US3250331A

US3250331A - Locking device for well tools

Info

Publication number: US3250331A
Application number: US228829A
Authority: US
Inventors: William G Boyle
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-10-08
Filing date: 1962-10-08
Publication date: 1966-05-10
Anticipated expiration: 1983-05-10

Description

y 9 w. G. BOYLE 3,250,331

LOOKING DEVICE FOR WELL TOOLS Filed Oct. 8, 1962 2 Sheets-Sheet l S 2 R Y 5 O E d 9 a 8 5 .0 N M w m m e w 5 Q/fi W A M 22., .1; 7/ f m L 1 r I. If \?0v 4. ,.v R G 2 m M V l O .W M F W Y M B 3 .m G F. in

May 10, 1966 w. s. BOYLE LOCKING DEVICE FOR WELL TOOLS 2 Sheets-Sheet 2 Filed Oct. 8, 1962 INVENTOR William G. Boyle 6 W BY M W ATTORNEYS United States Patent 3,250,331 LOCKING DEVICE FOR WELL TOOLS William G. Boyle, 13559 Brookgreen, Dallas, 'Iex. Filed Oct. 8, 1962, Ser. No. 228,829 Claims. (Cl. 166-133) This invention relates to well tools and more particularly to locking mechanisms for releasably locking well tools in a well fiow conductor and to an expansible locking member for use in such locking mechanisms.

An object of this invention is to provide a new and improved locking mechanism for locking a well tool, such as a plug, in a predetermined position in a flow conductor.

Another object is to provide a locking mechanism having an expandable locking member movable outwardly from a retracted position relative to the tool toward an expanded position wherein it projects outwardly of the well tool and into position to be engaged by an internal shoulder of the well flow conductor to limit movement of the well tool'in the flow conductor.

Still another object is to provide a locking mechanism wherein the expandable locking member is very flexible to facilitate its expansion but has great strength to prevent its crushing or deformation when subjected to severe stresses.

A further object is to provide an expandable locking member for use in a locking mechanism which includes a substantially circular coil or garter spring and a central substantially circular core extending through the spring whereby the solid central ring prevents crushing of the garter spring while at the same time the locking member is quite flexible and is easily moved from its retracted position to its expanded position.

A still further object is to provide an expandable locking member substantially circular in form which has a relatively great thickness but is more flexible than a solid member of the same material and thickness, a coil or garter spring disposed about a solid core, the garter spring providing the desired thickness and the core preventing crushing or deformation of the spring upon the imposition of a shearing force on the locking member parallel to the central axis of the locking member.

Another object is to provide a locking member in the form of a split ring to facilitate its assembly in the locking mechanism.

Still another object is to provide a locking member wherein the core ring is segmented to facilitate fabrication of the locking member.

Additional objects and advantages of the invention will be readily apparent from the reading of the following description. of a device constructed in accordance with the invention, and reference to the accompanying drawings thereof, wherein:

FIGURE 1 is a partly sectional view of a well tool provided with the locking mechanism embodying the invention and showing the well tool as it appears during its movement to a predetermined position in a well flow conductor at which it is to be locked in place;

FIGURE 2 is a fragmentary sectional view showing the well tool locked in the predetermined position in the well flow conductor and also showing a running tool for moving the well tool to the predetermined position;

FIGURE 3 is a partly sectional view, with some parts broken away, of the expandable locking member of the locking mechanism;

FIGURE 4 is a top view, with some parts in section 'and broken away, showing the expandable lock member in its expanded position;

FIGURE 5 is a sectional view showing a modified form of the expandable locking member; and,

ice

FIGURE 6 is a sectional view of another modified form of the expandable locking member.

Referring now particularly to FIGURES 1 through 4 of the drawing, the plug 10 embodying the invention is employed to plug the well flow passage 13 of a nipple 14 which is threaded at its opposite ends so that it may be connected in and constitute a section of a flow conductor such as a well head or a string of tubing. The plug includes a body 16 having an upwardly opening central recess 18 in which is threaded the lower end of a tubular mandrel 19. The tubular mandrel has an internal annular flange 21 at its lower end whose lower end surface engages the upper surfaces of an O-ring 22 or other suitable seal means disposed in the annular upwardly opening recess 24 of the internal flange 25 of the body. The O-ring 22 is adapted to engage the intermediate seal surface 28 of a pressure equalizing valve 30 to prevent flow of fluid through the longitudinal flow passage 31 of the body and the flow passage 33 of the mandrel 19 when the valve is in the upper position in the body illustrated in FIGURES I and 2.

The valve has an external annular flange 34 whose upper surface 36 engages the downwardly facing annular shoulder 37 of the internal flange 25 of the body 16 to limit upward movement of the valve in the body. The valve is biased upwardly towards its closed position by a coil spring 40 disposed in the flow passage 31 whose upper end engages the lower end surface 42 of the valve and whose lower end engages .the retainer pin 44 disposed in suitable lateral bores 45 of the reduced lower portion 46 of the body and extending diametrically across the flow passage 31.

The upper reduced end portion 48 of the valve extends upwardly into the mandrel 19 where it is engageable by a suitable tool inserted into the mandrel to cause downward movement of the valve to open position when it is desired to open the valve to equalize pressures across the well tool when the well tool is in locked position in the nipple 14. The beveled surface 49 between the lower end of the upper portion 48 and the intermediate portion providing the sealing surface 28 is beveled to facilitate movement of the sealing surface 28 into engagement with the O-ring 22 as the valve moves upwardly from its open position wherein the sealing surface is below and spaced from the O-ring to-its closed position.

The body 16 of the plug has an external annular recess 51 in which is disposed an O-ring 52 adapted to engage the internal seal surface 53 of the nipple 14 below the internal annular upwardly facing shoulder 54 of the landing nipple which is engageable by the annular ex ternal downwardly facing shoulder 55 to limit downward movement of the body in the landing nipple.

A tubular expander 56 is mounted for limited longitudinal movement on the mandrel 19 between the upper position illustrated in FIGURE 1 wherein its upward movement is limited by the engagement of its upwardly facing annular shoulder 57 with the downwardly facing annular shoulder 58 of the external annular flange 60 at the upper'end of the mandrel and the lower position illustrated in FIGURE 2 wherein its downward movement is limited by the engagement of its downwardly facing shoulder 61 with the upwardly facing annular shoulder or surface 63 of the body defining the lower end of the annular upwardly opening recess 64 in the upper end of the body into which is telescopable the lower end portion of the expander.

The expander is enlarged at its lower end to provide the annular retainer surface 66 about which the expandable locking member 68 is disposed when the expander member is in its upper position. The expander also has an upwardly and outwardly beveled expander surface 70 which cams or moves the expander member outwardly upon downward movement of the expander member relative to the mandrel and the locking member 68. The expander surface extends from the upper end of the annular retainer surface 66 to the lower end of the annular locking surface 72 of greater diameter than the retainer surface which holds the locking member in locked and expanded position when the expander is moved to its lower position. A retainer flange 74 extends outwardly of and above the locking surface to provide a downward 1y facing shoulder 75 which prevents accidental upward displacement of the locking member relative to the expander during any movement of the well tool through a flow conductor. The upper end of the expander has an external annular-flange 77 which provides the annular undercut shoulder 78 which may be engaged by a suitable pulling tool.

The expandable locking member 68 includes a substantially annular coil or garter spring 80 through whose coil extends a split resilient core ring 81. The extreme free end portions 83' and 84 of the spring are crimped inwardly to engage the end surfaces 85 and 86, respectively, of the core ring to prevent displacement of the core ring from the spring. The core ring is made of a resilient metal and its'inherent position is that illustrated in FIG- URE 3 wherein its ends overlap so that the locking member 68 must be expanded when it is positioned on the expander and in engagement with the lower retainer surface 66 whereby the locking member is resiliently biased towards gripping engagement with the retainer surface so that the locking member will not move outwardly from the retainer surface until a longitudinal acting force is applied thereto.

The locking member is positioned in alignment with the internal annular locking recess 88 of the nipple when the body 16 of the plug is in the lowermost position in the nipple illustrated in FIGURE 2 with its downward movement arrested by the engagement of its stop shoulder 55 with the stop shoulder 54 of the nipple.

During downward movement of the expander on the mandrel from the upper position illustrated in FIGURE 1 relative to the mandrel and the body to the lower position illustrated in FIGURE 2, the locking member is engaged by the expander surface or shoulder 70 of the expander and is moved thereby to its expanded position wherein its outer portions extend outwardly of the body above the upwardly facing annular end surface 87 of the body and are received in the internal annular lock recess 88 of the landing nipple to engage the upwardly and in- Wardly beveled lock shoulder 89 defining the upper end of the internal lock recess to limit upward movement of the well tool in the landing nipple. The locking surface 72 then holds the locking member in expanded position and any upward movement of the body now causes its top end surface to engage the lower surface of the locking member and since the upper surfaces of the locking member now engage the lock shoulder 89 of the nipple, the plug is held against upward movement in the nipple by the locking member.

In use, if the landing nipple 14 is connected in a well head, the lower end of a rod, not shown, may be threaded in the internally threaded upper end portion 92 of the mandrel. The plug is then lowered into the well head and into the landing nipple 14 thereof with the expander disposed in its upper position with its retainer surface 66 in engagement with the locking member 68 which is now in retracted position with no portion thereof extending outwardly'of the body and with its lower surfaces engaging the top end surface. The frictional engagement of the lock ring which resiliently grips the lower retainer surface 66 of the expander holds the expander in its upper position, any downward movement of the expander being limited by the engagement of the beveled expander surface 70 of the expander with the top surface of the locking member since the lower surface of the locking member may engage the top end surface 8 7 of the body.

4 If desired, the expander may be held inits upper position by 'a shear screw 93 whichextends through a suitable aperture of the mandrel into a threaded bore of the mandrel 19.

When the plug has been lowered into the well head and moves into the nipple connected therein, the O-ring 52 moves into sealing engagement with the sealing surface 53 as it moves downwardly past the upwardly facing shoulder 54 which is beveled downwardly and inwardly to facilitate passage of the O-ring therepast without injury or damage to the O-ring. As the plug is moved further downwardly in the well head and the nipple by means of such rod, the downward movement of the body 16 of the plug and therefore of the mandrel 19 which is rigid therewith is stopped by the engagement of the shoulder 55 of the body with the upwardly facing shoulder 54 of the nipple. At this time, the locking member 68 is positioned in alignment with the lock recess 88 of the landing nipple below the upper lock shoulder 89 thereof.

A suitable pipe or sleeve may then be telescoped downwardly over the rod connected to the mandrel to engage either the upwardly facing top surface 95 or the intermediate upwardly facing annular shoulder 96 of the expander. A downwardly acting force exerted through such sleeve or pipe on the expander moves it downwardly on the mandrel. If the shear screw 93 is employed, the shear screw 93 is sheared to permit such downw ard movement of the expander. Such downward movement of the expander now causes the beveled expander surface 70 to expand the locking member radially and move it outwardly to the position illustrated in FIGURE 2 wherein outer portions of the locking member extend into the lock recess in position to be engaged by the upper lock shoulder 89 and the locking surface 72 moves inwardly of the locking member and holds it in such expanded posi tion. The locking member is easily moved to its expanded position because it is quite flexible since the split core ring 81 has a relatively small cross-sectional area or thickness and since the spring flexes easily and its coils may move readily relative to one another.

When downward movement of the expander is stopped by the engagement of the shoulder 61 of the expander with the upwardly facing shoulder 63 of the body, the pipe or sleeve which is telescoped over the rod is removed and the rod is then unscrewed from the upper end of the mandrel 19, the frictional engagement of the O.-ring 52 preventing rotation of the mandrel and body during this operation of removal of the rod. When the rod is removed from the well head, the plug is left in position closing the fiow passage of the nipple since the O-ring 52 is now in sealing engagement with the seal surface 53 below the shoulder 54 and since the pressure equalizing valve 30 is held in its upper position by the spring 40 and prevents any upward flow of fluids past the plug. The plug is held against downward movement in the flow conductor by the engagement of the

shoulders

55 and 54 of the plug and of the nipple, respectively, and against upward movement by the engagement of the locking member with the downwardly facing lock shoulder 89 of the lock recess 88.

It will be apparent that the locking member has a large annular or circular area engaged with the lock shoulder 89 and, since the coil spring 80 cannot be deformed or crushed by longitudinally acting forces which tend to move the plug upwardly, the plug will be held in position even though large upwardly acting pressure differentials may exist across the plug.

When it is desired to remove the plug from the well head, any suitable well known pulling tool, for example, the Type B Otis Pulling Tool illustrated on page 3933 of the Composite Catalog, Oil Field Equipment and Services, 1960-61 edition, may be lowered into the well head. The prong attached to such pulling tool enters into the mandrel 19, engages the upper end of the extension 48 of the pressure relieving valve and moves it downwardly to open position as the pulling tool is moved downwardly in the nipple to the position wherein its dogs move below and engage the undercut shoulder 78 of the upper flange 77 of the expander. Opening the pressure equalizing valve 30 permits the pressure across the plug to be equalized.

Upward movement of the running tool then causes the expander to be moved upwardly on the mandrel until its upwardly facing shoulder 57 engages the downwardly facing shoulder 58 of the mandrel 19. During such upward movement of the expander, the locking surface 72 and the expander surface 70 are moved upwardly relative to the locking member which retracts radially due to its inherent resilience as the expander surface moves therepast to engage theretainer surface 66 of decreased diameter. The locking member is held against upward movement until it moves to retracted position by its engagement with the downwardly facing lock shoulder 89 of the nipple. \Vhen the upward movement of the expander is stopped by the engagement of its shoulder 57 with the shoulder 58 of the mandrel, continued upward movement of the running tool will cause the plug to be moved upwardly and out of the nipple in the well head since the locking member is now in retracted position and cannot engage the lock shoulder 89 of the nipple.

Should the locking member, for any reason, fail to move back to its retracted position when the expander surface 7t) moves upwardly therepast, upon force imparted to the body 16, when the upward movement of the expander relative to the mandrel is arrested by the engagement of the

shoulders

57 and 58, will cause an upward force to be exerted on the locking member and the camming action between the outer surface of the locking member and the upwardly and inwardly beveled lock shoulder 39 will move the locking member back to its retracted position and permit upward removal of the plug from the well head.

If the nipple 14 is connected in a string of tubing and it is then desired to lower the plug into position in the nipple by means of the usual flexible line tool assembly which may include jars, the plug is releasably connected to such flexible line tool assembly by means of a running tool 100 whose lower tubular skirt 101 telescopes over the external annular flange 60 at the upper end of the mandrel and is releasably secured to the mandrel by means of shear pins 102 received in the tangential grooves 163 of the external flange 60 and which extend through suitable internal grooves 104 of the running tool. The lower end of the annular end surface of the skirt then engages the upper end surface 95 of the expander which is held in its raised position by the shear screw 93. The running tool is provided with an'upwardly extending threaded pin, not shown, by means of which it is connected to the flexible line tool assembly which in turn is connected to the lower end of a flexible line so that the plug may be lowered thereby through the string of tubing until the downward movement of the plug is stopped by the engagement of the shoulder 55 thereof with the upwardly facing shoulder 54 of the nipple. Downward jars are then imparted to the running tool in the usual manner by the jars of the tool assembly which first cause shearing of the shear pins 102 to freethe running tool 100 for downward movement relative to the mandrel and then cause shearing of the shear screw 93. Further downward jars imparted to the running tool then cause the expander 56 to move downwardly relative to the mandrel, the lock ing member being moved to its radially expanded position by the expander surface 70 as the expander moves downwardly on the mandrel to the position illustrated in FIGURE 2. The running tool may then be raised from the well since it now is no longer connected to the mandrel.

The plug 10 may, of course, be removed from the nipple'14, when the nipple is connected in the string of tubing, in the same manner and by the use of the same pulling tool as when it is mounted or connected in a well head. Such pulling tool would be lowered into the string of tithing preferably by means of a flexible line.

It will now be seen that a new and improved well tool has been illustrated whose locking mechanism includes a substantially annular resilient member which is expandable radially outwardly upon the longitudinal movement of an expander relative to the body of the well tool when downward movement of the body through a flow conductor is arrested.

It will further be noted that the expander member is easily moved to its expanded position since it includes a coiled spring of annular shape having a reinforcing member or core substantially annular in configuration which extends through the coil spring, the core being of relatively small thickness or cross-sectional area.

It will further be noted that the locking mechanism is of extremely simple construction and that the substantially annular coil spring provides a very large annular area of contact between with the locking shoulder 89 which it engages to lock the well tool in position against upward displacement in a flow conduct-or and that the provision of the core extending through the coils of the spring imparts great strength to the locking member whereby the locking member may hold a well tool in locked position in a well flow conductor even when an extremely high pressure differential exists across the well tool.

The locking member 125 illustrated in FIGURE 5 may be used in place of the locking member 68 and is substantially similar in structure having a coil or garter spring 126 of substantially annular configuration having ring segments 127 which extend through the coils of the spring.

' One of the segments preferably spans the gap between the ends of the coil spring to hold the ends of the spring against displacement relative to one another. It will be apparent that the ring segments may easily be inserted in the coils of the spring and that they prevent crushing or deformation of the spring in the same manner as does the split ring 81 of the locking member 68. If desired, the adjacent free ends 128 and 129 of the coil spring 126 could be connected together as by welding or soldering. The ring segments 127, unlike the split core ring 81, do not resiliently resist the radial expansion of the locking member since they are free to move relative to one another.

The locking member 135 illustrated in FIGURE 6 may also be used in place of the locking member 68 and includes a coil spring 136 which is provided with ring segments 137 which extend through the coils thereof. The

spring 136 is a continuous spring and rectangular in crosssection in order to provide a large surface area of contact with the ring segments and with the top end surface 87 of the body 16 so that the locking member provided with the coil spring of such rectangular cross-sectional area can withstand very high compressive forces without deformation or failure of the coil spring. It will be apparent that the coil spring and the coil spring 126 could als obe rectangular in cross-sectional configuration.

It will now be apparent that each of the locking members illustrated and described is annular in shape and formed of the coil spring whose coils are wound about an annular axis and in which is disposed a reinforcing or core means, such as the split ring 81 or the

ring segments

127 or 137 and that the locking member is easily radially expanded, as by the movement of the expander surface 70, the-rethrough, due to the coil construction of the spring and that reinforcing or core means which extends through the coils of such springs prevents deformation or crushing of the springs which would otherwise occur if such reinforcing members were not present.

It will also be apparent that the core means may be in the form of a resilient split ring or a plurality of arouate or ring segments and that the coil spring itself may be in the form of a split ring or in the form of a complete or continuous ring.

It will further be seen that in each of the forms the inherent internal diameter of the annular locking member is smaller than the diameter of the retainer surface 66 so that the locking member will engage and grip the retainer surface 66 and, when moved to radially expanded position by the expander surface 70, will tend to move back radially to its retracted position due to its own inherent resilience.

It will further be apparent that each form of the locking member comprises a resilient member wound in coils about an annular line or axis and disposed substantially annularly about the central axis of the annular axis about which the coils are wound whereby the resilient member forms a ring and that the reinforcing means whether of the split ring type or the ring segment type are disposed annularly about such central axis.

The foregoing description of the invention is explanatory only, and changes in the details of the construction illustrated may be made by those skilled in the art, within the scope of the appended claims, without departing from the spirit of the invention.

What is claimed and desired to be secured by Letters Patent is:

1. A well tool for use in a flow conductor provided with a pair of longitudinally spaced oppositely facing stop means including: a body having stop means for engaging one of said stop means of said flow conductor to limit movement of said well tool in one direction through said. flow conductor; and a substantially annular locking member carried by said body comprising a substantially annular member having helical coils extending about an annular axis, and a plurality of spaced arcuate core segments disposed in substantially annular alignment in said coils for preventing deformation of said coils, said. locking member being positionable between said spaced stop means of said flow conductor when movement of the well tool in said one direction through said flow conductor is arrested by engagement of said stop means of said body with said one of said stop means of said flow conductor and expandable radially of the longitudinal axis of said flow conductor, expander means movable longitudinally of said body for expanding said locking member radially from a retracted position wherein it is not engageable with the other of said stop means of said flow conductor to an expanded position wherein it extends outwardly of said body and is engageable with said other of said stop means on said flow conductor to limit movement of said well tool in said flow conductor in the direction opposite said one direction, said expander means having means engageable with said locking member for limiting movement of said locking member in a direction opposite said one ternal locking surface of greater diameter than said retainer surface, an external expander surface extending outwardly and in a second direction opposite said one direction from said retainer surface to said locking surface, and a stop means; and a substantially annular locking member carried by said body and disposed about said expander, said locking member being positionable between said spaced stop means of said flow conductor when movement of the well tool in said one direction in said flow conductor is arrested by engagement of said stop means of said body with said one of said stop means of said flow conductor, said locking member being radially expandable, said body having means engageable with said locking member for limiting movement of said locking memberin said one direction relative to said body, said locking means being in radially retracted position when disposed about said retainer surface and in radially expanded position when disposed about said locking surface, said locking member being moved by said expander surface from said retracted position to said expanded position when said expander is moved longitudinally in said one direction relative to said body from said inoperative position to said operative position, said stop means of said expander limiting movement of said locking member in said second direction on said expander.

3. The well tool of claim 2, wherein said tool has seal means carried by said body for sealing between said body and said flow conductor, said body having a flow passage for permitting flow of fluid past said seal means; and valve means for closing said flow passage to prevent flow of fluid in a predetermined direction through said flow passage.

4. The well tool of claim 2, wherein said tool has means releasably securing said expander to said body in said inoperative position.

5. The well tool of claim 4, wherein said tool has seal means carried by said body for sealing between said body and said flow conductor, said body having a flow passage for permitting flow of fluid past said seal means; and valve means for closing said flow passage.

References Cited by the Examiner UNITED STATES PATENTS 2,070,638 2/1937 McCombs 267-1 X 2,434,426 1/ 1948 Muller 2 85-32-1 2,506,680 5/1950 Otis 166-1 15 2,638,896 5/1953 Clark =267-1 X 2,776,015 1/1-957 'Bielstein 166-125 X 2,898,136 8/1959 Hall et al 166-243 X 2,922,665 1/1960 Beyer 285-318 X 2,939,728 6/ 1960 Bitel 285-315 2,939,729 6/1960 OShaughnessy 285-315 3,074,485 1/1963 McGowen 166-217 3,139,142 6/1952 Chisholm et al 166-224 FOREIGN PATENTS 484,214 6/1952 Canada. 946,580 8/1956 Germany.

CHARLES E. OCONNELL, Primary Examiner.

Claims

2. A WELL TOOL FOR USE IN A FLOW CONDUCTOR PROVIDED WITH A PAIR OF LONGITUDINALLY SPACED OPPOSITELY FACING STOP MEANS, SAID WELL TOOL INCLUDING: A BODY HAVING STOP MEANS FOR ENGAGING ONE OF SAID STOP MEANS OF SAID FLOW CONDUCTOR TO LIMIT MOVEMENT OF SAID WELL TOOL IN ONE DIRECTION THROUGH SAID FLOW CONDUCTOR; AN EXPANDER MOUNTED ON SAID BODY FOR LONGITUDINAL MOVEMENT THEREON BETWEEN AN OPERATIVE POSITION AND AN INOPERATIVE POSITION, SAID EXPANDER HAVING AN EXTERNAL RETAINER SURFACE, AN EXTERNAL LOCKING SURFACE OF GREATER DIAMETER THAN SAID RETAINER SURFACE, AN EXTERNAL EXPANDER SURFACE EXTENDING OUTWARDLY AND IN A SECOND DIRECTION OPPOSITE SAID ONE DIRECTION FROM SAID RETAINER SURFACE TO SAID LOCKING SURFACE, AND A STOP MEANS; AND A SUBSTANTIALLY ANNULAR LOCKING MEMBER CARRIED BY SAID BODY AND DISPOSED ABOUT SAID EXPANDER, SAID LOCKING MEMBER BEING POSITIONABLE BETWEEN SAID SPACED STOP MEANS OF SAID FLOW CONDUCTOR WHEN MOVEMENT OF THE WELL TOOL IN SAID ONE DIRECTION IN SAID FLOW CONDUCTOR IS ARRESTED BY ENGAGEMENT OF SAID STOP MEANS OF SAID BODY WITH SAID ONE OF SAID STOP MEANS OF SAID FLOW CONDUCTOR, SAID LOCKING MEMBER BEING RADIALLY EXPANDABLE, SAID BODY HAVING MEANS ENGAGEABLE WITH SAID LOCKING MEMBER FOR LIMITING MOVEMENT OF SAID LOCKING MEMBER IN SAID ONE DIRECTION RELATIVE TO SAID BODY, SAID LOCKING MEANS BEING IN RADIALLY RETRACTED POSITION WHEN DISPOSED ABOUT SAID RETAINER SURFACE AND IN RADIALLY EXPANDED POSITION WHEN DISPOSED ABOUT SAID LOCKING SURFACE, SAID LOCKING MEMBER BEING MOVED BY SAID EXPANDER SURFACE FROM SAID RETRACTED POSITION TO SAID EXPANDED POSITION WHEN SAID EXPANDER IS MOVED LONGITUDINALLY IN SAID ONE DIRECTION RELATIVE TO SAID BODY FROM SAID INOPERATIVE POSITION TO SAID OPERATIVE POSITION, SAID STOP MEANS OF SAID EXPANDER LIMITING MOVEMENT OF SAID LOCKING MEMBER IN SAID SECOND DIRECTION ON SAID EXPANDER.