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Publication numberUS3838613 A
Publication typeGrant
Publication dateOct 1, 1974
Filing dateOct 18, 1973
Priority dateApr 16, 1971
Publication numberUS 3838613 A, US 3838613A, US-A-3838613, US3838613 A, US3838613A
InventorsWilms C
Original AssigneeByron Jackson Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Motion compensation system for power tong apparatus
US 3838613 A
Abstract
A power well pipe tong assembly having a back-up tong unit and power tong unit above the back-up unit and interconnected for vertical movement one relative to the other on parallel horizontal planes and a presser device actuated by fluid pressure interposed between the two tong units to counterbalance the weight of the power tong during such vertical movement.
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Description  (OCR text may contain errors)

United States Patent [191 Wilms [451 Oct. 1,1974

[ MOTION COMPENSATION SYSTEM FOR POWER TONG APPARATUS [75] Inventor: Carl Alfred Wilms, La Habra, Calif.

[73] Assignee: Byron Jackson Inc., Long Beach,

Calif.

22 Filed: 0a. 18, 1973 211 Appl. No.: 407,698

Related US. Application Data [63] Continuation of Ser. No. 216.182. January 7. 1972, which is a continuation-in-part of Ser. No. 134.552. April 16. 1971. abandoned.

[52] US. Cl 81/5734, 81/57.]6, 173/164 [51] Int. Cl B25b 13/50, E2lb 19/16 [58] Field of Search 8l/57.15, 57.16, 57.22,

[56] References Cited UNITED STATES PATENTS 2/1954 Cormany 81/57.l6

2,969,702 1/1961 Cornish 81/57.l6 3,086,413 4/1963 Mason 8l/57.18 X 3,288,000 11/1966 F0ster.... ill/57.34 3,518,903 7/1970 Ham 81/57.]6

Primary Examiner-Al Lawrence Smith Assistant Examiner-.1. C. Peters Attorney, Agent, or Firm-John 0. Evans, Jr.

[ 5 7 ABSTRACT A power well pipe tong assembly having a back-up tong unit and power tong unit above the back-up unit and interconnected for vertical movement one relative to the other on parallel horizontal planes and a presser device actuated by fluid pressure interposed between the two tong units to counterbalance the weight of the power tong during such vertical movement.

20 Claims, 13 Drawing'Figures PAIENIEDBBI H 1 3,838,613

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FIG- 11. We

FIG: 12

MOTION COMPENSATION SYSTEM FOR POWER TONG APPARATUS BACKGROUND OF THE INVENTION This application is a continuation of copending application Ser. No. 216,182, filed Jan. 7, 1972, for Motion Compensation System for Power Tong Apparatus, now abandoned, which application is a continuation-in-part of application Ser. No. 134,552, filed Apr. 16, 1971, for Combined Back Up Tong and Power Tong with Joint Motion Compensation, now abandoned.

In the drilling of well bores, such as oil and gas wells, into the earth and in the periodic round-tripping of the drill string, it is necessary to make up and break out the tool joints of stands or lengths of drill pipe which together constitute the drill string. As is well known such tool joints are generally threaded joints consisting of an internally threaded box on the drill pipe which is disposed in the well bore and supported in the usual rotary table, and an externally threaded pin on the length or stand of drill pipe which is being added to or removed from the drill string. Such tool joints also generally include radial shoulders on the box and on the pin which engage with one another when the joint is tight.

To tightly make up such a tool joint or break out the joint, as the case may be, requires a substantial force which is applied to the respective tool joint pin and box sections by rotating the length or stand of drill pipe which is being added or removed, while the drill string in the well bore is held stationary. To initially shoulder the tool joint or to remove the pin from the box, the rotatable pipe stand is generally rotated at high speed to save time, per joint, such operation being referred to as spinning in or out, as the case may be.

The spinning operation, in any event, involves relative axial movement of the tool joint shoulders into and out of engagement, such axial movement being caused by the threads on the pin and in the box.

For the purpose of spinning and making up and breaking out tool joints in well drilling pipe, various power tongs have been heretofore provided and are adapted to grip the tool joint of the length or stand of drill pipe suspended in the derrick and impart rotation thereto. In addition, various back up tongs have been heretofore provided for engaging and holding stationary the tool joint at the upper end of the drill string which is supported in the usual master bushing by wedges or slips which are movable between pipe supporting and out of the way positions, either manually or by power actuated means.

Such operations, using a power tong and a back-up tong, inherently require that the power tong move towards and away from the back-up tong during the spinning of the pipe stand being added to or removed from the drill string, since if such movement cannot take place, then, the tool joint section engaged by the power tong will be forced to slide relative to the gripping I means of the power tong or the tongs will be relatively cocked.

THE PRIOR ART A power tong and a back-up tong combination which typifies the prior art, is shown and described in US. Pat. No. 3,518,903, granted July 7, 1970, wherein the back-up tong is suspended beneath the power tong, and the power tong is supported by a crane based on the derrick floor. Springs are interposed between the power tong and the back-up tong, and pin means shiftably supports the back-up tong beneath the power tong.

Such power tongs are also disclosed, for example, in the US. patent applications of Bela Geczy et a1, filed Apr. 16, 1971, Ser. No. 134,554, for Chain Driven Spinning Make Up and Break Out Tongs, now US Pat. No. 3,691,875, issued Sept. 19, 1972; and Carl A. Wilms, filed Apr. 16, 1971, Ser. No. 134,553, for Chain Actuated Pipe Tongs. The disclosures of these identified patent applications are specifically incorporated herein by reference.

SUMMARY OF THE INVENTION The present invention provides a power tong and back-up tong combination wherein the respective tongs are interconnected for relative vertical movement on planes normal to the direction of relative movement of the tool joint parts when they are being made up or broken out, whereby relative cocking of the tongs on either tool joint section is prohibited.

In addition, the present invention provides such a combination in which the back-up tong is supported or suspended above the derrick floor and the power tong is supported on the back-up tong by means which essentially counterbalance the weight of the power tong, so that the latter is easily movable vertically as a result of spinning of the pipe stand by the power tong, which spinning results in upward or downward movement of the power tong due to the progressive disengagement or engagement of the complemental threads of the pin and box sections of the tool joint.

More particularly, the present invention provides fluid pressure containing means or presser means acting between the back-up tong and the power tong in such a manner that the weight of the power tong may be substantially nullified. For example, when the tong combination is being employed to make up tool joints, under which circumstances the power tong must be in a starting position spaced upwardly from the back-up tong, the fluid pressure containing or presser means may over compensate for the weight of the power tong to a slight extent, so that as the tool joint spins up, the power tong is easily moved downwardly. On the other 'hand, for example, when the tong combination is being employed to break out tool joints, under which circumstances the power tong must be in its lower starting position, the presser means may compensate for slightly less than the weight of the power tong, so that the power tong is easily moved upwardly as the tool joint is being spun out.

In accomplishing the foregoing, the objectives of the invention include the provision of a power tong and back up tong combination which is simple in its construction, durable, and easy to control and operate.

This invention possesses many other advantages, and has other purposes which may be made more clearly apparent from a consideration of the forms in which it may be embodied. These forms are shown in the drawings accompanying and forming part of the present specification. They will now .be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of a power tong and back-up tong combination made in accordance with the invention and supported above the floor of a drilling derrick, and showing a drill string and a pipe stand in the relatively unthreaded positions;

FIG. 2 is a top plan of the combination of FIG. 1;

FIG. 3 is a side elevation of the power tong and backup tong of FIG. 1, but showing them in a position at which the tool joint is shouldered;

FIG. 4 is a detail view in vertical section, through a typical connector pin assembly, as taken on the line 44 of FIG. 2;

FIG. 5 is a detail view in vertical section through the fluid pressure containing means and portions of the tongs, as taken on the line 55 of FIG. 2;

FIG. 6 is an elevational view of an alternate embodiment of the present invention;

FIG. 7 is a partially cut away planview taken along the line -77 of FIG. 6;

FIG. 8 is a sectional view of an alternate embodiment of the fluid pressure containing means or presser means as taken along the line 88 of FIG. 7;

FIG. 9 is a partly sectional elevational view taken along the line 9-9 of FIG. 6;

FIG. 10 is a partially sectional elevational view taken along the line l010 of FIG. 9;

FIG. 11 is a sectional view taken along the line 11l1 of FIG. 10;

FIG. 12 is a sectional view taken along the line 1212 of FIG. 6; and FIG. 13 is a schematic illustration of the presser means and an adjustable pressure system for use with the same.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As seen in FIGS. 1, 2, 3, 6 and 7 of the drawings, the power tong and back-up tong combination BT of the present invention generally comprises a back-up tong assembly B and a power tong assembly T, support means S for the back-up tong B, a plurality of connector means C enabling relative movement of the tongs T and B toward and away from one another, and presser means or fluid pressure containing means P interposed between the tongs T and B and operable to more orless counterbalance the weight of the power tong T to allow the latter to move downwardly during the make up of a tool joint J and upwardly during the break out of the tool joint J in the drill pipe DP.

The power tong T may be of any type, including by way of example, that shown and described in detail in the aforementioned U.S. Pat. No. 3,518,903 and U.S.

patent disclosures. Likewise, the back-up tong B may be of any type, including by way of example, that shown and described in said patent and patent disclosures. Such tongs are well known in the art and without requiring detailed illustration and description herein will be understood to be used, when supported in the usual derrick or on the derrick floor, to thread the pin end 1 of the tool joint J into the box end 2, from the positions shown in FIG. 1 to the position shown in FIG. 3, at which the joint .I is tightly shouldered, when making up joints, or to unthread the pin 1 from the box 2 when the joint J is being broken out. During such operations, the box end 2 is held against rotation in the back-up tong B, while rotation of the pin end 1 is effected by the power tong T. Since both tongs tightly grip the tool joint parts, it is necessary that the power tong T move between the elevated position, spaced above the back-up tong B, as seen in FIG. 1, and the lower position, as seen in FIG. 3, the distance between these two positions being equal to the axial movement of the pin 1 caused by the threads as the joint J is made up and broken out.

In order to rotate the pin end 1 of the joint J. the power tong, generally, comprises gripping jaws 4 which are actuated from retracted positions to gripping positions, as seen in FIG. 2, and the pin end 1 is then revolved by a suitable power source, such as a hydraulic motor M through suitable gearing (not shown) in a housing 5 on the power tong body 6. A similar jaw system (not shown) is typically included in the back-up tong- B, but the jaws are held against revolution when actuated into engagement with the box end 2 of the joint J. As previously indicated the details of the tongs T and B may vary, and examples including gripping jaws and operating means therefor, are abundantly illustrated in the above-identified U.S. patent and are otherwise well known.

In order to support the drill pipe in the well bore, with the upper end or box 2 disposed, as seen in FIG. 1, in position for gripping engagement by the back-up tong B, suitable slip mechanism, say a power slip apparatus PS is supported on the derrick floor F and is operable to releasably engage the pipe below the box end 2, so that the drill pipe string is suspended in the well from the usual rotary table R, all as is well known.

The supporting means S previously referred to may take any convenient form, such as the customary cable support by which the tong combination is suspended from the derrick in a horizontal disposition and steadied by a stiff arm or other supporting means such as a pedestal or carriage of the nature shown in FIG. 6. In FIG. 1 the supporting means is shown as being of the suspended type. More particularly, a U-shaped member or yoke 10 is shown as straddling the power tong T and being connected by suitable fasteners 11 to the body of the back-up tong B, the connection being obviously the same at both sides. The bight portion 12 of the yoke 10 has a centrally located, upstanding ear 13 adapted to be connected to a clevis 14 at the lower end of a supporting cable 15 which will be understood to extend upwardly to a suitable connection (not shown) with hoist mechanism which may be employed to adjust the elevation of the tong combination with respect to the derrick floor F and thus the box 2 of the drill pipe. In addition, a stiff arm 16 is generally illustrated as being connected to one side of the tong combination adjacent the end remote from the pipe DP to stabilize the combination and provide a safety means to prevent reactive torque from causing the tong combination-to swing about the drill pipe DP if the power tong T is operated without gripping the box 2 with the back-up tong B. Otherwise, when the back-up tong is gripping the box 2 the reaction torque is taken by the connector means C.

These connector means C are conveniently located, preferably adjacent to the ends of the tong combination and, as previously indicated, function to interconnect the power tong T with the back-up tong B in such a manner that the power tong is vertically shiftable relative to the back-up tong, between the positions shown in FIGS. 1 and 3, in parallel relation to the back-up tong. In other words, the two tongs are horizontally extended on parallel planes and are vertically movable, one relative to the other, and the connector means C constrain the tongs to such movement.

As seen in FIG. 2, the connector means as illustrated are triangularly related with a pair of connector means at opposite forward corners of the tong combination and a third connector means at the rear or other end of the combination. A typical connector means C for the embodiment shown in FIGS. 1 and 2 is best illustrated in FIG. 4. The tong T has an ear providing a bore 21 in which a connector pin 22 is suitably affixed, the lower portion of the pin 22 extending downwardly and slidably through a bushing 23 which is affixed in a bore 24 provided in an ear 25 on the tong B. At its lower end, the pin 22 has a keeper in the form of a washer 26 secured by a fastener 27 to the pin 22 and having a diameter such that the washer will abut beneath the ear 25 to limit upward movement of the tong T.

It will now be understood that with the structure thus far described, the two tongs T and B are free to move relatively vertically while suspended by the supporting means S. Such vertical movement is necessary when the joint parts 1 and 2 of the joint J are being threaded in or out, to compensate for the relative axial movement of the joint parts 1 and 2, without causing longitudinal slippage of the tong gripping means on the joint parts 1 and 2. The connector means C hold the tongs T and B in parallel relation.

However, the power tong T is typically quite heavy, and therefore the presser means P previously referred to is provided to more or less counterbalance the weight of the power tong T to relieve the pipe gripping means from the load of the tong T.

The fluid pressure containing means P as illustrated in FIG. 5 comprises a presser bladder 30 of generally flat, circular form, interposed between the bottom wall 31 of the power tong T and the top wall 32 of the backup tong B. In the illustrated embodiment, the bladder seats in a complemental cavity 33 in the wall 32 of the back-up tong.

The presser bladder 30 is composed of elastomeric material and may be suitably reinforced against rupture or other failure. Centrally of the bottom wall 34 of the bladder 30 is a sleeve 35 which is suitably bonded in an opening 36 in the bladder wall 34 and adapted to extend downwardly into an opening 37 in the tong wall 32 and onto a cylindrical neck 38 of a fluid pressure inlet fitting 39 which is suitably affixed beneath the tong wall 32, as by welding at 40. Suitable seal means 41 are provided between the opposing cylindrical surfaces of the sleeve 35 and the neck 38, and fluid conduit 42 is connected to the fitting 39 so that fluid may be supplied to the interior of the presser bladder 30 at a selected and regulated pressure as will be later described.

Since the purpose of the presser bladder 30 is to more or less counterbalance the weight of the tong T, to .facilitate its movement vertically during the making up and breaking out of pipe joints 1, counterbalance presser means P is preferably located beneath the power tong T or applies lift to the tong T substantially at the center of gravity of the tong T which of course varies from power tong to power tong. In addition, while a bladder is illustrated as a simple, relatively inexpensive yet effective counterbalance device, it will be understood that other fluid pressure responsive presser devices as later described, are also applicable, the essential point being that the weight of the power tong is more or less counterbalanced as it moves upwardly or downwardly with the pin end or joint part 1 during the breaking out and making up of the joints J, so that the weight of the power tong T is not applied to the pipe gripping means or jaws 4 of the power tong T.

FIGS. 6-12 illustrate an alternate embodiment of the invention wherein the same indicia are assigned to components corresponding to those as previously described. The alternate embodiment as illustrated in FIGS. 6, 7 and 8 includes positioning apparatus having a vertically disposed column 76 formed of a web joined between two parallel flanges such as an I-beam, for example. Upper upper support 78 is connected with the top of column 76 as by bolted connection as shown, for example. Ypper support 78 is connected to a pivotable upper bearing unit 80 shown in FIG. 6. A lower support is connected to a pivotable lower bearing unit (not shown) in turn attached to a derrick floor. An alternate tong support means S is mounted in cantilever fashion from column 76 as before described.

A generally hollow and elongated rectangular support collar 82 of support means S is fitted about column 76 and adapted to be moved up and down along column 76. Collar 82 is maintained and rigidly supported in longitudinal movable alignment with column 76 by a roller assembly 84 incorporated within collar 82. As shown, a plurality of flanged rollers 86 are included in assembly 84 and mounted to abut and roll along the inner faces of the flanges of column 76 with the roller flanges abutting the side edges of the column flanges to restrain collar 82 in fixed horizontal or lateral relation with respect to the column.

A tong support yoke structure 88 is mounted to collar 82 and projects horizontally and radially from the pivotable axis of column 76. A power pipe tong assembly BT adapted to receive a well pipe DP and including a back-up tong B and a rotating power tong T is mounted within yoke 88 through a cradle assembly having cradle units 90 and 90' comprising part of connector means C. For the purpose of this description, the power tong assembly BT may be considered to be of construction such as disclosed in the previously referenced US. patent disclosures, for example.

Mounted in generally upright posture adjacent column 76 is a power source adapted for linear movement which is provided as a hydraulic piston and cylinder unit 92. As later described, power source 92 is pivotally mounted at its lower end to the lower end of column 76 (not shown) and terminates at its upper movable end with a force and movement crosshead unit 94. Flexible force and movement transfer means are provided as a pair of roller chains 96 (only one shown) which strad-.

dle power source 92 and which are respectively meshed across chain sprockets incorporated as part of crosshead unit 94. Chains 96 are also respectively anchored at their lower ends to the lower end of column 76 (not shown) and extend upwardly over crosshead unit 94 to a position below unit 94 where such chains are respectively anchored to yoke structure 88.

Upper support assembly 78 is removably attached to column 76 through provision of downwardly projecting flanges 98 which are respectively connected to the flanges of column 76 by means of bolts 100. Upper support member 78 is provided as removable to permit assembly of support collar 82 as shown in FIG. 6. Upper bearing unit 80 is a flanged ball bearing assembly connected to support 78 and to a cylindrical retaining bitt 102 by means of fasteners (not shown). Bitt 102 is equipped with a plurality of lobed and divided retainer rings such as indicated at 106 and 108. Rings 106 and 108,are assembled with fasteners such as cap screws 110, for example. Horizontal tie bars 112 and 114 are respectively connected to the lobes of rings 106 and 108 through clevis and pin arrangements 116 and 118. The other ends of tie bars 112 and 114 are connected in tension to the structure (not shown) of the well derrick. To be noted is that more than the two disclosed tie bars may be utilized as desired to provide appropriate horizontal stability in a particular installation.

The alternate embodiment of presser P is best shown in FIGS. 7 and 8 to include a movable piston 60 including an externally mounted sliding bearing sleeve 62 and a'fluid pressure seal means such as seal rings 64 interposed snugly and reciproeably fitted-within a cylinder 66. As shown cylinder 66 is firmly supported from the bottom wall of back-up tong B through support webs 68 connected to such bottom wall as by welding and connected in fluid sealed relation to the closed end of cylinder 66 by means of fasteners such as cap screws 70 and seal washers or gaskets 72 as shown. The upper open end of cylinder 66 extends through a hole defined in the top wall 32 of the tong B. A seal ring 74 is interposed between cylinder 66 and the hole in tong wall 32 to maintain the interior of tong B free of dirt and detritus as might enter therebetween.

As shown, fluid pressure entering cylinder 66 will cause upward movement of piston 60 into abutting contact with bottom wall 31 of rotating power tong T. The pressing force of presser P to counterbalance tong T as previously described is. thereon commensurate with the fluid pressure applied through conduit 42, as later described. Of note is that the face of piston 62 which abuts the bottom wall'3l of tong T is provided to permit free horizontal sliding contact between the piston face and such bottom wall, such horizontal movement being limited by the embodiments of connector means C as heretofore described with reference to FIGS. 1-4 and hereafter described with reference to FIGS. 612.

Yoke 88 (FIGQ6) of support means S includes a clevis box 120 mounted at the upper part of a load plate 122 comprising part of collar 82 and support arms 124 and 124' mounted to and projecting from the lower part of load plate 122. Support cradles 90 and 90' are respectively mounted to arms 124 and 124, as later described with reference to FIGS. -12, and secured through pinned connection to members 126 and 126' of a support fork 128 to clevis box 120. Clevis box 120 defines a cavity which will receive chain crosshead 94 and is provided with a chain anchor bracket 130 to which chains 96 are secured by bolted connection as shown in FIG. 6. Support means S also includes a torque section alignment pin 188 projecting from backup tong B and received in a hole defined in rotating power tong T as shown in FIGS. 6 and 7. The installation' of alignment pin 188 may be similar to an inverted arrangement of FIG. 4 without provision of washer 26 as shown.

Power source 92 as provided includes a piston and cylinder unit having a cylinder 132 with a piston rod 134 extending from the cylinder. Chain crosshead 94 is mounted to the distal end of rod 134 and cylinder 132 is pivotally mounted to the lower end of column 76 (not shown). Cylinder 132 is equipped with a fluid fitting (not shown) through which fluids under pressure may be forced into or discharged from the cylinder to cause extension and retraction of piston rod 134 with corresponding perpendicular movement of support yoke 88 as previously described. Though compressible fluids such as air may be used, incompressible hydraulic fluids such as oil is preferred in the operation of power source 92.

FIGS. 6, 7 and 9-11 show the supporting cradle including cradle units and 90'. Cradle unit 90' is .provided of construction which is in mirror image of the construction of cradle unit 90 and accordingly need not be described in detail. FIGS. 10, 11 and 12 best show the details of cradle unit 90. Cradle unit 90 generally includes a supporting guide 136 formed at the extremity of support arm 124. which guides and supports a tong unit carrier frame 138 in pivoting and raidally movable relation through a roller unit 140 as shown.

Supporting guide 136 is formed of generally rectangular configuration with a pair of upwardly extending ears which form a clevis 142 for attachment by means of a pin to support fork 128. Parallel trackways 144 are horizontally and radially defined within guide 136 and closed at the distal end of support arm 124 by a closure bar 146 connected across the trackways to guide 136 by fasteners such as cap screws 148 as shown. A flanged guide block 150 is snugly fitted in sliding relation within trackways 144 with the flanges of the guide block abutting the sides of the trackways and maintaining the guide block in radial alignment with support arm 124. Adjustable radial support of guide block 150 is provided by a threaded stud 152 projecting from the guide blocks through a hole in closure bar 146 with threaded lock nuts 154 adjustably threaded on stud 152 and tightened to lock on either side of bar 146. A short machined slot 156 having circular ends is horizontally defined in guide block 150 which slot receives roller 140 and permits limited radial movement of the roller within the slot for purposes later described. Roller 140, as disposed within slot 156, is secured by means of a pin to a clevis 158 formed as an upper part of carrier frame 138 in a manner as shown to cause carrier frame 138 to be suspended in pivoted and radially movable relation through roller 140 from guide block 150.

Carrier frame 138 is adapted to be rigidly connected to pipe back-up unit B by fasteners such as cap screws 160 to support lugs 162 which project from unit B as shown. As shown, four guide rollers 164 are mounted in rectangular formation on carrier frame 138 by means of pins to accommodate a guide bar 166 and maintain the guide bar in vertically movable alignment. Guide bar 166 is adapted to be rigidly connected by means of fasteners such as cap screws 168 to pipe rotating power unit T as shown.

Vertical movement of pipe rotating unit T relative to pipe back-up unit B is maintained within a predetermined limit by means of a dog 170 which is connected to and projects from guide bar 166 into a limit slot 172 defined in carrier frame 138 as shown.

The construction of cradle unit 90 as shown provides parallel alignment and limited vertical movement between rotating unit T and back-up unit B while permitting adjustable limited radial movement and vertical pivoting of the entire power tong assembly ET. The

limited radial movement of carrier frame 138 as provided by movement of roller unit.140 within slot 156 permits slight radial movement of power tong assembly BT with respect to column 76 to compensate for corresponding horizontal deviations of the well pipe within the well bore. Initial radial range adjustment is provided by adjustment of guide block 150 through positioning of adjustment stud 152.

Pivotal movement or rocking of power tong assembly BT about the axis of roller unit 140 is resiliently limited by a stabilizing unit 174 and 174', shown in FIGS. 6, 7 and 12. Only unit 174 needs to be described as a flanged bracket 176 extending inwardly and downwardly from support arm 124 of yoke 88. A bolt 178 extends upwardly through a lug 180 projecting from back up tong B and through a flange 182 projecting from bracket 176 and is secured in position by adjustable lock nuts 184.,A pair of resilient coil springs 186 are disposed between lug 180, the flange 182 and lock nuts 184 as shown. The bolt is fitted through lug 180 and flange 182 sufficiently loosely to permit the radial movement of tong assembly BT as previously described. Such construction provides firm yet resilient vertical support of tong assembly BT against movement about the axis of roller unit 140. Such resilience permits compensation for minor deviations from a vertical position of the well pipe DP extending through tong assembly BT.

Referring to FIG. 13, an exemplary fluid pressure control system is shown, whereby the presser bladder 30 of the fluid pressure counterbalancing means is maintained at a selected pressure during make up and break out of joints J. In this schematic system, it will be noted that a pneumatic system is shown, for example, and the conduit 42 which is connected to the presser bladder 30 is selectively connectable to an air source conduit 50 by a suitable selector valve SV and either of a pair of variable pressure regulators consisting of a joint break-out regulator RB and a joint make-up regulator RM.

Valve SU may be of any desired type and is simply shown as a manually actuated detented, two position valve, but in automated systems, the valve SV, obviously, may be pilot operated. In any event,in one position, as shown in FIG. 6, the valve SV connects the bladder conduit 42 with a conduit 51 which leads from the regulator RB to the valve SV so that the pressure in the presser bladder 30 is determined by the setting of the adjustable regulator RB; and in the other position of the valve SV, the bladder conduit 42 will be connected with a conduit 52 which leads from the regulator RM to the valve SV, so that the pressure in the bladder 30 will be determined by the setting of the adjustable regulator RM.

To properly counterbalance the weight of the power tong T during joint break out operations, as illustrated in FIG. 6, the regulator RB is adjusted so that the force derived from the presser bladder 30 due to internal pressure preferably is slightly less than the weight of tong T so that the power tong T will be initially lowered to the starting position of FIG. 3 and as the joint part 1 moves upwardly from the joint part 2, from the position of FIG. 3 to the position of FIG. 1, the power tong T easily moves correspondingly. As previously indicated, such movement occurs only in parallel planes due to the restraint of the connector means C against cocking of the tongs, one relative to the other. On the other hand, when the tong combination is being employed in joint make up operations, and the valve SV is in the alternate position from that shown, the regulator RM is adjusted so that the force derived from the presser bladder 30 due to internal pressure preferably is slightly greater than the weight of the power tong T,

so that the tong T will be initially in the upper position of FIG. 1 spaced from the'back-up tong B, but when the jaws 4 grip the tool joint part 1 to spin the latter into the joint part 2, the tong T is easily moved downwardly as the joint J isprogressively made up.

From the foregoing it will be apparent that the present invention provides a simple solution to the problem of relative tong movement when threaded tool joints of drill pipe are being made up and broken' out. While reference herein to the tool joints of drill pipe has been used for purposes of disclosing the invention in the environment of its main utility in the well drilling and completion field, it will be understood that the invention may also be availed of in other applications, such as making up casing couplings, if desired, or otherwise,

- where the relative movement of one joint part and another is encountered.

The foregoing description and drawing will suggest other embodiments and variations to those skilled in the art, all of which are intended to be included in the spirit of the invention as herein set forth.

What is claimed is: e

1. Pipe tong apparatus comprising: a power tong assembly including a pipe back-up tong unit disposed in horizontally parallel relation below a pipe rotating power tong unit, and presser means interposed between said tong unit to apply separating force between said tong units to substantially counterbalance the weight of said power tong unit as said power tong unit is vertically moved with respect to said back-up tong unit, said counterbalance means comprising a bladder interposed between said tong means, and means for supplying fluid under pressure to said bladder, said bladder acting on said power tong means to apply said force.

2. A tong assembly comprising: back-up tong means for holding a first pipe against rotation, power tong means for rotating a second pipe, said pipes having complementally threaded joint parts engageable and disengageable upon rotation of said second pipe, connector means interconnecting said tong means for movement only toward and away from one another responsive to threaded engagement and disengagement of said joint parts, and presser means interposed between said tong means to apply a force to separate said tong means, whereby to substantially counterbalance the weight of said power tong means when said back-up tong means is supported in a horizontal plane and said pipe is disposed vertically, wherein said presser means comprises a bladder between said tongs.

3. Pipe tong apparatus comprising: a power tong assembly including a pipe back-up tong unit disposed in horizontally parallel relation with a pipe rotating power tong unit; a vertically disposed support column provided with lower bearing means adapted to be mounted to a fixed support in a well derrick and upper bearing means adapted to be connected to the structure of the derrick to provide vertical and horizontal support for said column while permitting said column to pivot horizontally; a vertically movable support collar fitted about said column and supported in alignment for movement up and down said column; a pipe tong support yoke means rigidly mounted to said support collar at its first end to extend horizontally and radially pivotable from said support column; said yoke structure being adapted to receive and support said power tong assembly through a supporting cradle means mounted to the second end of said yoke; and presser means interposed between said tong units to apply separating force between said tong units to substantially counterbalance the weight of said power tong unit through vertical movement of said power tong unit, including a power source providing linear movement mounted in upright position adjacent said column with its lower end mounted to the lower end of said column and its upper end connected through a flexible force transfer means to said support yoke, said flexible force transfer means being anchored relatively between said yoke structure and said support column and being connected across a force transfer crosshead means mounted to the upper end of said power source.

4. Pipe tong apparatus comprising: a power tong assembly including a pipe back-up tong unit disposed in horizontally parallel relation with a pipe rotating power tong unit; a vertically disposed support column provided with lower bearing means adapted to be mounted to a fixed support in a well derrick and upper bearing means adapted to be connected to the structure of the derrick to provide vertical and horizontal support for said column while permitting said column to pivot horizontally a vertically movable support collar fitted about said column and supported in alignment for movement up and down said column; a pipe tong support yoke means rigidly mounted to said support collar at its first end to extend horizontally and radially pivotable from said support column; said yoke structure being adapted to receive and support said power tong assembly through a supporting cradle means mounted to the second end of said yoke; and presser means interposed between said tong units to apply separating force between said tong units to substantially counterbalance the weight of said power tong unit through vertical movement of said power tong unit, wherein said cradle means includes means providing resiliently pivoted vertical support of said back-up tong unit in parallel relation to said yoke structure and providing support with limited vertical and radial movement of said power tong unit with respect to said back-up tong unit and to said support yoke.

5. The positioning apparatus of claim 3, wherein said flexible force transfer means includes chain means an chored to the lower end of said support column and to said support yoke and said force transfer crosshead means includes chain sprocket means.

6. The positioning apparatus of claim 3, wherein said cradle means includes means providing resiliently pivoted vertical support of said back-up unit in parallel relation to said yoke structure and providing support with limited vertical and radial movement of said rotating unit with respect to said back-up unit and to said support yoke.

7. The positioning apparatus of claim 3, wherein said power source comprises a piston and cylinder unit having a piston rod connected to said force transfer crosshead means.

8. Th positioning apparatus of claim 7 including bydraulic fluid power means for actuating said piston and cylinder unit.

9. Pipe tong apparatus comprising: a power tong assembly including a pipe back-up tong unit disposed in horizontally parallel relation with a pipe rotating power tong unit; a vertically disposed support column provided with lower bearing means adapted to be mounted to a fixed support in a well derrick and upper bearing means adapted to be connected to the structure of the derrick to provide vertical and horizontal support for said column while permitting said column to pivot horizontally; a vertically movable support collar fitted about said column and supported in alignment for movement up and down said column; a pipe tong support yoke means rigidly mounted to said support collar at its first end to extend horizontally and radially pivot able from said support column; said yoke structure being adapted to receive and support said power tong assembly through a supporting cradle means mounted to the second end of said yoke; and presser means interposed between said tong units to apply separating force between said tong units to substantially counterbalance the weight of said power tong unit through vertical movement of said power tong unit, said presser means comprising a bladder interposed between said tong means, and means for supplying fluid under pressure to said bladder, said bladder acting on said power tong unit to apply said force.

10. A pipe tong assembly for making up or breaking out threaded joints in well pipe comprising a horizontally disposed back-up tong unit engageable with a vertically disposed, first threaded pipe joint part to hold I said part and said back-up tong unit against rotation and against vertical movement relative to each other, means for supporting said back-up tong unit in a selected vertical position upon a stationary base, a power tong unit disposed above said back-up tong unit and engageable with a second complementally threaded pipe joint part that is aligned with said first threaded pipe joint part for rotating said second threaded pipe joint part into or out of threaded engagement with said first threaded pipe joint part while holding said second threaded pipe joint against vertical movement relative to said power tong unit, and vertically expandable and contactible counterbalance means carried by said back-up tong unit and associated with said power tong unit for yieldably supporting said power tong unit upon said back-up tong unit for vertical movements with respect to said back-up tong unit, said counterbalance means being constructed and arranged to apply an upward force to said power tong unit substantially equal to the weight of said power tong unit as said power tong unit is vertically moved in response to thethreading of said second threaded pipe joint part into or out of threaded engagement with said first threaded pipe joint part, said counterbalance means being the sole means for vertically supporting said power tong unit, said counterbalance means comprising a bladder interposed between said back-up tong unit and said power tong unit, and means for supplying fluid under pressure to said bladder, said bladder. acting on said power tong unit to apply said upward force.

11. A pipe tong assemblyfor making up or breaking out threaded joints in vertically disposed well pipe comprising: a base member; a back-up tong unit; means for mounting said back-up tong unit on said base member and in horizontal disposition, and for vertical movement and also for horizontal movement with respect to said base member; a power tong unit; means for mounting said power tong unit on and superjacent to said back-up tong unit and in horizontal disposition, and for limited vertical movements with respect to said backup tong unit; said back-up tong unit having means releasably engageable with a vertically disposed, lower threaded pipe joint part to hold said part and said backup tong unit against relative rotation and vertical movement therebetween; said power tong unit having means releasably engageable with an upper complementally threaded pipe joint part that is aligned with said lower threaded pipe joint part for rotating said upper threaded pipe joint part into and out of threaded engagement with said lower threaded pipe joint part while holding said upper pipe joint part and said power tong unit against relative vertical movement therebetween; counterbalance means including vertically expandable and contractible means carried by said back-up tong unit, positioned between said back-up tong unit and said power tong unit, and yieldably supporting said power tong unit for vertical movements with respect to said back-up tong unit, said counterbalance means being constructed and arranged to apply an upward force to said power tong unit substantially equal to the weight thereof as said power tong unit is vertically moved with respect to said back-up tong unit in response to the threading of said upper threaded pipe joint part into and out of threaded enagement with said lower threaded pipe joint part; and connector means interconnecting said power tong unit and said back-up tong unit constraining said power tong unit to move horizontally with said back-up tong unit as the latter is moved horizontally with respect to said base member.

12. A pipe tong assembly as defined in claim 11, wherein said means for mounting said back-up tong unit on said base member includes pivot means having a vertical pivot axis for horizontal pivotal movement of said back-up tong unit with respect to said base member.

13. A pipe tong assembly as defined in claim 11, wherein said vertically expandable and contractible means comprises pneumatically expandable and contractible means.

14. A pipe tong assembly as defined in claim 1 1, said vertically expandable and contractible means being disposed substantially at the center of gravity of said power tong unit.

15. A pipe tong assembly as defined in claim 11, said vertically expandable and contractible means comprising a bladder interposed between said back-up tong unit and said power tong unit, and means for supplying fluid under pressure to said bladder, said bladder acting on said power tong unit to apply said upward force.

16. A pipe tong assembly as defined in claim 11, said vertically expandable and contractible means comprising a piston and cylinder means interposed between said back-up tong unit and said power tong unit, said piston and cylinder means acting on said power tong unit to apply said upward forcev 17. A pipe tong assembly as defined in claim 11, wherein said connector means also constrains said power tong unit to move vertically towards and away from said back-up tong unit only on parallel planes.

18. A pipe tong assembly as defined in claim 17 including keeper means for limiting movement of said power tong unit away from said back-up tong unit to a location at which said tong units both engage said joint parts when said joint is to be made up.

19. A pipe tong assembly as defined in claim 11, wherein said vertically expandable and contractible means comprises pressure fluid containing means, said counterbalance means including a make up pressure regulator and a break out pressure regulator for maintaining selected constant pressures in said pressure fluid containing means and to respectively maintain said upward force slightly greater than the weight of said power tong unit during the making up of said joints and slightly less than the weight of said power tong unit during the breaking out of said joints, and means including selector valve means for selectively communicating said regulators with said pressure fluid containing means.

20. Pipe tong apparatus comprising: a power tong assembly including a pipe back-up tong unit disposed in horizontally parallel relation below a pipe rotating power tong unit, presser means interposed between said tong units to apply separating force between said tong units to substantially counterbalance the weight of said power tong unit through vertical movement of said power tong unit with respect to said back-up tong unit; a vertically disposed support column provided with lower bearing means adapted to be mounted to a fixed support in a well derrick and upper bearing means adapted to be connected to the structure of the derrick to provide vertical and horizontal support for said column while permitting said column to pivot horizontally; a vertically movable hollow support collar fitted about said column and supported in alignment for movement up and down said column by roller means rigidly mounted with said roller and mounted in rolling contact with said column; a pipe tong support yoke means rigidly mounted to said support collar at its first end to extend horizontally and radially pivotable from said support column; said yoke structure being adapted to receive and support said power tong assembly through a supporting cradle means mounted to the second end of said yoke; a power source providing linear movement mounted in upright position adjacent said column member with its lower end mounted to the lower end of said support column and its upper end connected through a flexible force transfer means to said support yoke, said flexible force transfer means being anchored relatively between said yoke structure and said support column and being connected across a force transfer crosshead means mounted to the upper end of said power source.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2668689 *Nov 7, 1947Feb 9, 1954C & C Tool CorpAutomatic power tongs
US2969702 *May 19, 1955Jan 31, 1961O & M Machine Company IncApparatus for running thread-jointed oil well strings into and out of oil wells
US3086413 *Aug 22, 1960Apr 23, 1963Mason Carlton Tool CoPower operated pipe wrench and spinning means
US3288000 *Jan 28, 1965Nov 29, 1966Lewis Foster JamesSupporting and positioning mechanism for power tongs
US3518903 *Dec 26, 1967Jul 7, 1970Byron Jackson IncCombined power tong and backup tong assembly
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4545269 *Apr 28, 1983Oct 8, 1985Brissonneau Et Lotz MarineMachine to apply a screwing or unscrewing torque
US4813498 *Mar 3, 1988Mar 21, 1989National-OilwellUse in a derrick
US5060542 *Oct 12, 1990Oct 29, 1991Hawk Industries, Inc.Apparatus and method for making and breaking joints in drill pipe strings
US5081888 *Nov 27, 1989Jan 21, 1992Weatherford, U.S., Inc.Apparatus for connecting and disconnecting threaded members
US5259275 *Sep 22, 1992Nov 9, 1993Weatherford/Lamb, Inc.Apparatus for connecting and disconnecting threaded members
US5390568 *Jun 11, 1993Feb 21, 1995Weatherford/Lamb, Inc.For coupling/uncoupling threaded length of pipe
US5664310 *Jun 23, 1995Sep 9, 1997Bilco Tools, Inc.Combination power and backup tong support and method
US6412553Nov 19, 1997Jul 2, 2002Weatherford/Lamb, L.L.P.Apparatus for positioning a tong and drilling rig provided with such an apparatus
US6412554Mar 14, 2000Jul 2, 2002Weatherford/Lamb, Inc.Wellbore circulation system
US6591471Sep 2, 1998Jul 15, 2003Weatherford/Lamb, Inc.Method for aligning tubulars
US6598501Dec 23, 1999Jul 29, 2003Weatherford/Lamb, Inc.Apparatus and a method for facilitating the connection of pipes
US6668684Dec 7, 2001Dec 30, 2003Weatherford/Lamb, Inc.Tong for wellbore operations
US6684737Dec 24, 1999Feb 3, 2004Weatherford/Lamb, Inc.Power tong
US6745646Jul 14, 2000Jun 8, 2004Weatherford/Lamb, Inc.Apparatus and method for facilitating the connection of pipes
US6814149May 15, 2002Nov 9, 2004Weatherford/Lamb, Inc.Apparatus and method for positioning a tubular relative to a tong
US6827145Mar 19, 2002Dec 7, 2004Weatherford/Lamb, Inc.Methods and apparatus for severing nested strings of tubulars
US6854533Dec 20, 2002Feb 15, 2005Weatherford/Lamb, Inc.Apparatus and method for drilling with casing
US6857487Dec 30, 2002Feb 22, 2005Weatherford/Lamb, Inc.Drilling with concentric strings of casing
US6868906Jun 4, 2002Mar 22, 2005Weatherford/Lamb, Inc.Closed-loop conveyance systems for well servicing
US6896075Oct 11, 2002May 24, 2005Weatherford/Lamb, Inc.Apparatus and methods for drilling with casing
US6899186 *Dec 13, 2002May 31, 2005Weatherford/Lamb, Inc.Apparatus and method of drilling with casing
US6953096Dec 31, 2002Oct 11, 2005Weatherford/Lamb, Inc.Expandable bit with secondary release device
US6994176Mar 5, 2004Feb 7, 2006Weatherford/Lamb, Inc.Adjustable rotating guides for spider or elevator
US7004264Mar 14, 2003Feb 28, 2006Weatherford/Lamb, Inc.Bore lining and drilling
US7013997Dec 15, 2003Mar 21, 2006Weatherford/Lamb, Inc.Methods and apparatus for cementing drill strings in place for one pass drilling and completion of oil and gas wells
US7028585Feb 12, 2002Apr 18, 2006Weatherford/Lamb, Inc.Wrenching tong
US7028586Feb 26, 2001Apr 18, 2006Weatherford/Lamb, Inc.Apparatus and method relating to tongs, continous circulation and to safety slips
US7028787Dec 30, 2003Apr 18, 2006Weatherford/Lamb, Inc.Tong for wellbore operations
US7036610Jul 6, 2002May 2, 2006Weatherford / Lamb, Inc.Apparatus and method for completing oil and gas wells
US7040420Nov 19, 2003May 9, 2006Weatherford/Lamb, Inc.Methods and apparatus for cementing drill strings in place for one pass drilling and completion of oil and gas wells
US7043814Jul 1, 2003May 16, 2006Weatherford/Lamb, Inc.Method for aligning tubulars
US7090254Mar 31, 2000Aug 15, 2006Bernd-Georg PietrasApparatus and method aligning tubulars
US7096982Feb 27, 2004Aug 29, 2006Weatherford/Lamb, Inc.Drill shoe
US7100697Sep 5, 2002Sep 5, 2006Weatherford/Lamb, Inc.Method and apparatus for reforming tubular connections
US7100713Apr 2, 2001Sep 5, 2006Weatherford/Lamb, Inc.Expandable apparatus for drift and reaming borehole
US7104316Mar 24, 2004Sep 12, 2006John Paul HobgoodTong positioning and alignment device
US7107875Mar 5, 2003Sep 19, 2006Weatherford/Lamb, Inc.Methods and apparatus for connecting tubulars while drilling
US7156170Dec 7, 2004Jan 2, 2007Weatherford/Lamb, Inc.Methods and apparatus for severing nested strings of tubulars
US7188548Sep 20, 2004Mar 13, 2007Weatherford/Lamb, Inc.Adapter frame for a power frame
US7225865Jan 10, 2002Jun 5, 2007Weatherford/Lamb, Inc.Apparatus for positioning a tong and drilling rig provided with such an apparatus
US7281451Mar 5, 2004Oct 16, 2007Weatherford/Lamb, Inc.Tong
US7281587Mar 30, 2006Oct 16, 2007Weatherford/Lamb, Inc.Apparatus and methods for tubular makeup interlock
US7353880Nov 15, 2006Apr 8, 2008Weatherford/Lamb, Inc.Method and apparatus for connecting tubulars using a top drive
US7448456Feb 1, 2006Nov 11, 2008Weatherford/Lamb, Inc.Adjustable rotating guides for spider or elevator
US7451826Aug 15, 2006Nov 18, 2008Weatherford/Lamb, Inc.Apparatus for connecting tubulars using a top drive
US7506564Mar 15, 2005Mar 24, 2009Weatherford/Lamb, Inc.Gripping system for a tong
US7513300Mar 20, 2007Apr 7, 2009Weatherford/Lamb, Inc.Casing running and drilling system
US7654325Oct 31, 2007Feb 2, 2010Weatherford/Lamb, Inc.Methods and apparatus for handling and drilling with tubulars or casing
US7665531Nov 15, 2006Feb 23, 2010Weatherford/Lamb, Inc.Apparatus for facilitating the connection of tubulars using a top drive
US7669662Jul 20, 2005Mar 2, 2010Weatherford/Lamb, Inc.Casing feeder
US7694744Jan 12, 2006Apr 13, 2010Weatherford/Lamb, Inc.One-position fill-up and circulating tool and method
US7707913 *Dec 10, 2004May 4, 2010V-Tech AsMethod of disconnecting a pipe length
US7707914May 20, 2004May 4, 2010Weatherford/Lamb, Inc.Apparatus and methods for connecting tubulars
US7757759Apr 27, 2007Jul 20, 2010Weatherford/Lamb, Inc.Torque sub for use with top drive
US7793719Oct 31, 2007Sep 14, 2010Weatherford/Lamb, Inc.Top drive casing system
US7845418Jan 18, 2006Dec 7, 2010Weatherford/Lamb, Inc.Top drive torque booster
US7861618Apr 11, 2006Jan 4, 2011Weatherford/Lamb, Inc.Wrenching tong
US7874352Dec 12, 2006Jan 25, 2011Weatherford/Lamb, Inc.Apparatus for gripping a tubular on a drilling rig
US7882902Nov 15, 2007Feb 8, 2011Weatherford/Lamb, Inc.Top drive interlock
US7896084Oct 15, 2007Mar 1, 2011Weatherford/Lamb, Inc.Apparatus and methods for tubular makeup interlock
US7918273Jan 23, 2003Apr 5, 2011Weatherford/Lamb, Inc.Top drive casing system
US7984757 *Aug 23, 2010Jul 26, 2011Larry G. KeastDrilling rig with a top drive with an air lift thread compensator and a hollow cylinder rod providing minimum flexing of conduit
US8127836Jul 5, 2011Mar 6, 2012Larry G. KeastTop drive with an airlift thread compensator and a hollow cylinder rod providing minimum flexing of conduit
US8181721May 2, 2011May 22, 2012Keast Larry GTorque track and slide assembly
US8251151Feb 17, 2011Aug 28, 2012Weatherford/Lamb, Inc.Apparatus and methods for tubular makeup interlock
US8517090Aug 1, 2012Aug 27, 2013Weatherford/Lamb, Inc.Apparatus and methods for tubular makeup interlock
US8544537Feb 28, 2013Oct 1, 2013Larry G. KeastDrilling rig with a top drive with integral traveling block and airlift thread compensator
US8567512Jan 19, 2011Oct 29, 2013Weatherford/Lamb, Inc.Apparatus for gripping a tubular on a drilling rig
US8590610Feb 28, 2013Nov 26, 2013Larry G. KeastTop drive with integral traveling block and airlift thread compensator
EP0194956A2 *Mar 6, 1986Sep 17, 1986Varco International, Inc.Stand jumping and stabbing guide device and method
WO1990006418A1 *Nov 27, 1989Jun 14, 1990Lucas Brian RonaldApparatus for connecting and disconnecting threaded members
WO2007100259A1 *Mar 1, 2007Sep 7, 2007Nat Oilwell Norway AsTool for connecting and disconnecting tubulars
Classifications
U.S. Classification81/57.34, 81/57.16, 173/164
International ClassificationE21B19/00, E21B19/16
Cooperative ClassificationE21B19/16
European ClassificationE21B19/16
Legal Events
DateCodeEventDescription
Aug 18, 1988ASAssignment
Owner name: HUGHES TOOL COMPANY-USA, 5425 POLK AVE., HOUSTON,
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:BAKER HUGHES INCORPORATED;REEL/FRAME:004944/0763
Effective date: 19880718
Owner name: HUGHES TOOL COMPANY-USA, A DE CORP.,TEXAS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:BAKER HUGHES INCORPORATED;REEL/FRAME:4944/763
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:BAKER HUGHES INCORPORATED;REEL/FRAME:004944/0763
Feb 22, 1983ASAssignment
Owner name: HUGHES TOOL COMPANY, P.O. BOX 2539, HOUSTON, TX. 7
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:BJ-HUGHES INC.,;REEL/FRAME:004098/0273
Effective date: 19821231