat passageway 
adjacent the second end of the valve seat; and an urging means, 
positionable in the valve seat passageway, for urging the floating seat 
against the ball assembly. The ball assembly comprises a ball valve having 
a passageway extending therethrough. The connection between the control 
arm and the ball assembly defines an axis of rotation for the ball 
assembly. The valve apparatus also includes at least one operating lug 
which is positionable in the housing and is connectable to the ball 
assembly. The connection between the operating lug and the ball assembly 
lies outside of the axis of rotation of the ball assembly. Further, one of 
said valve assembly and said operating lug is a reciprocating component 
which is reciprocatable in the housing while the other of these components 
is positionable in fixed position in the housing. Consequently, the ball 
assembly can be rotated about its axis of rotation by reciprocating the 
reciprocating component in the housing. 
The inventive valve apparatus substantially alleviates the safety valve 
leakage problem discussed hereinabove. As indicated, the inventive valve 
apparatus generally includes: a valve seat; a ball valve; at least one 
control arm which holds the ball valve adjacent the lower end of the valve 
seat; a floating seat which is positioned in the passageway of the valve 
seat; and an urging means, positioned in the valve seat passageway, which 
continually urges the floating seat against the ball valve. Thus, even if 
the pressure acting on top of the ball valve substantially exceeds the 
formation pressure acting on the bottom of the ball valve such that the 
ball valve is urged away from the valve seat, the urging means of the 
inventive valve apparatus maintains the floating seat in sealing 
engagement with the ball valve and thus prevents the inventive valve 
apparatus from leaking. 
Further objects, features, and advantages of the present invention will be 
readily apparent to those skilled in the art upon reference to the 
accompanying drawings and upon reading the following description of the 
preferred embodiments.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
An embodiment 2 of the valve apparatus of the present invention is 
illustrated in FIGS. 1, 2A, 2B, and 3. Inventive valve apparatus 2 
comprises: a valve seat 4; a ball valve 6 which is rotatably positionable 
adjacent valve seat 4; coupling discs 8 and 9 which are connectable to the 
sides of ball valve 6; control arms 10 and 11 which are connectable 
between the valve seat and the ball valve; control frames 12 and 13 which 
are associatable with coupling discs 8 and 9 and are operable for slidably 
receiving control arms 10 and 11; a floating seat 14 positionable in valve 
seat 4; and a resilient member 16 which is operable for urging floating 
seat 14 against ball valve 6. 
Valve seat 4 has a first end 18, a second end 20, and a cylindrical 
exterior surface 22. A flat surface 24 extending from second end 20 of 
valve seat 4 is formed on one side of cylindrical exterior surface 22. An 
identical flat surface 26 is formed on the opposite side of cylindrical 
exterior surface 22. A lateral groove 28 having a substantially 
rectangular cross section is formed across flat surface 24. An identical 
lateral groove 30 is formed across flat surface 26. A passageway 32 
extends longitudinally through valve seat 4 from the first end 18 to the 
second end 20 of valve seat 4. Passageway 32 includes: a threaded bore 33 
extending from first end 18; a first cylindrical bore 34 adjacent threaded 
bore 33; a second cylindrical bore 35 adjacent cylindrical bore 34 and 
having an inside diameter greater than the inside diameter of cylindrical 
bore 34; a third cylindrical bore 36 adjacent cylindrical bore 35 and 
having an inside diameter greater than the inside diameter of cylindrical 
bore 35; a radial surface 37 defined by the transition from first 
cylindrical bore 34 to second cylindrical bore 35; a radial surface 38 
defined by the transition from second cylindrical bore 35 to third 
cylindrical bore 36; and a curved surface 40 extending between second 
cylindrical bore 36 and the second end 20 of valve seat 4. The curvature 
of curved surface 40 matches the curvature of the exterior of ball valve 
6. 
Ball valve 6 is a generally spherical member having a cylindrical 
passageway 42 extending therethrough. Ball valve 6 includes: a first flat 
surface 44 formed in the exterior of ball valve 6; a matching second flat 
surface 46 formed in the exterior of ball valve 6 directly opposite first 
flat surface 44; a cylindrical aperture 48 formed through the center of 
flat surface 44; a matching cylindrical aperture 50 formed through the 
center of flat surface 46; a cylindrical cavity 56 formed in flat surface 
44 adjacent cylindrical aperture 48; a matching cylindrical cavity 58 
formed in flat surface 46 adjacent aperture 50; a tab-shaped cavity 60 
formed in flat surface 44 adjacent cylindrical aperture 48; and an 
identical tab-shaped cavity formed in flat surface 46 adjacent aperture 
50. Cylindrical cavity 56 formed in flat surface 44 is directly opposed to 
cylindrical cavity 58 formed in flat surface 46. Further, tab-shaped 
cavity 60 formed in flat surface 44 is directly opposed to the tab-shaped 
cavity formed in flat surface 46. 
Coupling disc 8 comprises: a flat outside surface 64; a flat inside surface 
66 which is positionable against flat surface 44 of ball valve 6; and a 
cylindrical boss 68 formed on inside surface 66 which is receivable in 
cylindrical cavity 56 of ball valve 6. Coupling disc 8 also includes a 
cylindrical aperture 70 which extends through the center of disc 8 and a 
tab-shaped aperture 72 positioned adjacent cylindrical aperture 70. 
Cylindrical aperture 70 and tab-shaped aperture 72 substantially 
correspond, respectively, to cylindrical aperture 48 and tab-shaped cavity 
60 of ball valve 6. 
Coupling disc 9 is identical to coupling disc 8. Coupling disc 9 includes: 
a flat inside surface 74 which is positionable against flat surface 46 of 
ball valve 6; a cylindrical boss 76 formed on surface 74 which is 
receivable in cylindrical cavity 58 of ball valve 6; a cylindrical 
aperture 78 extending through the center of coupling disc 9 which 
substantially corresponds to cylindrical aperture 50 of ball valve 6; and 
a tab-shaped aperture 80 which substantially corresponds to the tab-shaped 
cavity formed in surface 46 of ball valve 6. 
Control arm 10 comprises an elongate member 82 having a flat outside 
surface 84, a flat inside surface 86, and a substantially rectangular 
cross-sectional shape. A lateral cross member is attached to inside 
surface 86 at or near one end of elongate member 82. The cross-sectional 
shape of lateral cross member 88 corresponds to the cross-sectional shape 
of lateral groove 28 formed in valve seat 4. Thus, cross member 88 is 
receivable in lateral groove 28 for connecting control arm 10 to valve 
seat 4. Cylindrical boss 90 is formed on inside surface 86 at or near the 
other end of elongate member 82. Cylindrical boss 90 is sized to extend 
through cylindrical aperture 70 of coupling disc 8 and into cylindrical 
aperture 48 of ball valve 6. 
Coupling arm 11 is identical to coupling arm 10. Coupling arm 11 includes: 
an elongate member 92 having a flat inside surface 94; a lateral cross 
member 96 connected to inside surface 94 at or near one end of elongate 
member 92; and a cylindrical boss 98 formed on inside surface 94 at or 
near the other end of elongate member 92. Lateral cross member 96 of 
control arm 11 is receivable in lateral groove 30 of valve seat 4. 
Cylindrical boss 98 of coupling arm 11 is sized to extend through 
cylindrical aperture 78 of coupling disc 9 and into cylindrical aperture 
50 of ball valve 6. 
Control frame 12 is an elongate member comprising: a semi-cylindrical 
outside surface 100; a flat inside surface 102; an elongate rectangular 
groove 104 formed in inside surface 102 and extending from one end of 
control frame 12 to the other end of control frame 12; a tab 106 (or, 
alternatively, a slot) extending from (or into) one end of control frame 
12 for securing control frame 12 in fixed position in a valve housing; and 
a cylindrical lug 108 formed on inside surface 102 adjacent one side of 
rectangular groove 104. The cross-sectional shape of rectangular groove 
104 corresponds to the cross-sectional shape of elongate member 82 of 
control arm 10 such that elongate member 82 of control arm 10 is slidably 
receivable in rectangular groove 104. Cylindrical lug 108 of control frame 
12 is receivable in tab-shaped aperture 72 of coupling disc 8. If desired, 
cylindrical lug 108 can be sized to extend through the tab-shaped aperture 
72 of coupling disc 8 and into tab-shaped cavity 60 of ball valve 6. 
Control frame 13 is a mirror image duplicate of control frame 12. Control 
frame 13 includes: a flat inside surface 103; an elongate rectangular 
groove 105 formed in surface 103; a tab 107 formed at one end of control 
frame 13 for holding control frame 13 in fixed position in a valve 
housing; and a cylindrical lug 109 formed on inside surface 103 adjacent 
one side of rectangular groove 105. The cross-sectional shape of elongate 
rectangular groove 105 corresponds to the cross-sectional shape of 
elongate member 92 of control arm 11 such that elongate member 92 of 
control arm 11 is slidably receivable in elongate groove 105. Cylindrical 
lug 109 of control frame 13 is receivable in tab-shaped aperture 80 of 
coupling disc 9. If desired, cylindrical lug 109 can be sized to extend 
through tab-shaped aperture 90 and into tab-shaped cavity 62 of ball valve 
6. 
Floating seat 14 comprises: a cylindrical interior surface 110; a radial 
first end 112; a curved second end 114; a first cylindrical exterior 
surface 116 extending from the outer edge of radial first end 112; a 
second cylindrical exterior surface 118 adjacent cylindrical exterior 
surface 116 and extending to the outer edge of curved second end 114, 
second cylindrical exterior surface 118 having an outside diameter larger 
than the outside diameter of first cylindrical exterior surface 116; and a 
radial exterior surface 120 defined by the transition from first 
cylindrical exterior surface 116 to second cylindrical exterior surface 
118. 
First cylindrical exterior surface 116 of floating seat 14 is receivable in 
second cylindrical bore 35 of valve seat 4 and second cylindrical exterior 
surface 118 of floating seat 14 is receivable in third cylindrical bore 36 
of valve seat 4. The curvature of curved end 114 of floating seat 14 
corresponds to the exterior curvature of ball valve 6. 
Resilient member 16 is positionable between radial interior surface 38 of 
valve seat 4 and radial exterior surface 120 of floating seat 14. As 
discussed above, resilient member 16 operates to urge the curved end of 
floating seat 14 against the exterior of ball valve 6. Examples of 
resilient members suitable for use in inventive apparatus 2 include 
springs and O-rings. Resilient member 16 is preferably an O-ring. 
Inventive apparatus 2 is assembled by: connecting coupling discs 8 and 9 to 
flat surfaces 44 and 46 of ball valve 6 such that cylindrical boss 68 of 
disc 8 is received in cylindrical cavity 56 of ball valve 6 and 
cylindrical boss 76 of coupling disc 9 is received in cylindrical cavity 
58 of ball valve 6; inserting resilient member 16 into cylindrical bore 36 
of valve seat 4 such that resilient member 16 rests against radial surface 
38 of valve seat 4; inserting floating seat 14 into cylindrical bore 36 of 
valve seat 4 such that resilient member 16 rests between radial exterior 
surface 120 of floating seat 14 and radial interior surface 38 of valve 
seat 4; inserting cylindrical boss 90 of control arm 10 through 
cylindrical aperture 70 of coupling disc 8 and into cylindrical aperture 
48 of ball valve 6; placing lateral cross member 88 of control arm 10 in 
lateral groove 28 of valve seat 4; inserting cylindrical boss 98 of 
control arm 11 through cylindrical aperture 78 of coupling disc 9 and into 
cylindrical aperture 50 of ball valve 6; placing lateral cross member 96 
of control arm 11 in lateral groove 30 of valve seat 4; associating 
control frame 12 with apparatus 2 by (a) inserting cylindrical lug 108 of 
frame 12 through tab-shaped aperture 72 of control disc 8 and into 
tab-shaped cavity 60 of ball valve 6 and (b) placing elongate member 82 of 
control arm 10 in rectangular groove 104 of frame 12; and associating 
control frame 13 with valve apparatus 2 by (a) inserting cylindrical lug 
109 of frame 13 through tab-shaped aperture 80 of coupling disc 9 and into 
tab-shaped cavity 62 of ball valve 6 and (b) placing elongate member 92 of 
control arm 11 in rectangular groove 105 of control frame 13. 
As depicted in FIGS. 2A and 2B, inventive valve apparatus 2 is preferably 
positioned in a valve housing 122 such that control frames 12 and 13 are 
held in fixed position in housing 122 and the remainder of apparatus 2 is 
reciprocatable in housing 122. However, as will be understood by those 
skilled in the art, inventive valve apparatus 2 can be modified such that 
control frames 12 and 13, or similar members, are reciprocatable in 
housing 122 while the remainder of inventive apparatus 2 is held in fixed 
position in housing 122. 
Control arms 10 and 11 hold ball valve 6 and coupling discs 8 and 9 
adjacent the second end 20 of valve seat 4. Additionally, cylindrical boss 
90 of control arm 10 is directly opposed to cylindrical boss 98 of control 
arm 11 such that bosses 90 and 98 define an axis of rotation for ball 
valve 6 and for coupling discs 8 and 9. Ball valve 6 and coupling discs 8 
and 9 are rotatable about this axis of rotation to (a) allow fluid flow 
out of passageway 32 of valve seat 4 by placing passageway 42 of ball 
valve 6 in communication with passageway 32 and (b) seal passageway 32 of 
valve seat 4 by taking passageway 42 of ball valve 6 out of communication 
with passageway 32. Resilient member 16 urges curved second end 114 of 
floating seat 14 against the exterior of ball valve 6 such that, when 
valve apparatus 2 is closed (i.e., when passageway 42 of ball valve 6 is 
not in communication with passageway 32 of valve seat 4), floating seat 14 
prevents fluid from flowing between valve seat 4 and the exterior of ball 
valve 6. 
When control frames 12 and 13 are fixed in housing 122 and the remainder of 
valve apparatus 2 is reciprocated, lugs 108 and 109 of frames 12 and 13 
engage the edges of tab-shaped apertures 72 and 80 of discs 8 and 9 and 
thus cause ball valve 6 and discs 8 and 9 to rotate about the 
above-mentioned axis of rotation. The operation of control discs 8 and 9 
with respect to the rotation of ball valve 6 is fully discussed in U.S. 
Pat. No. 5,050,839, the entire disclosure of which has been incorporated 
herein by reference. As discussed in U.S. Pat. No. 5,050,839, coupling 
discs 8 and 9 can optionally be configured with respect to apertures 48 
and 50 and cavities 56, 58, 60, and 62 of ball valve 6 such that the 
control discs operate to (a) urge ball valve 6 away from valve seat 4 when 
ball valve 6 is rotated from its closed position to its open position 
and/or (b) urge ball valve 6 toward valve seat 4 when ball valve 6 is 
rotated from its open position to its closed position. 
FIGS. 2A and 2B depict inventive valve apparatus 2 positioned in a downhole 
safety valve 124. The general construction and operation of downhole 
safety valve 124 is fully discussed in U.S. Pat. No. 5,050,839. U.S. Pat. 
No. 5,050,839 also discloses an alternative downhole safety valve into 
which a valve apparatus provided by the present invention can be 
incorporated. 
In downhole safety valve 124, valve seat 4 of inventive apparatus 2 is 
threadedly connected to the end of an actuator tube 126. Actuator tube 126 
has a piston 128 formed on the exterior thereof. A spring 130 is 
positioned beneath piston 128 in chamber 132. 
As fully described in U.S. Pat. No. 5,050,839, ball valve 6 of downhole 
safety valve 124 is rotated to its open position (i.e., passageway 42 of 
ball valve 6 is placed in communication with passageway 32 of valve seat 
4) by increasing the pressure of a control fluid contained in control 
fluid charge line 134, control fluid conduit 136, and control fluid 
chamber 138. As the fluid pressure in line 134, conduit 136, and chamber 
138 increases, piston 128 is forced downward. As piston 128 moves 
downward, actuator tube 126, valve seat 4, control arms 10 and 11, 
coupling discs 8 and 9, and ball valve 6 also move downward. When ball 
valve 6 moves downward, lugs 108 and 109 of control frames 12 and 13 
engage the edges of tab-shaped apertures 72 and 80 of coupling discs 8 and 
9 such that coupling discs 8 and 9 and ball valve 6 are caused to rotate 
about the axis of rotation defined by cylindrical bosses 90 and 98 of 
control arms 10 and 11. The rotation of ball valve 6 as ball valve 6 and 
valve seat 4 move downward places cylindrical passageway 42 of ball valve 
6 in communication with passageway 32 of valve seat 4. 
In order to close downhole safety valve 124, the fluid pressure in control 
fluid charge line 134, control fluid conduit 136, and control fluid 
chamber 138 can be reduced such that spring 130 is allowed to urge piston 
128 upward. As also described in U.S. Pat. No. 5,050,839, the operation of 
spring 130 can be assisted by increasing the pressure in spring chamber 
132. The pressure in spring chamber 132 is increased by pumping fluid into 
spring chamber 132 via balance line 140, balance conduit 142, balance 
conduit 144, and float valve 146. 
As piston 128 is urged upward in safety valve 124, actuator tube 126, 
control arms 10 and 11, coupling discs 8 and 9, and ball valve 6 also move 
upward. When ball valve 6 moves upward, fixed lugs 108 and 109 of control 
frames 12 and 13 engage coupling discs 8 and 9 such that coupling discs 8 
and 9 and ball valve 6 rotate about the axis of rotation defined by 
cylindrical bosses 90 and 98 of control arms 10 and 11. The rotation of 
ball valve 6 as ball valve 6 is pulled upward moves passageway 42 of ball 
valve 6 out of communication with passageway 32 of valve seat 4. As 
discussed above, when ball valve 6 is thus placed in closed position, 
resilient member 16 maintains floating seat 14 in sealing engagement with 
the exterior of ball valve 6 such that fluid is not allowed to flow 
between valve seat 4 and the exterior of ball valve 6. 
Thus, the present invention is well adapted to carry out the objects and 
attain the ends and advantages mentioned above as well as those inherent 
therein. While presently preferred embodiments have been described for 
purposes of this disclosure, numerous changes and modifications will be 
apparent to those skilled in the art. Such changes and modifications are 
encompassed within the spirit of this invention as defined by the appended 
claims.