Patent Publication Number: US-2005135902-A1

Title: Pipe transfer apparatus

Description:
CROSS REFERENCES TO RELATED APPLICATIONS  
      NONE  
     STATEMENTS AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT  
      NONE  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to an apparatus for transferring tubular goods from a pipe rack v-door to a well bore on a drilling rig. More specifically, the present invention relates to an apparatus for transporting tubular goods from a v-door to a well bore on a drilling rig.  
      2. Brief Description of the Prior Art  
      Standard drilling rigs typically comprise a supportive rig floor, a derrick extending vertically above said rig floor, and a traveling block which can be raised and lowered within said derrick. During drilling operations, such rig equipment is often used to manipulate tubular goods (e.g. drill pipe, tubing, casing and the like) and/or downhole tools in a well bore situated under such derrick. For example, drill bits and/or other equipment are often inserted into a well bore and manipulated within such well bore via tubular drill pipe. Moreover, once a well has been drilled to a desired depth, large diameter and relatively heavy pipe called casing is often installed in the well bore and cemented in place in order to provide structural integrity to the borehole and to isolate downhole formations from one another.  
      When installing casing, drill pipe or other tubular goods into a well bore, such pipe is typically installed in a number of sections of roughly equal length. These pipe sections, often called “joints,” are typically installed one at a time, and screwed together or otherwise joined end-to-end to make a roughly continuous string of pipe. In order to commence the process of inserting pipe in a well bore, a first joint of pipe is lowered into the well bore at the rig floor, and suspended in place using a set of “slips.” Thereafter, a second joint of pipe is connected to the top of said first joint, the slips are removed, and both joints are then lowered into the well bore. The slips are then installed at the rig floor, and the process is repeated until the desired length of pipe has been run into the well bore.  
      In many instances, pipe and other tubular goods are stored horizontally on one or more pipe racks in the general vicinity of the rig floor. As such pipe/tubular goods are needed for installation in a well bore, the desired number of joints are transferred from such pipe rack(s) into the drilling rig derrick; thereafter, such joints are either installed directly into the well, or stored vertically within the derrick. Because most rig floors and associated derricks are typically elevated above such pipe rack(s), transferring pipe sections between a pipe rack and an elevated rig floor requires careful handling of such pipe. Care must be taken to protect the pipe, as well as the personnel around the rig. This is especially true with casing and drill collars, since heavy joints of casing and/or drill collars are frequently more difficult to handle than smaller and lighter pipe, such as drill pipe and tubing.  
      When pipe is transferred from a pipe storage rack to an elevated rig floor, one or more joints of pipe are typically loaded on a ramp-like member, commonly referred to as a “v-door”, which extends between said pipe rack and said elevated rig floor. Because of the difference in elevation between the pipe rack and rig floor, the v-door is frequently inclined at an angle. Once pipe is loaded on to said v-door, the pipe is thereafter lifted, typically one joint at a time, from the v-door into a vertical position in the derrick above the elevated rig floor. Once a joint of pipe is aligned over the well bore (as well as any pipe which has already been inserted therein), the suspended section of pipe can then be connected to the top of the pipe string which is protruding from the well bore. Thereafter, the pipe string can be lowered into said well bore, and the process can be repeated until the desired amount of pipe is inserted into the well.  
      This method of transferring pipe between a pipe storage rack and a derrick has certain limitations. For example, when a section of pipe is lifted from the v-door into the derrick of a rig, the pipe will typically ride or slide up the v-door until the bottom of said pipe reaches the top of said v-door. Once the bottom of said section of pipe reaches the top of the v-door, the lower end of the pipe will often swing across the rig floor in a dangerous and/or uncontrolled manner. This danger increases when the rig is a floating vessel, such as a drill ship or semi-submersible drilling rig, which is susceptible to unpredictable rocking and swaying with wave action.  
      One common practice is to place a rope or other line across the opening in a derrick where the v-door meets the rig floor. This rope is used as a barrier to hold tension against a section of pipe as it is lifted from said v-door; once the bottom of a section of pipe clears the top of the v-door, the rope provides resistence to prevent the pipe from swinging across the rig floor in a dangerous or uncontrolled manner. In most cases, at least one worker will hold on to one end of said rope. Once the bottom of a section of pipe clears the top of the v-door, the worker can gradually let out slack in the rope in order to guide the pipe section in the direction of the well bore in a controlled manner. This practice is labor intensive, in that at least one worker is required to maintain tension in the rope and guide movement of said pipe section. This practice is also dangerous, because one or more workers must frequently be stationed in awkward or precarious positions.  
      It can be seen that it would be desirable to be able to grip a section of pipe positioned on a drilling rig v-door, move same into vertical orientation over a well bore to permit insertion of the subject pipe in such well bore. Numerous devices have been proposed to assist in the movement of tubular members between a pipe storage rack and an elevated rig floor. However, such devices generally do not address problems associated with moving pipe from a rig v-door to the well bore within a derrick. Further, existing pipe handling devices are generally complex in construction, designed for use with a particular type or style of drilling rig, and not easily transported from one drilling rig to another. To this end, a need exists for an improved pipe transfer device which is simple in construction, easy to transport and operate, and which is adapted to be used with a variety of different types of drilling rigs.  
     BRIEF DESCRIPTION OF THE PRESENT INVENTION  
      An object of the present invention is to provide a pipe transfer apparatus for transferring pipe between: (1) a drilling rig v-door; and (2) a vertical position over a well bore. A further object of the present invention is to allow movement of pipe sections between a v-door and a drilling rig derrick, such that said pipe sections can be advanced into a well bore for ultimate use in the drilling process, or as otherwise desired. It is to be appreciated that use of the term “pipe” herein encompasses any elongate element or tubular good which can be inserted into, or otherwise used within, a well bore.  
      The present invention can be easily transported and rapidly installed on a standard drilling rig without substantial alteration of the rig. Moreover, the present invention occupies a minimum amount of space, and does not interfere with other operations performed on a rig.  
      The apparatus of the present invention comprises a substantially horizontal track having two ends, said track being situated on, or in general proximity to, the rig floor of a drilling rig. One terminus of said track is located at or near the opening of the well bore, while the other terminus of said track extends near the upper edge of the v-door where said v-door meets the rig floor. A traveling base member, slidably disposed on said track, can move along the length of said track. In the preferred embodiment, said traveling base member is a platform having a substantially planar upper surface. A means is provided for advancing said base member along the length of said track. In the preferred embodiment, said means for advancing said base member along the length of said track is a ball reverser. Although said ball reverser can be powered using any number of different power sources, in the preferred embodiment hydraulic power is used for this purpose. However, it is to be understood that said ball reverser can be pneumatically or electrically powered, for example.  
      An elongate mast is provided. One end of said mast is pivotally affixed to said traveling base member. Said mast can pivot about a horizontal axis which runs generally perpendicular to the longitudinal axis of said substantially horizontal track. Said mast can also be rotated three hundred sixty (360°) degrees about a vertical axis passing through said base member. In the preferred embodiment of the present invention, said mast is rotated by a slew drive. Although said slew drive can be powered using any number of different power sources, in the preferred embodiment hydraulic power is used for this purpose. However, it is to be understood that said slew drive can be pneumatically or electrically powered.  
      A pipe gripper is affixed to the distal end of said mast. In the preferred embodiment of the invention, said pipe gripper includes opposing arcuate jaws, which can be selectively opened and closed, as desired, around the outer circumference of a section of pipe or other tubular member. Said pipe gripper can be rotated three hundred sixty (360°) degrees by rotating said mast about a vertical axis passing through said traveling base member using said slew drive. Further, said pipe gripper can also be tilted, up or down, relative to said mast. In the preferred embodiment, said pipe gripper can be tilted relative to said mast using a cylinder assembly. Although said cylinder assembly can be powered using any number of different power sources, in the preferred embodiment said cylinders are powered using hydraulic power. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  depicts a fragmentary side view of a drilling rig.  
       FIG. 2  depicts a side view of the pipe transfer apparatus of the present invention with the mast in a reclined position.  
       FIG. 3  depicts a side view of the pipe transfer apparatus of the present invention with the mast in an upright vertical position.  
       FIG. 4  depicts the pipe gripper of the present invention in an open position.  
       FIG. 5  depicts the pipe gripper of the present invention in a closed position.  
       FIG. 6  depicts an overhead plan view of the pipe transfer apparatus of the present invention.  
       FIG. 7  depicts a partially exploded side view of the ball reverser of the present invention.  
       FIG. 8  depicts an end view of the pipe transfer apparatus of the present invention.  
       FIG. 9  depicts a side view of the pipe transfer apparatus of the present invention with the pipe gripper in a tilted position.  
       FIG. 10  depicts a side view of the pipe transfer apparatus of the present invention with the pipe gripper in a tilted position and the mast leaning at an angle from vertical.  
       FIG. 11  depicts a side view of the pipe transfer apparatus of the present invention with a section of pipe received within the pipe gripper.  
       FIG. 12  depicts an overhead sequential view of the pipe transfer apparatus of the present invention transferring a section of pipe.  
       FIG. 13  depicts an overhead sequential view of the pipe transfer apparatus of the present invention being repositioned to receive a section of pipe.  
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION  
       FIG. 1  depicts a fragmentary side view of a drilling rig  100 . Drilling rig  100  comprises derrick  101  which extends vertically over substantially horizontal rig floor  102 . Pipe section  103  is partially installed in well bore  104 , and suspended in place within such well bore using lower slips  105 , so that upper end  103   a  of pipe section  103  partially protrudes from well bore  104  and extends above rig floor  102 . Although not specifically depicted in  FIG. 1 , it is to be understood that well bore  104  can extend a desired length into the surface of the earth. Furthermore, although only pipe section  103  is shown as being installed in well bore  104 , it is to be understood that one or more additional sections of pipe can be connected below section  103 , thereby forming an elongate pipe string which can extend a significant distance into the earth via well bore  104 . Pipe section  106  is suspended from elevators  107  within derrick  101  above well bore  104  prior to being threadably connected to pipe section  103 .  
      V-door  108  extends from pipe rack  109  to rig floor  102  which is elevated above said pipe rack  109 . Said v-door  108  essentially forms an inclined ramp between pipe rack  109  and rig floor  102 . Pipe section  110  is positioned on said v-door in advance of being lifted into derrick  101 . Because  FIG. 1  is for illustration purposes, it is to be understood that multiple sections of pipe could be loaded on to v-door  108  at any given time, and individual sections of pipe could thereafter be lifted from said v-door  108  and into derrick  101  as desired. Furthermore, although pipe sections  103 ,  106  and  110  are depicted as being relatively small diameter pipe (such as drill pipe or production tubing), it is to be understood that such pipe could also be large diameter pipe, such as well casing and the like.  
      One end of a cable or other line is typically attached to upper end  110   a  of pipe section  110 , while the other end of said cable or other line can be attached to movable elevators  107  or, alternatively, a hoist situated within derrick  101 . As pipe section  110  is lifted using said cable or line, upper end  110   a  of pipe section  110  is pulled upward into derrick  101 , while the remainder of said pipe section  110  slides up v-door  108  toward rig floor  102 . As pipe section  110  continues to be lifted, eventually bottom  110   b  of pipe section  110  will reach the top of v-door  108  and the upper surface of rig floor  102 .  
      A common practice utilized in the oil and gas industry is to secure a rope or other line horizontally across the opening in derrick  101  a short distance above the area where v-door  108  meets rig floor  102  and generally perpendicular to the longitudinal axis of pipe section  110 . As pipe section  110  is lifted into derrick  101 , said pipe section will essentially ride up v-door  108  and slide against said horizontally-stretched rope. As pipe section  110  continues to ride up v-door  108 , eventually bottom  110   b  of pipe section  110  will clear the upper surface of v-door  108  and rig floor  102 . The aforementioned rope, which is typically held in tension across the opening in derrick  101  by a roughneck or other worker, provides resistance against pipe section  110  and acts to prevent end  110   b  of pipe section  110  from swinging freely across rig floor  102 . Thereafter, a worker holding on to said rope will typically gradually reduce the tension in said rope, so that bottom  110   b  of pipe section  110  can be guided across rig floor  102  in a controlled manner. Thereafter, hanging pipe section  110  can be placed into alignment with pipe section  103  which partially protrudes from well bore  104 .  
      The present invention eliminates the need for such a rope and the dangers that accompany the aforementioned prior art practice described herein. The pipe transfer apparatus of the present invention can grip and secure a section of pipe which is being lifted from a v-door into a derrick in order to prevent the base of said section of pipe from swinging across a rig floor in a dangerous or uncontrolled manner. Further, the present invention eliminates the manpower requirements and safety concerns associated with existing methods of using a rope or other line to control the movement of pipe across a rig floor as described above.  
      The apparatus of the present invention comprises a substantially linear horizontal track having two (2) ends, wherein said track is situated on, or in general proximity to, the rig floor of a drilling rig. One terminus of said track is located at or near a well bore such as well bore  104  in  FIG. 1 , while the other terminus of said track extends to the upper edge of a v-door such as v-door  108  in  FIG. 1 . A traveling base member is slidably disposed on said track. In the preferred embodiment, said traveling base member is a platform having a substantially planar upper surface, with a means for advancing said base member substantially along the length of said track.  
       FIG. 2  depicts a side view of the pipe transfer apparatus  200  of the present invention. Said pipe transfer apparatus comprises substantially horizontal track member  201 . Although said track member  201  can take any number of sizes and/or shapes, in the preferred embodiment, said track member has lower base  201   a  and upper rails  201   b . Traveling base member  202  is slidably mounted to upper rails  201   b  of track member  201 . Slew drive base  203  is affixed to the upper surface of traveling base member  202 , while mounting bracket  204  is in turn mounted to the upper surface of said slew drive base  203 . In the preferred embodiment, said mounting bracket  204  is semi-circular in shape, with a curved upper surface. Said mounting bracket  204  also forms a central channel. Although said central channel is not visible in  FIG. 2 , said channel is oriented substantially parallel to the longitudinal axis of substantially horizontal track member  201  in  FIG. 2 .  
      Elongate mast  205  is pivotally mounted at one end within the central channel of mounting bracket  204  using pivot pin  206 , thereby allowing elongate mast  205  to pivot within the central channel of mounting bracket  204  about a horizontal axis passing through pivot pin  206 . Mounting bracket  204  and, thus, elongate mast  205 , can also be rotated about a vertical axis passing through slew drive base  203 ; a slew drive (not shown in  FIG. 2 ) connected to said slew drive base  203  powers such rotation about a vertical axis. Elongate mast  205  can be locked in place in a reclined position within the central channel of mounting bracket  204  using bolt  217  which can be installed through aligned bores in mounting bracket  204  and elongate mast  205 . Alternatively, said elongate mast  205  can be locked into an upright, vertical position using bolt  218 , or a substantially upright tilted position using bolt  219 ; in either instance, said bolts can be inserted through aligned bores in mounting bracket  204  and elongate mast  205 . In the preferred embodiment, bolts  217 ,  218  and  219  can be locked in place in aligned horizontal bores extending through mounting bracket  204  and elongate mast  205 .  
      Pipe gripper  300  is affixed to the distal end of said elongate mast  205 . In the preferred embodiment of the invention, said pipe gripper  300  comprises opposing arcuate jaws, which can be selectively opened and closed around a section of pipe, as desired. Said opposing arcuate jaws can be closed, for example, around the outer circumference of a section of pipe or other tubular member. Said pipe gripper can also be tilted up and down relative to said mast.  
      In the preferred embodiment, pipe gripper mounting bracket  207  is located at or near the distal end of elongate mast  205 . Pipe gripper assembly  300  is pivotally mounted to said gripper mounting bracket  207  using pivot pin  208 , thereby permitting said pipe gripper assembly  300  to pivot about a horizontal axis passing through said pivot pin  208 .  
      Pivoting of said pipe gripper assembly  300  about said horizontal axis passing through pivot pin  208  is powered by hydraulic cylinder  209 . One end of hydraulic cylinder  209  is anchored to elongate mast  205  using anchor bracket  211  and anchor pin  212 . Hydraulic cylinder  209  further includes piston rod  210 , depicted in the retracted position in  FIG. 3 . The outer end of piston rod  210  is connected to mounting bracket  301  of pipe gripper assembly  300  using anchor pin  213 . As piston rod  210  of hydraulic cylinder  209  strokes, pipe gripper assembly  300  pivots about pivot pin  208 , and can tilt up or down about a horizontal axis passing through said pivot pin  208 , as desired. Although not visible in  FIG. 2 , in the preferred embodiment, the aforementioned mechanism for tilting pipe gripper assembly  300  comprises side-by-side tandem hydraulic cylinders  209 .  
       FIG. 3  depicts a side view of the pipe transfer apparatus of the present invention with elongate mast  205  in an upright, vertical position. In this position, said elongate mast  205  pivots about pivot pin  206  and is lifted upward within the central channel of mounting bracket  204 . When said elongate mast is oriented vertically within said central channel of mounting bracket  204 , it can be locked in place using bolt  218 . Pipe gripper assembly  300  can be rotated three hundred sixty (360°) degrees about a vertical axis passing through elongate mast  205  via rotation of elongate mast  205  using a slew drive (not visible in  FIG. 3 ) connected to slew drive base  203 .  
      Pipe gripper mounting bracket  207  is situated near the distal (upper) end of elongate mast  205 . Pipe gripper assembly  300  is pivotally mounted to said pipe gripper mounting bracket  207  via pivot pin  208 . One end of hydraulic cylinder  209  is anchored to elongate mast  205  using anchor bracket  211  and anchor pin  212 . The outer end of retracted piston rod  210  is connected to mounting bracket  301  of pipe gripper assembly  300  using anchor pin  213 .  
       FIG. 4  depicts a perspective view of pipe gripper assembly  300  of the present invention in a substantially open position. Pipe gripper  300  is comprised of opposing arcuate jaws  302   a  and  302   b . Said opposing arcuate jaws  302   a  and  302   b  are pivotally attached to back member  303  of pipe gripper assembly  300  using pivot pins  304   a  and  304   b , and can swing about said pivot pins  304   a  and  304   b  to permit opening and closing of pipe gripper assembly  300 . In the preferred embodiment, opposing arcuate jaws  302   a  and  302   b  operate in synchronized fashion, such that said opposing arcuate jaws  302   a  and  302   b  open and close together.  
      Hydraulic cylinder  305 , which is connected to and supplied hydraulic fluid by hydraulic lines  311 , powers the synchronized opening and closing of opposing arcuate jaws  302   a  and  302   b . Hydraulic cylinder  305  has piston rod  306 , which can be actuated to an extended or retracted position. One end of hydraulic cylinder  305  is anchored to extension fingers  309  using anchor rod  310 . Similarly, piston rod  306  is anchored to extension fingers  307  using anchor rod  308 . By actuating hydraulic cylinder  305 , and thereby causing piston rod  306  to stroke in and out, opposing arcuate jaws  302   a  and  302   b  can be selectively opened and closed by pivoting about pivot pins  304   a  and  304   b , respectively.  
       FIG. 5  depicts a perspective view of pipe gripper assembly  300  in a substantially closed position. Opposing arcuate jaws  302   a  and  302   b  are depicted as gripping a section of cylindrical pipe, such as a joint of large diameter casing  120 , around the outer peripheral surface of said pipe. For illustration purposes, said cylindrical pipe can be identical to pipe section  110  in  FIG. 1 , or a larger diameter pipe section such as pipe joint  120  shown in outline in  FIG. 5 . As piston rod  306  extends relative to hydraulic cylinder  305 , opposing arcuate jaws  302   a  and  302   b  pivot about pivot pins  304   a  and  304   b , respectively, thereby closing together in synchronized manner and gripping around the outer peripheral surface of casing section  120 , thus gripping and securing said pipe section  120  within opposing arcuate jaws  302   a  and  302   b . Said opposing arcuate jaws  302   a  and  302   b  can be opened by pivoting of each of said arcuate jaws about their respective pivot pins,  304   a  and  304   b.    
       FIG. 6  depicts an overhead plan view of the pipe transfer apparatus of the present invention. Substantially horizontal track member  201  has tandem upper rails  201   b ; in the preferred embodiment of the present invention, said upper rails  201   b  are oriented parallel to one another, thereby defining central channel  240  between said upper rails  201   b . Traveling base member  202  is slidably mounted to said tandem upper rails  201   b  of track member  201 , and can move substantially along the length of said track member  201 . Bearings  214  reduce friction between said traveling base member  202  and upper rails  201   b  of track member  201 . Linear movement of said traveling base member  202  along track member  201  is powered by ball reverser  215 . Said ball reverser is rotatably received at one end of track member  201  in flange bearing  215   a  and at the other end of track member  201  in flange bearing  215   b . In the preferred embodiment, said ball reverser is hydraulically powered; however, it should be noted that other power sources could be utilized for this purpose.  
      Elongate mast  205  is shown in  FIG. 6  in the upright position. When in such a position, elongate mast  205  can be rotated about its central longitudinal axis by rotation of slew drive base  203 . Such rotation of slew drive  203  and, thus, elongate mast  205 , is powered by slew drive  216 . In this manner, pipe gripper assembly  300 , which is attached to the upper end of elongate mast  205 , can be rotated three hundred sixty (360°) degrees about a vertical axis passing through said elongate mast  205 . Although said elongate mast  205  is shown in the upright vertical position in  FIG. 6 , said mast can be tilted from vertical by pivoting said mast  205  about pivot pin  206  within the central channel formed by mounting bracket  204 . Said elongate mast  205  can also be locked in a vertical position using bolt  218  (not visible in  FIG. 6 ).  
       FIG. 7  depicts ball reverser  215  of the present invention. Ball reverser  215  comprises central shaft  230  having cross-oriented grooves  231  formed along the surface of central shaft  230 . Central shaft  230  is rotatably received within flange bearing  215   a  at one end, and flange bearing  215   b  at the other end. Motor  232  supplies torque to central shaft  230  via drive mechanism  233 , causing said central shaft  230  to rotate within flange bearings  215   a  and  215   b . Traveling collar  234  is movably mounted on central shaft  230 . As central shaft  230  rotates about its longitudinal axis, traveling collar  234  is directed by grooves  231  and moves substantially along the length of said central shaft  230 . Moreover, because traveling base member  202  is connected to traveling collar  234 , operation of ball reverser  215  causes said traveling base member  202  to move along the length of substantially horizontal track member  201 .  
       FIG. 8  depicts an end view of the pipe transfer apparatus of the present invention. Substantially horizontal track member  201  has tandem upper rails  201   b  which are aligned parallel to one another, thereby defining central channel  240  between said tandem upper rails  201   b . Traveling base member  202  is slidably mounted to said tandem upper rails  201   b  of track member  201 , and can move substantially along the length of said track member  201 . Bearings  214  reduce friction between said traveling base member  202  and upper rails  201   b  of track member  201 . In the preferred embodiment, roller bearings  220  are also provided to reduce the friction between said traveling base member  202  and upper rails  201   b  of track member  201 . Linear movement of said traveling base member  202  along track member  201  is powered by ball reverser  215  (not shown in  FIG. 8 ) which extends substantially along the length of track member  201 . Said ball reverser is rotatably received at one end of track member  201  in flange bearing  215   a.    
      Elongate mast  205  is shown in the upright position. Said elongate mast  205 , which is received within the central channel formed by mounting bracket  204 , can be rotated about its central longitudinal axis by rotation of slew drive base  203 , which is powered by slew drive  216 . In this manner, pipe gripper assembly  300 , which is attached to the upper end of elongate mast  205 , can be rotated about a vertical axis passing through said elongate mast  205 . Although said elongate mast  205  is shown in the upright vertical position, said mast can be tilted from vertical by pivoting about pivot pin  206 . Further, said elongate mast  205  can be locked in an upright vertical position using bolt  218 .  
      Still referring to  FIG. 8 , pipe gripper assembly  300  can be titled about a horizontal axis using tandem hydraulic cylinders  209 . One end of said tandem hydraulic cylinders  209  is anchored to elongate mast  205  using anchor brackets  211 . Hydraulic cylinders  209  further include piston rods  210  (which are depicted in the retracted position in  FIG. 8 ). The outer end of said piston rods  210  is pinned to mounting brackets  301  of pipe gripper assembly  300 . As said piston rods  210  extend, pipe gripper assembly  300  can be tilted about a horizontal axis passing through pivot pin  208 .  
       FIG. 9  depicts a side view of the pipe transfer apparatus of the present invention with elongate mast  205  in an upright position and pipe gripper assembly  300  in a tilted position. Traveling base member is shown at approximately the mid-point of substantially horizontal track member  201 . Elongate mast  205  is oriented in a substantially vertical position within the central channel of mounting bracket  204 ; that is, perpendicular to track member  201 . If desired, elongate mast  205  can be secured in a substantially vertical position using bolt  218 . Piston rod  210  is extended from hydraulic cylinder  209 , thereby causing pipe gripper  300  to tilt about a horizontal axis passing through pivot pin  208 . It is to be observed that the greater the stroke of piston  210 , the more that pipe gripper  300  will tilt and, consequently, the greater angle “x” in  FIG. 9  will be.  
       FIG. 10  depicts a side view of the pipe transfer apparatus of the present invention. Elongate mast  205  is depicted in a position which is tilted from vertical. As said elongate mast  205  pivots about pivot pin  206  within the central channel of mounting bracket  204 , said mast can tilt from vertical and, if desired, be locked in this position using bolt  219 . It is to be observed that the more that elongate mast  205  is tilted from vertical, the greater angle “y” in  FIG. 10  will be.  
       FIG. 11  depicts the pipe transfer apparatus of the present invention in substantially the same position as depicted in  FIG. 10 . Elongate mast  205  is tilted from vertical, and locked in place within the central channel of mounting bracket  204  using bolt  219 . Piston rod  210  is extended from hydraulic cylinder  209 , and pipe gripper apparatus  300  is itself tilted upward relative to said elongate mast  205 . Opposing arcuate jaws  302   a  and  302   b  of pipe gripper assembly  300  are in a substantially closed position around the outer circumference of cylindrical pipe section  110 .  
      It is noted that opposing arcuate jaws  302   a  and  302   b  are not completely closed about the outer surface of pipe section  110 . While said pipe section may lean to one side or the other, there is generally circumferential clearance around much of the outer surface of said pipe section within said opposing arcuate jaws  302   a  and  302   b . In this way, pipe gripper assembly  300  can grab and/or facilitate handling of said pipe section. However, because of such clearance within jaws  302   a  and  302   b , said pipe section can ideally be raised and lowered, as well as rotated, even when said opposing arcuate jaws  302   a  and  302   b  are closed around said pipe section  110 . As described above, elongate mast  205  and pipe gripper assembly  300  can be tilted, as desired, to facilitate handling of pipe section  110 , particularly when said pipe section is located on an inclined v-door.  
       FIG. 12  depicts an overhead sequential view of the pipe transfer apparatus of the present invention transferring a section of pipe. In position “a”, opposing arcuate jaws  302   a  and  302   b  of pipe gripper  300  are shown in the substantially open position, and said pipe section  110  is received within said jaws. In position “b”, said opposing arcuate jaws  302   a  and  302   b  are closed around the outer surface of pipe section  110 . Elongate mast  205 , depicted in an upright, vertical position, is rotated 90° using slew drive  216 . In positions “c” and “d”, traveling base  202  travels along the length of substantially horizontal track member  201  (not shown in  FIG. 12 ). Said traveling base  202  continues moving along to substantially horizontal track member  201  until it reaches the desired position, which is typically the terminus of said substantially horizontal track member  201 . In this position, position “e” on  FIG. 12 , elongate mast is rotated an additional 90° using slew drive  216 . In position “e”, the orientation of pipe gripper  300  is 180° from its orientation in position “a”. Opposing arcuate jaws  302   a  and  302   b  of pipe gripper assembly  300  are then opened, allowing pipe section  110  to be easily removed from said pipe gripper assembly.  
       FIG. 13  depicts an overhead sequential view of the pipe transfer apparatus of the present invention being reset to receive another pipe section, such as pipe section  110 . In position “e”, elongate mast  205  is in an upright vertical position and opposing arcuate jaws  302   a  and  302   b  of pipe gripper assembly  300  are open. Pipe section  110  has been removed from pipe gripper assembly  300 . In position “f”, said elongate mast  205  rotates  900  and traveling base  202  slides along the length of substantially horizontal track member  201  (not shown in  FIG. 13 ). In position “f”, said traveling base member is shown at approximately the mid-point of said horizontal track member. In position “g”, said traveling base  202  has continued along the length of said horizontal track member, and elongate mast  205  has rotated an additional 90°, thereby presenting pipe gripper assembly  300  in the open position to receive another section of pipe for transfer.  
      In operation, the pipe transfer apparatus of the present invention can be installed on a drilling rig or other similar location. Specifically, the substantially linear horizontal track is situated on, or in general proximity to, the rig floor of a drilling rig. One end of said track is located at or near a well bore, while the other end of said track is located at or near the upper end of a v-door.  
      The pipe gripper assembly of the present invention is positioned at or near the upper end of said v-door, typically in a fully open position (see position “g” in  FIG. 13 ). As a section of pipe is lifted off of said v-door, and into the derrick of said drilling rig, said pipe section is directed into said open pipe gripper assembly (see position “a” in  FIG. 12 ). After said pipe section has cleared the top of said v-door, said pipe gripper assembly is closed around said section of pipe. Thereafter, pipe gripper assembly swivels  900  (see position “b” in  FIG. 12 ), and travels along the length of the substantially linear horizontal track (see positions “c” and “d” in  FIG. 12 ).  
      After the pipe gripper assembly reaches the end of said track and is at or near the well bore, the pipe gripper assembly is rotated 90° and opened (see position “e” in  FIG. 12 ). Thereafter, the pipe section can be removed from the pipe gripper assembly and connected to a string of pipe suspended within the well bore. Said pipe gripper assembly can be rotated and returned to its original position (see positions “f” and “g” in  FIG. 13 ). The process can be repeated until the desired amount of pipe has been installed in said well bore.  
      Although the apparatus of the present invention has been depicted in a particular form constituting a preferred embodiment, it will be understood that various changes and modifications in the illustrated and described structure can be effected without departure from the basic principles which underlie the invention. Changes and innovations of this type are deemed to be circumscribed by the spirit and scope of the invention except as such spirit and scope may be necessarily limited by the appended claims, or reasonable equivalents thereof.