Abstract:
A valve, actuator and control system that allows minimizing the size of the actuator and operation of the control system in a manual mode that automatically prevents accidental operation by pipeline pressure is disclosed. The actuator uses gas pressure from the pipeline to power the actuator. In the event gas pressure is unavailable, a pair of manual hand pumps are incorporated to allow operation of the actuator and valve.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to a system of a hydraulic actuator for operating a valve between open and closed positions and the control system used to regulate the operation of the actuator. This system is particularly suited for operation of ball valves used in the oil and gas industry. These ball valves are typically used in gas pipelines to control the flow of gas through the pipeline. The actuator of the present invention uses gas pressure from the pipeline to power the actuator. In the event gas pressure from the pipeline is unavailable or inaccessible, a pair of manual hand pumps are incorporated to allow operation of the actuator and valve. 
   Prior actuators utilizing the gas pressure of the pipeline as a power source typically have a double acting piston upon which the gas acts to drive the actuator and hence the valve to be opened or closed. These actuators have vented the gas pressure from one side of the double acting piston as gas pressure is applied to the other side of the piston. This venting is necessary to ensure that equal pressure is not acting on both sides of the piston simultaneously. In this event, the force acting on both sides of the piston would balance and the actuator would fail to operate or be “pressure locked” as commonly referred to in the industry. 
   As a result of the need to vent each side of the actuator piston to ensure proper operation, the gas pressure is usually vented to atmosphere. This gas is not a pure gas but in fact has hydrocarbon liquids entrained in the gas, known as condensate in the industry. When this venting to atmosphere occurs, the hydrocarbon liquid condensate condenses and becomes a sticky, unsightly oily residue on the ground adjacent the valve and actuator. In recent years this venting to the atmosphere of the gas has raised environmental concerns due to possible contamination of the ground and groundwater by this oily residue. 
   Another concern with prior valve, actuator and control system assemblies has been the interface and operation of the manual hand pumps that are required to operate the actuator and valve when gas pressure from the pipeline is not available. This may occur during new installations when the pipeline has not been filled with gas yet and opening or closing of the valve is needed. Other times when maintenance is to be performed on the valve or actuator, the pipeline must be bled of gas pressure as a safety precaution. When it is desired to operate the valve prior to subsequent pressurization of the pipeline, the ability to operate the valve and actuator manually is required. Prior valve, actuator and control system assemblies have had problems in their design and operation that allowed possible scenarios in which pressurization of the pipeline and thus the actuator, could result in inadvertent operation of the actuator while manual operation of the actuator was occurring and possible injury to an operator. It is therefore desirable to have a valve, actuator and control system assembly that allows minimizing the size of the actuator and operation of the control system in a manual mode that automatically prevents accidental operation by pipeline pressure. The valve, actuator and control system of the present invention offers such novel features. 
   2. Description of Related Art 
   U.S. Pat. No. 6,231,027 B1 to G. S. Baker et al. shows a valve actuator that utilizes a variable helix angle to generate greater operating torque near the end of its travel. 
   A subsea rotary adjusting device for valves is disclosed in PCT International Publication No. WO 02/37008 A1 to K. Biester et al. The device utilizes a helical slot in a sleeve to translate axial motion into rotary motion. 
   PCT International Publication No. WO 03/025428 A1 to K. Biester et al. shows a travel multiplying device utilizing three concentric pipes with spherical linking elements to magnify relative longitudinal motion between adjacent pipes. 
   SUMMARY OF THE INVENTION 
   The present invention relates to a system of a hydraulic actuator for operating a valve between open and closed positions, the valve itself and the control system used to regulate the operation of the actuator. The valve is installed in a gas pipeline, typically used in the oil and gas industry, to control flow through the pipeline. The actuator of the present invention uses gas pressure from the pipeline to power the actuator. 
   The valve is a ball valve that uses a spherically shaped ball to control fluid flow through the valve. End flanges are welded to the outer body shell for connection to mating pipeline connections. A quarter turn of the ball moves the valve from open to closed positions. The valve actuator is mounted on top of the valve and rotates the ball between open and closed positions when operated. 
   The valve actuator is comprised of a lower actuator housing with a bore therethrough to which an actuator cylinder housing having a counterbore is secured in sealing engagement to a first end of the lower actuator housing. A lower actuator plate with a bore is secured to the second end of the lower actuator housing. A helix sleeve is secured within the lower actuator housing bore and seals therein. The helix sleeve has a pair of helical slots cut in its wall and a reduced diameter bore on one end. An actuator drive shaft extends between the actuator cylinder housing bore and the reduced diameter bore of the helix sleeve and seals within these bores and is axially restrained between them. 
   An actuator piston sleeve is sealingly disposed in the annulus between the actuator drive shaft and the actuator cylinder housing with the actuator piston sleeve axially moveable in response to hydraulic pressure. The actuator piston sleeve has a reduced diameter portion extending into the annulus between the actuator drive shaft and the helix sleeve with the reduced diameter portion of the actuator piston sleeve sealing on the actuator drive shaft and the reduced diameter portion of the actuator piston sleeve having a pair of axially disposed slots. A pair of rollers are attached to the reduced diameter portion of the actuator piston sleeve and engage the helical slots in the helix sleeve and a second pair of rollers are attached to the actuator drive shaft and engage the axially disposed slots in the reduced diameter portion of the actuator piston sleeve such that reciprocation of the actuator piston sleeve causes rotation of the actuator drive shaft. 
   The hydraulic control system for the valve actuator is comprised of open and close circuits with each circuit including a control valve, a pair of pilot operated valves and a fluid supply tank for supplying control fluid under pressure to the appropriate actuator function. The outlet port of the second pilot operated valve in each circuit is connected to an exhaust orifice valve. The control valve in each circuit receives pressurized gas from an outlet on the pipeline and directs this pressurized gas to the appropriate tank when the control valve is operated. This pressurized gas is also used to operate the pilot operated valves to control venting of pressure from one tank while the other is being pressurized to prevent pressure lock and allow equalization of pressure between the tanks after the valve is moved to its fully open or closed position. 
   A principal object of the present invention is to provide a valve, actuator and control system that allows minimizing the size of the actuator and operation of the control system in a manual mode that automatically prevents accidental operation by pipeline pressure. 
   Another object of the present invention is to provide a valve, actuator and control system that is modular in construction to allow adaptation to different valve sizes. 
   A final object of the present invention is to provide a valve, actuator and control system for gas pipelines that minimizes the condensate vented to the atmosphere during operation. 
   These with other objects and advantages of the present invention are pointed out with specificness in the claims annexed hereto and form a part of this disclosure. A full and complete understanding of the invention may be had by reference to the accompanying drawings and description of the preferred embodiments. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and advantages of the present invention are set forth below and further made clear by reference to the drawings, wherein: 
       FIG. 1  comprises a perspective view of a system for controlling fluid flow through a pipeline including valve, actuator and control system assembled together.  FIG. 2  is a perspective view from the opposite side with partial sectional views of valve  12  and actuator  14  to show the main components sectional view of a wellhead system with the right half of the view showing a combination of standard casing hangers and packoff assemblies and the left half of the view showing a combination of casing hangers and packoff assemblies for emergency situations in which the casing sticks in the well bore while being lowered into position. 
       FIG. 2  comprises a perspective view from the opposite side with partial sectional views of the valve and actuator to show the main components. 
       FIG. 3  comprises a sectional view of the valve actuator in the valve closed position. 
       FIG. 4  comprises a sectional view of the valve actuator in the valve open position. 
       FIG. 5  comprises a perspective view of the actuator and actuation of the helix sleeve therein. 
       FIG. 6  comprises a schematic view of the control system. 
       FIG. 7  comprises a view of the flow diagram of the control system. 
       FIG. 8  comprises a sectional view of the fluid supply tanks and manually operated valves mounted thereon of the control system. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   With reference to the drawings, and particularly to  FIG. 1  a perspective view of a system  10  for controlling fluid flow through a pipeline including valve  12 , actuator  14  and control system  16  assembled together is shown.  FIG. 2  is a perspective view from the opposite side with partial sectional views of valve  12  and actuator  14  to show the main components. Valve  12  is a ball valve of the type commonly used in the oil and gas industry, with a welded body  18  and end flanges  20  for installing valve  12  into a pipeline (not shown) through which valve  12  will control the flow of oil and gas. Valve  12  includes a flow controlling member or ball  22 , disposed in welded body  18 , with a bore  24  therethrough. Seal elements  26  in welded body  18  seal against ball  22 . Rotation of ball  22  a quarter turn by actuator  14  closes valve  12 . 
   Actuator  14  includes lower actuator housing  28  to which actuator cylinder housing  30  is secured. Helix sleeve  32  is disposed within lower actuator housing  28  and actuator piston sleeve  34  is positioned within helix sleeve  32 . Details of construction of actuator  14  and actuation of helix sleeve  32  are shown in sectional views  FIGS. 3 and 4  and perspective view  FIG. 5 .  FIG. 3  shows actuator  14  in the position of valve  12  being closed and  FIG. 4  shows actuator  14  in the position of valve  12  being open. Lower actuator housing  28  has bore  36  extending therethrough. Actuator cylinder housing  30  has counter bore  38  extending therein and is secured to lower actuator housing  28  by suitable securing means as studs  40  and nuts  42 . Bore  36  and counterbore  38  are axially coincident. Lower actuator housing  28  is sealed against actuator cylinder housing  30  by sealing means in the form of seal ring  44 . 
   Lower actuator plate  46  and guide sleeve  48  are secured to the opposite end of lower actuator housing  28  by suitable securing means as studs  50  and nuts  52 . Lower actuator plate  46  and guide sleeve  48  have bores  54  and  56  therethrough. Helix sleeve  32  is secured within lower actuator housing  28  by lower actuator plate  46  and actuator cylinder housing  30 . Seal ring  58  seals helix sleeve  32  to lower actuator housing  28  while first and second securing means in the form of anti-rotation or dowel pins  60  and  62  between helix sleeve  32  and lower actuator housing  28  prevent helix sleeve  32  from rotational movement with respect to lower actuator housing  28  and actuator cylinder housing  30 . 
   Helix sleeve  32  includes reduced diameter bore  64  on the end adjacent lower actuator plate  46 . Actuator drive shaft  66  is a cylindrical member that extends between bore  68  in actuator cylinder housing  30  and reduced diameter bore  64  of helix sleeve  32 . Actuator drive shaft  66  is sealed in bores  64  and  68  by seal rings  70  and  72 , respectively. Bore  68  is axially coincident with counter bore  38  as is stepped bore  74  in actuator cylinder housing  30 . Adjacent reduced diameter bore  64  is stepped bore  76  in helix sleeve  32 . Stepped bores  74  and  76  act to axially restrain actuator drive shaft  66  when actuator  12  is assembled. 
   Actuator piston sleeve  34  is sealingly disposed in the annulus between actuator drive shaft  66  and counter bore  38  of actuator cylinder housing  30 . Seal rings  80  and  82  seal actuator piston sleeve  34  to actuator drive shaft  66  and counter bore  38  of actuator cylinder housing  30 . Actuator piston sleeve  34  has a reduced diameter portion  84  that extends into the annulus between actuator drive shaft  66  and helix sleeve  32  and seals on actuator drive shaft  66  with seal ring  86 . Reduced diameter portion  84  of actuator piston sleeve  34  has a pair of axially disposed slots  88  formed therein. An actuation means in the form of a pair of rollers  90  are secured to actuator drive shaft  66  at approximately its middle and rollers  90  engage axially disposed slots  88  for purposes to be described hereinafter. Helix sleeve  32  includes a pair of helical slots  92  formed in its wall. As best seen in  FIG. 5 , a second actuation means in the form of a pair of rollers  94  are secured to the lower end of reduced diameter portion  84  of actuator piston sleeve  34  at right angle to axially disposed slots  88  and engage helical slots  92  in helix sleeve  32 . 
   First end  96  of actuator drive shaft  66  extends beyond stepped bore  74  and includes indicator means or slot  98  formed thereon to indicate the rotational position of actuator drive shaft  66 . Opposite or second end  100  of actuator drive shaft  66  extends beyond stepped bore  76  and includes engaging means in the form of male spline  102  formed thereon. Valve closure adapter  104  engages spline  102  and connects to valve  12  with spline  106  to transmit the torque generated by actuator  14 . Ports  108  and  110  in actuator cylinder housing  30  allow pressurized hydraulic fluid, supplied by control system  16  in a manner to be described hereinafter, to operate actuator  12  in the following manner. 
   As noted above,  FIG. 3  shows actuator  14  in the position with valve  12  closed. Actuator piston sleeve  34  is at the bottom of its stroke. When it is desired to open valve  12 , pressurized hydraulic fluid to supplied to port  108  while port  110  is vented. The pressurized hydraulic fluid acts on the underside of actuator piston sleeve  34  against the annular piston area defined by seals  80  and  82  while seals  44 ,  58  and  70  maintain pressure in lower actuator housing  28 . As actuator piston sleeve  34  is urged upwardly, slots  88  move axially over rollers  90  on actuator drive shaft  66 . Simultaneously, rollers  94  on reduced diameter portion  84  of actuator piston sleeve  34  are engaging helical slots  92  of helix sleeve  32 . As helix sleeve  32  is anti-rotated with respect to lower actuator housing  28  by pins  60  and  62 , rollers  94  are forced to move along helical slots  92  of helix sleeve  32  which causes actuator piston sleeve  34  to rotate with respect lower actuator housing  28 . This rotation of lower actuator housing  28  is transmitted through axial slots  88  and rollers  90  to actuator drive shaft  66 , thus rotating valve closure adapter  104  and valve  12  through splines  106  to move valve  12  to its open position shown in  FIG. 4 . When it is desired to close valve  12 , pressurized hydraulic fluid is supplied to port  110  while port  108  is vented to reverse the direction of rotation. 
   Operation of valve  12  and actuator  14  is regulated by control system  16  which is shown in schematic form in  FIG. 6  and in flow diagram form in  FIG. 7 .  FIG. 6  shows control system  16  includes first and second control valves  200  and  202  controlling operation of actuator  14  through first through fourth pilot operated valves  204 ,  206 ,  208  and  210 . Valves  200 – 210  control hydraulic fluid flow from first and second actuator fluid supply tanks  212  and  214  to the open and close ports  108  and  110  of actuator  14 . Control system  16  includes a fluid pressure source  216  which is gas pressure supplied from the pipeline (not shown) through which valve  12  and actuator  14  control gas flow. Control system  16  further includes a normally open double pilot operated two way valve  218  to equalize gas pressure between tanks  212  and  214  which is bled to atmosphere through exhaust orifice valve  220 . First and second actuator fluid supply tanks  212  and  214  have hydraulic fluid  222  in their lower portion which is the pressurized fluid supplied to actuator  14 . Hydraulic fluid  222  is pressurized by the action of pipeline gas pressure acting thereon. 
   The flow diagram of  FIG. 7  shows details of the construction of the components of control system  16  and the gas and hydraulic fluid flow therebetween. Control system  16  is divided into first and second control circuits  224  and  226 . First control circuit  224  acts to supply hydraulic fluid  222  to port  108  and operate actuator  14  to close valve  12 , while second control circuit  226  acts in reverse to supply hydraulic fluid  222  to port  110  and operate actuator  14  to open valve  12 . Additionally, control system  16  includes manually operated hand pumps  228  and  230  mounted on first and second actuator fluid supply tanks  212  and  214 , respectively, for purposes to be described hereinafter. 
   First and second control valves  200  and  202  are manually operated valves including inlet port  232 , outlet port  234  and vent port  236 . In the closed position, fluid flow between inlet port  232  and outlet port  234  is blocked while outlet port  234  is connected to vent port  236 . In the open or operating position, fluid flows between inlet port  232  and outlet port  234  while vent port  236  is blocked. First through fourth pilot operated valves  204 ,  206 ,  208  and  210  are two way normally closed pilot operated valves including inlet port  238 , outlet port  240  and pilot port  242 . In the closed position, i.e., no pressure supplied to pilot port  242 , fluid flow between inlet port  238  and outlet port  240  is blocked. In the open, i.e., pilot operated position, pilot pressure supplied to pilot port  242  allows fluid flow between inlet port  238  and outlet port  240 . First and second control valves  200  and  202  and first through fourth pilot operated valves  204 ,  206 ,  208  and  210  are mounted in a manifold block (not shown) in a manner well known to those of ordinary skill in the art Control system  16  also includes double pilot operated two way valve  218  with pilot pressures supplied from first and second control circuits  224  and  226 . 
   First and second actuator fluid supply tanks  212  and  214  are identical in construction. Tanks  212  and  214  are supplied with hydraulic fluid  222  partially filling the tanks. Baffles  246  are positioned in tanks  212  and  214  to aid in maintaining separation between the pressurized gas supplied by the pipeline and hydraulic fluid  222 . Manually operated hand pumps  228  and  230  and mounted on tanks  212  and  214 , respectively, and each pump  228  and  230  includes shuttle valve  252  mounted thereon. 
   Details of construction and operation of tanks  212  and  214 , pumps  228  and  230  and shuttle valves  252  are shown in  FIG. 8 . Only the description of tank  212 , pump  228  and shuttle valve  252  are given as tank  214  and pump  230  are identical thereto. Pump  228  is mounted to tank  212  by double flange  254  with pump  248  extending into tank  212  and immersed in hydraulic fluid  222 . Pump  228  is of the “sucker rod” type well known to those of ordinary skill in the art with hydraulic fluid  222  being drawn into pump  228  through spring loaded ball  256  when handle  258  is stroked away from tank  212 . Hydraulic fluid  222  is pressurized in pump  228  as handle  258  is stroked toward tank  212  and unseats spring loaded ball  260  and is directed out port  262  to shuttle valve  252 . Shuttle valve  252  shuttles between a position in which fluid from port  262  flows through shuttle valve  252  to outlet port  264  and to either port  108  or  110 , depending on which tank is being used, and a second position in which pressurized hydraulic fluid  222  is received into port  266  and to outlet port  264 . Pressurized hydraulic fluid  222  is supplied to port  266  through a by pass passage  268  in double flange  254 . Pressurized hydraulic fluid  222  is only supplied to by pass passage  268  when tank  212  is pressurized by gas supplied through first and second control circuits  224  and  226 . 
   A typical sequence of operation for control system  16  would be as follows assuming valve  12  is in the open position and it is desired to close valve  12 . Referring to the flow diagram of  FIG. 7 , first control circuit  224 , i.e., the “close” circuit, is operated by depressing first control valve  200 . This operation causes the following functions to happen as pressurized gas is supplied:
         (i) directs pressurized gas pressure to pilot operated normally open valve  218  to equalize pressure between actuator open fluid supply tank  214  and actuator close fluid supply tank  212 ;   (ii) directs pressurized gas pressure from outlet port  234  of first control circuit control valve  200  to pilot port  242  of first pilot operated valve  204  of valve closing first control circuit  224  to operate first pilot operated valve  204  and allow pressurized gas pressure to pressurize hydraulic fluid  222  in actuator close fluid supply tank  212  and supply pressurized hydraulic fluid  222  through by pass passage  268 , through port  266  to outlet port  264  and thence to port  108  (close port) of actuator  14  to close valve  12 ; and,   (iii) directs pressurized gas pressure from outlet port  240  of first pilot operated valve  204  of first control circuit  224  to pilot port  242  of fourth pilot operated valve  210  of valve opening second control circuit  226  to operate fourth pilot operated valve  210  and vent pressurized gas pressure from actuator open fluid supply tank  214  through exhaust orifice valve  220 . Closure of first control circuit control valve  200  to a closed position and operation of second control circuit control valve  202  to an open position results in the same operations described above but in reverse order to open valve  12 .       

   If pressurized gas pressure is not available as in the case of a break in the pipeline and it is necessary to close valve  12 , manually operated hand pump  228  on actuator close fluid supply tank  212  may be operated. Such operation pressurizes hydraulic fluid  222  in tank  212  as described above and directs such fluid  222  through port  262  to port  108  of actuator  14  to close valve  12 . Note that such operation causes shuffle valve  252  to shift and block port  264  and automatically lock out gas powered control circuit  224 , if any residual pressure is present. Should opening of valve  12  be desired, pump  230  in actuator open fluid supply tank  214  may be operated to reverse operation and open valve  12 . 
   The construction of our system for controlling fluid flow through a pipeline including valve, actuator and control system will be readily understood from the foregoing description and it will be seen that we have provided a system that allows minimizing the size of the actuator and operation of the control system in a manual mode that automatically prevents accidental operation by pipeline pressure while minimizing the condensate vented to the atmosphere during operation. Furthermore, while the invention has been shown and described with respect to certain preferred embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of the specification. The present invention includes all such equivalent alterations and modifications, and is limited only by the scope of the appended claims.