US2589159A - Hold-down slip assembly - Google Patents

Description

March 11, 1952 A. 1.. STONE HOLD-DOWN SLIP ASSEMBLY Filed Feb. 19, 1948 IN VEN TOR.

Patented Mar. 11, 1952 HOLD-DOWN SLIP ASSEMBLY Albert L. Stone, Redondo Beach, Calif., assignor,

by mesne assignments, to Standard Oil Development Company, Elizabeth, N. J., a corporation of Delaware Application February 19, 1948, Serial No. 9,600

2 Claims. (01. 25523) The present invention is directed to a slip assembly for holding sections of pipe.

In the handling of sections of pipe in drilling operations it is often desirable or necessary to hold the sections against downward and rotative movement. At the present time most wells for producing petroleum and gas are drilled by the rotary drilling method which involves the use of a rotary table for producing rotative motion of the drill stem. The drill stem is constructed by fastening sections of pipe together by means of screw threads. Incidental to the actual drilling operation it is necessary to add sections of pipe to and remove sections of pipe from the drill stem and in this operation it is common to support the drill stem by using a slip assembly mounted on a master bushing which in turn is carried by the rotary table.

It is necessary to support the drill stem below the joint to be made up or broken out when adding or removing sections of pipe. The operation of attaching or removing a section of pipe by screwing or unscrewing a joint requires that the pipe on one side of the joint be held against rotative movement while the pipe on the other side of the joint is rotated.

It is common to use a slip assembly for holding the drill pipe against vertical movement in such operations. The slip assembly usually consists of a member called a slip bowl which defines a cavity having sides tapering upwardly and outwardly. Cooperating and fitting within the slip bowl are slip members having outer surfaces tapering downwardly and inwardly with the several members cooperating to define a central passage. The slip members are provided with die members adjacent the central passage for gripping a section of pipe.

When a section of pipe is supported from the slip members the weight of the pipe exerts a force having components directed radially outwardly as well as downwardly.

When a conventional slip assembly is supporting a section of pipe, the application of a rotative force between the section of pipe and the slip bowl will produce a horizontal component directed radially outwardly and a vertical component directed upwardly. It will be evident that in a conventional slip assembly the slip assembly cannot be used to prevent rotative movement between the suspended pipe and the slip bowl unless the weight of the pipe is such that the vertical downward component exerted by the pipe on the wedge surface of the slip members is great enough to overcome the upward component produced by the rotative force. For this reason it is impossible to use conventional slip assemblies to hold a back up or to transmit rotative movement to a section of pipe when breaking out or making up a joint unless the section of pipe suspended from the slips has a weight greater than a certain minimum. When breaking-out joints of pipe in rotary drilling operations, it is conventional to use a tong on each side of the joint for the entire drill stem and when making up joints of pipe it is conventional to use a tong to hold a back up until the weight of the drill stem becomes suflicient to allow the use of the slips for this purpose.

It is an object of the present invention to provide an arrangement for holding a section of pipe against downward movement and against rotative movement. More particularly, it is an object of the present invention to provide a slip assembly provided with a positive locking means for holding the slip sections in position whereby the slip assembly may be used for holding sections of pipe against vertical and rotative movement with respect to the rotary table when breaking out and making up joints of pipe.

The deviceof the present invention may be briefly described as including a slip bowl anchored a ainst a vertical movement, as by mounting it in a rotary table, slip members arranged to fit within the slip bowl and provided with die members for gripping a section of pipe and a cam member secured against vertical movement and adapted to lock releasably the slip members against upward movement in the bowl.

The present invention will now be described in greater detail in conjunction with the drawing in which:

Fig. 1 is a plan view of a slip assembly embodying the present invention;

Fig. 2 is an elevation, partly in section, of the device shown in Fig. l with a section of pipe gripped thereby;

Fig. 3 is a view taken along lineIII-III of Fig.2;

Fig. 4 is a fragmentary section taken along line IVIV of Fig. 2;

Fig. 5 is the device shown in Fig. 4 in a different position;

Fig. 6 is an elevation showing an embodiment of the present invention; and

Fig. 7 is a view showing a single die element to illustrate the construction thereof.

Turning now specifically to they drawing, a rotary table A define a central passage, the lower portion of which is defined by a cylindrical wall H and the upper portion is a wall l2 square in configuration with the two wall portions connected by upwardly facing surface or shoulder l3.

A slip bowl member or master bushing B has its outer surface fitting slidably within the central passage defined by rotary table A, that is to say, its lower outer surface is cylindrical and its upper portion is in the shape of a square head which sets within member A and is supported from shoulder I3. Slip bowl B defines a central passage I4 with the surface l5 which defines the upper portion of the passage tapering upwardly and outwardly for receiving the slip member assembly.

Slip members C are adapted to set within the slip bowl. Each member C includes a body I6 having an outer arcuate surface I! and an inner arcuate surface IS. The upper portion of each body i defined by a horizontal surface l9 and a wedge surface 20 which tapers outwardly and downwardly to join surface IS with surface I1.

In the drawing, the slip bodies I6 occupy an arc of approximately 120 so that three slip assemblies C may be arranged within the slip bowl and when so arranged the surfaces 8 define a central passage for receiving a section of pipe.

Die members 2| are mounted on each body l6 for gripping the pipe to be retained by the assembly. Each die member is pivoted to the slip body with a lower pivot 22 extending into a suitable opening provided in slip body [6 and an upper pivot 23 extending into an opening of plate 24 which, in turn, may be secured to body l6 by any suitable means such as screws 25.

For convenience, the arrangement of the slip assembly C whereby die members 2| may be pivoted when a rotative force is exerted on a section of pipe engaged by the slip assembly is designated as self-energizing because the application of a rotative force between the slip bowl and a section of pipe supported by the assembly causes an increased force to be exerted against the pipe by the dies.

In Fig. 2, a section of pipe 26 is shown supported from the slip assembly.

The several slip assemblies C are provided with interlocking means so that the members will move vertically as a unit. In the drawing, the interlocking means are provided by a laterally extending projection 21 extending from the side of each body I6 which, in turn, fits into a mating opening 28 defined by the edge of the slip body l6 adjacent the projection 21. With this arrangement the slip assemblies C are raised and lowered as a single unit. It will be understood that the movement of the slips vertically may be provided manually or by suitable mechanical means but since the means for moving the slip assemblies C vertically does not in itself form a part of the present invention, such a means has not been shown in the drawing.

It is a feature of the present invention that the component of forces directed vertically upwardly when a rotative force is exerted between slip members C and 'slip bowl B is resisted by releasable locking means. In the embodiment shown in the drawing, the releasable locking means is designated as D and includes a housing 29 secured to the rotary table A by suitable means such as cap screws 30. Housing 29 defines a passage, rectangular in shape, in which is slidably arranged a movable cam member 3| The outer surface of the cam member is generally rectangular in shape which allows it to move slidably withinhousing 29 but the end of the undersurface thereof defines a slanting or wedge surface 32. Cam member 3| defines a central cylindrical cavity in which piston 33 is slidably arranged. Piston 33 is attached to piston rod 34 which, in turn, is secured to housing 29.

A packing 35 is mounted on the piston to prevent leakage between the exterior surface thereof and the wall of cam member 3|. Another packing 36 is provided around piston rod 34 to prevent leakage around the piston rod. The portion of the cavity defined by member 3| between the piston and packing 36 is designated as 31 while the portion of the cavity to the right of the piston is designated as 38. Piston rod 34 defines a central passage communicating with cavity 38 and connected through conduit 39 to a suitable source of hydraulic pressure, not shown. Cam member 3| defines a side port 40 connecting with cavity 37 and connected through conduit 4| to a suitable source of fluid pressure not shown.

It will be seen that by exerting pressure in cavity 38 while releasing pressure from cavity 31, the cam member 3| may be pushed toward the center of the slip assembly to force wedge surface 3| thereof into contact with surface 20 of slip assembly C. With the two wedge surfaces in contact, the fluid pressure exerted against cam member 3| biases a member C downwardly and this bias is transmitted by the interlocking means previously described to the adjacent members C, the three members cooperating to exert a downward component for resisting the upward component resulting when a rotative force is exerted between bowl B and pipe 23.

In normal operation of the device movement of cam member 3| radially away from the center line of the assembly releases slip assembly C so that these assemblies may be moved upwardly and outwardly, this, for example, will allow tool joints to be passed down through slip assemblies. When it is desired to support a section of pipe, the slip assemblies C are allowed to drop downwardly with the surface I5 of the slip bowl contacting surfaces I! of the slip bodies to move the slip bodies radially inwardly as they move downwardly so that die members 2| contact the section of pipe to be suspended. If the slips are to be used to prevent relative rotative mo tion between the suspended section of pipe and slip bowl B, the members C are then looked downwardly by forcing cam member 3| inwardly so that its wedge surface 3| biases against slanting surface 2|! of a slip body I6. Upon exerting relative force between the section of suspended pipe and slip bowl B, the die members 2| move arcuately on their pivots so that the edges thereof bite more deeply into the section of pipe to increase the gripping exerted by the die members. As heretofore explained, this rotative force exerts a component against body l6 of assembly C, this component being directed vertically upwardly. This vertical upward component is resisted by cam member 3| and as long as the cam member resists this force, the slip assembly holds the pipe against relative rotative movement as well as relative downward movement.

While I have described a single embodiment of the present invention, it will be obvious to a workman skilled in the art that various changes may be made without departing from the scope thereof. For example, in the drawing, a single releasable locking means D is shown for locking the slip assembly C in position to resist the upward vertical component exerted against assemblyv C upon relative rotative motion between a section of pipe engaged by the assembly and the slip bowl B. It will be obvious that if de- 1. A device for releasably holding a section of pipe comprising, in combination, a rotary table for a drilling rig, a slip bowl carried by the rotary table, a plurality of self-energizing slip members, each member having at least one die section mounted for independent rocking movement to present a portion of its pipe gripping edge inwardly of its normal position for pipe gripping purposes, said members being withdrawable from the slip bowl and arranged to fit into the slip bowl for holding a section of pipe against downward and angular movement, a housing secured to the upper surface of said rotary table, a cam member having a cam surface slidably carried by said housing for horizontal movement and arranged to move into a first position with its cam surface in contact with a cooperating surface of one of the slip members to lock said slip in position against upward movement and movable from the first to a second position out of contact with said slip member, said housing and said cam member cooperating to form a piston and cylinder assembly and a conduit for fluid operatively connected to said housing whereby the cam member may be moved from one to the other of its positions by fluid pressure.

2. A device for releasably holding a section of pipe comprising, in combination, a rotary table for a rotary drilling rig, a. slip bowl carried by the rotary table, a plurality of self-energizing slip members, each member having at least one die section mounted for independent rocking movement to present a portion of its pipe gripping edge inwardly of its normal position for pipe gripping purposes, said members being withdrawable from the slip bowl and arranged to fit into the slip bowl for holding a section of pipe against downward and angular movement, a housing with a passage having its axis making substantially a right angle with the path of withdrawal of a slip member secured to the upper surface of said rotary table, a locking member having a wedge surface slidably arranged for horizontal movement in said passage of the mounting member and arranged to move to a first locking position with its wedge surface in contact with a cooperating surface of one of the slip members to lock said slip in position against upward movement and movable from the first position to a second position out of contact with said slip member, and said housing and said looking member cooperating to form a piston and cylinder assembly and a conduit for fluid operatively connected to said housing whereby the locking member may be moved from one to the other of its positions by fluid pressure.

ALBERT L. STONE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,400,940 Clarke Dec. 20, 1921 1,556,094 Fletcher Oct. 6, 1925 1,560,701 Layton Nov. 10, 1925 1,650,101 Taylor Nov. 22, 1927 1,973,809 Heggem Sept. 18, 1934 2,076,042 Peniok et a1 Apr. 6, 1937 2,231,923 Koen Feb. 18, 1941 2,287,432 Kinzbach June 23, 1942

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