Abstract:
An internal caisson/jacket leg cutter and method provides a frame having upper and lower end portions. The upper end portion has rigging that enables the frame to be lifted. Extensible arms are movably supported upon the frame. The arms extend and retract along generally radially extending lines. Extension of the arms enables them to contact the inside surface of a caisson/jacket leg and thus center and anchor the frame within the caisson/jacket leg interior. A cutting mechanism at the lower end portion of the frame includes one or more rotary cutters or milling devices that cut the caisson/jacket leg wall as these cutters traverse an arc shaped path, tracking the caisson/jacket leg wall.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a continuation of U.S. patent application Ser. No. 13/153,562, filed on Jun. 6, 2011 (issued as U.S. Pat. No. 9,103,088 on Aug. 11, 2015), which is a continuation of International Patent Application Serial No. PCT/US2010/020856, filed Jan. 13, 2010, which application claims benefit of U.S. Provisional Patent Application Ser. No. 61/144,268, filed Jan. 13, 2009. 
     
    
       [0002]    Each of these applications are incorporated herein by reference. Priority of each of these applications is hereby claimed. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0003]    Not applicable 
       REFERENCE TO A “MICROFICHE APPENDIX” 
       [0004]    Not applicable 
       BACKGROUND 
       [0005]    Offshore marine platforms are often constructed for the purpose of producing oil and/or gas from a formation below a seabed. These offshore marine platforms typically employ an undersea structure referred to as a “jacket”. Patents have issued that are directed to platform jackets. One example is U.S. Pat. No. 4,721,416 entitled “Submersible Offshore Drilling and Production Platform Jacket” issued to Garcia. U.S. Pat. No. 4,721,416 is incorporated herein by reference. 
         [0006]    Patents have issued that relate to the disposal of jackets. An example is U.S. Pat. No. 6,354,765 entitled “Method of Transporting and Disposing of an Offshore Platform Jacket” issued to Jones. U.S. Pat. No. 6,354,765 is incorporated herein by reference. 
         [0007]    After the useful life of a marine platform is over, the platform and the jacket must be removed so that they are not a hazard to navigation. Because portions of a marine jacket can extend into the seabed (for example, see  FIG. 1  of U.S. Pat. No. 4,721,416), part of the jacket (sometimes referred to as a jacket leg) must be removed below the mud line. It is important to remove jacket legs below the mud line because they are a hazard to navigation. They are also a hazard to fishing boats that employ nets, such as shrimp boats. 
         [0008]    A caisson can be one of several columns made of steel or concrete that serve as the foundation for a rigid offshore platform rig, such as the concrete gravity platform rig. A caisson can also be a steel or concrete chamber that surrounds equipment below the waterline of a submersible rig, which can protect such equipment from damage. 
         [0009]    Prior art methods of removal of caisson/jacket legs below the mud line have included digging a trench around the exterior of the caisson/jacket leg and, after such trench has been dug, cutting the caisson/jacket leg. This prior method has the disadvantage of requiring the extra step of digging the trench, dealing with the materials removed when digging the trench, along with maintaining the stability of such trench during cutting of the caisson/jacket leg. If stability of the trench is not maintained, the trench can collapse during cutting operations risking bodily injury along with damage to equipment. 
       BRIEF SUMMARY 
       [0010]    One embodiment relates to a method and apparatus for removing tubular members that are embedded in a seabed such as offshore marine caisson/jacket legs that extend below the seabed mud line. More particularly, one embodiment relates to an improved internal caisson/jacket leg cutter apparatus and method wherein rotary cutters are supported by a frame that engages the interior caisson/jacket leg wall, a part of the frame providing a bearing that rotates as rotary cutters form a cut in the wall of the caisson/jacket leg. In one embodiment, two rotary cutters are circumferentially spaced apart so that when the frame rotates about one hundred eighty (180) degrees, a complete three hundred sixty (360) degree cut is made. 
         [0011]    In one embodiment is provided an improved method and apparatus for removing tubular members such as caisson/jacket legs from a seabed. In one embodiment is provided an internal caisson/jacket leg cutter that is configured to be lowered into the interior of a caisson/jacket leg. 
         [0012]    In one embodiment is provided extendable/retractable arms of a frame which can extend to the inner surface of the caisson/jacket leg holding/stabilizing the frame relative to the caisson/jacket leg. 
         [0013]    In one embodiment is provided a cutting mechanism employing one or more milling devices that are rotary cutters. These rotary cutters cut the caisson/jacket leg wall as the cutter travels along horizontal plane perpendicular to the central axis of the cutter. 
         [0014]    In one embodiment the cutter can travel along a curved or arc shaped path when making a cut. 
         [0015]    In one embodiment, a pair of cutters are provided, spaced about one hundred eighty (180) degrees apart. 
         [0016]    In one embodiment the operator of the internal caisson/jacket leg cutter can be above water and the cutting mechanism be below water. In one embodiment the operator can use the resistance on the cutters to determine when to rotationally advance the cutters. In one embodiment the resistance can be relatively determined based on the back pressure (e.g., hydraulic back pressure) to the rotational feed motor and/or back pressure to the driving motors for the cutters. 
         [0017]    In one embodiment the pressures are monitored and system is programmed to monitor the pressure to maintain a relatively constant feed rate. 
         [0018]    In one embodiment the operator of the internal caisson/jacket leg cutter can rotationally advance the cutters until a specified resistance is seen. At this point the operator can decrease the rotational feed rate until the resistance on the cutters decreases. Upon decrease of the resistance to the cutters the operator can again increase the feed rate of the cutting bit. This feed rate adjusting process can be repeated until the cut is completed. 
         [0019]    In one embodiment the internal caisson/jacket leg cutter can include a mounting bracket for one or more underwater lights along with one or more cameras for visual monitoring at the surface. In one embodiment cutting operations can be visually recorded on the surface using a video monitoring system such as a video camera. In one embodiment a fiber optic cable can be used to transmit the video signal from the camera to the surface. 
         [0020]    In one embodiment high frequency sonar and/or infra red imagery can be used to scan and/or view the cut as it progresses. 
         [0021]    One embodiment includes an internal caisson/jacket leg cutter comprising: a) a frame having upper and lower end portions; b) the upper end having rigging that enables the frame to be lifted; c) extensible arms movably supported upon the frame and that extend and retract along generally radial lines, extension of the arms enabling the arms to center the frame inside a caisson/jacket leg; d) an extensible cylinder on the frame that simultaneously extends the arms during centralization of the frame within a caisson/jacket leg; and e) a cutting mechanism that includes circumferentially spaced apart cutters that cut the caisson/jacket leg wall as each cutter travels along an arc shaped path traversing the caisson/jacket leg wall. 
         [0022]    In one embodiment, there can be one cutter, a pair of the cutters, or three or more cutters. In one embodiment, each cutter is a rotary mill. In one embodiment, there are upper and lower pluralities of arms. In one embodiment, a motor drive rotates each cutter along the arc shaped path. In one embodiment, each cutter is movable between extended and retracted positions. In one embodiment, a rack and pinion drive moves the cutters between extended and retracted positions. In one embodiment, the frame includes a top that is configured to rest upon the top of a caisson/jacket leg to be cut. In one embodiment, the extensible arms are mounted in between a pair of plates. 
         [0023]    In one embodiment, one of the plates is a static plate and the other plate is a rotating plate. In one embodiment, the extensible cylinder rotates one plate relative to the other plate. In one embodiment, there are a plurality of curved slots on the static plate and pins on the extensible arms that travel in the curved slots. In one embodiment, there are a plurality of curved slots on the static plate, a plurality of straight slots on the rotating plate and pins on the extensible arms that travel in both the curved slots and the straight slots. In one embodiment, the slots have inner and outer end portions, the pin positioned at the inner end portions of the slots when the arms are in the retracted position. In one embodiment, the pin of each arm is positioned at the outer end portion of the slots when the arms are in the extended position. 
         [0024]    One embodiment includes an internal caisson/jacket leg cutter comprising: a) a frame having upper and lower end portions; b) the frame upper end portion having rigging that enables the frame to be lifted; c) upper and lower spacing assemblies, each spacing assembly comprising a plurality of circumferentially space apart, radially extending arms that are movably supported upon the frame and that each extend and retract along generally radial lines, the spacing assemblies spacing the frame inwardly of a caisson/jacket leg inner surface at upper and lower spaced apart positions; d) each spacing assembly having static and rotating plates and an operator that simultaneously extends the arms during a spacing of the frame within a caisson/jacket leg by rotating the moving plate relative to the static plate; and e) a cutting mechanism that includes one or more rotary cutters that cut the caisson/jacket leg wall as each cutter travels along an arc shaped path traversing the caisson/jacket leg wall. 
         [0025]    In one embodiment, each cutter is a rotary mill. In one embodiment, each cutter is movable between extended and retracted positions. In one embodiment, the extensible arms are mounted in between a pair of plates, wherein one of the plates is a static plate and the other plate is a rotating plate. In one embodiment, the cutters are hydraulically powered. In one embodiment, a rotary bearing connects the cutting mechanism to the lower spacing assembly. In one embodiment, the cutter includes static and rotating portions. In one embodiment, there are a pair of cutters. In one embodiment, the cutters are about 180 degrees apart. In one embodiment, the cutters are circumferentially spaced. In one embodiment, the cutters are extendable from a retracted position to an extended position. In one embodiment, each spacing assembly is vertically adjustable relative to the frame. In one embodiment, the frame includes multiple vertically extending members. In one embodiment, the spacing assemblies include an extensible cylinder. 
         [0026]    In one embodiment, each spacing assembly includes a rotating plate with curved slots and a static plate with slots, each arm having a pin that travels in slots of each plate. 
         [0027]    In one embodiment, the arms are in between the static and rotating plates. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0028]    For a further understanding of the nature, objects, and advantages of the present invention, reference should be made to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein: 
           [0029]      FIG. 1  is an overall perspective view of one embodiment of an internal cutter. 
           [0030]      FIG. 2  shows the cutter of  FIG. 1  schematically indicating extension of the upper and lower sets of stabilizing/anchoring arms; rotation of the positioning ring in a horizontal plane; axial rotation of the double milling bits; extension of the double milling cutters; and rotation of the milling bits in the horizontal plane perpendicular to the centerline axis CL of the internal cutting tool. 
           [0031]      FIG. 3  is a top view of the upper set of stabilizing arms shown in a retracted condition. 
           [0032]      FIG. 4  is a top view of the upper set of stabilizing arms shown in an extended condition. 
           [0033]      FIG. 5  is a bottom view of the positioning ring showing a double track expansion and retraction system for the double milling cutters, along with a driving gear rotationally positioning the positioning ring 180 degrees so that both cutters combine to make a 360 degree cut. 
           [0034]      FIG. 6  shows the internal cutter being lowered into a caisson/jacket leg to be cut where the caisson/jacket leg extends an amount above the sea floor, and where all items are in a retracted condition (upper and lower sets of stabilizing arms along with double milling cutters). 
           [0035]      FIG. 7  shows the internal cutter now resting on top of the caisson/jacket leg in preparation of a cut to be made below the sea floor. 
           [0036]      FIG. 8  schematically illustrates the step of extending the upper and lower sets of stabilizing arms. 
           [0037]      FIG. 9  schematically illustrates the step of extending the double milling cutters and rotating the positioning ring. 
           [0038]      FIG. 10  schematically illustrates the step, after making a cut about the caisson/jacket leg, of retracting the double milling cutters along with the upper and lower sets of stabilizing arms. 
           [0039]      FIG. 11  illustrates the step removing the cutting system from the now cut caisson/jacket leg. 
           [0040]      FIG. 12  illustrates the step of removing the cut portion of the caisson/jacket leg and showing the remaining caisson/jacket leg located at a depth below the sea floor. 
           [0041]      FIG. 13  shows a bottom view of an alternative embodiment where the double milling cutters are extended and retracted automatically with double hydraulic cylinders showing the system cutting an asymmetrically shaped caisson/jacket leg. 
           [0042]      FIG. 14  is a perspective view of an alternative embodiment from  FIG. 13  now having upper and lower stabilizer sections each with a plurality of hydraulic cylinders for extending and retracting the stabilizing arms where the stabilizing arms are in a retracted state. 
           [0043]      FIG. 15  shows the embodiment of  FIG. 14  where the stabilizing arms have been extended along with the double milling cutters being in an extended state. 
           [0044]      FIG. 16  is a top view of one of the stabilizing sections showing the stabilizing arms in a retracted state. 
           [0045]      FIG. 17  is a top view of the stabilizing section of  FIG. 16  where the stabilizing arms are in an extended state. 
           [0046]      FIG. 18  is a perspective view of an alternative embodiment having upper and lower stabilizer sections each with a plurality of hydraulic cylinders for extending and retracting the stabilizing arms where the stabilizing arms are in a retracted state. 
           [0047]      FIG. 19  shows the embodiment of  FIG. 18  where the stabilizing arms have been extended along with the double milling cutters being in an extended state, and showing hydraulic piston guards on some of the extension cylinders. 
           [0048]      FIG. 20  is a top view of one of the stabilizing sections of  FIG. 18  showing the stabilizing arms in a retracted state. 
           [0049]      FIG. 21  is a top view of the stabilizing section of  FIG. 18  where the stabilizing arms are in an extended state. 
           [0050]      FIG. 22  is a bottom view of the embodiment shown in  FIGS. 18 and 19  showing a double hydraulic piston expansion and retraction system for the double milling cutters, along with a driving gear rotationally positioning the positioning ring. 
           [0051]      FIG. 23  shows the view of  FIG. 22  with the double milling cutters in an extended state. 
       
    
    
     DETAILED DESCRIPTION 
       [0052]      FIGS. 1-2  show the preferred embodiment of the apparatus of the present invention, designated generally by the numeral  10 .  FIG. 1  is an overall perspective view of one embodiment of an internal caisson/jacket leg cutter apparatus  10 .  FIG. 2  shows the cutter  10  schematically indicating extension of the upper and lower sets of stabilizing arms (schematically indicated by arrows  42 ); rotation of the positioning ring  32  in a horizontal plane also rotating the double milling cutters  68  (schematically indicated by arrows  44 ); extension of the double milling cutters  68  (schematically indicated by arrows  71 ); and rotation of the milling bits in the double milling cutters (schematically indicated by arrows  92 ). 
         [0053]    Internal caisson/jacket leg cutter apparatus  10  can be lifted and lowered using a lift line  11  (e.g. crane lifting line) and rigging that can include a lifting ring  12  or like fitting and cables or slings  13  (such as shown in  FIG. 6 ). 
         [0054]    The internal caisson/jacket leg cutter apparatus  10  provides an upper frame  14  portion that can be used to rest the apparatus  10  upon a section of caisson/jacket leg  20  to be cut (for example see  FIG. 7 ). The upper frame portion  14  can include peripheral beams  15  and diagonal beams  16 . Upper frame portion  14  can be welded metal construction. Eyelets  17  or other suitable fittings are provided on upper frame portion  14  which can be used to form a connection between frame  14  and cables or slings  13  as shown. 
         [0055]    Caisson/jacket leg  20  is typically a leg or a caisson of a massive caisson/jacket leg that was used to support an offshore marine platform, such as an oil and gas well drilling or production platform. Such caisson/jacket legs are known and can be of varying sizes in inches of about 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, or greater. In various embodiments cutting apparatus  10  can be used to cut caisson/jacket legs ranging between about any two of the above specified sizes. In various embodiments cutting apparatus  10  can be used to cut caisson/jacket legs greater than any one of the above specified sizes. When a platform is removed from the marine environment, the legs  20  (or piling or any other tubular) of the caisson/jacket leg must be removed below the mud line  21  to a specified depth below the mud line (as indicated by “H” in  FIG. 6 ). Removal is important because caisson/jacket legs  20  that remain in position are a hazard to navigation and to fishing boats that employ nets (such as shrimp boats). In various embodiments the specified depth can be about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, and 25 feet. In various embodiments the specified depth of removal can be between a range between any two of the above specified depths of removal. In various embodiments cutting apparatus  10  can be used to cut caisson/jacket legs greater than any one of the above specified depths. In one embodiment cutting apparatus  10  can be adjustable to cut caisson/jacket legs greater than any one of the above specified depths by changing or adjusting adjustable legs  33  (for example see  FIG. 1 ). In one embodiment cutting apparatus  10  can be adjustable to cut caisson/jacket legs between any two of the above specified depths by changing or adjusting adjustable legs  33 . 
         [0056]    A caisson/jacket leg  20  (such as shown in  FIG. 6 ) is typically cylindrically shaped, providing a generally cylindrically shaped wall  18  and having an interior  19 . In order to remove the caisson/jacket leg  20  at a position below the mud line  21 , a cut  22  must be made through wall  18 . The cut section  23  can then be removed by lifting using rigging  24  that can include a shackle  25  or other suitable lift fitting and a lift line  26  as shown by arrow  27  in  FIG. 12 . 
         [0057]    In order to make the cut  22  (such as shown in  FIG. 11 ), internal caisson/jacket leg cutter apparatus  10  can be lowered to a position located inside the caisson/jacket leg  20  to be removed as shown in  FIGS. 6 and 7 . In  FIG. 7 , the internal caisson/jacket leg cutter apparatus  10  has been positioned within interior  19  of caisson/jacket leg  20 . In  FIG. 6 , arrow  59  schematically illustrates a lowering of the apparatus  10  into interior  19  of caisson/jacket leg  20  using lift line  11  and rigging  12 ,  13 . 
         [0058]    A plurality of vertical supports  33  extend downwardly from disc  34 . Disc  34  is attached to frame  14  (e.g. welded or bolted) as shown in  FIGS. 1-2 . Each of the vertical supports  33  can be provided with a plurality of vertical adjustment openings  28 . In one embodiment vertical adjustment openings  28  can be used to adjust the length “L” from the upper frame portion  14  to the location of the cutters  68  using pinned or bolted connections or other fasteners (“L” is schematically shown in  FIG. 7 ). In this manner the depth of cut from the sea floor  21  can be determined based on the length L along with the height H of the upper edge  29  of caisson/jacket leg  20  compared to the sea floor  21 . 
         [0059]    In one embodiment vertical adjustment openings  28  can enable attachment of upper and lower spacing assemblies or centralizers  30 ,  31  to connect at a selected elevational position to vertical supports  33 . In one embodiment a plurality of adjustment openings  28  can also be included in the vertical supports  33  between centralizers  30  and  31 . 
         [0060]    A cutter assembly  32  can be attached to the lower end portion of each of the vertical supports  33 . Stops  35 ,  36  can be attached to upper frame portion  14  for registering upper frame portion  14  upon the upper edge  29  of caisson/jacket leg  20  as shown in  FIG. 7 . The stops can include inner stops  35  and outer stops  36 . A gap  37  is provided between each of the pair of stops  35 ,  36  (see  FIGS. 1-2  and  6 - 10 ). The upper edge  29  of caisson/jacket leg  20  registers in the gaps  37  that are between pairs of stops  35 ,  36  as shown in  FIG. 7 . 
         [0061]      FIG. 3  is a top view of the upper set of stabilizing arms or spacing assemblies  30 , 31  shown in a retracted condition.  FIG. 4  is a top view of the upper set of stabilizing arms or spacing assemblies  30 , 31  shown in an extended condition. 
         [0062]    Each of the spacing assemblies  30 ,  31  can employ a plurality of stabilizing pads  40  and arms  41 . The pads  40  engage the inside surface  38  of caisson/jacket leg  20  when the arms  41  are extended as shown by arrow  42  in  FIGS. 2 ,  8  and  9 . Such engagement can stabilize cutting apparatus  10  while a cut is being made in caisson/jacket leg  20 . 
         [0063]    Each of the spacing assemblies  30 ,  31  can be of substantially the same construction. In one embodiment each spacing assembly  30 ,  31  can employ an extensible cylinder  45  operatively connected to the stabilizing pads  40 . The extensible cylinder  45  can include cylinder  46  and pushrod  47  portions. The extensible cylinder  45  can be used to rotate a rotating plate  49  relative to a static plate  48 . The plates  48 ,  49  can be connected with a rotary connection such as hub  50  or other suitable rotary bearing. In one embodiment curved slots  51  are provided in rotating plate  49 . Straight slots  55  are provided in static plate  48 . Each arm  41  provides a pin  54  that tracks both slots  51 ,  55  when cylinder  45  is expanded as illustrated in  FIG. 4 . The extensible cylinder  45  is attached to static plate  48  with pinned connection  52 . The extensible cylinder  45  is attached to the rotating plate  49  with pinned connection  53 . The extent of rotation of the rotating plate  49  relative to the static plate  48  can be controlled with stops or stop pins  57 . These stop pins  57  can be attached (e.g. welded, bolted) to static plate  48  and travel in curved slots  56  of rotating plate  49 . When the stop or stop pin  57  reaches an end of curved slot  56 , the pin  57  limits the further rotation of the plate  49  relative to the plate  48 . The stop pins  57  and slots  56  stabilize one plate  48  relative to the other plate  49 . 
         [0064]    Spacers or bearings  39  can be positioned in between plates  48 ,  49 . In one embodiment as rotating plate  49  rotates each of the plurality of stabilizing pads  40  extend a equal amount compared to the other stabilizing pads. In this manner a single extensible cylinder  45  can be used to extend and retract the plurality of stabilizing pads  40  on the particular spacing assembly as desired. In other embodiments each stabilizing pad can be connected to an individual extensible cylinders  45  for extension and retraction. For example, if there are three stabilizing pads  40 , there can be three extensible cylinders which retract and extend as desired the respective stabilizing pad. 
         [0065]    Cutter assembly  32  can be mounted to lower spacer assembly  31  using a plurality of spacers or hangers  58  and a rotational bearing assembly  43 .  FIG. 5  is a bottom view of the positioning ring  43  showing a double track expansion and retraction system for the double milling cutters, along with a driving gear  65  rotationally positioning the positioning ring 180 degrees so that both cutters  68  combine to make a 360 degree cut (schematically indicated by two sets of 180 degree arrows). The bearing assembly  43  can comprise rotating  63  and non-rotating  67  rings. Bearing assembly  43  can be conventionally available such as the Low Clearance Split Frame offered by E.H. Wachs Company, 600 Knightsbridge Parkway, Lincolnshire, Ill. 60069. 
         [0066]    In one embodiment cutter assembly  32  (such as shown in  FIG. 6 ) employs a stabbing guide or positioning cutter frame  60  that includes a plurality of circumferentially spaced apart radially extending plates  62 . Each radially extending plate  62  is attached to the rotating ring  63  of bearing assembly  43 . Each plate  62  also attaches to plate  61 . The rotating ring  63  carries an arcuate toothed rack  64 . A pinion gear  65  of motor drive  66  engages the arcuate toothed rack  64  as shown in  FIG. 5 . Motor drive  66  can be mounted on an upper, non-rotating ring  67  of bearing assembly  43 . In one embodiment motor  66  can be located on the interior of rotating ring  63  with arcuate toothed rack  64  also being located on the interior. 
         [0067]    Arrows  44  in  FIGS. 2 and 9  illustrate that ring  63  rotates relative to ring  67 . Likewise, plates  62  and plate  61  rotates with ring  63 . Also, the rotary mills  68  rotate with ring  63 . Each mill  68  can be driven with motor drive  96 . The mills  68  and motor drives  96  can be mounted on rail  70  to travel between retracted ( FIGS. 1 ,  6 - 8  and  10 - 11 ) and extended ( FIGS. 5 ,  9 ) positions. Arrows  71  in  FIGS. 2 ,  5  and  9  illustrate travel of each mill  68  to the extended position. Arrows  72  in  FIG. 10  illustrates travel of each mill  68  to the retracted position. 
         [0068]      FIG. 5  illustrates that mills  68  can be moved between extended and retracted positions with a pinion gear  73  and toothed racks  74 . Reversible motor drive  75  can rotate pinion gear  73 . Rail  70  is attached to rotating ring  63  and rotates with ring  63 . Toothed racks  74  can be mounted on sliding sections  76  that slide upon rail  70 . Mills  68  and motor drives  96  travel with sliding sections  76 . 
         [0069]    Rollers  77  are provided on rail  70  next to mills  68  as shown in  FIG. 5 . The rollers  77  can be positioned to control a depth of cut for each mill  68 , insuring that wall  18  of caisson/jacket leg  20  is properly cut and that mills  68  are not damaged. Rollers  77  enable only mills  68  and not motor drives  96  to engage wall  18  as seen in  FIG. 5 . 
         [0070]    In one embodiment, where caisson/jacket leg  20  is not circular (such as shown in  FIG. 13 ) but substantially symmetrically shaped, mills  68  can extend and retract to follow the shape of caisson/jacket leg  20 . In this embodiment mills  68  can be extended until rollers  77  contact interior wall  18  of caisson/jacket leg  20  and mills  68  rotated in the direction of arrows  44 . However, as mills  68  are rotated in the direction of arrow  44  the wall  18  of caisson/jacket leg  20  can become farther away from mills  68  causing rollers  77  to lose contact with wall  18 . Where a motor  75  is energized (such as by the application of a specified hydraulic pressure) during rotation in the direction of arrow  44 , motor  75  can cause mills  68  to extend further until contact is made between rollers  77  and interior wall  18 . In the alternative, as mills are rotated in the direction of arrow  44  wall  18  of caisson/jacket leg  20  can become closer placing increases pressure on rollers  77 . Such increased pressure on rollers  77  can overcome the resistance of motor  75  allowing mills  68  to retract until motor  75  can overcome the back pressure caused by contact forces between rollers  77  and interior wall  18 . In this manner changing dimensions in caisson/jacket leg  20  can be automatically addressed as mills  68  are rotated in the direction of arrows  44 . In other embodiments mills  68  can be rotated in the opposite direction of arrows  44 . 
         [0071]      FIG. 6  shows the internal cutter apparatus  10  being lowered into a caisson/jacket leg  20  to be cut where the caisson/jacket leg  20  extends an amount H above the sea floor  21 , and where all items are in a retracted condition (upper and lower sets of stabilizing arms and pads  40  along with double milling cutters  68 ).  FIG. 7  shows the internal cutter apparatus  10  now resting on top  29  of the caisson/jacket leg  20  in preparation of a cut to be made below the sea floor  21  (at a depth D). 
         [0072]      FIG. 8  schematically illustrates the step of extending the upper and lower sets of stabilizing arms and pads  40  (schematically indicated by arrows  42 ). Stabilizing apparatus  10  during the cut will assist in making a complete cut  22  around caisson/jacket leg  20 . 
         [0073]      FIG. 9  schematically illustrates the step of extending the double milling cutters  68  (schematically indicated by arrows  71 ) and the step of rotating the positioning ring  32  while cutters  68  are making a cut in caisson/jacket leg  20 . Preferably, cutters  68  are extended in the direction of arrows  71  without positioning ring  32  being rotated in the direction of arrow  44 . Cutters  68  are rotated in the directions of arrows  92  and make the initial cut into and through wall  18 . After penetrating wall  18  and rollers  77  contacting interior  38  or wall  18 , positioning ring  32  can be rotated in the direction of arrow  44  (or in the opposition direction of arrow  44 ). After penetration, continued rotation of cutters  68  in the direction of arrows  92  (or in the opposite direction of arrows  92 ) along with rotation of positioning ring  32  in the direction of arrow  44  will allow a cut  22  to be made in caisson/jacket leg  20 . For a complete cut to be made in caisson/jacket leg  20  it is preferred that positioning ring  32  be rotated at least 180 degrees. In this manner each of the cutters  68  will make at least a 180 degree cut  22 ′ and  22 ″ in caisson/jacket leg  20  with the combined cut being at least 360 degrees (schematically indicated by the double sets of 180 degree arrows in  FIG. 5 ). 
         [0074]    In an alternative embodiment only a single cutter  68  is used. In this embodiment positing ring  32  should be rotated at least 360 degrees in the direction of arrow  44 . In another alternative embodiment three cutters  68  symmetrically and radially spaced can be used. In this alternative embodiment positioning ring  32  should be rotated at least about 120 degrees in the direction 
         [0075]      FIG. 10  schematically illustrates the step, after making a cut  22  about the caisson/jacket leg  20 , of retracting the double milling cutters  68  (schematically indicated by arrows  72 ) along with the upper and lower sets of stabilizing arms or pads  40  (schematically indicated by arrows  90 ). 
         [0076]      FIG. 11  illustrates the step removing (schematically indicated by arrows  100 ) the cutting system  10  from the now cut caisson/jacket leg  20 . 
         [0077]      FIG. 12  illustrates the step of removing (schematically indicated by arrow  27 ) the cut portion  23  of the caisson/jacket leg  20  and showing the remaining caisson/jacket leg  20  located at a depth below the sea floor at a depth D. 
         [0078]      FIGS. 14 through 17  show an alternative embodiment for upper and lower spacing/stabilizer sections  30 , 31 .  FIG. 14  is a perspective view of an alternative embodiment from  FIG. 13  now having upper and lower stabilizer sections  30 , 31  each with a plurality of hydraulic cylinders ( 200 , 202 , 204 ) for extending and retracting the stabilizing arms ( 240 , 242 , 244  with pads  40 ) where the stabilizing arms are in a retracted state.  FIG. 15  shows stabilizing arms ( 240 , 242 , 244 ) in an extended state along with the double milling cutters  38  being in an extended state. 
         [0079]    In this alternative embodiment each stabilizing/spacing section  30 , 30  can comprise upper and lower plates  350 , 360 ; a plurality of stabilizing arms (e.g.,  240 , 242 , 244 ) which can be radially and symmetrically disposed about a central axis CL of the apparatus  10 ′. In this embodiment three stabilizing arms  240 , 242 , 244  are shown radially spaced apart at 120 degree increments. Stabilizing arms  240 , 242 , 244  can be contained and slidably connected to upper and lower plates  350 , 360 . Operatively connected to each stabilizing arm can be a hydraulic cylinder (respectively  200 , 202 , 204 ). Each hydraulic cylinder can include a push rod (respectively  240 , 242 , 244 ). 
         [0080]      FIG. 16  is a top view of stabilizing section  30  showing stabilizing arms  240 , 242 , 244  in a retracted state.  FIG. 17  is a top view of stabilizing section  30  where stabilizing arms  240 , 242 , 244  are in an extended state. Arrows  300  schematically indicated that stabilizing arms can be extended and retracted. To stabilize apparatus  10 ′, stabilizing arms  240 , 242 , 244  can be extended until pads  40  contact the interior surface of the item to be cut. 
         [0081]      FIG. 18  is a perspective view of an alternative embodiment  10 ″ having upper and lower stabilizer  30 , 31  sections each with a plurality of hydraulic cylinders (respectively  200 , 202 ,  204 ) for extending and retracting the stabilizing arms (respectively  240 , 242 , 244 ) where the stabilizing arms are in a retracted state.  FIG. 19  shows the embodiment of  FIG. 18  where the stabilizing arms  240 , 242 , 244  have been extended (schematically indicated by arrows  300  and  310 ) along with the double milling  68  cutters being in an extended state (schematically indicated by double arrows  83 ), and showing hydraulic piston guards ( 260  and  264 ) on some of the extension cylinders (respectively  210  and  214 ). In this embodiment the stabilizing arms for upper section  30  are out of phase with the stabilizing arms for lower section  31  (such as by sixty degrees as shown in  FIG. 23 ) which can help increase the overall stability of apparatus  10 ″ when making a cut on an irregularly shaped member. In one embodiment hydraulic piston guards can be placed around all hydraulic cylinders. 
         [0082]      FIG. 20  is a top view of one of the stabilizing sections of  FIG. 18  showing the stabilizing arms in a retracted state.  FIG. 21  is a top view of the stabilizing section of  FIG. 18  where the stabilizing arms are in an extended state. 
         [0083]      FIG. 13  shows a bottom view of an alternative embodiment where the double milling cutters  68  are extended and retracted automatically with double hydraulic cylinders  78  and  79 , where the system is cutting an asymmetrically shaped caisson/jacket leg  20 ′ compared to a symmetrically shaped caisson/jacket leg  20  (shown in dashed lines). In  FIG. 13 , each cutting mill  68  and motor drive  96  is moved independently of the other using extensible cylinders  78 ,  79 . Rail  80  is attached to and rotates with rotating ring  63 . Each cylinder  78  or  79  moves a sliding section  81  or  82 . Each sliding section slides upon rail  80  between extended and retracted positions as indicated by arrows  83  in  FIG. 13 . Each cylinder  78 ,  79  employs a cylinder body  84  and extensible pushrod  85 . Each cylinder body attaches to rail  80  with attachments  69  (e.g. welded, bolted) as seen in  FIG. 5 . The embodiment of  FIG. 13  can be useful if caisson/jacket leg  20  has an irregular cross section, as indicated schematically by phantom lines  86  in  FIG. 13 , as the movement of one mill cutter  68  and motor drive  96  is independent of the other. This embodiment can automatically accommodate non-symmetrical changes in dimension of caisson/jacket leg  20  during the cutting process. 
         [0084]      FIG. 22  is a bottom view of the embodiment shown in  FIGS. 18 and 19  showing a double hydraulic piston expansion and retraction system (cylinder/rods  280 / 282  and  286 / 288 ) for the double milling cutters  68 , along with a driving gear motor  66  rotationally positioning the positioning ring  63 .  FIG. 23  shows the view of  FIG. 22  with the double milling cutters  68  in an extended state. In one embodiment cylinders  280  and  286  can be pivotally connected to ring  63  (respectively by pivoting pins  283  and  289 ). 
         [0085]    Although not shown (for clarity), in one embodiment a flow diverter can be used to control the rate and/or amount of extension of each push rod  220 , 222 , 224  so that each stabilizing arm will extend respectively at about the same rate and about equal amounts. 
         [0086]    Extending equally can substantially center the centerline CL of apparatus  10 ′ in the item to be cut which can assist keeping the item to be cut within the cutting area of double milling cutters  68  (even where double milling cutters  68  can extend and retract during a cut (schematically indicated in  FIG. 13 ). 
         [0087]    In one embodiment a  6 -way hydraulic flow diverter (not shown for clarity) can be employed on the tool  10 , 10 ′ to simultaneously direct the hydraulic fluid, supplied via a control valve on the surface (not shown for clarity), in equal volumes to each of the six anchor/centralizer hydraulic cylinders ( 200 , 202 , 204 ) that are independent and attached to each of the six anchor/centralizer arms ( 240 , 242 , 244 ). The equal supply of fluid provided by the flow diverter ensures that each arm substantially simultaneously extends the same distance measured from the center line CL of the cutting tool  10 , 10 ′. Once the pads  40  of the arms ( 240 , 242 , 244 ) on each centralizer section ( 30 , 30 ) come in contact with the interior wall ( 18  or  86 ) of the caisson, the arms ( 240 , 242 , 244 ) act to centralize the cutting tool  10 , 10 ′ within the caisson. The flow diverter can substantially ensure that an equal amount of pressure, monitored and controlled from the surface control panel (not shown for clarity), is applied to each arm ( 240 , 242 , 244 ) to maintain a constant and equal anchoring force. 
         [0088]    In one embodiment the anchoring arms ( 240 , 242 , 244 ) can serve to: (a) centralize the cutting tool  10 , 10 ′ along the center line (CL) of the caisson being cut; (b) stabilize the cutting tool  10 , 10 ′ to prevent upward or downward movement during the cutting process; and (c) provide anchoring force to oppose the counter rotational force created by the resistance of the mill bits  38  against the material being cut during the cutting process (cutting schematically indicated by arrow  44 ). 
         [0089]    In one embodiment each hydraulic cylinder can be pivotally connected to upper plate  350  (respectively at pivot points  230 , 232 , 234 ). In one embodiment each pushrod or arm can also be pivotally connected to its respective stabilizing arm. Being pivotally connected to both upper plate  350  and the respective stabilizing arm allows each hydraulic cylinder to absorb differential vertical movement between the stabilizing arm and stabilizing/spacing section  30 . 
         [0090]    In one embodiment a flow diverter  400  can be used to control the extension and retraction of double cylinders  84  and double pushrods  85  (shown in  FIG. 13 ). 
       Typical Method of Subsea Operation 
       [0091]    The following includes steps in one embodiment for operating the cutting saw in a subsea environment: 
       SEQUENCE OF OPERATIONS 
       [0092]    1. Sever Caisson/Jacket Leg Above the Mud Line Approximately 5 Feet Above the Mud Line (If Required) 
         [0093]    2. Lowering the Cutter  10  into the Casing  20   
         [0094]    (a) Adjust the upper depth legs  33  to position the cut at the proper desired depth “D” (schematically indicated by “L” in  FIG. 7 ) below the top  29  of the casing  20 . The adjustment is achieved by removing the bolts (adjustment openings  28 ) on the telescopic arms  33 , and then inserting the bolts (adjustment openings  28 ) at the required locations. 
         [0095]    (b) Ensure that the cutting mills  68  dovetail slides are in the fully retracted position ( FIG. 6  shows retracted position). The centralizers (spacing assemblies  30  and  31 ) should also be in the fully retracted position. 
         [0096]    (c) Lower the entire tool  10  into the casing (schematically shown in  FIGS. 6 and 7 ). The stabbing guide  60  will help to protect the retracted milling cutters  68  from contacting the casing wall  18  upon entrance into the casing  20 . Continue to lower the tool  10  until the casing top stop or upper frame  14  contacts the top  29  of the casing  20  (shown in  FIG. 7 ). 
         [0097]    (d) In an alternative embodiment raise the tool  10  approximately  1  foot to ensure that the tool  10  is hanging from the crane, and not resting on the top stop or upper frame  14 . (If the casing  20  is cut unevenly on the top  29 , this uneven cut could cause the tool  10  to sit cocked or off center to the casing  20  if it were allow to rest on the top  29 .) 
         [0098]    3. Making a Cut 
         [0099]    (a) Extend the centralizers (upper and lower centralizers—spacing assemblies  30  and  31 ) by actuating the extend centralizers lever on the control console (located above the surface of the water and not shown for clarity). The clamping pressure can be adjusted by using the centralizer clamp pressure relief valve and pressure gauge on the control console. 
         [0100]    (b) Begin rotating the cutting mill bits  68  (in the direction of arrows  92 ) by actuating the rotate mill bits lever on the control console (located above the surface of the water and not shown for clarity). The maximum cutting torque can be adjusted by using the cutting torque relief valve and pressure gauge on the control console. 
         [0101]    (c) Extend the cutting mill dovetail slides (schematically indicated by arrows  71  in  FIGS. 5 and 9 ) by actuating the extend mill slides lever on the control console (located above the surface of the water and not shown for clarity). The maximum extend force can be adjusted by using the mill extend force relief valve on the control console. The slides will extend until the guide rollers  77  contact the inside diameter  38  of the pipe  20  (contact is shown in  FIG. 9 ). 
         [0102]    (d) Rotate in the direction of arrow  44  the bottom ring  63  by actuating the bottom ring rotate lever on the control console (located above the surface of the water and not shown for clarity). The maximum torque can be adjusted by using the bottom ring rotate relief valve and pressure gauge on the control console. The bottom ring  63  can rotate 360 degrees continuously. However, only 180 degrees should be necessary to make a cut in the preferred embodiment. 
         [0103]    4. Removing the Cutter from the Casing 
         [0104]    (a) Stop the bottom ring  63  rotation. 
         [0105]    (b) Retract the milling cutter  68  slides. 
         [0106]    (c) Stop the milling cutter bits  68 . 
         [0107]    (d) Retract the centralizers (pads  40  for upper and lower spacing assemblies  30  and  31 ). 
         [0108]    (e) Remove the tool  10  from the cut casing  20 . 
       DESCRIPTION OF HYDRAULIC METHODS USED FOR OPERATION 
       [0109]    1A. Cylinder Centralizers 
         [0110]    (a) In one embodiment ( FIGS. 14 through 17 ) each centralizer (upper  30  and lower  31 )(pads  40  for upper and lower spacing assemblies  30  and  31 ) is actuated by three hydraulic cylinders ( 200 , 202 , 204 ). Each hydraulic cylinder ( 200 , 202 , 204 ) is connected to a telescopic arm ( 240 , 242 , 244 ) made of square tubing with a toothed die affixed to one end to grip the inside diameter of the pipe. 
         [0111]    (b) Both the upper and lower centralizers ( 30 , 31 ) can be operated (pads  40  for upper and lower spacing assemblies  30  and  31 ) for extension and retraction by a single control lever (located above the surface of the water and not shown for clarity). The upper and lower centralizers extension and retraction can be synchronized by utilizing a synchronizing rotary flow divider. This type of valve allows all cylinders ( 200 ,  202 ,  204 ) to move at substantially the same rate. However, should one centralizer ( 30  or  31 ) contact and clamp the casing/pipe/caisson/jacket leg  20  before another, the non-contacting centralizer can still allowed to extend and clamp the casing/pipe/caisson/jacket leg  20  . 
         [0112]    (c) A pressure control valve will be used on the extend side of the cylinders ( 200 , 202 , 204 ) to control the maximum force output of the cylinders. This will limit the force between the centralizer arms ( 240 , 242 , 244  and pads  40 ) and the inside diameter of the casing/pipe/caisson/jacket leg  20 . 
         [0113]    1B. Rotational Centralizers 
         [0114]    (a) In one embodiment each centralizer (upper and lower) (pads  40  for upper and lower spacing assemblies  30  and  31 ) is actuated by a single hydraulic cylinder  45 . Extending or retracting the cylinder causes a rotation of the centralizer cam ring (rotating plate  49 ). The cam ring  49  has three curved cam slots  51 . These cam slots  51  are cut in such a manner that given a constant rotational torque, the linear force output at the centralizer arm  41  will be a constant anywhere on the path of the cam. As the cam ring  49  rotates (schematically indicated by arrow  110  on  FIG. 2 ), cam followers (pins  54 ) on the centralizer arms  41  will follow the cam slots  51 , extending/ retracting the arms  41  and pads  40 . 
         [0115]    (b) Both the upper and lower centralizers will be operated (pads  40  for upper and lower spacing assemblies  30  and  31 ) for extension and retraction by a single control lever (located above the surface of the water and not shown for clarity). The upper and lower centralizers extension and/or retraction can be synchronized by utilizing a synchronizing flow divider. This type of valve allows all cylinders  45  to move at the same rate. However, should one centralizer contact and clamp the casing/pipe/caisson/jacket leg  20  before the other centralizer, the non-contacting centralizer is still allowed to extend and clamp the casing/pipe/caisson/jacket leg  20 . 
         [0116]    (c) A pressure control valve will be used on the extend side of the cylinders  45  to control the maximum force output of the cylinders  45 . This will limit the force between the centralizer arms  41 /pads  40  and the inside diameter of the casing  20 . 
         [0117]    2. Dovetail Mill Slides 
         [0118]    (a) The two dovetail mill slides  81 , 82  will each be extended and/or retracted by a hydraulic cylinder (shown in  FIG. 13  as cylinders  84 ). Both mill slides  81 , 82  will be operated by a single control lever (located above the surface of the water and not shown for clarity). A single, adjustable pressure reducing/ relieving valve will be used on the extend side of both cylinders  84  (schematically indicated by arrows  83 ). The mill slides  81 , 82  may move at different rates or one may extend and contact the casing/pipe/caisson/jacket leg  20  before the other moves, as the hydraulic fluid will take the path of least resistance. 
         [0119]    (b) Once contacting the casing/pipe/caisson/jacket leg  20 , the mill bits  68  will push against the casing/pipe/caisson/jacket leg  20  with a constant force, limited by the pressure reducing/ relieving valve until the rotating mill bits  68  penetrate the casing/pipe/caisson/jacket leg  20 . Once the mill bits  68  penetrate, the guide wheels  77  will contact the inside diameter of the casing/pipe/caisson/jacket leg (shown in  FIG. 13 ), with a constant force limited by the pressure reducing/ relieving valve. As the bottom ring  63  is rotated in the direction of arrow  44 , the guide wheels  77  will follow the inside wall  38 ′ of the casing/pipe/caisson/jacket leg  20 ′ with a constant applied force, regardless of casing/pipe/caisson/jacket leg  20 ′ ovality or concentricity (such extending and retracting movement is schematically indicated by arrows  83  in  FIG. 13 ). 
         [0120]    3. Rotating Mill Bits 
         [0121]    (a) The two hydraulic motors  96  will be controlled from a single lever valve (located above the surface of the water and not shown for clarity). The motors  96  will be connected hydraulically in series, so that both motors  96  turn at the same rate (schematically indicated by arrows  92 ), regardless of the load applied to the mill bits  68 . A pressure relief valve will be used to control the torque output. A flow control valve will be used to control the rotational speed. 
         [0122]    4. Rotating Bottom Ring 
         [0123]    (a) The rotating bottom ring  63  is driven by a single hydraulic motor  66 , driving a pinion gear  65  in contact with a ring gear  64 . The hydraulic motor  66  will be controlled by a single lever valve (located above the surface of the water and not shown for clarity). Rotational speed will be adjustable by using a flow control valve. A pressure relief valve will limit the rotational torque. 
         [0124]    The following is a list of reference numerals which are used in this application along with a description of the reference numeral. 
         [0000]    
       
         
               
             
               
               
             
               
               
             
           
               
                   
               
               
                 REFERENCE NUMERAL LIST 
               
             
          
           
               
                 Reference Number 
                 Description 
               
               
                   
               
             
          
           
               
                 10 
                 interval caisson/jacket leg cutter apparatus 
               
               
                 11 
                 lift line 
               
               
                 12 
                 ring 
               
               
                 13 
                 cable/sling 
               
               
                 14 
                 upper frame portion 
               
               
                 15 
                 peripheral beam 
               
               
                 16 
                 diagonal beam 
               
               
                 17 
                 eyelet 
               
               
                 18 
                 wall 
               
               
                 19 
                 interior 
               
               
                 20 
                 caisson/jacket leg 
               
               
                 21 
                 mud line 
               
               
                 22 
                 cut 
               
               
                 23 
                 cut section 
               
               
                 24 
                 rigging 
               
               
                 25 
                 shackle 
               
               
                 26 
                 lift line 
               
               
                 27 
                 arrow 
               
               
                 28 
                 adjustment opening 
               
               
                 29 
                 upper edge 
               
               
                 30 
                 spacing/stabilizing assembly 
               
               
                 31 
                 spacing/stabilizing assembly 
               
               
                 32 
                 cutter assembly 
               
               
                 33 
                 vertical support 
               
               
                 34 
                 disk 
               
               
                 35 
                 inner stop 
               
               
                 36 
                 outer stop 
               
               
                 37 
                 gap 
               
               
                 38 
                 inside surface 
               
               
                 39 
                 spacer/bearing 
               
               
                 40 
                 pad 
               
               
                 41 
                 arm 
               
               
                 42 
                 arrow 
               
               
                 43 
                 bearing assembly 
               
               
                 44 
                 arrow 
               
               
                 45 
                 extensible cylinder 
               
               
                 46 
                 cylinder 
               
               
                 47 
                 pushrod 
               
               
                 48 
                 static plate 
               
               
                 49 
                 rotating plate 
               
               
                 50 
                 hub/rotary connection 
               
               
                 51 
                 curved slot 
               
               
                 52 
                 pinned connection 
               
               
                 53 
                 pinned connection 
               
               
                 54 
                 pin 
               
               
                 55 
                 straight slot 
               
               
                 56 
                 curved slot 
               
               
                 57 
                 stop pin 
               
               
                 58 
                 spacer 
               
               
                 59 
                 arrow 
               
               
                 60 
                 cutter frame 
               
               
                 61 
                 circular plate 
               
               
                 62 
                 radial plate 
               
               
                 63 
                 rotating circular ring 
               
               
                 64 
                 arcuate toothed rack 
               
               
                 65 
                 pinion gear 
               
               
                 66 
                 motor drive 
               
               
                 67 
                 non-rotating ring 
               
               
                 68 
                 rotary mill 
               
               
                 69 
                 attachment 
               
               
                 70 
                 rail 
               
               
                 71 
                 arrow 
               
               
                 72 
                 arrow 
               
               
                 73 
                 pinion gear 
               
               
                 74 
                 toothed rack 
               
               
                 75 
                 motor drive 
               
               
                 76 
                 sliding sections 
               
               
                 77 
                 roller 
               
               
                 78 
                 extensible cylinder 
               
               
                 79 
                 extensible cylinder 
               
               
                 80 
                 rail 
               
               
                 81 
                 sliding section 
               
               
                 82 
                 sliding section 
               
               
                 83 
                 arrows 
               
               
                 84 
                 cylinder body 
               
               
                 85 
                 pushrod 
               
               
                 86 
                 phantom lines 
               
               
                 90 
                 arrow 
               
               
                 92 
                 arrow 
               
               
                 96 
                 motor drive 
               
               
                 100 
                 arrow 
               
               
                 110 
                 arrow 
               
               
                 200 
                 extension support 
               
               
                 202 
                 extension support 
               
               
                 204 
                 extension support 
               
               
                 210 
                 cylinder 
               
               
                 212 
                 cylinder 
               
               
                 214 
                 cylinder 
               
               
                 220 
                 rod 
               
               
                 222 
                 rod 
               
               
                 224 
                 rod 
               
               
                 230 
                 pivot 
               
               
                 231 
                 pivot 
               
               
                 232 
                 pivot 
               
               
                 233 
                 pivot 
               
               
                 234 
                 pivot 
               
               
                 235 
                 pivot 
               
               
                 240 
                 arm 
               
               
                 242 
                 arm 
               
               
                 244 
                 arm 
               
               
                 250 
                 track 
               
               
                 252 
                 track 
               
               
                 254 
                 track 
               
               
                 260 
                 cover 
               
               
                 262 
                 cover 
               
               
                 264 
                 cover 
               
               
                 270 
                 plurality of vertical spacing supports between 
               
               
                   
                 upper and lower stabilizing sections 
               
               
                 280 
                 cylinder 
               
               
                 282 
                 rod 
               
               
                 283 
                 pivoting pin 
               
               
                 286 
                 cylinder 
               
               
                 288 
                 rod 
               
               
                 289 
                 pivoting pin 
               
               
                 300 
                 arrows 
               
               
                 310 
                 arrows 
               
               
                 350 
                 upper plate 
               
               
                 360 
                 lower plate 
               
               
                 400 
                 flow diverter 
               
               
                   
               
             
          
         
       
     
         [0125]    All measurements disclosed herein are at standard temperature and pressure, at sea level on Earth, unless indicated otherwise. All materials used or intended to be used in a human being are biocompatible, unless indicated otherwise. 
         [0126]    The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.