GB2168281A - Apparatus for rotating a tubular member - Google Patents

Abstract

Tongs for holding and rotating a tubular member comprise opposed relatively movable clamping jaws 2 and 4. Jaw 2 is fixedly mounted on a body member 1 and jaw 4 is pivotally connected through a link 6 to a lever 5 fulcrumed at 12 on the body member. An actuating handle 13 is pivotally connected at one end through a pin 14 to the body member 1 and extends generally parallel to the lever 9 to which it is connected by a transverse pivoted link 15 relocatable at different distances from the lever fulcrum (21, 22, 23) to allow the gripping force applied to the tubular member to be adjusted. <IMAGE>

Description

SPECIFICATION Apparatus for rotating a tubular member This invention relates to apparatus for imparting torsion to a tubular member. In the drilling industry such apparatus is called tongs and the tongs are used to rotate drill pipe,tubing and casing.

U.S. Patent No.4,192,206 discloses a powertongs which includes a special pipe-centering feature and gripping arrangement to provide maximum protection for the operator under high load conditions. The tongs include a substantially crescent shaped carrier member rotatably mounted within a gear rim, lever arms being mounted on the carrier member and in turn pivotally supporting symmetrically opposite clamping jaws. The gear rim carries cams which are engaged by rollers mounted on the lever arms. Upon rotation of the carrier member relative to the cams by a power drive means which drives the gear rim, the cams acting through the rollers on the lever arms actuate the gripping jaws to contact and grip the pipe.

The above powertongs are extremely effective and give consistently reliable performance over a wide range of drilling and workover operations.

However, due to their size and weight the power tongs require power assistance to handle and move them. They are not capable of being handled and moved manually. Neither are they readily usable with dual'completion strings beca'usethecarrier member and the working parts des'cribed are located within a housing having a radially recessed opening provided with a latch for closing off the opening during operation of the apparatus, thus restricting access to the gripping members.

A light weight manually handleable back-up tongs is known which comprises a jaw provided with a die forcontactingthetubularmemberandachainfixed -at one end to the jaw. The chain is passed around the tubular member, and the free end thereof is secured relative to a handle pivoted on the jaw. By pulling on the handle, the chain istensioned around the tubular member and draws the member into contact with the die. However, it has been found that when such tongs are dimensioned to operate on tubular members of smaller dimensions, for example tubing in the range of 32" to 4-" diameter, that chain strength limitations preventsufficienttension being applied to the chain to attain sufficient die "pull on" loads to give initial skin penetration and die indentation.Being self energising, a coefficient of friction = 0.3 would be required between the chain and the tubing to cause the initial grip to take place. If higher strength chain were used and the mechanical advantage changed to provide the magnitude of chain tension required, crushing of the wall of the tubing could be expected.

Chain back-up tongs, whilst being very effective on larger diameters oftubular member, are sensitive on the smallerdiametersto grade and weight ofthe tubular member, coefficient of friction between the tubular member and the chain and maximumtorque requirements. Such chain back-up tongs do however have the advantage of requiring little space for their operation, which makes them attractive to contemplate for use in situations where access space is limited, such as on 32" dual completion tubing strings. However, their disadvantages enumerated above render them unsuitable for use in practice.

A requirement therefore existsfortongswhich have the same gripping performance as the power tongs of U.S. Patent No. 4,192,206 mentioned above, buy which are of sufficiently lightweightto enable them to be manipulated and handled manually, and are of a size to permit them to be used in situations where access space is restricted.

It is also desirablethatsuch tongs should be capable of providing for adjustment ofthe gripping force applied tothetubularmember, so thatthe marking ofthetubularmembercan be controlled and damage thereto can be minimized.

It is an object ofthe present invention to provide tongs which meet these requirements.

The present invention provides a novel and efficientapparatusforholding and rotating atubular member which comprises opposed relatively movable clamping jaws for engaging a tubular member inserted between the jaws, means for actuating thejawsto cause them to exert a grip on thetubularmember,and meansforvaryingthe gripping load exerted by the jaws.

One constructional form of the apparatus includes a substantially crescent shaped body member on which a fixed jaw is mounted. Another jaw is pivotally mounted on a lever pivotally mounted on the carrier member. An actuating handle also pivoted onthecarrier member is coupled to the lever bya transverse link. Movement of the handle in the appropriate direction pivots the lever about its mounting to move the jaws together. The gripping load is varied by repositioriing the transverse link at different distances from the lever fulcrum on the carrier member.

An example of an apparatus in accordance with the present invention is illustrated in the accompanying drawing, which is a plan view ofthe apparatus in operation on a completion tubing string.

Referring to the drawing, the apparatus comprises a substantially crescent shaped carrier or body member 1 to one end of which is rigidly attached a jaw 2 provided with gripping dies 3. A second jaw4 in symmetrically opposite relation to the jaw 2 and similarly provided with gripping dies 3 is pivotally connected by a pin 5 to one end of a link 6, the other end of which is pivotally connected by a pin 7 to the head end portion 8 of a rigid lever 9. Pin 5 also connects jaw 4to one end of a radius arm 10 the other end ofwhich is pivotallysecured bya pin 11 to the body member 1. The lever 9 is in turn pivotally mounted on the opposite end ofthe body member 1 bya pin 12 which acts as afulcrumforthe lever 9. A handle 13 has one end thereof pivotally secured by a pin 14 to the body member 1 and extends generally parallel to the lever 9, to which it is connected by a short pivoted link 15. A double-acting hydraulic piston and cylinder type actuator 16 has its cylinder pivotally mounted on the body member 1, the piston rod 17 of the actuator being pivotally connected to the handle 13 buy a pin 18.

In operation, the actuator 16 is extended to rotate the handle 13 and, with itthe iever 9, to the rightto move the jaw 4 away from the fixed jaw 2, and the jaws are then offered to the tubing 19. The actuator 16 is then operated to contract it to move the jaw 4 into gripping engagement with the tubing. The interposition of the link 6 and radius arm 10 between the lever9 and body member 1 respectively and the jaw 4 ensures that the final part of the gripping movement is not accompanied by any substantial circumferential movement of the jaw 4. The geometry of the apparatus is such that the dies 3 are brought into contact with the tubing 19 with sufficientloading to give an initial die penetration through the "skin" of the tubing. Torque is applied through a back up line 20 connected to the handle 13.Because the tongs are located and made to grip the tubing 19 without the need for any rotary movement, the restricted space available for insertion of the tongs at an "H" member on a dual completion tubing string can be fully utilised.

In one form of the illustrated apparatus, a subtended angle of 60 of movement can be achieved on dual completion tubing string at centres of 4t".

Torque measurement can be performed by means of a hydraulic load cell and gauge (not shown) incorporated in the back up line 20.

When "ratcheting" the tongs to obtain further rotation of the tubing 19, a slight relaxation of the gripping pressure exerted by the actuator 16 will allow the tongs to be rotated around the tubing 19 ready for another rotation A particular feature of the present tongs is the ability to vary the maximum gripping loads applied to the tubing 19. Variation of the gripping load is obtained by relocating the link 15 at one of the alternative positions 21,22 and 23 thus changing the distance between the connection of the handle 13 to the lever 9 represented by the link 8, and the pivot axis or fulcrum 12 of the lever 9. The shorter the distance, the less the maximum gripping load applied by the jaws to and for the tubing 19. Thus by appropriately selecting the placement of the link 15, marking of the tubing 19 is minimized and the risk of crushing deformation of tubing of lighter grades and weights is reduced.

A hanger loop 25 attached to the body member 1 enables the weight of the tongs to be supported from a suitable hanger.

For break out the tongs may be inverted.

In order to obtain a satisfactory gripping load conducive to minimum marking and maximum torque capability curved dies 3 may be utilised.

However, if the tongs are to be used on tubular members of different diameters, the "fit" of curved dies on to the tubular member cannot be guaranteed and therefore the exemplary tongs of the present invention illustrated in the drawing is provided with two circumferentially spaced dies 3 on each jaw, each die having a double row of teeth.

Claims (7)

1. Apparatus for gripping a tubular member which comprises opposed relatively movable gripping jaws for engaging a tubular member inserted between the jaws, means for actuating the jaws to cause them to exert a grip on the tubular member, and means for varying the gripping load exerted by the jaws.

2. Apparatus according to Claim 1, comprising a pair of said opposed relatively movable gripping jaws, a substantially crescent shaped body member on which one of said jaws is fixedly mounted, a lever which is pivotally mounted on the body member and to which the other of said jaws is pivotally connected, an actuating handle pivoted on the body member to extend generally parallel to the lever and a relocatable transverse link coupling the lever to the actuating handle so that movement of the handle in the appropriate direction pivots the lever about its mounting to move the jaws towards each other to exert a gripping load determined by the location ofthe link.

3. Apparatus according to Claim 2 in which the actuating handle and the lever are formed to allow the link to be selectively located at different distances from the lever fulcrum on the carrier member measured longitudinally of the lever and the actuating handle.

4. Apparatus as claimed in claim 2 or claim 3, wherein said other jaw is connected to said lever through a link which extends in a direction lengthwise of the lever and which has its two ends pivotally connected to the lever and to said other jaw respectively and wherein a radius arm extending transversely with respect to said link is pivotally connected between said other jaw and said body member.

5. Apparatus according to any one of claims 2 to 4 including a hydraulic piston and cylinder assembly for actuating the jaws, said assembly being pivotally connected between the body member and the actuating handle.

6. Apparatus according to any one ofthe preceding claims, wherein each said gripping jaw is provided with two circumferentially spaced gripping dies, each die having a double row of teeth.

7. Apparatus for holding and rotating a tubular member and for exerting a variable grippirig load thereon, substantially as hereinbefore described with reference to the accompanying drawing.