CA1141746A - Well slip unit - Google Patents

Abstract

WELL SLIP UNIT

Abstract of the Disclosure A slip unit for releasably supporting a well pipe, including a support structure to be positioned on and turn with a rotary table and preferably taking the form of a slip bowl, and a vertically movable slip carrier structure suspending a number of pipe-gripping slips and adapted to be releasably retained by latch means in a lower active position, with the carrier and slips being yieldingly urged upwardly to inactive positions when the latch means are released. The support structure and carrier structure are both desirably formed of complementary sections hinged for relative swinging movement between closed positions about the pipe and open positions permitting movement of the unit laterally relative to the pipe, and with an additional latch being provided for retaining the structures in their closed positions. The carrier structure and slips are urged upwardly by spring cartridges which are removable as units from the slip assembly in a condition maintaining the actuating springs under compression and preventing injury or damage by release of the spring force during removal. Vertical guides are provided circularly between the slips for centering a well pipe in a manner preventing damage to the slips by engagement with enlargements on the pipe.

Description

11417~6 1 Back round of the Invention I g

2 ¦ This invention relates to well slip units for releasably 31 supporting a well pipe from a rotary table.
41 The slip units of the present invention are of a general 51 type similar to that shown in prior copending Canadian 6 ¦ application Serial Num~er 320,802 filed Feburary 2, 1979.
7 ¦ That prior application shows a device including a support 8 ¦ structure which is adapted to be supported by and to turn ~ ¦ with a well drilling rotary table, and a carrier structure 10 ¦ suspending a number of slips and mounted for upward and down-11 ¦ ward movement with the slips between a lower active pipe-12 ¦ gripping position and an upper retracted position. Latch 13 ¦ means are provided for releasably retaining the carrier and 14 slips in their lower active positions, together with yielding means for returning the carrier and slips upwardly when the 16 latch means are released. In certain instances, the support 1~ structure desirably takes the form of a slip bowl, having 18 inner tapering surfaces for camming the slips inwardly into 19 engagement with the well pipe upon downward movement of the 21 slips.

Summary of the Invention 26 In units embodying the present invention, the support 27 structure which is plac~d on the rotary table and the rela-28 tively vertically movable slip carrier structure are both pre-29 ferably formed of complementary sections which are intercon-nected for relative swinging movement between closed positions 31 ¦ of extension about the well pipe and open positions providing a 32 ¦ lateral opening through which the well pipe may pass to permlt 1 ¦ movement of the unit horizontally between a position about 2 ¦ the pipe and a position at a side of the pipe. A latch may

3 ¦ be provided for releasably retaining the structures in their

4 ¦ closed active positions, and is desirably carried by the

5 ¦ discussed support structure.

6 ¦ An additional feature of the invention relates to the

7 ¦ construction of the yielding means.for urging the slips and

8 ¦ their carrier upwardly relative to the lower support structure

9 ¦ when the carrier is released from its lower active position.
lO ¦ For this purpose, I desirably employ a number of spring 11 cartridges, including vertically extending coil springs 12 maintained under compression to exert upward force against 13 the slip carrier and downward force against the lower support 14 ¦ structure. Each of these cartridges is so constructed as to 15 ¦ be removable as a unit from the remainder of the device, with 16 ¦ the cartridge being designed to maintain the spring undex 17 ¦ compression during removal in a manner preventing injury to 18 ¦ a workman or damage to the e~uipment by release of the spring 1~ ¦ tension during such disassembly. A cartridge may therefore be 20 ¦ removed in the field for repair or replacement, or during 21 ¦ repair of other portions of the equipment, with safety. If 22 ¦ desired, a damaged spring cartridge may be replaced by 23 ¦ another such cartridge, and the damaged one be returned to 24 ¦ the factory or other repair location with the spring still under compression until it can ultimately be disassembled by 26 trained personnel and with proper equipment for effectively 27 preventing injury or damage by the spring force during 28 disassembly. To achieve these results, the cartridge includes 29 two elements at opposite ends of the spring against which the force of the spring is exerted, together with stop means 31 limiting relative separating movement of those elements in a 32 manner retaining the spring under compression as the elements 11417~6 1 ¦ and spring are removed from the remainder of the apparatus as 2 ¦ a unit. Each of the two elements may have a projection which 3 ¦ in assembled condition of the apparatus is received within an 4 ¦ opening in either the lower support structure or the upper 5 ¦ slip carrier structure, and is connectable thereto by a 6 ¦ fastener. The stop apparatus may consist of telescopically 7 ¦ interfitting parts attached to the two end elements and having 8 ¦ shoulders limiting relative axial separating movement thereof.
9 ¦ To protect the slips against damage by contact with 0 ¦ enlarged joints or other enlargements on the well pipe, a 11 ¦ unit embodying the invention may include vertically extending 12 ¦ pipe centering guides located circularly between the slips 13 ¦ and engageable with a well pipe (or enlargement thereon) to 14 ¦ center it and thereby hold it out of contact with the slips when the latter are retracted. These guides may be carried 16 by the lower support structure and project upwardly thereabove.

18 Brief Description of the Drawings ~9 The above and other features and objects of the invention will be better understood from the following detailed 21 description of the typical embodiment illustrated in the 22 accompanying drawings, in which:
23 Fig. 1 is a central vertical section through a well slip 24 unit constructed in accordance with the invention, shown positioned in a rotary table and with a well pipe extending 26 vertically therethrough, and taken on line 1-1 of Fig. 2;
27 Fig. 2 is a plan view on line 2-2 of Fig. l;
28 Fig. 3 is an enlargement of a portion of Fig. 1, showing 29 the slip carrier latched in its lower active position;
Fig. 4 is a reduced scale illustration of one of the 31 spring cartridges removed from the device;
32 Fig. 5 is a horizontal section taken on line 5-5 of Fig. l;

17~i 1 Fig. 6 is a fragmentary view taken on line 6-6 of Fig. 5 2 and showing the slip bowl sections and their latch elements 3 in slight~y open condition;
4 Figs. 7 and 8 are enlarged fragmentary vertical sections taken on lines 7-7 and 8-8 respectively of Fig. l;
6 Fig. 9 is a fragmentary view taken on line 9-9 of Fig. 8;
7 and 8 Fig. 10 is a reduced elevational view of one of the vertical guides, taken on line 10-10 of Fig. 3.
'11 13 Description of the Preferred Embodiment 14 Referring first to Figs. 1 and 2, there is illustrated at 10 a slip assembly constructed in accordance with the 16 invention, shown positioned within and supported by the 17 rotating member 11 of a well drilling rotary table. A well 18 pipe 12 extends vertically along an axis 13 through the 19 center of the rotary table and through slip assembly 10 to be supported thereby while connections are made to the upper end 21 of the pipe. The rotary table member 11 is power driven about 22 axis 13, and contains a central vertically extending opening 23 14 through which the pipe extends. Opening 14 is of circular 24 cross-section up to the location of a horizontal support shoulder 15 at the bottom of an upper enlarged square drive 26 recess 16 which receives an upper square portion 17 of a 27 tubular master bushing 18 to support the master bushing in ~he 28 rotary table and turn the bushing with the table. A lower 29 portion 19 of the master bushing projects downwardly within the lower circular portion 20 of rotary table opening 14.
31 Internally, master bushing 18 has a lower cylindrical portion 32 21 and an upper slightly enlarged diameter cylindrical portion 2 1~41746 1 with an annular generally horizontal support shoulder 23 2 at the juncture of portions 21 and 22 to support the unit-'10 3 in the master bushing.
4 The slip unit 10 includes a lower support structure 24 forming a slip bowl, a plurality of (typically three) pipe 6 supporting slips 25, ana an up~per slip carrier 26. The 7 carrier 26 and the suspended slips 25 are guided for onl~
8 vertical movement relative to slip bowl 24, and are yieldingly 9 urged upwardly to the Fig. 1 retracted position, by a number of guide and spring cartxidges 27 coacting with vertical 11 guide passages 28 in the slip bowl structure. The carrier 2~
12 and slips are releasably retainable in lower active positions 13 (Fig. 3) by a spring-urged latch element 29. Enlargements on 14 the well pipe are centered in the device by three circularly spaced vertical guide members 30 carried by the slip bowl 16 structure 24.
1~ As best seen in Figs. 2 and S, the slip bowl or support 18 structure 24 includes two similar semi-circular and 19 complementary bowl sections 31 and 32, connected together at their lower ends by a hinge 33 for relative horizontal ~1 swinging movement abou~ an axis 34 offset from and parallel to 22 the main vertical axis 13 of the device. Hinge 33 may include 23 a vertical hinge pin 35 received within aligned openings in 24 hinge lugs 36 carried by the two sections 31 and 32. The two bowl sections are free to swing between the closed position 26 of Fig. 5 in which their free ends 37 are in closely proximate 27 relation, and an open position in which those end surfaces are 28 spaced apart far enough to form therebetween an opening larger 29 in diameter than pipe 12 and permitting the device to be moved horizontally between a position about the pipe and a laterally 31 offset position at a side of the pipe. The bowl is retained 32 in the closed condition by a latch element 38 mounted to the 11~1'746 1 end of section 31 by bearing lugs 39 for relative pivotal 2 movement about a vertical axis 40, and engageable with a 3 hook element 41 welded to the end of the second bowl segment 32 4 to latch the ends of the bowls against relative separating or opening movement. A coil spring 138 contained within a 6 recess in latch part 38 and bearing against a surface on bowl 7 segment 31 yieldingly urges the latch to its holding position, 8 while an upwardly projecting handle arm 42 permits manual 9 pivotal actuation of latch element 38 about axis 40 and out of engagement with the coacting latch part 41 to release the 11 bowl segments for opening ~ovement.
~2When the two bowl segments 31 and 32 are in their closed 13 condition of Fig. 5, they form together an essentially circular 14 tubular or annular bowl having outer cylindrical surfaces 43 15and 44 engageable with master bushing surfaces 21 and 22, and 16 ¦ having an annular downwardly facing support shoulder 45 17 ¦ engageable with support shoulder 23 of the master bushing to 18 ¦ support and center the slip bowl structure within the master 19 ¦ bushing. Internally, this annular two segment bowl has a 20 ¦ lower downwardly tapering frusto-conical cam surface 46 which 21 ¦ is circularly continuous except at the locations of the 22 ¦ vertical guide members 30, and an upper downwardly tapering 23 ¦ frusto-conical camming surface 47 which is similarly con~inuous 24 ¦ circularly and about axis 13 except at the locations of the 25 ¦ vertical guides 30. As will be apparent from Fig. 1, these 26 ¦ two camming surfaces 46 and 47 are in alignment with one 2~ ¦ another frusto-conically, and taper at a corresponding angle, 28 ¦ to engage outer similarly downwardly tapering cam surfaces 29 ¦ 48 and 49 on slips 25 to cam the slips inwardly into tight 30 ¦ gripping engagement with the pipe when the slips are in the 31 ¦ broken line position of Figs~ 1, 2 and 5. Vertically between the 3Z ~ two outer cam surfaces 48 and 49, each slip contains an external 1 recess 50 as seen in Fig. 1. Vertically between the two cam 2 surfaces ~6 and 47 of the slip bowl, the essentially annular 3 wall of that bowl contains at the location of each of the 4 slips an opening 51, which extends through the entire radial thickness of the wall to its outer surface 44. When each 6 slip 25 is in its upper full line retracted position of Fig. 1, 7 the lower portion of the slip on which surface 48 is formed 8 projects outwardly into a coacting one of the openings 51 in 9 the wall of the slip bowl, and the upper portion 52 of the bowl above that opening is received within the recess 50 of 11 the slip, to maximize the ~ovement of the slip radially 12 outwardly from its active pipe gripping position and thereby 13 allow reception between the retracted slips o~ relatively 14 large joints or enlargements on the pipe. At its radially inner side, each of the slips 25 may be curved arcuately in 16 horizontal section in correspondence with the outer surface 17 of the well pipe 12, and carry conventional pipe gripping 18 dies 53 having gripping teeth cur~ing arcuately in correspondenc 19 with the outer surface of the pipe and shaped to effectively support the pipe when the slips are in their lower active 21 broken line position of Fig. 1.
22 The three vertical guide members 30 are rigidly carried 23 by the two slip bowl segments 31 and 32, and may if desired 24 be formed integrally with those segments, but preferably are cast or otherwise formed separately and then rigidly secured 26 to the segments by welding or otherwise. More particularly, 27 as seen in Fig. 5, the two segments 31 and 32 may initially 28 be formed to contain three evenly circularly spaced vertically 2g extending cylindrical recesses or bores 54 centered about three vertical axes 55 and opening horizontally inwardly to 31 the interior of the slip bowl structure at 56. Each of the 32 guide members 30 is forrned as a radially inner portion of a mer,~er 57 having a vertically extending cylindrical tubular I' ., l portion 58 received within one of the vertical passages 54 2 formed in a corresponding one of the bowl segments 31 or 32, 3 and appropriately welded to the bowl segment as at 158 in 4 Fig. 1. The vertical pipe guide portion 30 may be considered as extending vertically from a lower extremity 59 (Fig. 1) to 6 an upper extremity 60, and has inner surfaces 61 extending 7 essentially cylindrically about vertical axis 13 of the device 8 to define together an interrupted essentially circular guide 9 structure of a diameter larger than pipe 12 for engaging enlarged joint ends or enlarged rubber sleeves or the like ll carried on the outside of the pipe. These en~argements on 12 the pipe when thus centered by guide elements 30 are held in 13 positions in which they cannot contact and damage the slips 14 when the slips are in their retracted positions (Figs. l and 2 full line positions of the slips). At their upper ends, the 16 inner surfaces of guide members 30 may flare outwardly frusto-l~ conically at 62, to cam the pipe enlargements into centered 18 positions as the pipe moves downwardly. In order to lighten 19 the guide members, the cylindrical surfaces 61 may be discontinuous, with a number of recesses 63 being formed in 21 the radially inner sides of the guide members, but with the 22 various inner surfaces 64 of the ribs which bound recesses 23 63 being disposed cylindrically as discussed for centering 24 contact with the pipe. The outer cylindrical portions 58 of the parts 57 which form guides 30 contain the previously 26 mentioned vertical cylindrical guide passages 28 which coact 27 with spring cartridges 27 in a manner to be discussed 28 in greater detail at a later point.
29 The upper slip carrier 26 may be considered as extending generally horizontally at a location spaced above the slip 31 bowl 24, and is composed of two complementary essentially 32 semi-circular sections or segments 6S and 66 forming together an essentially annular carrier. The sections 65 and 66 may 11~17~

1 ¦ include inner complementary semi-circular castings 67 and 68, 2 ¦ rigidly attached by radially extending spokes 69 to radially 3 ¦ spaced inher ring segments 70 and 71 and outer ring segments 4 ¦ 72 and 73. The two ring segments 70 and 71 form together an 5 ¦ almost circularly continuous annular horizontal structure, 6 ¦ while the outer ring segments 72 and 73 are also substantially 7 ¦ complementary and substantially continuous and fonn together 8 ¦ a second horizontal ring about the pipe. One or more workmen 9 ¦ may stand on the rings 70 through 73 and the associated spokes

10 ¦ 69 to urge the carrier downwardly by the weight of the

11 ¦ workmen and to the active pipe supporting position of Fig. 3.

12 The carrier is releasably retained in that lowered position

13 by latch element 29, which is pivotally connected to the

14 slip bowl structure by attachment to an outwardly projecting bearing lug 74 on one of the members 57. Latch element 29 16 pivots about a horizontal axis 75 relative to the connected 1~ slip bowl segment, and is urged yieldingly in a counter-18 clockwise direction about axis 75 as viewed in Fig. 3 by a 19 torsion spring or other spring 76. The latch is released by downward actuation of an operating arm 77 on the latch 21 element, which arm extends generally horizontally and may be 22 pressed downwardly by the foot of a workman. As carrier 26 23 is moved downwardly from the Fig. 1 position to the Fig. 3 24 position, a calruning shoulder 78 at the underside of a latch shoulder 79 on the carrier engages inclined surface 80 on 26 the latch element 29 to deflect the latch element in a 27 clockwise direction sufficiently to pass latching shoulder 79 28 and then return inwardly at the upper side of that shoulder 29 to the Fig~ 3 position in which the latch element releasably retains the carrier in its lowered active position.
31 The slips are suspended movably from carrier 26 by links 32 180. Two such links are provided at opposite sides of each of 1~1746 1 ¦ the slips, with the lower ends of the links being pivoted 21 by a horizontal pin 81 to the slip, and with the upper ends 3 ¦ of the links being pivoted by a second parallel horizontal 41 pin 82 to a pair of bearing lugs 83 projecting downwardly 51 from one of the inner ring segments 67 or 68 of the carrier.
6¦ The links thus permit inward deflection of the slips as they 7 ¦ move downwardly with the carrier, to thereby grip the pipe.
8 ¦ One of the guide members 30 is provided circularly between ~ ¦ each pair of adjacent slips, with the inner cylindrically curv-10 ¦ ing surfaces 61 and 64 of the guide members 30 being closer to 11 ¦ axis 13 than are the gripping surfaces or any portions of the 12 ¦ slips in the radially outwardly retracted positions of the 13 slips (full lines in Figs. 1, 2 and 5). In the active pipe-14 gripping posit'ons of the slips (broken lines in Figs. 1, 2 and lS 5), the inner gripping edges of the slips are closer to axis 13 16 of the device than are inner cylindrically curved guide 17 surfaces 61 and 64 of guide mem~ers 30. It is also noted that 18 the upper end portions of the vertical guide members 30, 19 at a level above the locations of the slips when they are in gripping engagement with the pipe, may be somewhat wider 21 circularly than are the lower portions of members 30, as 22 illustrated at 84 in Figs. 1 and 10, in order to maximize the 23 guiding effectiveness of the upper portions of the guides while 24 maintaining the lower portions of the guides sufficiently narrow to avoid interference with inward movement of the 26 slips to their active gripping positions.
27 The two complementary sections 65 and 66 of slip carrier 28 26 are connected together for relative swinging movement 29 about the same axis 34 as are the two segments 31 and 32 of the bowl structure. For this purpose, a hinge 85 (Figs. 1, 2 31 and 7) is formed between first ends of the two inner ring 32 elements 67 and 68, by provision of a hinge pin 86 received 11~17~6 1 ¦ within mating vertically aligned hinge lugs 87 projecting from 21 the two elements 67 and 68 respectively. At their opposite 3 ¦ ends, the'se parts 67 and 68 have end surfaces 186 which move 41 between closely proximate closed positions (Fig. 2) and 5 ¦ separated open positions leaving a gap or passage between those 6 ¦ surfaces through which the pipe 12 may pass to enable the device 7 ¦ to be moved onto and off of the pipe. To enhance the rigidity 8 ¦ of the closed structure, the parts 67 and 68 may have inter-9 ¦ fitting projections at their unattached ends, as represented 10 ¦ in Figs. 8 and 9, including a horizontally projecting lug 187 11 ¦ carried by part 67 and slidably receivable between two 12 vertically spaced lugs 88 and 89 on the part 68 in the Figs. 2, 13 8 and 9 closed position of the device to lock the free ends of 14 parts 67 and 68 against relative vertical movement. At their hinge ends, the members 67 and 68 may be cut away at 90 (Fig. 2) 16 to enable the desired opening movement of the carrier, and the 17 ring elements 70 through 73 may be similarly interrupted at 91 18 to avoid interference by these rings with the opening of the 19 carrier. A chain or other flexible but ine~tensible member 92 may interconnect the extremities of ring segments 72 and 73 as 21 seen in Fig. 2, to limit the closing movement of the parts 22 in the Fig. 2 position and form in effect a continuation of 23 the ring elements at that location.
24 The three spring cartridges 27 for yieldingly urging slip carrier 26 and the carried slips upwardly 26 relative to bowl 24 may be of identical configuration.
27 ~ach of these cartridges includes a first rigid vertical 28 guide tube 90 (Fig. 3) which is secured rigidly at its 29 upper end to a vertically extending rigid connector member 91, with the connection desirably being made by a ring 92 received 31 radially between the two parts 90 and 91 and welded to both 32 of those parts in horizontally extending condition. The upper 1141~6 1 ¦ end of externally cylindrical part 9i projects upwardly 2 ¦ through a cylindrical opening 93 in a horizontal wall 94 of 3 ¦ one of th'e carrier parts 67 or 68, and is secured rigidly 4 ¦ thereto by a bolt or other fastener 95 threadedly connected 5 ¦ to internal threads in part 91 and clamping a washer 96 ~ ¦ against wall 94. This connection secures tube 90 in a 7 ¦ position in which its axis 97 extends directly vertically 8 and parallel to central axis 13 of the slip unit.
9 Each of the tubes 90 extends downwardly into one of the vertical passages 28 in one of the parts 57 of the slip bowl 11 assembly, and is guided thareby for only directly ver~ical 12 movement along the axis 97 of that tube. To enhance the 13 effectiveness of this guiding action, each of the passages 14 ~8 may contain in an upper portion thereo~ a vertical tubular bushing 98 of brass or other suitable bearing material, 16 having an internal cylindrical surface slidably engaging the 17 ¦ outer cylindrical surface of the tube 90. A deformable seal 18 ¦ ring 99 of rubber o~ other material prevents access of 19 ¦ foreign material to the bushing.
20 ¦ At the lower end of each of the guide passages 28 in 21 the slip bowl structure, there is provided a horizontal rigid 22 bottom wall 100, containing a circular opening 101 through 23 which an externally cylindrical portion 102 of a bottom connecto~
24 element 103 projects, with an annular flange element 104 being welded to the outside of element 103 and being engageable 26 downwardly against the upper surface of bottom wall 100 to 27 apply downward force thereto. A screw 105 is connectable 28 upwardly into an internally threaded bore 106 in part 103, to 29 clamp a washer 107 and associated lock washer 108 upwardly against wall 100 in a manner rigidly securing part 103 thereto 31 in vertically extending position, centered about the previously 32 mentioned vertical axis 97. A coil spring 109 extends verticall~
between flange 104 and the previously mentioned flange 92, to li~Li746 1 ~ yieldingly urge the slip carrier upw~rdly relative to the 2 ¦ bowl assembly. This spring is at all times maintained under 3 ¦ compression, and remains under compression even when the 4 ¦ slip carrier is in its upper Fig. 1 position. The upward 5 ¦ movement of the carrier is limited in that position by 6 ¦ engagement of a rod llO rigidly secured to and projecting 7 ¦ downwardly from member 91 with a telescopically interfitting 8 ¦ rigid tube 111 secured rigidly to and projecting upwardly 9 ¦ from lower element 103. These two parts 110 and 111 are 10 ¦ centered about and move relative to one another along axis 97, 11 ¦ with the upper end of rod 110 typically being received within 12 ¦ a recess 112 in part 91 and being welded thereto as 13 represented at 113. The lower end of tube 111 may be received 14 abo~lt the upper extremity of part 103, and be welded or otherwise secured thereto at 114. At its upper end, t~be 111 16 is welded to and carries a short internal sleeve 115 forming 17 a shoulder engageable with enlarged diameter flange 116 18 formed on the lower end of rod 110 to limit upward movement 19 of the slip carrier and slips in the Fig. 1 position of the parts.
21 To discuss now the manner of use of the unit 10 22 illustrated in the drawings, assume first of all 'chat a pipe 23 10 is in a position of extension through the rotary table 11 24 of Fig. 1, and assume that the master bushing 18 is already positioned in the table. Assume also that the unit 10 is 26 initially at a side of the well. In order to permit the 27 unit 10 to be moved to a position of support on the rotary 28 table, an operator first releases the latch element 38 of 29 Fig. 5, to enable the entire device to be swung open about the two hinges 33 and 85. The two segments 31 and 32 o~ the 31 slip bowl swing open about their hinge 33, while the two 32 sections or segments 65 and 66 of the carrier 26 simultaneously 11~1746 1 swing open, with the vertical guide and spring cartridges 27 2 serving to interconnect the carrier and bowl segments for 3 swinging ~ovement in unison. The entire unit is then moved 4 horizontally to a position about pipe 12, and then lowered about the pipe until the slip bowl structure 24 extends 6 downwardly into the master bushing and is supported thereby 7 in the position of Fig. ~. When it is desired to grip pipe 12 8 in supporting relation, one or more workmen stand on the 9 rings of the carrier 26 to actuate the carrier downwardly against the tendency of the compression springs 109 by the 11 weight of the workmen. The strength of the springs is so 12 predetermined, in conjunction with the weight of the 13 vertically movable parts, as to enable such downward actuation 14 by a predetermined weight, desirably at least about 100 pounds lS and preferably approximately 400 pounds, to permit effective 16 actuati~n of the carrier when desired while preventing 17 unintended accidental downward displacement of the slips.
18 As the carrier and slips move downwardly, the slips are 19 deflected inwardly toward the pipe by bowl surfaces 46 and 47, and in the lower active Fig. 3 position of the parts the 21 slips effectively grip the pipe and very positively suspend it 22 from the device 10 and the rotary table. The latch element 23 29 engages shoulder 79 of the carrier to retain it and the 2~ slips in their active pipe-suspending positions. When it is desired to release the slips, an operator merely presses 26 downwardly on arm 77 of latch element 29, to move the upper 27 hook portion of the latch element out of engagement with 28 shoulder 79 and permit slip carrier 26 and the suspended slips 29 to be returned upwardly by the force of the three return springs 109. The device 10 may be left in the rotary table 31 while the pipe 12 is lowered or raised for a next successive 3Z connecting or disconnecting operation, with the vertical guides lS

11~17~6 1 30 engaging and centering any enlargements on the pipe to 2 prevent contact of those enlargements with the laterally 3 retracted'slips. The device may then be reactuated to again 4 support the pipe in a changed position.
If it becomes necessary or desirable to partially 6 disassemble the device, and in particular to remove one or 7 more of the cartridges 27, this may be done without releasing 8 the springs from compression. To attain such detachment of 9 the cartridges, the upper and lower cartridge attaching screws 95 and 105 are threadedly detached from the connected 11 elements 91 and 103, so that the carrier and its slips can 12 be withdrawn upwardly, leaving the cartridges 27 free for 13 upward removal from the passages 28 in the slip bowl structure.
14 Fig. 4 illustrates the cartridges thus removed. In this lS condition, the engagement of flange 116 on rod 110 with the 16 upper sleeve 115 in tube 111 (as seen in Fig. 1) limits 17 expansion of the spring and holds it in compressed condition 18 during detachment from the rest of the apparatus. Substitute 19 cartridges 27 may then be replaced in the unit, and the entire device reassembled, all without any danger of injury 21 or damage to parts by release of the spring force.
22 ~he formation of slip bowl structure 24 to have openings 23 21 extending entirely through the wall thickness of that bowl 24 maximizes the radial displacement and radial retraction of the slips which is possible between active and retracted 26 positions of the slips while at the same time minimizing the 27 thickness of the wall dimension.
28 While a certain specific embodiment of the present 29 invention has been disclosed as typical, the invention is of course not limited to this particular form, but rather is 31 applicable broadly to all such variations as fall within 321 the scope of the appended claims.
l 16

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. The combination comprising:
a slip bowl; and a plurality of slips receivable within and movable relative to said slip bowl;
an individual one of said slips having two vertically spaced outer camming surfaces which taper to a reduced diameter as they advance downwardly, and having a recess extending radially inwardly vertically between said camming surfaces;
said slip bowl having a vertically extending side wall with two vertically spaced camming surfaces formed at the inside thereof, which surfaces taper essentially in correspondence with said surfaces of said individual slip and are engageable therewith in a lowered active position of the slip;
said side wall of the slip bowl containing an opening extending entirely through the radial thickness of said side wall vertically between said two spaced surfaces of the bowl and into which a lower one of said two camming surfaces on said individual slip is movable in an upper retracted position of the slip.