weatherford lamb power tong in stock

The 14-100 hydraulic power tong provides 100,000 ft-lb (135,600 N∙m) of torque capacity for running and pulling 7- to 14-in. casing. The tong has a unique gated rotary, a free-floating backup, and a hydraulic door interlock.

Our 14-50 high-torque casing tong provides 50,000 ft-lb (67,790 N∙m) of torque capacity for running and pulling 6 5/8- to 14-in. casing. The tong has a unique gated rotary, a free floating backup, and a hydraulic door interlock.

The 16-25 hydraulic casing tong provides 25,000 ft-lb (33,900 N∙m) of torque capacity for running and pulling 6 5/8- to 16-in. casing. The tong features a unique gated rotary and as many as seven contact points that create a positive grip without damaging the casing.

Rigged up without rig modifications, our 21-300 riser tong is the only tong capable of producing 300,000 ft-lb (406,746 N∙m) of continuous rotational torque in both makeup and breakout mode. The power it achieves in a compact size compares with a conventional 24-in. casing tong.

The 24-50 high-torque casing tong provides 50,000 ft-lb (67,790 N∙m) of torque capacity for running and pulling 10 3/4- to 24-in. casing. The tong features a unique gated rotary, a free-floating backup, and a hydraulic door interlock.

The 30-100 high-torque casing tong provides 100,000 ft-lb (135,600 N∙m) of torque capacity for running and pulling 16- to 30-in. casing. The tong features a unique gated rotary, a free-floating backup, and a hydraulic door interlock.

The 5.5-15 hydraulic tubing tong provides 15,000 ft-lb (20,340 N∙m) of torque capability for makeup and breakout of 1.66- to 5.5-in. tubing and premium or standard connections on corrosion‑resistant alloy tubulars. The tong features an ergonomic, lightweight design with a free-floating hydraulic backup.

The 7.6-30 hydraulic tubing tong provides 30,000 ft-lb (40,670 N∙m) of torque capability for makeup and breakout of 2 3/8- to 7 5/8-in. tubing and premium or standard connections on corrosion‑resistant alloy tubulars. The tong features an ergonomic, lightweight design with a free-floating hydraulic backup.

Our SpeedTork 8.0-70 tong provides torques up to 70,000 ft-lb (94,900 N∙m) and 360° rotation in makeup and breakout operations. It can torque drillpipe connections, drillstring components, drilling tools, packers, couplings, and valves.

The 9-5/8” power tong with Rineer GA15-13 two-speed hydraulic motor, motor valve, lift cylinder valve, rigid sling, FARR® hydraulic backup, configured for compression load cell.

Power tongs are an essential tool in the drilling industry and are used to make up, break out, apply torque and to grip the tubular components. We are distributors for both Starr Power Tongs and McCoy Global hydraulic power tongs in multiple sizes and torque ranges from high torque to low torque that can be used to run both casing, drill pipe and tubing. When determining which power tong is best for your project, you will want to select the power tong that best fits your tubular size ranges and torque required.

All of our power tongs are available with either the McCoy\\\\\\\\\\\\\\\"s patented WinCatt data acquisition software recently updated to the MTT systems or AllTorque\\\\\\\\\\\\\\\"s computer monitoring system for all the torque and turn control system needed in today\\\\\\\\\\\\\\\"s market for the making of tubular connections. Discover our wide selection of McCoy and Starr casing tongs, tubing tongs and power tongs for sale below!

Pipe tongs are employed in the oil and gas industry to grip and rotate drill pipe. Some operate manually, while others are power assisted. It is necessary to grip drill pipe with extremely high compressive forces while applying a high degree of torque in order to break apart or tighten threaded pipe connections. In order to develop these forces, power tongs have been designed for gripping and rotating pipe. Back-up power tongs have been designed to hold one joint or segment of pipe while power tongs grip and rotate the adjacent joint of pipe. As can be seen, the gripping force of the back-up power tongs must be at least equal to that of the associated power tongs. Examples of power tongs and back-up tongs may be seen in the following U.S. Patents:

While back-up power tongs must develop a significant gripping force, rotary action is not required. The combination rotary/gripping action of power tongs has historically been produced by a cam assembly. Prior art back-up power tongs have also employed cam action to grip and hold pipe. As can be seen by referring to U.S. Pat. No. 4,290,304, cam action has also been employed to impart gripping forces in back-up power tongs. The assemblies comprising prior art back-up power tongs have heretofore been complicated and required a conversion of rotative forces to compressive forces, resulting in heavy, inefficient and expensive devices.

As can be seen in the above listed patents, the actual contact with the pipe is accomplished through the use of die inserts which are pressed into some type of jaw member. When the power tongs are in operation the die inserts are urged against the drill pipe and torque is applied. Examples of various configurations of die inserts may be found in FIG. 4 of U.S. Pat. No. 4,404,876 (see reference numerals 144,148 and 149), FIG. 5 of U.S. Pat. No. 4,082,017 (see reference numeral 34), and in FIGS. 4 and 5 of U.S. Pat. No. 4,290,304 (see reference numeral 92). As can be seen, the die inserts are relatively narrow in comparison to the jaw members to which they are attached, as well as to the total area of pipe covered by the jaw members. The die inserts are most commonly held in place through a dovetail key arrangement. Those die insert configurations illustrated above are virtually a standard in the industry.

Therefore, it is an object of this invention to provide back-up power tongs which are inexpensive to construct, yet provide the necessary gripping force to hold a pipe against rotation.

It is another object of this invention to provide back-up power tongs in which dies may be easily changed in order to adapt the back-up power tongs to different pipe sizes.

It is still another object of this invention to provide back-up power tongs which are lightweight, have a minimum number of moving parts, and have easily replaceable parts.

Accordingly, back-up power tongs are provided, for holding a tubular member, such as a drill pipe, against rotation of a connected tubular member, the tongs comprising a body, having a center opening of sufficient size for the tubular member to pass therethrough, a slot communicating between the edge of the body and the center opening, and a cavity disposed within the body. A plurality of jaw members are disposed within the body around the perimeter of the center opening, each jaw member having a concave surface generally conforming to the curvature of the tubular member and facing the interior of the opening so as to be grippingly engageable with the tubular member. At least one cylinder assembly is disposed within the cavity and fixedly connected to one jaw member so as to extend or retract the jaw member on a radial path centered at the center of the tubular member.

As shown in FIG. 1, the jaw assembly 5 comprises two major pieces--the jaw member 6 and the die 7. The jaw member 6 can be made to accommodate any of several different types of tongs or other pipe gripping devices currently on the market. For example, the jaw 6 shown in the figures is provided with a pin 8 which allows the jaw member 6 to pivot within a set of power tongs. The die 7 is slidably attachable to the jaw member 6. The configuration of the jaw assembly 5 allows for a much larger area of contact when the die 7 is urged against a tubular member 9, such as a drill pipe, eliminating pipe deformation caused by jaw member/die combinations currently in use.

As shown in FIGS. 5-7, the jaw assembly 5 of the invention may be utilized as a component of a new design for back-up power tongs 100. In FIG. 5, back-up tongs 100 are shown connected to first joint 101 of drill pipe, and to a conventional set of power tongs 200. Power tongs 200 are grippingly connected to a second joint 102 of drill pipe. In order to tighten or loosen threaded connection 103, power tongs 200 grip and rotate second joint 102 while back-up tongs 100 grip and hold first joint 101. Back-up power tongs 100 employ a simplified direct pressure hydraulic gripping action in lieu of conventional cam operated tong systems. The back-up tongs 100 generally comprise a hollow body 104, having a body cavity 128 containing at least two jaw assemblies 5 and and least one cylinder assembly 109. Access to body cavity 128 is provided by removing cover 110. Body 104 is rigidly connectible to power tongs 200 via frame assembly 105. Conventional means, such as a load cell 106 and gauge 107 may be employed to indicate torque. Legs 201 are provided on many power tongs 200 to align the power tongs 200 with back up tongs 100 and to support power tongs 200 when resting on a flat surface. Alignment holes 134 in body 104 may be provided for legs 201.

As shown in FIG. 6, it is preferable that the backup tongs 100 have three jaw assemblies 5, radially spaced around a center opening 111 so as to maximize circumferential contact with the first joint 101. Slot 108 provides access to center opening 111. As previously described, each jaw assembly 5 comprises a jaw member 6 and a die 7, with their previously described features. As shown in FIG. 7, die 7 maybe additionally secured by cover plate 131 and cover plate screws 135. Preferably, jaw assemblies 5 are each fixedly connected to a cylinder assembly 109, such that cylinder assembly 109 extends or retracts jaw assembly 5 on a radial path centered at the center of first joint 101. Cylinder assemblies 109 are driven by hydraulic pressure, thus providing a means for applying direct gripping pressure to first joint 101 without the complicated and inefficient cam assemblies of the prior art.

By providing three cylinder assemblies 109 operated by a common fluid system, back-up tongs 100 provide a simplified, yet powerful back-up device. When cylinder assemblies 109 are coupled with jaw assemblies 5, variations in the diameter of first joint 101 may be accommodated by simply changing dies 7. Of course, it should be understood that conventional jaw assemblies could be utilized in conjunction with back-up power tongs 100. A further simplified version of back-up tongs 100 would comprise a stationary jaw assembly 5, positionable against first joint 101, and at least one cylinder assembly 109 and associated jaw assembly 5, positionable on the opposite side of first joint 101 from the stationary jaw assembly 5. Of course, other embodiments of the invention will occur to those skilled in the art, and are intended to be within the scope and spirit of the following claims.

The tongs head of oscillating double jaw plate is made by precision casting, in this way, not only the outline is beautiful, but also the strength is high and the dismounting is convenient. The perfect design can ensure that the clamping is reliable and the backslide is easy.It adopts ribbon brake apparatus, and the brake moment is high. The operation is so easy that it’s convenient to repair and change.With hydraulic torque indicator and installation interface of torque gauge, it can equip model NKY torque control recorder, so as to realize the computer management.

This invention is directed to apparatus and methods for aligning wellbore tubulars; and to power tongs used in making and breaking joints of tubular members such as wellbore casing and tubing; to parts thereof; including, but not limited to gripping elements, and methods of their use.

During the drilling of oil and gas wells and the production of materials therefrom, various operations require the connection and disconnection of successive lengths of threaded tubulars such as pipe, casing, or tubing. Tools known as tongs are used to "make" and "break" such connections. Certain known power tongs have a body, a rotary rotatably mounted in said body and at least one active jaw which, on rotation of the rotary is cammed against a pipe in the rotary and grips it for rotation with the rotary. In known arrangements the camming action is generated by a cam member which is bolted to the rotary and is shaped so that the active jaw is cammed against the pipe on rotation of the rotary relative to the active jaw in one sense and will be released on rotation of the rotary relative to the active jaw in the opposite sense.

With known tongs high torques are applied to tubulars due to combinations of factors such as thread sealing requirements, the presence of corrosion, the existence of distortion, and pipe size and weight. Both in the "make" direction of rotation when a shoulder is suddenly encountered, and in the "break" direction at initial engagement of the tong and disengagement of the threads high shock forces may arise; e.g., with a power-driven tong, in excess of 50,000 foot-pounds of torque may be exerted, while relatively small die elements on jaws of the tong engage the pipe with extremely high force loadings. Slippage occurs and pipe surfaces become marred, marked, indented, or otherwise damaged.

Dies for gripping jaws have been provided with multiple serrations, or penetration features, to provide the interference contact at the joint surface. Grip element penetration into the joint surface is limited and controlled. The distribution and balance of grip element energizing forces are critical factors in the design, development and evaluation of such tong mechanisms. Linkages, levers, wedges, and cams are used to balance force components. Grip elements, or dies, are accurately disposed within carrier bodies, or jaws, which span a circumferential segment of the joint surface.

Uneven die loading can cause excessive indentation, marring or damage to a tubular surface. Drag or braking devices are used in certain tongs to effect proper biting of the dies relative to the pipe. The head or other member supporting the dies is frictionally restrained to insure that the dies do not simply rotate with the rotary as the rotary is driven.

Other tongs use an endless belt, chain or flexible material loop for gripping a tubular. Such tongs are disclosed in U.S. Pat. Nos. 3,799,010; 3,906,820; 3,892,140; 4,079,640; 4,099,479; and 4,212,212. There are a variety of problems associated with certain of these tongs:

Jaw/die tongs and the belt/chain tongs are used with relatively hard and rigid metal tubulars such as casing and tubing. If these tongs are used with thick tubulars or tubulars made from relatively "softer" metals or from premium metals such as high alloy steels or low carbon steels or tubulars made from non-metal materials such as fiber glass, they often literally chew up the tubular. The use of strap wrenches is inadequate since the torque applied with such wrenches cannot be precisely controlled.

Certain tubulars are treated with a rust or corrosion resistant material or coating. If the coating is indented, gouged, or broken, its protective purpose is defeated. Producing enough force in a tong to join such tubulars while not injuring a protective coating presents a dilemma.

The present invention, in certain embodiments, discloses a power tong for joining tubulars so that marking of, indentation of, and surface injury to tubulars are reduced or eliminated. In one aspect a power tong is provided and a method of its use for handling tubulars coated with a corrosion-resistant material which should not be broken or penetrated. In one embodiment such a tong has one or more gripping jaws with gripping elements made of aluminum alloys, zinc, zinc alloys, aluminum, brass, bronze, cermet, plastic, fiberglass, metal alloys, or a combination thereof which present a smooth face (straight or curved) to a tubular without any teeth, pointed projections, or toothed dies. In one aspect the gripping elements are releasably connected directly to jaws. In another aspect the gripping elements are releasably connected to a jacket or holder which itself is releasably connected to a jaw.

In one aspect the cylinder(s) are powered by a small air-driven hydraulic pump with an hydraulic fluid reservoir mounted on a plate on the movable or fixed jaw. Air is supplied to activate a motor of the pump and the pump then provides hydraulic fluid to move a piston of the hydraulic cylinder(s). The motion of the cylinder moves the movable jaw on its roller to travel to a pre-load position on the cam. The cylinder applies pressure until the hydraulic pressure is released. A hydraulic fluid accumulator and a valve may be used to maintain hydraulic pressure at all times so that the cylinder(s) continuously maintain the desired load on the jaw until the air supply to the pump is removed.

In another aspect the cylinders are connected to a rotary of the tong or to any other member that rotates with the rotary rather than to a fixed jaw. Such a pre-load system may, according to this invention, be used with any tong including a tong that does use toothed dies.

In one embodiment the present invention discloses a gripping arrangement for a tong with a sheet of grit which is preferably bonded to a carrier plate. In another embodiment the gripping arrangement comprises a layer of flexible material having a smooth flat surface or a surface with ridges and valleys, for example in the fashion of the surface of a file. The flexible material, in one aspect, is metal, for example sheet aluminum, zinc, brass, bronze, zinc alloy, aluminum alloy, stainless steel, or steel having a thickness of about 1.5 mm. The layer of flexible material may be used in conjunction with a carrier plate or on its own. In a further embodiment the gripping arrangement may comprise a layer of perforate material one of both surfaces of which are preferably coated with grit to facilitate adhesion. The layer will typically be formed from metal having a thickness of about 1.5 mm. The layer may be used in conjunction with a carrier plate or used on its own. In yet another embodiment the gripping arrangement may comprise a layer of expanded mesh, e.g. metal mesh, which has been flattened. One or both surfaces of the expanded mesh may be coated with grit and the layer may be used in conjunction with a carrier plate or used on its own. The grit may comprise, for example, diamond dust, particles of silicon, zircon, tungsten carbide and mixtures thereof. The gripping arrangement may comprise end plates which are attached to the carrier plate. Preferably, the carrier plate is provided with side flanges for insertion into a jaw holder. The present invention also provides a jaw assembly fitted with a gripping arrangement in accordance with the present invention. Preferably, the jaw assembly includes a jaw holder having an arcuate recess which accommodates an arcuate pad of resilient elastomeric material which supports said gripping arrangement. Advantageously, at least one shim is provided which is disposed between said arcuate pad of resilient elastomeric material and said gripping arrangement. The shim will be flexible and generally from 0.5 mm to 1.0 mm thick and made from sheet metal. The present invention also provides a tong fitted with at least two such jaw.

In one embodiment the present invention discloses an apparatus for aligning tubulars and includes a guide on one of a power tong and a backup tong. In one embodiment the apparatus has a socket centralizer mounted on said one of said power tong and said backup tong. In one aspect, said one of said power tong and said backup tong is said power tong. In another embodiment, the apparatus includes a power tong and a backup tong, and the guide is mounted on the power tong and apparatus is provided to maintain the power tong and the backup tong in a certain juxtaposition during a stabbing operation. Preferably, said apparatus includes locating rods on one of the power tong and the backup tong and blocks shaped to receive at least the ends of the locating rods on the other of the power tong and the backup tong. Advantageously, the backup tong is provided with at least two prismatic jaw assemblies to locate the backup tong in fixed juxtaposition with respect to a tubular being gripped.

The present invention, in one aspect, provides a jaw unit for use in a tong, which jaw unit comprises a jaw holder and a jaw movable with respect to said jaw holder, characterized in that said jaw is slidably mounted on said jaw holder. Preferably, said jaw is slidable with respect to said jaw holder about an arcuate path. Advantageously, said jaw has a gripping surface which is substantially arcuate for gripping the surface of a tubular and the center of curvature of such arcuate path lies between the center of curvature of said grip ping surface and said arcuate path. The gripping surface may be a continuous surface or defined by several spaced apart gripping elements. Preferably, the center of curvature of said arcuate path lies between the center of curvature of said grip ping surface and said gripping surface. Advantageously, the center of curvature of said arcuate path is substantially midway between the center of curvature of said gripping surface and said gripping surface. Preferably, one of said jaw and said jaw holder is provided with an arcuate track which defines said arcuate path, and the other of said jaw and said jaw holder is slidably mounted in said arcuate track.

The present invention also provides a jaw assembly comprising two jaw units in accordance with the present invention. Preferably, said jaw units are mounted for pivotal movement about a common pivot shaft. Advantageously, said jaw assembly includes means which bias said jaw units apart. The present invention also provides a rotary fitted with a jaw unit in accordance with the present invention, a rotary fitted with a jaw assembly in accordance with the present invention, and a tong fitted with a rotary in accordance with the present invention.

One of the features of existing tongs is that their rotaries are difficult to furnish. Thus, routine maintenance usually involves dismantling the whole rotary, checking the parts and reassembling the whole. While this is a straightforward procedure in the clean conditions of a workshop it can be problematic when carried out in a muddy field, in sand or in snow. The present invention aims to help solve this problem and provides a rotary which comprises a top section, a bottom section, and a peripheral wall therebetween, characterized in that at least one of said top section and said bottom section is provided with an elongate slot which, when said rotary is in use, accommodates a pivot shaft on which a jaw assembly can be pivotally mounted.

Jaw holders and jaws for tongs are traditionally machined from a solid piece. This is a comparatively expensive procedure. The present invention proposes to make such parts from a stack of individually cut laminations.

Such methods and devices including a power tong with at least one jaw with at least one tubular gripping element having a smooth gripping surface (flat or curved) and, in one aspect, such an element which is flexible;

FIG. 2A is a perspective view of a tubular connection system according to the present invention. FIGS. 2B and 2C are perspective views of a casing tong of the system of FIG. 2A.

FIG. 5A shows schematically an initial position of elements of a tong system according to the present invention. FIG. 5B shows pre-loading on a pipe of the jaws of the system of FIG. 5A. FIG. 5C shows a tubular gripped with the system of FIG. 5A.

FIGS. 1A-1C show a typical prior art power tong that uses fixed jaws and a movable jaw to grip pipe for tubular disconnecting and connecting operations. An outer case houses a powered rotary to which the jaws are mounted. A cam surface of the rotary moves a movable (ACTIVE or MASTER) jaw into (and away from) gripping contact with a tubular, e.g. pipe. Each jaw has toothed gripping inserts to facilitate engagement with the surface of the tubular (see FIG. 1B). FIG. 1C shows the tong in an "OPEN" position in which the tubular is not gripped.

The tong shown in FIG. 1A is a Weatherford Model 14.5-50 High Torque Tong. The brochure "New ! Weatherford Model 14.5-50 High Torque Tong," (1991) and the manual entitled "Model 14.5-50 Hydraulic Power Tong Installation, Operation and Maintenance" (1993) are submitted herewith and incorporated herein fully by reference for all purposes. It is to be understood that the teachings of the present invention are applicable to any tong and any tong system that has one or more gripping elements or jaws and that the Model 14.5-50 tong is shown here for illustrative purposes and not by way of limitation of the scope of the present invention.

As shown in FIG. 2A a system 10 according to the present invention includes a power tong 100 according to the present invention which is like the tong of FIG. 1A but which also includes a unique jaw system 110 with inserts 150 on fixed jaws 120 and insert 152 on movable jaw 122 and at least one jaw pre-load assembly like that shown in FIG. 5A. The system 10 includes a free floating backup tong 12.

As shown in FIGS. 2B and 2C, rods 112 are connected to the movable jaw 122. The inserts 150 are on fixed jaws 120 and the insert 152 is on a movable jaw 122 (corresponding to the fixed jaws and active jaw, respectively, of the tong of FIG. 1A).

FIGS. 4A-4G illustrate an alternative jaw mounting system in which holders are interposed between jaw bodies and inserts. The holders protect the jaws from damage if the inserts wear down and a variety of different types and/or sizes of inserts may be used with and interchanged on a single holder. In one aspect it is within the scope of this invention to use these holders to mount conventional toothed dies to a tong jaw and to use them for easy substitution of new and/or different dies.

FIG. 4A shows a jaw system 400 for a tong (like the tong of FIG. 2A) which has two fixed jaws 402 and a movable (movable toward and away from a tubular to be gripped 403) jaw 404. Each jaw 402 has a jaw body 405 with a holder 406 secured thereto. In one aspect dovetail keys 407 secured to the holder or releasably mounted thereto fit in corresponding slots 408 of the jaw bodies 405 to releasably mount the holder 406 to the body. In one aspect dovetail keys 409 releasably mount the holders 406 to jaw bodies 405. The dovetail keys 409 are releasably held in corresponding recesses 411 in the holders 406. One or more dovetail keys 409 may be used (two shown for each holder 406).

FIG. 5A shows a tong system 500 with a tong having a movable rotary 502, fixed jaws 504, 505, and a movable jaw 506 (remainder of tong, not shown, like the tong of FIG. 2A; like the tong of FIG. 1A, but with the added features discussed here). Pins 520 pin the fixed jaws to the rotary. Inserts 522 on the fixed jaws 504, 505 are like the inserts described herein for other fixed jaws. Insert 524 on the movable jaw 506 is like other inserts described herein for movable jaws. A pre-load cylinder 508 to assist in make-up is pivotably connected at one end to the fixed jaw 505 and at the other end to the movable jaw 506. A pre-load cylinder 510 to assist in break-out is pivotably connected at one end to the fixed jaw 504 and at the other end to the movable jaw 506. It is within the scope of this invention for the ends of cylinders connected to the fixed jaws to instead be secured to the rotary or to a support ring or other member that rotates with the rotary. It is within the scope of this invention to employ one cylinder interchangeable between the positions of the cylinders 508 and 510 (FIG. 5A) or one cylinder connectible to the fixed jaw 506 at one end for break-out and at the other end of the fixed jaw 506 for make-up with the other cylinder end secured to the rotary. Rollers 530 rotatably mounted on the movable jaw 506 co-act with cam surfaces 532 on the rotary 502 to move the jaw 506 to operative and inoperative positions.

Air in a line 640 selectively applied with a control system 650 (e.g. mounted on the rig floor, on the tong or remote controlled) selectively actuates the pump 630 to pump fluid through the valve 602 to the pre-load cylinders. The directional control valve 602 is either manually operated or operated by remote control. Correct fluid pressure is monitored with a gauge 651.

As shown in FIG. 5C the tubular 650 has been gripped due to the action of the pre-load cylinder 510 with a suitable pre-load force (e.g., but not limited to, about 500, 1000, 5000, 10000 or 50000 pounds of force). This force is sufficient that when the rotary 502 of the tong is rotated the jaws do not slip on the tubular 650; but the pre-load force is sufficiently low that the jaws do not mark or damage the tubular 650.

FIG. 8 shows schematically a top view of a power tong according to the present invention. A power tong T has an hydraulic motor M with control/monitor apparatus C on a tong case S. A movable jaw J is moved and rotated by a rotary R which is moved by interconnection, via appropriate gearing, by the motor M. Fixed jaws F and G are secured to the rotary R. A first pre-load cylinder D connects the movable jaw J to the fixed jaw G for applying a pre-load to the movable jaw for make-up operations. A second pre-load cylinder L connects the movable jaw J to the fixed jaw F for applying a pre-load to the movable jaw for break-out operations. An insert I (any insert disclosed herein) is secured to the movable jaw J and inserts K (any insert disclosed herein) are secured to the fixed jaws F and G.

FIG. 9 shows a tong jaw 450 according to the present invention with an insert 454 (any insert disclosed herein) and rods 452 secured thereto, e.g. by welding. The rods 452 provide a member to which either a cylinder body or a piston of a pre-load piston cylinder apparatus is connectible. Instead of the rods 452 as shown which extend from above the jaw 450 to a point below it, only rod sections may be used secured to one or both sides of the jaw to provide a securement member for an end of a pre-load apparatus.

According to the present invention a variety of apparatuses and devices may be employed to pre-load a tong jaw having one or more smooth faced gripping insert elements thereon. In one aspect a manually activated pre-load cylinder is used which has fluid or material manually introduced therein to apply a pre-load or manually removed therefrom to release a pre-load. In another aspect a pre-load cylinder is pivotably secured at one end to a rotary or part thereof and the other end is releasably connectible to either end of a movable jaw so that a pre-load may be applied, selectively, to either end of the movable jaw for make-up or break-out operations as desired. In one aspect such a pre-load cylinder has a rod with an end member receivable in and movable in a slot in the movable jaw or there are recesses at either end of the jaw for holding the end member of the rod so that a pre-load can be applied. A secondary small cylinder may be used to selectively move the pre-load cylinder in the jaw slot or it can be moved manually. In another embodiment the tong"s movable jaw has one or more upwardly projecting lugs engageable by a forked piston rod end of a pre-load piston/cylinder that is attached to the rotary. The rotary is rotated so that the jaw is cammed into the pipe to be rotated in a pre-load position and then the forked rod is removed for further tong operations.

In use, two or more jaw assemblies are placed in a tong and are disposed around a length of casing. The jaw assemblies 1001, 1001" are then advanced radially inwardly in the direction of arrows "A" (FIG. 12) until they engage and firmly grip the casing. Because of the flexible construction of the gripping arrangement 1007, the shims 1006 and the arcuate pad 1004, the friction layer 1009 substantially conforms to the circumference of the casing and grips the casing with a substantially uniform gripping action. Once the casing has been firmly gripped the jaws are rotated by the tong in the usual manner. It will be noted that circumferential forces applied to the friction layer are transmitted through the carrier plate 1008 so that any local loads caused, for example by an irregularity in the surface of the casing are redistributed by the carrier plate 1008 and transmitted to the jaw holder 1002 via the side flange 1011 and the arcuate pad 1004 (see FIG. 18).

Referring to FIGS. 19A and 19B of the drawings there is shown a conventional tong assembly which is generally identified by the reference numeral 2001.

The power tong 2002 comprises a pair of gates 2004, 2005 which are held together in the position shown by latch 2006. When the latch 2006 is released the gates 2004, 2005 can be swung open by admitting hydraulic fluid to piston and cylinder assemblies 2007 and 2008. The power tong 2002 also contains a rotary 2009 which is provided with four jaw assemblies 2010. The rotary 2009 can be rotated by a hydraulic motor 2011.

The backup tong 2003 is provided with two gates 2012, 2013 which are held together by latch 2014 but which, when latch 2014 is released can be swung to an open position.

Once the pin is correctly located the stabbing guide is removed. The gates 2004, 2005 of the power tong 2002 and the gates 2012, 2013 of the backup tong 3 are then opened and the tong assembly 2001 moved towards the casing until the lower length of casing lies within the backup tong 2003 and the upper length of casing lies within the power tong 2002. The gates 2004, 2005, 2012, 2013 are then closed and latched. Jaw assemblies in the backup tong are then advanced to engage the lower length of casing while jaw assemblies in the power tong 2002 are advanced to grip the upper length of casing. The hydraulic motor 2011 is then actuated to turn the rotary 2009 and rotate the upper length of casing relative to the lower length of casing. The tong assembly 2001 is supported by a pneumatic lifting cylinder 2015 which enables the power tong 2002 to move towards the backup tong 2003 as the pin enters the socket. Reaction forces are transmitted by columns 2016 disposed to either side of the tong assembly 2001 and by a series of levers in a known manner. It should be noted that the power tong 2002 is free to move in a plane parallel to the backup tong 2003 within certain limits.

The apparatus 2100 comprises a tong assembly 2101 which is generally similar to the tong assembly 2001 shown in FIGS. 19A and 19B and parts of the tong assembly 2101 similar to the tong assembly 2001 have been identified by similar reference numerals in the "2100" series.

Turning first to the guide 2117 it will be seen from FIG. 21B that this comprises four identical components 2118 which are bolted to the top of the power tong 2102. As best shown in FIG. 21C each component is tapered so as to guide the pin of an upper casing to the center of the opening of the power tong 2102.

Referring now to FIG. 22, the backup tong 2103 is provided with three prismatic jaw assemblies 2119a, 2119b, and 2119c which, when actuated, hold a lower length of casing 2120 in a fixed position relative to the backup tong 2103.

As shown in FIG. 23 the backup tong 2103 is provided with three upwardly extending locating rods 2121 which are each provided with a conical tip 2122. Similar, the underside of the power tong 2102 is provided with three blocks 2123 each of which is provided with a recess 2124 shaped to receive the conical tip 2122 of a respective locating rod 2121.

In use, the lower length of casing 2120 is first secured by slips on the rig floor in the usual manner. The gates 2112 and 2113 of the backup tong 2103 are then opened and the tong assembly 2101 moved into position with the backup tong 2103 circumjacent the lower length of casing 2120 and immediately below the socket 2125 thereof.

The gates 2112 and 2113 are then closed by hydraulic piston and cylinder assemblies 2126 and 2127 and the latch 2114 closed. The prismatic jaw assembly 2119a is fixed while prismatic jaw assemblies 2119b and 2119c are automatically advanced by a predetermined distance when the latch 2114 is closed. This grips the lower length of casing firmly and also ensures that the backup tong 2003 is in a fixed position relative to the lower length of casing 2120. The position thus far attained is shown in FIG. 23.

At this time pneumatic lifting cylinder 2115 is extended which lowers the backup tong 2003. The conical tips 2122 of the locating rods 2121 enter the recesses 2124 of the blocks 2123 and thus locate the power tong 2002 with respect to the backup tong 2003. This in turn locates the guide 2117 with respect to the lower length of casing 2120 so that the center of the guide 2117 is coaxial with the axis of the lower length of casing 2120. This position is shown in FIG. 24.

The power tong 2102 is then raised so that the blocks 2123 are well clear of the locating rods 2121. At this point the jaw assemblies in the power tong 2102 are applied to the upper length of casing 2128 and the hydraulic motor 2111 actuated to rotate the rotary and screw the pin 2129 into the socket 2125. During the procedure the power tong 2102 moves towards the backup tong 2103. However, even when the joint is tightened to the required torque the blocks 2123 still lie a short distance above the conical tips 2122 of the locating rods 2121.

At this stage the jaw assemblies of both the power tong 2102 and the backup tong 2103 are relaxed, the gates 2104, 2105, 2112 and 2113 opened and the tong assembly 2101 retracted in preparation for the casing being lowered. It will be noted that one component 2118 of the guide 2117 is mounted on each of the gates 2104, 2105 and accordingly the guide 2117 opens and closes with the gates 2104, 2105.

For certain applications a backup tong is not required, for example where the power tong can conveniently be restrained by a chain attached to the drilling tower.

The apparatus 2200 comprises a power tong 2202 which is generally similar to the power tong 2002. The basic construction of the power tong 2202 is similar to the power tong 2002 and parts having similar functions have been identified by the same reference numeral in the "2200" series.

The main differences are that the apparatus 2200 does not include a backup tong and that it is provided with a guide 2217 and a socket centralizer 2230.

In use, the lower length of casing 2220 is first secured by slips (not shown) with the socket 2225 facing upwardly close to the slips. The power tong 2202 is then lowered onto the socket 2225 so that the socket 2225 enters the socket centralizer 2230 and aligns the socket centralizer 2230, the socket 2225 and the guide 2217. The upper length of casing 2228 is then lowered so that its pin 2229 enters the guide 2217, is center there by and enters the socket 2225. At this point power tong 2202 is raised. Its jaw assemblies are then advanced to grip the upper length of casing 2228 which is then rotated to screw the pin 2229 into the socket 2225. Once the joint is tightened to the required torque the gates 2204, 2205 are opened and the power tong 2202 withdrawn.

The embodiment shown in FIG. 29 is generally similar to that shown in FIG. 28 except that the apparatus 2300 also includes a backup tong 2303. Since the upper length of casing 2328 and the lower length of casing 2320 are being aligned by the guide 2317 and the socket centralizer 2330 no special arrangements need be made for aligning the power tong 2302 and the backup tong 2303.

The procedure for connecting the upper length of casing 2328 to the lower length of casing 2320 is as follows. First, the lower length of casing 2320 is secured in slip (not shown). The gates 2312, 2313 of the backup tong are then opened and the apparatus 2300 maneuvered so that the lower length of casing 2320 is disposed within the backup tong 2303. The power tong 2302 is then lowered until the socket 2325 on the lower length of casing 2320 is received within the socket centralizer 2330. The upper length of casing 2328 is then lowered until the pin 2329 passes through guide 2317 and enters the socket 2328. Only at this stage are gates 2312, 2313 closed and the jaw assemblies of the backup tong 2303 activated to grip the lower length of casing 2320. The power tong 2302 is then raised and its jaw assemblies activated to grip the upper length of casing 2328 which is then rotated to cause the pin 2329 to enter the socket 2325 and the joint to be tightened to the desired torque. The jaw assemblies are then relaxed and the gates 2304, 2305, 2312, 2313 of the power tong 2302 and the backup tong 2303 opened prior to retracting the apparatus 2300.

Various modifications to the embodiments described are envisaged, for example, if desired, the guide and the socket centralizer could be mounted on the backup tong 2303 rather than the power tong 2302. Alternatively, the guide could be mounted on the backup tong without a socket centralizer. Such an arrangement is shown in FIG. 30.

The embodiment shown in FIG. 30 is generally similar to that shown in FIG. 19a and 19b and parts of the tong assembly 2401 similar to the tong assembly 2001 have been identified by similar reference numerals in the "2400" series. One difference is that the top of the backup tong 2403 is provided with a guide 2417.

In use, the lower length of casing 2420 is first secured by stops 2431 on the rig floor in the usual manner. The gates 2412 and 2413 of the backup tong 2403 are then opened. Since two of the four components 2418 of the guide 2417 are mounted on the gates 2412 and 2413 the guide 2417 opens with the gates 2412 and 2413 so that the lower length of casing 2420 can enter the backup tong 2403 when the carriage 2432 which supports the apparatus 2400 is advanced towards the casing 2420 on rails 2433. When the lower length of casing 2420 is fully within the backup tong 2403 the gates 2412 and 2413 are closed. The components 2418 of the guide 2417 have a stepped interior (not visible in FIG. 30) so that the lower part of each component 2418 touches the socket on the top of the lower length of casing 2420 whilst the upper part of the interior of each component 2418 tapers inwardly to form a funnel. Once the lower length of casing 2420 has been gripped the upper length of casing 2428 is lowered through the power tong 2402 towards the lower length of casing 2420. The guide 2417 guides the pin on the bottom of the upper length of casing 2428 into the socket. The power tong 2402 is disposed a small distance above the guide 2417. Once the pin of the upper length of casing 2428 has entered the socket on the lower length of casing the jaws of the power tong 2402 are applied to the upper length of casing 2428 which is rotated until the joint reaches the desired torque.

Referring now to FIG. 38, the rotary 3100 is shown fitted in a tong 3116. As shown in FIG. 39 and 40, the rotary 3100 is formed as a one piece casting which comprises a top section 3117, a bottom section 3118, and a peripheral wall 3119 on which is formed a toothed track 3120. Both the top section 3117 and the bottom section 3118 are provided with an elongate slot 3121, 3122 respectively. Each elongate slot 3121, 3122 has its center of curvature on the center of rotation of the rotary 3100.

As can be seen in FIG. 38 and FIGS. 31 to 37, the sides of the rotary 3100 are provided with cams 3128, 3129, 3130 and 3131 which are screwed to the rotary 3100. The rotary 3100 is located in the tong 3116 by nine guide rolls 3132, five of which are visible in FIG. 38. The guide rolls 3132 each have an upper and a lower roller which bears against the peripheral wall 3119 of the rotary 3100 above and below the toothed track 3120 respectively.

The present invention relates generally to power tongs and, more specifically, to power tongs that may be used for making and breaking connections in oil well tubular strings such as drill pipe and casing.

Power tongs have been used for many years for making and breaking tubular connections. However, as power tong systems have become larger and heavier so as to include back-up grips, spinners, and other valuable features that reduce time and improve reliability of the made up tubular connections, it has become necessary to build tracks and the like to control movement of the power tongs on the rig floor. The large size of and heavy weight of modern power tongs makes cable supports a less desirable means of supporting such systems. Movement of large heavy power tong systems either laterally or rotationally produces logistics problems on the rig floor and increases the likelihood of accidents.

U.S. Pat. No. 4,492,134, issued Jan. 8, 1985, to Reinholdt et al., discloses a power tongs for threadedly connecting together pipes which are to constitute casings for boreholes, which has a platform for a reciprocable slide which supports a power-driven threading clamp and a counter device. The clamp and the counter device are connected to each other by several level compensating hydraulic cylinders each of which is movable horizontally within limits relative to the slide against the opposition of resilient support elements. The upper end portions of the cylinders are connected to a holding plate for the clamp.

U.S. Pat. No. 4,082,017, issued Apr. 4, 1978, to Emery Eckel, discloses a hydraulically or pneumatically powered drill pipe tongs of the scissors-type used in making up or breaking apart joints of drill pipe, drill collars, and the like including an upper tong and a lower tong each including tong die heads for biting into or gripping the upper and lower joints of drill pipe, drill collars and the like with the upper and lower tongs being swivel connected and being swiveled by a hydraulically or pneumatically powered torqueing piston and cylinder assembly for rotating the upper and lower tongs in relation to each other when making up or breaking apart the drill pipe joints. Each of the upper and lower tongs includes a sliding door having one of the tong die heads thereon that can be moved a substantial distance toward and away from the tong body by the use of a pair of hydraulically or pneumatically powered piston and cylinder assemblies to enable tool joints, drill pipe protectors and the like to pass through the tongs while leaving the tongs on the pipe. Each of the tongs also includes a hinged mounting for one edge portion of the tong door and a latch for the other edge portion to enable the tong door to be latched or unlatched and swung outwardly in a manner to enable the tongs to be removed from the drill pipe when necessary.

U.S. Pat. No. 5,081,888, issued Jan. 21, 1992, to Joerg E. Schulze-Beckinghausen, discloses an apparatus for connecting and disconnecting threaded members including a power tong, a backup unit disposed below the power tong for tripping a second pipe, and apparatus for transmitting reaction forces generated by the power tong to the backup unit, the backup unit having devices for transmitting compressive or tensile forces between its members from the power tong which, in one embodiment, includes a hydraulic connection between a double acting hydraulic piston and cylinder assemblies incorporated in the members.

U.S. Pat. No. 6,138,776, issued Oct. 31, 2000, to Hart et al., discloses a pipe handling system comprising a rig floor supported frame adapted to be positioned above the rotary table and in alignment with the hole in the rotary table. It incorporates a centrally located bowl lined with the frame to enable a string of pipe to extend through the rotary table. Appropriate releasable slips are moved into and out engagement. The frame supports an overhead mounting plate, and one version thereof incorporates hydraulic jacks to raise and lower the mounting plate. The mounting plate supports a horizontally directed hydraulic ram which moves the two end lengths of a long multi length chain looped into a bight to go around a pipe passing near the end of the mounting plate. The bight in the chain grips the coupling of the pipe to hold it fast. This mechanism cooperated with an overhead power tong assembly to enable threading or unthreading of pipe casing and tubing.

U.S. Pat. No. 6,142,041, issued Nov. 7, 2000, to David A. Buck, discloses a power tong positioning apparatus, including a power tong support positionable on the surface of drilling rig deck and attachable to at least one power tong. The power tong support is adapted to position at least one power tong so that it may engage the tubular member. The power tong positioning apparatus a frame, a base moveably positioned on the frame, at least one arm pivotally attached to the base, a power tong support pivotally attached to the arm(s) and movably attachable to at least one power tong.

U.S. Pat. No. 6,142,040, issued Nov. 7, 2000, to Vernon J. Bouligny, discloses a spider, preferably a flush mounted spider, and powered lead tong which are coupled by a rotationally rigid structure so that torque reaction forces apply no side load to pipe. The tong preferably tilts upward to clear larger objects approaching the spider. An optional grabber is mounted, preferably atop the lead tong, and may tilt with the lead tong. Fluid powered motors, linear or rotary, provide the tilting energy and extend and retract the grabber. The tong and related structure has quick coupler provisions for removal from the spider.

The above power tong systems show tongs that either move laterally with respect to the pipe and/or have outer housings that rotate around the pipe and/or do not include a complete power tong assembly capable of spinning, backing up, applying torque, automatic slips, and the like. Consequently, it would be desirable to provide a system and method that is designed to avoid lateral and rotational movement of large power tong housings and provide virtually all functions required at the rig floor for making and breaking connections of either drill pipe or casing. Those skilled in the art will appreciate the present invention that addresses the above and other needs and problems. SUMMARY OF THE INVENTION

Therefore, in accordance with the present invention, an apparatus is disclosed for a power tong system for making and breaking connections in a tubular string. The power tong system may be used on a rig floor and comprises one or more elements such as a power tong housing, and at least one rotary drive tong mounted within the power tong housing for encircling and gripping a first portion of the tubular string. The rotary drive tong preferably has a rotatable gear therein for applying rotational force to the first portion of the tubular string. Other elements may include at least one backup tong having gripping elements therein for holding a second portion of the tubular string while the rotary drive tong applies the rotational force to the first portion of the tubular string. A plurality of lift assemblies may each include slidable shafts for moving the power tong housing upwardly and downwardly. The plurality of lift assemblies may be secured with respect to the rig floor such that the power tong housing is moveable upwardly and downwardly with respect to the rig floor and such that the power tong housing is prevented from rotating with respect to the rig floor.

Preferably the system includes powered slips operable for powered movement of slips into and out of gripping engagement with the tubular string. The powered slips are operable for supporting a weight of the tubular string.

In one embodiment, a collar locator produces a collar locator signal in response to at least one of the connections in the tubular string. A tong control is responsive to the collar locator signal for automatically controlling the upwardly or downwardly movement of the power tong housing for positioning the rotary drive tong and the backup tong with respect to one of the connections.

A drive gear may be provided within the at least one rotary drive tong which completely encircles the tubular string. A plurality of cams may be mounted to the drive gear for movement therewith. A removable section for the drive gear may be provided such that when removed the drive gear can be laterally moved away from the tubular string.

An expandable connection may be provided between the rotary drive tong and backup tong to permit relative up and down movement therebetween. Moreover, an extension member may be used for connecting between the at least one rotary drive tong and the at least one backup tong to permit the rotary drive tong and the backup tong to both grip either on a respective portion of the connection or simultaneously above and below the connection.

A plurality of piston driven gripping elements may be provided within the backup tong for selectively engaging and disengaging the second portion of the tubular string.

Thus, in one embodiment, the power tong system may comprise at least one rotary drive tong for gripping a first portion of the tubular string having a rotatable gear therein for applying rotational force to the first portion of the tubular string and at least one backup tong having gripping elements therein for holding a second portion of the tubular string while the rotary drive tong applies the rotational force to the first portion of the tubular string. A plurality of lift assemblies move the rotary drive tong upwardly and downwardly with respect to the rig floor. The plurality of lift members may be secured with respect to the rig floor. Powered slips are preferably provided that are operable for powered movement of slips into and out of gripping engagement with the tubular string for supporting a weight of the tubular string as desired. As well, a preferred embodiment includes a collar locator for producing a collar locator signal in response to at least one of the connections in the tubular string, and a control responsive to the collar locator signal for automatically controlling the upwardly or downwardly movement of the plurality of lift members.

A method for making or breaking connections in a tubular string as the tubular string is run into or out of a wellbore may comprise steps such as providing a power tong housing with a rotatable drive gear therein such that the power tong housing remains encircling the tubular string as the tubular string is run into or out of the wellbore. Other steps may include securing a back up power tong with respect to the power tong housing and/or moving the rotary drive tong and the back up power tong in a direction substantially parallel with respect to the tubular string. In a preferred embodiment, the method of the invention may comprise steps such as supporting the rotary drive tong to prevent rotation of the power tong housing during the making or breaking of the connections and/or producing an electronic signal in response to locating a connection. The method may further comprise positioning the rotary drive tong and the power tong backup in response with respect to the tubular string in response to the electronic signal. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view, partially in section, of a power tong system in accord with the present invention with automatic slips in the open position as the elevators raise the pipe string;

FIG. 7A is an elevational view of a representative sliding connection for relative movement of a wrap around tong and back up clamp in an open position in accord with the present invention;

FIG. 7B is an elevational view of a representative sliding connection for relative movement of a wrap around tong and back up clamp in an open position in accord with the present invention;

FIG. 8 is an elevational view, partially in section, showing a power tong system in accord with the present invention having tong and backup above and below a joint of casing for gripping in accord with one embodiment of the invention;

FIG. 12 is a schematic view of one representative flush-mounted power slips assembly as part of a power tong system in accord with the present invention.

Referring now to the drawings and, more particularly to FIG. 1, FIG. 2, and FIG. 3, there is shown a power tong system 10 in accord with the system of the present invention in different stages of operation. One problem the present invention is designed to eliminate is that of moving a large tong system laterally with respect to the pipe string for each joint to be connected or disconnected. Instead the present invention remains in the same lateral position and preferably does not rotate during operation. The present invention preferably remains wrapped around the drill string as the entire string is built into or removed from the wellbore. To further enhance operation, the present invention preferably incorporates powered slips therewith for improved operation as discussed hereinafter. The present invention preferably utilizes a collar locator for automatic height positioning, and also preferably utilizes an inspective device to locate or otherwise identify cracks, holes, leaks and other anomalies in the tubulars being made up or broken out of an oil well tubular string. Moreover, the tong system of the present invention incorporates a simplified arrangement as discussed hereinafter.

FIG. 1 discloses power tong system 10 in a retracted or lowered position with respect to rig floor 12. Power slips 14, shown schematically, are positioned upwardly in bowl 16 and therefore disengaged from tubular string 18 which is now supported by elevators 20. In FIG. 1, elevators 20 are used to lift tubular string 18 upwardly as indicated using rig blocks (not shown) for removing the pipe string from the wellbore. For installing tubular string 18, the process would be the reverse.

In FIG. 2, as the tubular string is removed the various joints for each stand pass through power tong system 10 until the desired joint to be broken, such as joint 22, is positioned within operating range of tong system 22. Joint 22 is the connection of an upper pipe 24 and a lower pipe 26 with respecting pin connection 28 and box connection 30. For operation of tong system 10 with drill pipe, it may be desirable or required that torque be applied only to the strengthened and enlarged or upset pin connection 28 and box connection 30. For operation of tong system 10 with casing, it may be more desirable or required that torque be applied to the pipe sections rather than the joint as suggested in FIG. 8, discussed hereinafter. Once connection 22 is positioned as desired, the operator engages power slips 14. Thus, an operator uses a control for tong system 10 to insert power slips 14 downwardly in bowl 16 to thereby support the weight of pipe string 18 so that connection 22 can be broken and pipe 24 or the stand to which pipe 24 connected can be removed such as for stacking.

FIG. 12 shows a schematic representation for power slips 34 flush-mounted with respect to rig floor 12 which may use power actuators such as actuators 32 for inserting or removing slips 14 with respect to bowl 16. FIG. 12 is only intended to be representative of power slips and other configurations can be used within tong system 10 of the present invention. One advantage of using power slips is improved safety in that personnel may then avoid having to work adjacent to moving equipment such as the power tongs. Since power tong system 10 does not move laterally from the pipe stand for each connection, automatic or powered slip operation increases safety of operation by reducing the need for personnel to work next to moving equipment.

Referring now to FIG. 3, once joint 22 is positioned and slips 14 are engaged, then power tong housing 36 must be positioned appropriately with respect to joint 22 such that rotary drive 38 and back up 40 are positioned correctly. For instance, with drill pipe it may be required that rotary drive 38 and back up 40 be position on enlarged pin 28 and enlarged box 30 in order to apply torque to connection 22 without damaging the drill pipe.

Since tong system 10 is already positioned correctly laterally, it is only necessary that power tong housing 36 be moved upwardly or downwardly, i.e., axially along pipe string 18 in a direction substantially parallel to pipe string 18 until power tong housing 36 is adjacent connection 22. For this purpose, powered lift assembly 41 is preferably used whereby shafts 42 may preferably be telescopically mounted with respect to cylinders 44 and/or 46. Shafts 42 may therefore extend or retract with respect to cylinders 44 and/or 46. In this manner, powered lifts thereby extend or retract power tong housing 36 so as to locate power tong housing 36 adjacent connection 22. Power for powered lift assembly 41 may include hydraulic, pneumatic, or electric power. Other means for operating powered lifts or constructions of powered lift assembly 41 could also be used. For instance, a screw drive might be used. A single cylindrical powered lift might be used whereby the cylinder surrounds pipe 18. However regardless of construction thereof, preferably openings such as opening 48 are provided for power lift assembly 41, so that power tong system 10 can be moved laterally with respect to pipe string 18, if and when necessary.

Preferably powered lift assembly 41 is securely fastened with respect to rig floor 12. In many cases, rig floor 12 will often have standard openings therein that can be used for this purpose. If cross bars or supports are used between shafts 42, then one portion of the cross bars or shaft would then preferably be removable. Thus, foot elements 50 are preferably fixably secured to rig floor 12 to prevent any movement of foot elements 50 with respect to rig floor 12. Some slight movement or preferably adjustments, usually less than one inch, may be made as necessary to centralize pipe string 18 with respect to the power tongs with adjustment elements located at a convenient position of tong system 10. Thus, rotational movement of power tong system 10 is preferably substantially or completely prevented so as to avoid the safety problem of having large equipment rotate. Moreover, the secure fastening permits secure upward and downward movement of power tong housing 36 with respect to rig floor 12 without permitting rotational movement of power tong housing 36.

FIG. 4 shows a view of rotary drive 38 which may be used for applying rotational force to pipe string 18. Rotary drive 38 preferably includes drive gear 52 that may be driven preferably by several rotary drives such as 54, 56, 58, and 60 positioned around the circumference of drive gear 52 such that forces within drive gear 52 are substantially distributed around the circumference thereof. Use of multiple rotary drives therefore increases the life and durability 10 of rotary drive 38. Thus, teeth on rotary drives 54-60 engage outer teeth 62 for rotating drive gear 52 within power tong housing 36.

As an example of operation, as drive gear 52 rotates as shown by arrow 64, then cams 66 wedge slips 68 radially inwardly to thereby force grips 70 to engage and thereby grip pipe string 18 for applying rotational force thereto. The use of a ring gear, such as drive gear 59 that completely encircles pipe string 18 is desirable to distribute forces and provide a longer lasting system. However, a ring gear that completely encircles pipe string 18 would prevent tong system 10 from the capability of moving laterally for removal of the system, if desired. Wh