Patent Publication Number: US-11377915-B2

Title: Wellbore tong

Description:
BACKGROUND 
     Field 
     Embodiments described herein generally relate to a tong for use at a wellbore. In particular, embodiments described herein relate to a braking assembly for a tong. In particular still, embodiments described herein relate to a brake band for a braking assembly for a tong. 
     Description of the Related Art 
     Wellbore tongs are well known in the art for making and breaking threaded connections between tubulars as strings are assembled or disassembled for use in a wellbore. Typically, a back-up or lower tong holds a tubular extending from the wellbore while an upper tong grasps and then rotates a new tubular into or out of the string. In most cases, the upper tong includes a mechanism to grasp the tubular and then, in a separate step, rotates the tubular to perform threading or unthreading. During the grasping step, one rotating portion of the assembly must be held in place while the gripping assembly operates. Thereafter, both portions are rotated as a unit during the threading operation. There is a need for an improved braking assembly for preventing or stopping a rotatable component of the tong. 
     SUMMARY 
     In one embodiment, a tong for use at a wellbore includes a tong body; at least one door pivotally coupled to the tong body and movable between an open position and a closed position; a carrier ring rotatable relative to the tong body; and a brake plate coupled to the carrier ring. The tong also includes a brake band configured to move with the at least one door between the open and closed positions, and a braking member for moving the brake band into contact with the brake plate to stop rotation of the carrier ring. 
     In another embodiment, a method of operating a tong includes opening a door of the tong, wherein the tong includes a tong body; the door pivotally coupled to the tong body; a carrier ring rotatable relative to the tong body; a brake plate coupled to the carrier ring; and a brake band having a door band portion attached to the door. The method also includes moving the door band portion of the brake band with the door as the door opens; closing the door; moving the brake band into contact with the carrier ring, thereby preventing rotation of the carrier ring; and rotating a gear ring relative to the carrier ring. 
     In another embodiment, a method of operating a tong includes opening a door of the tong. The tong may include a tong body; the door pivotally coupled to the tong body; a carrier ring rotatable relative to the tong body; a brake plate coupled to the carrier ring; and a brake band having a door band portion attached to the door. The method also includes moving the door band portion of the brake band with the door as the door opens; closing the door; rotating the carrier ring; and moving the brake band into contact with the brake plate, thereby stopping rotation of the carrier ring. 
     In one embodiment, a tong for use at a wellbore includes a tong body; at least one door pivotally coupled to the tong body and movable between an open position and a closed position; a gripping assembly rotatable relative to the tong body; and a brake plate coupled to the gripping assembly. The tong may also include a brake band configured to move with the at least one door between the open and closed positions; and a braking member for moving the brake band into contact with the brake plate to stop rotation of the gripping assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments. 
         FIG. 1  is a perspective view of a wellbore tong. 
         FIG. 2  is a perspective view of a portion of the tong including a rotatable brake plate, a gripping assembly rotatable therewith and a separately rotatable gear ring. 
         FIG. 3  is a top view of the assembly of  FIG. 2  showing gripping members that are a part of the gripping assembly. 
         FIG. 4  is a perspective view of the gear ring showing a plurality of ramps formed on an inner surface thereof. 
         FIG. 5  is a perspective view of the gripping assembly illustrating a double pair of wheels on a first side and a single wheel on a second side. 
         FIG. 6  is a top view partially in section, taken through one wheel of the double pair of wheels. 
         FIG. 7  is a top view partially in section, taken through the single wheel. 
         FIG. 8  is a top view partially in section, taken through the single wheel and showing the gripping assembly actuated around a tubular. 
         FIG. 9  is a top view partially in section, taken through the single wheel and showing the tubular member having been rotated in a clockwise direction to make a wellbore connection between tubulars. 
         FIGS. 10 and 11  are top views of a braking member illustrating its operation in conjunction with a brake band to prevent rotation of the brake plate. 
         FIG. 12  is a perspective view of a brake plate illustrating the location of brake pads along an outer perimeter thereof. 
         FIG. 13  is a perspective view of another embodiment of a wellbore tong. 
         FIG. 14  shows a door of the tong of  FIG. 13  in a closed position. 
         FIG. 15  shows the door of  FIG. 14  in an open position. 
         FIG. 16  is a perspective bottom view of another embodiment of a wellbore tong. 
         FIG. 17  is a perspective view of the tong of  FIG. 16  with one door in the open position. 
         FIG. 18  is a perspective view of an embodiment of a brake band. 
         FIG. 19  is a perspective view of the brake band of  FIG. 18  with a first door band in the disengaged position and a second door band in a partially disengaged position. 
         FIG. 20  is a perspective view of the brake band of  FIG. 18  with both door bands in the disengaged position. 
         FIG. 21  is a partial, perspective view of another embodiment of a wellbore tong. 
         FIG. 22  is a partial, perspective view of the tong of  FIG. 21  with one door in the open position. 
         FIG. 23  is a partial, perspective view of another embodiment of a wellbore tong. 
         FIG. 24  is a partial, perspective view of the tong of  FIG. 23  with one door in the open position. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a perspective view of a wellbore tong. The tong has two functions: it grasps a tubular (not shown) using a gripping assembly generally shown as  110  and thereafter, it rotates the tubular relative to a tubular therebelow in order to make or break a threaded connection therebetween. A door  120 , shown in a closed position, permits the tubular to be inserted into the gripping assembly  110  of the tong  100 . A hydraulic motor assembly generally shown as  130  rotates a gear ring (not visible) that is responsible for rotation of the tubular when a connection is made. Separately, a “cage” or brake plate  140  is rotatable independent of the gear ring. In the embodiment shown, the gripping assembly  110  is associated with the rotatable brake plate  140  and rotates therewith. Separately, inwardly facing ramps (not visible) are formed on an inner surface of the gear ring. To grip a tubular with the tong  100 , it is necessary to rotationally fix the brake plate  140  with its gripping assembly  110  while rotating the gear ring in order to urge the ramps of the gear ring under a plurality of wheels associated with the gripping assembly  110 . The action of the wheels and ramps acts to close gripping members  112 ,  115  around the tubular. With the tubular gripped, both the gear ring and the brake plate  140  rotate together to make (or break) a connection. 
       FIG. 2  is a perspective view of a portion of the tong  100  including the rotatable brake plate  140 , the gripping assembly  110  rotatable therewith and a separately rotatable gear ring  150 . The gear ring includes teeth formed on a perimeter thereof for engagement with corresponding teeth associated with the motor assembly  130  ( FIG. 1 ). Also shown in  FIG. 2  is a braking assembly for the brake plate in order to stop its rotation during the gripping portion of the operation. The breaking assembly, as will be described in additional detail herein, includes a brake band  160  that can be tightened thereby providing friction between the band  160  and the brake plate  140 . The tightening takes place at each end of the band with piston-actuated braking members  165   a ,  165   b.    
       FIG. 3  is a top view of the assembly of  FIG. 2  showing gripping members  112 ,  115  that are a part of the gripping assembly  110 . As illustrated, the gripping members can be actuated towards or away from the centerline of a tubular. 
       FIG. 4  is a perspective view of the gear ring  150  showing a plurality of ramps  205   a ,  210   a ,  215   b  formed on an inner surface thereof opposite an opening or throat of the ring. The upper and lower ramps  205   a ,  210   a  are constructed and arranged to operate with a set of double wheels  305 ,  310  ( FIG. 5 ) in order to actuate one gripping member  115  of the gripping assembly  110  when a threaded connection is being made. The center ramp  215   b , as is evident by its direction is constructed and arranged to actuate a single wheel  315  associated with gripping member  112  when a connection between tubulars is being broken. An opposite group of ramps, two of which  215   a ,  205   b  are visible in  FIG. 4  are responsible for a reverse arrangement wherein a second set of double ramps (upper ramp  205   b  is visible) operates with the double wheels  305 ,  310  to break a connection and a second single ramp  215   a  operates with the single wheel  315  when a connection is made. 
       FIG. 5  is a perspective view of the gripping assembly  110  illustrating the double pair of wheels  305 ,  310  on a first side and the single wheel  315  on a second side. The gripping assembly  110  is made up of two gripping members  112 ,  115 , each operating like a slip with an inner surface having a concave shape to match the outer surface of the tubular to be grasped by the tong  100 . As illustrated, the gripping assembly  110  utilizes the single wheel  315  associated with one gripping member  112  and the two-wheel set  305 ,  310  operating with a second gripping member  115 . In operation, the wheels (along with the brake plate  140 ) remain rotationally fixed while the gear ring  150  with its various ramps rotates to a position wherein each wheel has ridden up a ramp. The result is a clamping action forcing the gripping members  112 ,  115  into contact with the tubular to be grasped. The make or break nature of the operation determines which set of ramps is utilized by the wheels as the tubular is gripped. 
       FIG. 6  is a top view partially in section, taken through one wheel  305  of the double pair of wheels  305 ,  310  and  FIG. 7  is a top view partially in section, taken through the single wheel  315 . In both Figures, the gripping mechanism is de-activated, meaning that the wheels and ramps are not in contact with one another as indicated by the open position of the gripping members  112 ,  155  in each Figure. For example, in  FIG. 6 , upper wheel  305  of the pair of wheels  305 ,  310  is visible above the ramp  215   a  that is designed to operate in conjunction with single wheel  315  when a connection is being made up. Similarly in  FIG. 7 , on the left side of the Figure, the single wheel  315  is visible with the lower ramp  210   b  below it. 
       FIG. 8  is a top view partially in section, taken through the single wheel  315  and showing the gripping assembly  110  actuated around a tubular  400 . More specifically,  FIG. 8  is a top section view of the assembly shown in  FIGS. 7 and 8  with the view taken through the single wheel  315 . However, in  FIG. 8  the gear ring  150  with its sets of ramps has been rotated clockwise while the brake plate  140  and gripping assembly  110  have been rotationally held in the same orientation as they are in  FIGS. 7 and 8 . The result is that the ramps have changed location relative to the wheels  305 ,  310 ,  315  in a manner whereby the wheels have mounted the ramps  215   a ,  205   a ,  210   a  that are designed to be utilized in actuating the gripping mechanism in order to make a connection. Because the wheels have been actuated by the ramps, the gripping mechanism  110  is actuated and the tubular  400  is gripped. 
       FIG. 9  is a top view partially in section, taken through the single wheel  315  and showing the tubular member  400  having been rotated in a clockwise direction to make a wellbore connection between tubulars. Comparing  FIGS. 8 and 9 , in  FIG. 9  the entire tong unit including gear ring  150  and brake plate  140  has been rotated as a unit. In this manner the tubular  400  retained by the upper portion of the tong  100  is rotated relative to a tubular gripped by a lower portion (not shown) in order to make a threaded connection. It will be appreciated the operation can be reversed, using the same wheels but operating on another set of ramps having reverse formations. In this manner, the tong assembly can be used to make or break a threaded connection between tubulars. 
     As described above, in order to actuate the gripping assembly  110 , the brake plate  140  and gripping assembly must be rotationally fixed or at least rotationally limited relative to the gear ring while the gear ring  150  with its inwardly facing ramps rotates to a location whereby the ramps interact with the wheels of the gripping assembly to close the gripping members  112 ,  115  around a tubular  400 . Thereafter, the gear wheel  150  and brake plate  140  rotate together to make or break a threaded connection. In one embodiment, rotation of the brake plate  140  is prevented with the use of a brake band  160  that is tightened around an outer surface of the plate in order to prevent its rotation. The brake band  160  and braking members  165   a, b  are shown in  FIGS. 2 and 3 . As shown, the band  160  extends around an outer perimeter of the plate  140  and is held at each end by one of the braking members. By holding the band at each end, the brake members can tighten the band  160  by urging each end towards the door  120  of the assembly, essentially removing slack in the band and thereby increasing its friction with the side of the brake plate  140 . In one embodiment, the braking members each include a piston that urges a corresponding end of the brake band  160  in order to tighten it. 
       FIGS. 10 and 11  are top views showing the operation of one of the braking members  165   b  and its relationship with the brake plate  140 . In  FIG. 10  the brake is un-actuated as shown by a gap  146  formed between the band and an outer edge of a brake pad  145  disposed around an outer edge of the plate.  FIG. 11  is a similar view however, in  FIG. 11  the brake band has been tightened as apparent by the absence of gap  146  in the Figure. Arrow  149  illustrates the direction of a force placed upon the band in order to tighten it. 
     One novel aspect of the invention relates to brake pads and their location relative to the brake band and brake plate. In prior art devices, friction and heat generated between the tightened band and brake plate create wear and can cause failure of the entire tong assembly, essentially shutting down operations at a well site. In prior art devices, brake material including non-metallic, semi metallic and ceramic materials has been used on an inner surface of the brake band in order to effect braking between the band and brake plate. In order to extend the life of the brake band and to reduce friction and resulting heat between the surfaces, grease is applied at the intersection of the band and plate. The addition of grease reduces the heat and wear but must be replaced regularly requiring precious time at the working wellsite. Additionally, with or without grease, flexing of the band as it is tightened or loosened can cause the brake material to separate from the band. In one embodiment of the present invention, these problems and others are overcome by placing brake pads made of breaking and friction-reducing material not on the band but on the outer perimeter of the brake plate where it contacts the band. 
       FIG. 12  is a perspective view of the brake plate having apertures  142  around its perimeter for attachment of brake pads. One exemplary brake pad  145  is shown in the Figure. By fastening the brake pads with fasteners around the perimeter, a braking surface is provided in a manner whereby the material is protected from the flexing of the brake band. Additionally, the pieces can be replaced in any area where excessive wear has occurred without replacing the entire band or a large strip of the braking material. In one example, the brake pads are constructed primarily of bronze or sintered bronze. Bronze is an alloy consisting primarily of copper, commonly with about 12% tin and often with the addition of other metals and sometimes non-metals or metalloids such as arsenic, phosphorus or silicon. 
       FIG. 13  is a perspective view of another embodiment of a wellbore tong  300 . The tong  300  includes a body  505  and two doors  321 ,  322  pivotally connected to the body  505 . The doors  321 ,  322  are opened to allow ingress or egress of a tubular. The doors  321 ,  322  can be opened using any suitable manner, such as a piston and cylinder assembly or manually. The tong  300  includes a gripping assembly having a carrier ring  350  housing one or more gripping members. It is contemplated that any suitable carrier ring and gripping members, such as those shown in  FIGS. 1, 2, 16, and 17  may be used. 
     In one embodiment, the carrier ring  350  is a segmented carrier ring having a body ring portion and two door ring portions. When the tong  300  is in the unactivated position, the body ring portion is coupled to the body  505 , and each door ring portion is coupled to a door  321 ,  322 . The door ring portion is movable with the respective door  321 ,  322 , when the door  321 ,  322  opens or closes. A gear ring (e.g., gear ring  459  shown in  FIG. 17 ) is coupled to the carrier ring  350 . 
     The tong  300  includes a segmented brake plate  340  having a body plate  343  and two door plates  341 ,  342 . The body plate  343  is attached to the body ring portion, and each door plate  341 ,  342  is attached to a door ring portion. The brake plate  340  is rotatable with the carrier ring  350 . In this embodiment, the brake plate  340  is attached to an upper surface of the carrier ring  350 . In another embodiment, the brake plate  340  is attached to a lower surface of the carrier ring  350 . The door plates  341 ,  342  are movable with the respective door  321 ,  322 , when the door  321 ,  322  opens or closes. In one embodiment, a brake pad  345  is attached to a perimeter wall surface of the brake plate  340 . An exemplary brake pad  345  is the brake pad  145  described in  FIGS. 10-12 . As discussed, one or more of the brake pads  345  can be attached to apertures in the perimeter wall surface of the brake plate  340 . In another embodiment, the brake pads can be attached to the brake band  361 ,  362 . 
     In one embodiment, the tong  300  includes one or more segmented brake bands  361 ,  362 . As shown in  FIG. 13 , two brake bands  361 ,  362  are provided on the tong  300 . For sake of clarity, only one brake band  361  will be described.  FIGS. 14 and 15  show the brake band  361  disposed on the tong  300 , which is shown with only one door  321 .  FIG. 14  shows the door  321  in the closed position. The brake band  361  includes a first band portion  371  coupled to a second band portion  372  using a braking member  365 . In one example, the braking member  365  such as a cylinder assembly is used to couple the first and second band portions  371 ,  372 . A piston extends out of one end of the cylinder assembly and is pivotally coupled to one end of each band portion  371 ,  372 . The outer end of the first band portion  371  is pivotally coupled to the first door  321 , such as via a first pin connection  376 . The outer end of the second band portion  372  is pivotally coupled to the tong body  505 , such as via second pin connection  377 . In one embodiment, the distance between the first and second pin connections  376 ,  377  is from 25% to 75% of the circumference of the brake plate  340  or from 35% to 60% of the circumference of the brake plate  340 . It is contemplated the braking member can be a dual piston and cylinder that pivotally couples the first band portion  371  and the second band portion  372 . 
       FIG. 15  shows the door  321  in the open position. As the door  321  swings out, the brake band  361  is allowed to pivot about both pin connections  376 ,  377 . The band portions  371 ,  372  also pivot about the connections with the pistons of the braking member  365 . 
     The brake band  361  is shown in  FIG. 14  in the unactuated position. A gap exists between the brake band  361  and the brake plate  340 . To stop rotation of the brake plate  340 , the braking member  365  is actuated to tighten the brake band  361 . For example, one or both of the pistons of the braking member  365  are retracted to move at least a portion of the brake band  361  into contact with the brake plate  340 . As a result, friction between the brake band  361  and the brake plate  340  is increased, thereby stopping rotation of the brake plate  340  and the carrier ring  350 . 
       FIG. 16  is a perspective bottom view of another embodiment of a wellbore tong  400 .  FIG. 17  is a perspective view of the tong  400  with one door  422  in the open position. The tong  400  includes a body  405  and two doors  421 ,  422  pivotally connected to the body  405 . The doors  421 ,  422  are opened to allow ingress or egress of a tubular. The doors  421 ,  422  can be opened using any suitable mechanism, such as a piston and cylinder assembly or manually. The tong  400  includes a gripping assembly having a carrier ring  450  housing one or more gripping members  408 . 
     In one embodiment, the carrier ring  450  is a segmented carrier ring having a body ring portion  453  and two door ring portions  451 ,  452 . When the tong  400  is in the unactivated position, the body ring portion  453  is coupled to the body  405 , and each door ring portion  451 ,  452  is coupled to a door  421 ,  422 . The door ring portion  451 ,  452  is movable with the respective door  421 ,  422 , when the door  421 ,  422  opens or closes. A gear ring  459  is coupled to the carrier ring  450  and is selectively rotatable relative to the carrier ring  450 . The gear ring  459  is segmented to accommodate movement of the door ring portions  451 ,  452  with the doors  421 ,  422 . 
     The tong  400  includes a segmented brake plate  440  having a body plate  443  and two door plates  441 ,  442 . The body plate  443  is attached to the body ring portion  453 , and each door plate  441 ,  442  is attached to a door ring portion  451 ,  452 . The brake plate  440  is rotatable with the carrier ring  450 . In this embodiment, the brake plate  440  is attached to a lower surface of the carrier ring  450 . In another embodiment, the brake plate  440  is attached to an upper surface of the carrier ring  450 . The door plates  441 ,  442  are movable with the respective door  421 ,  422 , when the door  421 ,  422  opens or closes. In one embodiment, a brake pad  445  is attached to a perimeter wall surface of the brake plate  440 . An exemplary brake pad  445  is the brake pad  145  described in  FIGS. 10-12 . As discussed, one or more brake pads  445  can be attached to apertures in the perimeter wall surface of the brake plate  440 . In another embodiment, the brake pads can be attached to the brake band  460 . 
     In one embodiment, the tong  400  includes a brake band  460  having a plurality of segments  461 ,  462 ,  463 .  FIG. 18  shows an exemplary embodiment of the brake band  460 . The brake band  460  is disposed around a perimeter of the brake plate  440  and configured to make contact with the brake plate  440 . The brake band  460  includes a body band  463  coupled to the body  405  of the tong  400 . The brake band  460  may be attached to the body  405  using a bracket  466 . One or more retainers  467  may be used to keep the brake band  460  in position around the brake plate  440 . The first and second door bands  461 ,  462  are coupled to the doors  421 ,  422 , respectively, and are movable with the doors  421 ,  422  as the doors  421 ,  422  open or close. In this embodiment, the door bands  461 ,  462  are coupled to the doors  421 ,  422  using a braking member  465  such as a piston and cylinder assembly. In one embodiment, the door bands  461 ,  462  include a hinge  456  for pivotally coupling with the piston of the braking member  465 . For example, a pin can be inserted through a hole  457  in the hinge  456  and a hole in the piston. In this manner, the door bands  461 ,  462  can be moved by the respective braking member  465 . 
     In one embodiment, the door bands  461 ,  462  are connected to the body band  463  using a latch  470 , as shown in  FIG. 18 . The latch  470  includes a catch  471 ,  472  on the door bands  461 ,  462  for receiving a dog  473 ,  474  protruding from the body band  463 . In one example, the catch  471 ,  472  has a hook shape. When the dog  473 ,  474  is engaged in the catch  471 ,  472 , a pull force from the braking member  465  is transferred to the body band  463  to tighten the brake band  460  around the brake plate  440 . The latch  470  is configured such that as the doors  421 ,  422  open, the catch  471 ,  472  disengages from the dogs  473 ,  474 .  FIG. 17  shows the catch  471  on the first door band  461  engaged with the dog  473  on the body band  463 , and the catch  472  on the second door band  462  fully disengaged from the dog  474  on the body band  463 .  FIG. 19  shows the catch  471  on the first door band  461  fully disengaged from the dog  473  on the body band  463 , and the catch  472  on the second door band  462  partially disengaged from the dog  474  on the body band  463 .  FIG. 20  shows the catch  471 ,  472  on both door bands  461 ,  462  fully disengaged from the dogs  473 ,  474  of the body band  463  as a result of opening the doors  421 ,  422 . 
     In operation, the doors  421 ,  422  are opened to allow a tubular to enter the tong  400 . As the doors  421 ,  422  open, the door bands  461 ,  462  move with the doors  421 ,  422  and disengage from the dogs  473 ,  474  on the body band  463 .  FIG. 20  shows the door bands  461 ,  462  disengaged from the body band  463 . After the tubular enters the tong  400 , the doors  421 ,  422  are closed. As the doors  421 ,  422  rotate back, the catch  471 ,  472  will engage the respective dog  473 ,  474 .  FIG. 19  shows the first door band  461  still disengaged from the body band  463 , and the second door band  462  partially engaged with the door band  463 . It can be seen the dog  474  is partially engaged with the catch  472  on the second door band  462 . When the doors  421 ,  422  are closed, the door bands  461 ,  462  are engaged with the body band  463 .  FIG. 18  shows the catch  471 ,  472  on both door bands  461 ,  462  engaged with the dogs  473 ,  474  of the body band  463  as a result of closing the doors  421 ,  422 . 
     To grip a tubular, the braking member  465  is activated to tighten the brake band  460  around the brake plate  440 . The brake band  460  applies a frictional force against the brake plate  440  to prevent rotation of the carrier ring  450 . In this respect, the gear ring  459  is allowed to rotate relative to the carrier ring  450 . The gear ring  459  may act as a cam to urge the gripping members  408  into contact with the tubular. 
       FIG. 21  is a partial, perspective view of another embodiment of a wellbore tong  500 .  FIG. 22  is a perspective view of the tong  500  with one door  522  in the open position. Because the tong  500  has many of the same features described in the tong  400  shown in  FIG. 17 , the tong  500  will be described with respect to only one of the doors  522 . The door  522  pivots at the door hinge  526  relative to the tong body. The door  522  is opened to allow ingress or egress of a tubular. The door  522  can be opened using any suitable mechanism, such as a piston and cylinder assembly or manually. The tong  500  includes a gripping assembly having a carrier ring  550  housing one or more gripping members. It is contemplated that any suitable carrier ring and gripping members, such as those shown in  FIGS. 16 and 17  may be used. 
     In one embodiment, the carrier ring  550  is a segmented carrier ring having a body ring portion and two door ring portions, e.g., carrier ring  450  of  FIGS. 16, 17 . Only one door  522  is shown in  FIG. 22 . The door ring portion is movable with the door  522 , when the door  522  opens or closes. However,  FIG. 22  shows the door ring portion in the closed position while the door  522  is open in order to more clearly show the features of the brake band  560 . 
     The tong  500  includes a segmented brake plate  540  having a body plate  543  and two door plates  541 ,  542 . The body plate  543  is attached to the body ring portion, and each door plate  541 ,  542  is attached to a door ring portion. The brake plate  540  is rotatable with the carrier ring  550 . In this embodiment, the brake plate  540  is attached to a lower surface of the carrier ring  550 . In another embodiment, the brake plate  540  is attached to an upper surface of the carrier ring  550 . The door plate  542  is movable with the respective door  522 , when the door  522  opens or closes. In one embodiment, a brake pad is attached to a perimeter wall surface of the brake plate  540 . An exemplary brake pad is the brake pad  145  described in  FIGS. 10-12 . As discussed, one or more brake pads can be attached to apertures in the perimeter wall surface of the brake plate  540 . 
     In one embodiment, the tong  500  includes one or more brake bands  560  for holding or stopping rotation of the carrier ring  550 . In  FIG. 22 , the brake band  560  is coupled to the door  522 . While not shown, another brake band  560  is preferably coupled to the other door. The brake band  560  includes a first segment  561  pivotally coupled to a second segment  562 . In another embodiment, the brake band  560  is a single segment or includes three or more segments. A first end of the brake band is pivotally coupled to a braking member  565 , and a second end of the brake band is pivotally coupled to the tong body. In this embodiment, a band hinge plate  563  is attached to the tong body. The first segment  561  of the brake band  560  is pivotally attached to a pin  574  on the door hinge plate  563 . In this embodiment, a hinge cut out  528  is formed in the door hinge plate  527  to accommodate the pin  574  and the door band  560 . The second segment  562  is pivotally attached to a hinge  567  of the braking member  565 . The hinge  567  extends from the piston of the braking member  565  and is movable with the piston. 
     In operation, the doors of the tong  500  are opened to allow a tubular to enter the tong  500 . For sake of clarity, only the operation of one of the doors  522  will be described. As the door  522  opens, the brake band  560  moves with the door  522  and pivot about the pin  574  on the band hinge plate  575 . The brake band  560  also pivots relative to the braking member  565 . The piston of the braking member  565  also moves the hinge  567  as the door  522  opens.  FIG. 22  shows the brake band  560  in the open position with the door  522 . After the tubular enters the tong  500 , the door  522  is closed. As the door  522  rotates back, the brake band  560  will rotate with the door  522  about the pivotal connections  574 ,  567 .  FIG. 20  shows the brake band  560  in the closed position. The hinge  567  has moved from the position shown in  FIG. 22 . The braking member  565  is activated to tighten the brake band  560  around the brake plate  540 . The brake band  560  applies a frictional force against the brake plate  540  to prevent rotation of the carrier ring  550 . In this respect, a gear ring is allowed to rotate relative to the carrier ring  550 , thereby urging the gripping members into contact with the tubular. 
       FIG. 23  is a partial, perspective view of another embodiment of a wellbore tong  600 .  FIG. 24  is a perspective view of the tong  600  with one door  621  in the open position. Because the tong  600  has many of the same features described in the tong  400  shown in  FIG. 17 , the tong  600  will be described with respect to only one of the doors  621 . The other door is not shown for sake of clarity. The door  621  pivots at the door hinge  626  relative to the tong body  605 . The door  621  is opened to allow ingress or egress of a tubular. The door  621  can be opened using any suitable mechanism, such as a piston and cylinder assembly or manually. The tong  600  includes a gripping assembly having a carrier ring (such as carrier ring  450  of  FIGS. 16, 17 ) and a gripping member, which are not shown for sake of clarity. It is contemplated that any suitable gripping assembly, such as those shown in  FIGS. 1-2 and 16-17  may be used. In one embodiment, the carrier ring is a segmented carrier ring having a body ring portion and two door ring portions. The door ring portion is movable with the door  621 , when the door  621  opens or closes. 
     The tong  600  includes a segmented brake plate  640  having a body plate  643  and two door plates  641 ,  642 . The body plate  643  is attached to the body ring portion, and each door plate  641 ,  642  is attached to a door ring portion. The brake plate  640  is rotatable with the carrier ring. In one embodiment, the brake plate  640  is attached to a lower surface of the carrier ring. In another embodiment, the brake plate  640  is attached to an upper surface of the carrier ring. The door plate  641  is movable with the respective door  621 , when the door  621  opens or closes. In one embodiment, a brake pad  645  is attached to a perimeter wall surface of the brake plate  640 . An exemplary brake pad is the brake pad  145  described in  FIGS. 10-12 . As discussed, one or more brake pads can be attached to apertures in the perimeter wall surface of the brake plate  640 . 
     In one embodiment, the tong  600  includes a brake band  660  having a plurality of segments.  FIG. 23  shows an exemplary embodiment of the brake band  660 . The brake band  660  is disposed around a perimeter of the brake plate  640  and configured to make contact with the brake plate  640 . The brake band  660  includes a body band  663  coupled to the body  605  of the tong  600 . The brake band  660  may be attached to the body  605  using a bracket and one or more retainers may be used to keep the brake band  660  in position around the brake plate  640 . The brake band  660  also includes a first door band  661  and a second door band. For sake of clarity, this embodiment will be described with respect to the first door band  661  since the second door band operates in a similar manner. The first door band is coupled to the door  621  and is movable with the door  621  as the door  621  opens or closes. The first door band  661  is coupled to the door  621  using a braking member  665  such as a piston and cylinder assembly. In one embodiment, the first door band  661  includes a hinge for pivotally coupling with the piston of the braking member  665 . For example, a pin can be inserted through a hole in the hinge and a hole in the piston. In this manner, the first door band  661  can be moved by the respective braking member  665 . 
     In one embodiment, the door bands  661  are connected to the body band  663  using a guide slot  670 , as shown in  FIG. 23 . In this embodiment, the guide slot  670  is attached to the body band  663 . A pin  671  on the first door band  661  is disposed in the guide slot  670 . The guide slot  670  is configured to accommodate movement of the pin  671  as the first door  621  opens or closes. In one example, the guide slot  670  has a curved shape. The pin  671  may be coupled to the first door band  661  using an adapter  674 . In  FIG. 23 , the first door  621  is in a closed position. When a pull force from the braking member  665  is applied to the first door band  661 , the pull force is transferred from the first door band  661  to the body band  663  via the pin  671  and guide slot  670 . In this respect, the braking member  665  can apply the pull force to tighten the brake band  660  around the brake plate  640 .  FIG. 24  shows the first door  621  in the open position. The pin  671  has moved outwardly with the first door  621  and along the guide slot  670 . 
     In operation, the doors of the tong  600  are opened to allow a tubular to enter the tong  600 . For sake of clarity, only the operation of one of the doors  621  will be described. As the door  621  opens, the first door band  661  moves with the door  621  and the pin  671  of the first door band  661  moves along the guide slot  670 .  FIG. 24  shows the door  621  and the first door band  661  in the open position. After the tubular enters the tong  600 , the door  621  is closed. As the door  621  rotates back, the pin  671  of the first door band  661  moves back along the guide slot  670  toward the body band  663 .  FIG. 23  shows the door  621  and the first door band  461  in the closed position. The braking members  665  are activated to tighten the brake band  660  around the brake plate  640 . Force from the braking member  665  is applied to the first door band  661  and transferred to the body band  663  via the pin  671  and the guide slot  670 . The brake band  660  applies a frictional force against the brake plate  640  to prevent rotation of the carrier ring  550 . In this respect, the gear ring is allowed to rotate relative to the carrier ring  550 , thereby urging the gripping members into contact with the tubular. 
     In one embodiment, a method of operating a tong includes opening a door of the tong. The tong may include a tong body; the door pivotally coupled to the tong body; a carrier ring rotatable relative to the tong body; a brake plate coupled to the carrier ring; and a brake band having a door band portion attached to the door. The method also includes moving the door band portion of the brake band with the door as the door opens; closing the door; rotating the carrier ring; and moving the brake band into contact with the brake plate, thereby stopping rotation of the carrier ring. 
     In one embodiment, a tong for use at a wellbore includes a tong body; at least one door pivotally coupled to the tong body and movable between an open position and a closed position; a carrier ring rotatable relative to the tong body; a brake plate coupled to the carrier ring; a brake band configured to move with the at least one door between the open and closed positions; and a braking member for moving the brake band into contact with the brake plate to stop rotation of the carrier ring. 
     In one embodiment, a tong for use at a wellbore includes a tong body; at least one door pivotally coupled to the tong body and movable between an open position and a closed position; a gripping assembly rotatable relative to the tong body; and a brake plate coupled to the gripping assembly. The tong may also include a brake band configured to move with the at least one door between the open and closed positions; and a braking member for moving the brake band into contact with the brake plate to stop rotation of the gripping assembly. 
     In one or more of the embodiments described herein, the brake band includes a body band attached to the tong body; and a door band attached to and movable with the door, wherein the door band is engaged with the body band when the door is in the closed position, and the door band is disengaged from the body band when the door is in the open position. 
     In one or more of the embodiments described herein, the door band includes a catch configured to receive a dog of the body band when the door is in the closed position. 
     In one or more of the embodiments described herein, the braking member is attached to the door. 
     In one or more of the embodiments described herein, the brake plate includes a body plate attached to the tong body and a door plate attached to and movable with the door. 
     In one or more of the embodiments described herein, the tong includes a first door and a second door, and the brake band includes a body band attached to the tong body; a first door band attached to and movable with the first door; and a second door band attached to and movable with the second door, wherein the first and second door bands are engaged with the body band when the doors are in the closed position, and the first and second door bands are disengaged from the body band when the doors are in the open position. 
     In one or more of the embodiments described herein, the first end of the brake band is pivotally attached to the door, and a second end of the brake band is pivotally attached to the tong body. 
     In one or more of the embodiments described herein, the second end of the brake band is pivotally attached to a pin on the tong body. 
     In one or more of the embodiments described herein, the braking member is attached to the door, and wherein the first end of the brake band is pivotally coupled to the braking member. 
     In one or more of the embodiments described herein, the brake band includes a first brake band portion pivotally coupled to a second brake band portion. 
     In one or more of the embodiments described herein, the door includes a hinge cut out to accommodate the pin. 
     In one or more of the embodiments described herein, the brake band includes a first brake band portion pivotally coupled to a second brake band portion. 
     In one or more of the embodiments described herein, the braking member pivotally couples the first brake band portion to the second brake band portion. 
     In one or more of the embodiments described herein, the braking member includes a first piston coupled to the first brake band portion and a second piston coupled to the second brake band portion. 
     In one or more of the embodiments described herein, the tong includes a first door and a second door, wherein the first end of the brake band is pivotally attached to the first door and the second end of the brake band is pivotally attached to the tong body. The tong may further include a second brake band having a first end pivotally attached to the second door and a second end pivotally attached to the tong body. 
     In one or more of the embodiments described herein, the brake band includes a body band attached to the tong body and having a guide slot; and a door band attached to and movable with the door, wherein the door band is coupled to the guide slot. 
     In one or more of the embodiments described herein, the door band includes a pin disposed in the guide slot. 
     In another embodiment, a method of operating a tong includes opening a door of the tong, wherein the tong includes a tong body; the door pivotally coupled to the tong body; a carrier ring rotatable relative to the tong body; a brake plate coupled to the carrier ring; and a brake band having a door band portion attached to the door. The method also includes moving the door band portion of the brake band with the door as the door opens; closing the door; moving the brake band into contact with the carrier ring, thereby preventing rotation of the carrier ring; and rotating a gear ring relative to the carrier ring. 
     In one or more of the embodiments described herein, moving the door band portion includes disengaging the door band portion from a body band portion of the brake band attached to the tong body. 
     In one or more of the embodiments described herein, closing the door includes engaging the door band portion with the body band portion. 
     In one or more of the embodiments described herein, moving the brake band into contact includes transferring a force from the door band portion to the body band portion. 
     In one or more of the embodiments described herein, moving the door band portion includes moving a pin of the door band portion along a guide slot of a body band portion of the brake band. 
     In one or more of the embodiments described herein, moving the brake band into contact with the brake plate includes actuating a braking member to apply a force to the brake band to move the brake band relative to the brake plate. 
     While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.