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FIELD OF THE INVENTION 
     This invention relates generally to operations involving the handling and deployment of sand control screens used in down hole oil and gas well completion packing operations and more particularly to the apparatus used to make up and uncouple the various screen assemblies used in such operations. 
     GENERAL BACKGROUND 
     After the open hole in a well has been cleaned, what is known in the art as a gravel-packing screen and/or gravel-packing tool assemblies are run into the well bore. The tool assembly is usually run with one or more subsection screen sections extending from the toe of the well to the well casing with at least one joint located inside the well casing followed by several joints of blank tubing before being connected to a shear-out safety joint and the gravel pack tool itself. A wash pipe is usually run inside the screen for effective circulation of fluids. 
     The function of the gravel pack tool is to maintain hydrostatic pressure on the open-hole section of the well at all times to prevent bore hole collapse. Maintaining a hydrostatic over-balance throughout all operations and the use of proper fluid characteristics eliminates the need to run alternative flow path devices. 
     When running the gravel pack tool and the various screen assemblies in or out of the well bore, a screen table or support structure adaptively fixed to the rotary table located at the drill rig floor, is used to catch or capture the sand screen subsections of the tool assembly at each joint connection. The tubing string containing the screens is thus suspended within the well bore without damaging the screens or the gravel packer itself. The screen table is used to support the string in place of pipe slips because of the limited space at the joint between the screen subsections and to prevent damage to the screens. However, in some cases, slips are used in conjunction with the screen table to capture and suspend the wash pipe being inserted or withdrawn from within the screen string assembly. 
     Presently the screen and wash pipe connections are made up with conventional pipe wrenches or manual pipe tongs. However, recent requirements make it necessary to apply specified torques to these joints, thereby presenting a problem. Conventional power tongs having torque setting capability are simply too large due to space limitations and too expensive to downsize in most cases due to limited applications requirements. 
     Until recently hand tongs or pipe wrenches had no torque setting capability. Generally only the larger tongs and pipe spinner system have torque control and presetting capability. However, in some cases, torque indication systems have been employed whereby the tong or other such gripping tools are attached to a cable (cat line) that in turn is attached to a load cell. This arrangement requires significant time to set up and use and requires significantly more space than is generally available when working with sand screen replacement. Such systems are inherently inaccurate, dangerous, cumbersome, and lack efficiency. 
     A more unitized hand tong is available that utilizes a traditional torque setting handle integral with the tong as seen in U.S. Pat. No. 6,439,064. However, even this tool is too slow in some cases and requires a significant amount of labor, generally two men to manipulate the tong and a backup gripping tool in place and then apply the proper torque to each joint. 
     A more convenient and labor reducing assembly is obviously needed that allows for both a relatively small torque head and backup tong assembly. The tong assembly should remain in place adjacent the centerline of the well bore and be capable of swiftly coupling and uncoupling sand screens where space between the screen elements is minimal. It is equally important that the tong assembly be capable of coupling and uncoupling wash pipe being inserted within the sand screen string, also with preset torque capability. It would be advantageous for such an arrangement to utilize a manual tong assembly with shorter tong handles than are in current use and be confined to within the perimeter of the screen or rotary table and further reduce the manpower required to make up such connections. It is therefore an object of the following disclosure to provide such an apparatus. 
     SUMMARY OF THE INVENTION 
     A screen table and tong assembly whereby a sand screen table structure adaptable to a rotary table is used to capture and suspend sand screen subsections within the well bore is further adapted to include a pair of articulated opposing manual tong assemblies. The tong assemblies are pivotal and transversely positionable relative to the screen table. Provision is made for adapting a slip set in cooperation with said screen table and tong assembly for capturing and supporting wash pipe within the sand screen subsections. Additional adaptations include a custom spinner tong assembly for rotating the sand screen tubular subsections and wash pipe sections. 
     The tongs and their torque arm assemblies are interchangeable with a range of tong heads of different types and sizes including pipe wrenches, chain tongs, and strap wrenches and provide reversibility between left and right hand torque applications. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a further understanding of the nature and objects of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, in which, like parts are given like reference numerals, and wherein: 
     FIG. 1 is a frontal isometric view of the screen table and tong assembly; 
     FIG. 2 is a rear isometric view of the screen table and tong assembly; 
     FIG. 3 is a top view of the screen table and tong assembly with torque applicator extended; 
     FIG. 4 is a top view of the screen table and tong assembly with torque applicator retracted; 
     FIG. 5 is a partial elevation view of the screen table with tongs gripping the screen tool joints; 
     FIG. 6 is a partial isometric view of the torque and retaining tongs seen in FIG. 1; 
     FIG. 7 is an isometric exploded view of the tong and screen table assembly; 
     FIG. 8 is an isometric exploded view of the tong torque assembly; 
     FIG. 9 is an isometric exploded view of the retainer tong assembly; 
     FIG. 10 is an isometric view of the screen table assembly without tongs; 
     FIG. 11 is an isometric view of the screen table with retaining tong and screen coupling joint; 
     FIG. 12 is an isometric view of the screen table with both torque tong and retaining tong and screen coupling joint; 
     FIG. 13 is a partial isometric view of the screen table, retaining tong with spinner attachment; and 
     FIG. 14 is a side elevation view of the retaining tong with spinner attachment as shown in FIG.  13 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Looking first at FIG. 1 it can be seen that the screen table assembly  10  is composed of a screen table  12  attached to the rotary table  14  generally located on the floor  16  of an oil and gas well platform. Slips used for gripping and supporting the tubing string within the well bore when coupling and uncoupling the various sections of pipe, tubing or tool joints that make up the well&#39;s tubular string are not used when coupling and uncoupling sand screen subsections during packing operations. However, a set of slips  18  is required when inserting washout tubing  20  within the screen sections  22  being suspended within the well bore by the screen table  12 . The slip set  18  is supported by a slotted plate  24 , which is in turn supported by a slotted tubing collar  26 . 
     As seen in FIGS. 1 and 2, the screen table assembly  12  is fitted with a threaded vertical column  28  from which a pair of tong assemblies  30 ,  32  is pivotally attached, one of the tong assemblies being a backup or retaining tong assembly  30  and the other being a hydraulic or gas actuated torque tong assembly  32 . Upon grippingly engaging the wash pipe  20  adjacent the pipe joint  33 , the torque tong assembly  32  is actuated, thus rotating the upper pipe and uncoupling the joint  34  as shown in FIG.  1 . Conversely, as seen in FIG. 2, retracting the torque arm assembly  32  tightens the joint  33  to a pre-set torque requirement. 
     Turning now to FIGS. 3 and 4 we see that the tong assemblies  30 ,  32  work in close proximity to the screen table assembly  12  thus providing clear movement around the rotary table  14  and requiring no cables or long extension torque arms to be manipulated by rig personnel. Further, as seen In FIG. 3, the back up tong assembly  30  and the torque tong assembly  32  are positioned at  90  degrees to one another. When the torque tong assembly  32  is actuated and the pipe is rotated all pivotal motion is inboard as seen in FIG. 4, thereby reducing risk for personnel. It should also be noted that only one person may manipulate the arm easily. 
     Looking now at FIG. 5 we see that the tong assemblies  30 ,  32  may also traverse the threaded vertical column  28  to a point slightly above the screen table assembly  12 . In FIG. 6 the tong assembly heads  34  and arms  36  may be replaced with larger ones, as seen in FIG. 5, to accommodate the sand screen collars by removing the pins  42  and the clips  76  in each of the tong assemblies as shown in FIG.  6  and better seen in FIG.  9 . The tong heads  34  may be any type of tubular griping apparatus including pipe wrenches, chain wrenches or strap wrenches as well as the tong heads shown. 
     As seen in FIG. 7, the tong assemblies  30 ,  32  and their vertical, threaded, support column  28  may be easily removed from their support sockets  44  for transport. The vertical. threaded column  28  may be secured within the socket  44  at assembly or simply allowed to rotate therein. Rotating the vertical threaded column  28  while holding the tong assemblies  30 ,  32  traverses the tong assemblies from a high to a lower position or vise-versa. 
     Looking now as FIG. 8 we see that the torque assembly  32  includes a mounting plate  50  attached perpendicularly to a threaded collar  52  and an actuator adaptor plate  54  mounted perpendicularly to the mounting plate  50 , and a pair of linear actuators  56  attached to the adaptor plate  54  in a manner whereby the rods  58  of the actuators are attached to a pivot head assembly  60  and are free to extend and retract the pivot head assembly  60  relative to the mounting plate  50 . 
     As seen in FIG. 9 the backup or retainer tong assembly  30  includes a pivot head assembly  60  attached to a box tube arm  62 , which is in turn attached to a threaded collar  64 . The pivot head  60  further includes a base clevis member  66 , a pivotal hub member  68  having a central pin bore  72 , and a perpendicular bore  74  is captured within the clevis member by removable flanges  70  attached externally to the base clevis member  66 . The tong head  34  and its arm  36  are rotatably connected to the pivotal hub member  68  by inserting the arm portion  36  through the perpendicular bore  74  and securing it with clip  76 . It should be noted that the tong head  34  may be reversed for opposite left or right hand rotation gripping by removing the pull pin  42  inserted in a perpendicular bore  78  located in the tong arm  36 . It should be noted that the tong arms  36  and heads  34  are interchangeable and easily exchanged by removing the pull pins  42  and the clips  76 . 
     Turning now to FIG. 10, we can see that down hole sand screens are connected as close as possible, leaving little or no room for gripping the tubular joint  80  without damaging the screens  21 ,  22 . Therefore, as previously discussed, slip sets  18  are not applicable. Suspension of the screen string is therefore accomplished by utilizing what is known in the industry and previously referred to herein as a screen table assembly  12 , the table being placed directly over the well head and supported by the rotary table and rig floor partially encircles the tubular column extending into the well bore. When the screens  21 ,  22  are being run in or out of the well bore, capture doors  82  as shown in FIG. 10 are positioned below the box end  85  of the tubular joint  80 . This allows the string to be held in suspension while the upper screen section  21  is added or removed from the lower screen section  22 . Simply sliding the doors  82  in or out within the channel  84  captures or releases the screen string. 
     Once the screen string has been captured by the screen table assembly  12 , as illustrated by FIG. 11, the backup or retaining tong assembly  30  is traversed into position along the threaded vertical column  28  to a position laterally adjacent the screen tubular joint  80  being captured and the tong head  34  is positioned around the joint to be coupled or uncoupled. Likewise, the torque arm tong assembly  32  is traversed into position along the vertical threaded column  28 , as seen in FIG. 12, to a point above the retainer tong assembly  30  and positioned for engagement with the screen section  21 ,  22  to be coupled or uncoupled. The actuators  56  are then engaged, thus applying rotative torque to the joint. 
     In some cases it may be advantageous to spin the tubulars into place prior to applying the required torque. Therefore, a miniature spinner assembly with torque actuator  86  as shown in FIG. 13 may be provided in combination with the backup or retainer tong  30 . In this case the spinner assembly grips the upper tubing section of the joint  80 , as seen in FIG. 14, while the backup tong assembly  30  grips the lower tubular section. The spinner assembly  86  then rotates the upper section through several turns to engage or disengage the pipe threads comprising the joint  80 . When the spinner  86  has reached a predetermined torque, the linear actuator  89  provides the final predetermined torque to the joint  80 . 
     Because many varying and different embodiments may be made within the scope of the inventive concept herein taught, and because many modifications may be made in the embodiments herein detailed in accordance with the descriptive requirement of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in any limiting sense.

Summary:
A screen table and tong assembly whereby a sand screen table structure adaptable to a rotary table is used to capture and suspend sand screen subsections within the well bore is further adapted to include a pair of articulated opposing manual tong assemblies. The tong assemblies are pivotal and transversely positionable relative to the screen table. Provisions are made for adapting a slip set in cooperation with said screen table and tong assembly for capturing and supporting wash pipe within the sand screen subsections. Additional adaptations include a custom spinner tong assembly for rotating the sand screen tubular subsections and wash pipe sections.