US2695068A - Packing device - Google Patents

Description

J. R. BAKER ETAL 2,695,068

PACKING DEVICE 3 Sheets-Sheet 2 Nov. 23, 1954 Filed June 1, 1951 NOV. 23, 1954 J, R, BAKER ETAL 2,695,068

PACKING DEVICE Filed June l, 1951 3 Sheets-Sheet 3 INVENTORS. tH/v R. B4/ 52,

BY EA/JAM/N l. AUST/N,

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United States Patent 2,695,358 Patented Nov. 23, 1954 nice PACKING DEVICE John R. Baker, Pasadena, and Benjamin Lewis Austin, Downey, Calif., assignors to Baker Oil rllools, Inc., Vernon, Calif., a corporation of California Application .lune 1, 1951, Serial N0. 229,352 Claims. (Cl. 1645-294) The present invention relates to packing devices for forming a seal against a companion wall, and more particularly to well packers embodying a packing structure for sealing against the inner wall of well casings, or similar well conduits.

Well packers embodying packing structures are set in well conduits to prevent ow of uids between the packers and the conduits. Ample clearance is ordinarily provided between the packer and conduit to facilitate lowering of the former to the desired setting point at which the initially retracted packing structure is expanded outwardly into leakproof engagement with the conduit. In some well bores, the packers are subjected to comparatively high pressures and temperatures, which produce cold Howing of the rubber, or rubber-like, packing material through the clearance space between the packer and the well conduit, at times causing its complete displacement and dissipation from the region of sealing against the conduit wall, resulting in leakage past the packer.

The aforementioned difculty has been overcome to a substantial extent by placing a pliant, inelastic annulus, such as a lead ring, at the end portions of the rubber packing element, as described in the patent to Reuben C. Baker, Patent No. 2,204,648. rl`hese lead rings are stretched outwardly against the conduit wall to bridge the aforenoted clearance spaces, and prevent the dissipation of the packing material into and through such spaces. Although highly effective in preventing cold flow of the packing material, yet under certain extreme conditions even the lead rings are forced into and through the annular clearance spaces to the extent in which they are no longer present to prevent dissipation of the rubber or rubber-like packing material.

Accordingly, it is an object of the present invention to prevent cold flow or dissipaiton of lead, or similar rings from their bridging position across clearance spaces around a packer device, holding them in such locations to preclude cold ow of the rubber packing material through such clearance spaces.

Another object of the invention is to cause the expansion of a pliant, inelastic annulus to produce an adjoining comparatively rigid bridge across which is capable of supporting and backing up the annulus, holding the latter in its appropriate position to, in turn, serve as a bridge or barrier through which the rubber or rubber-like packing material cannot pass.

A further object of the invention is to cause the pliant, inelastic annulus placed around a rubber packing element to form a lip type of seal against an adjoining wall, as a result of expansion of the annulus and packing element against such wall.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of several forms in which it may be embodied. Such forms are shown in the drawings accompanying and forming part of the present specification. These forms will now be described in detail, illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by' the appended claims.

Referring to the drawings:

Figure l is a longitudinal section through a well packer embodying the invention disposed in a vwell casing, with certain of the packer parts in retracted position;

Fig. 2 is a view similar to Fig. l, of the packer anchored in packed-ntf condition against the casing;

the clearance space 3 is a cross-section taken along the line 3 3 on 1g.

Fig. 4 is a fragmentary longitudinal section, on an enlarged scale, disclosing the anchoring and packing portion of the packer, with the parts in retracted position;

Fig. 5 is a view similar to Fig. 4, disclosing certain parts in expanded condition against the well casing;

Fig. 6 is a fragmentary longitudinal section through another embodiment of the invention disposed in a well casing, with parts in retracted position;

Fig. 7 is a view similar to Fig. 6 disclosing the parts in expanded position against the well casing;

Fig. 8 is a fragmentary longitudinal section through still another embodiment of the invention, with the parts disposed in a well casing in retracted position;

Fig. 9 is a view similar to Fig. 8, disclosing the parts expanded against the well casing.

The invention is illustrated in the drawings as applied o a well packer A, that is to be anchored in packed-off condition in a well lcasing B through use of a setting tool C secured to the lower end of a tubular running-in string The well packer, however, may be anchored in packed-off condition in the well casing through use of other specific instrumentalities, without departing from the present invention.

As disclosed in the drawings, the well packer A has its upper portion threadedly secured to a setting tool C, which actually forms the lower end of a tubular runningin string D running to the top of the well bore, and by means of which the packer is lowered to the desired setting or anchoring pointv within the well casing. The packer includes a tubular body 10 having an .abutment and guide 11 threaded on its lower end, and a head 12 at its upper end around which the skirt 13 of a cylinder 14 is disposed. A cylinder head 15 is integral with and extends inwardly from the lower end of the skirt, carrying a suitable side Seal ring 16 for slidable sealing engagement with the external surface of the body 10. A suitable side seal ring 17 is also provided on the body head 12 fr slidable engagement with the interior of the cylinder s irt 13.

A set of upper segmental slips 18 is disposed around the body immediately below the cylinder head 15. These slips are held initially in retracted position by shear screws 19, or other frangible devices, which attach the slips to an upper conical expander 20 initially secured to the body by one or more shear screws 21. The converging surfaces 22 of the upper set of slips and upper expander are so disposed with respect to one another as to secure the packer against movement in an upward direction within the casing B, or other well conduit following outward expansion of the slips 18 into engagement with the casmg.

A set of lower segmental slips 23 is provided adjacent the body abutment 1l, these slips also being secured by shear screws 24 to a lower tapered expander 25 attached initially to the body by one or more shear screws 26. The direction of taper of the exterior 27 .of the lower expander and of the cooperable surfaces on the lower slips is such as to hold the well packer against movement in a downward direction following expansion of the slips 23 outwardly to casing engaging position.

A suitable lock is provided between the body 10 and lower expander 25, to permit upward movement of the body within this expander, but to preclude its downward movement. Such lock may be constituted by a split tapered wedge ring 28 received within a tapered groove 29 within the lower expander.

A packing structure 30 is initially held in retracted position around the body l0 between the upper and lower expanders 20, 25. When the expanders are moved longitudinally relatively toward each other, the packing structure is foreshortened and expanded outwardly against the wall of the well casing B.

As stated above, the setting tool C is threaded, as by a left-hand thread 31, into the upper head 12 of the packer body 10. This setting tool has a lower head 32 carrying suitable side seals 33 for sealing engagement with the inner wall of the body 1t), below body ports 34 that provide communication between the interior of the body and the cylinder space 3S between the body head 12 and the cylinder head 15. Fluid can iiow from the passage 36 through the setting tool C, through elongate ports 37 in the latter, and through the body ports 34 into the cylinder space 35, in order to impose a uid pressure acting in a downward direction on the cylinder head 15.

The well packer A is run in the well bore with the slips 18, 23 and packing structure 30 in retracted position, as disclosed in Figs. 1 and 4. The cylinder 14 is held initially in its upper position by one or more shear screws 38 securing the skirt 13 to the body head 12. During the lowering of the packer A in the well casing B, the tubular string D is filled automatically with the iinid in the well casing, which ows upwardly through the packer body and the central passage 36 in the setting tool into the tubular string.

Upon reaching the point in the well casing at which the packer is to be anchored in packed-off condition, a trip ball 39 is dropped into the tubing string D, and is pumped, or allowed to gravitate, into engagement with a seat 40 in the setting tool head 32, closing the central passage 41 through the latter and enabling the pressure of the fluid in the tubing string D, setting tool C, its ports 37, body ports 34 and cylinder space 35 to be increased to a degree sufficient to overcome the shear value of the screws 38, 19 holding the cylinder 14 in its uppermost position and the upper slips 18 to the upper expander 20. Following rupture of these screws 38, 19, the cylinder 14 is moved downwardly to slide the upper slips 18 down along the tapered surface 22 of the upper expander 20 and outwardly into engagement with the wall of the casing B.

The shear screws 21 attaching the upper expander 20 to the body 10 have a greater shear valueY than the cylinder screws 38 and the screws 19 holding the upper slips 18 to the upper expander 20. The screws 26, 24 holding the lower expander 25 to the body 10 and the lower slips 23 to the lower expander have a greater shear value than the screws 21 attaching the upper expander to the body. It is, accordingly, apparent that only the first two sets of screws 38, 19 mentioned above are first sheared, causing the movement of the upper slips 18 into anchoring position against the casing. `Following such anchoring, the tubular string D is pulled upwardlv. to first disrupt the screws 21 holding the upper expander 20 to the body, then moving the packer body upwardly within this upper expander and carrying the lower expander 25 with the body toward the upper expander. Bv virtue of the movement of the lower expander 25 toward the upper expander 20, the packing structure 30 is foreshortened and expanded outwardly into firm sealing engagement with the casing B, and also is urged into firm sealing engagement with the exterior of the packer body 10. Following expansion of the packing structure in the manner described. a continuation of the upward strain on the tubular string D shears the lower expander screws 26 and the slip screws 24, causing the abutment 11 to move the lower slips 23 upwardlv along the lower expander 25 and outwardly into firm anchoring engagement against the wall of the well casing (Fig. 2i. After the well packer A has been completely set, in the manner described. the tubular string D may be rotated to the right. to unserew the setting tool C from the body head 12 at the left-hand threads 31, which allows the tubular string and setting tool to be removed from the well casing B.

The upper slips 18 prevent upward movement of the well packer and its body 10 with respect to the well casing B. The lower slips 23 prevent downward movement of the well packer and its body with respect-to the well casing, any tendency for the body to move downwardly being transmitted through the wedge lock 28 to the lower expander 25. and through the lower slips 23 to the casing. Accordingly. the well packer A is prevented from moving in either longitudinal direction.

It is desirable for the slips 18, 23 and packing structure 30 to be disposed in retracted position during lowering of the well packer in the well casing. To facilitate such lowering, suicient clearance is allowed between the well packer parts and the wall of the well casing. Thus. a substantial clearance space or gap G exists between the periphery of each expander 20, 25 and the wall of the well casing B, and this gap is bridged by the packing strtlrlcture 30 following its expansion against the casing wa Under some conditions encountered in well bores, the packing material, which usually includes natural or synthetic rubber, will pass into and through the aforenoted clearance spaces G following expansion against the casing. In particular, high pressures and temperatures cause the rubber or rubber-like packing material to fiow into and through such clearance spaces. At times, the ow may be of such an extent as to result in substantially complete dissipation of the packing material from its location between the expanders 20, 25, thereby leaving very little, if any, packing material available for the performance of its sealing function against the casing wall and the periphery of the packer body 10. As noted above, it has been proposed to place pliant, inelastic annuli, such as lead rings 45, at the end portions of a rubber packing element 46, which annuli are forced outwardly by the compressed rubber packing to effect a bridge across the clearance spaces G and thereby preclude cold flowing of the rubber packing material into and through such spaces. Although highly effective in rnost cases, the lead annuli 45 are themselves, at times, forced into and through the aforenoted clearance spaces. Following their dissipation through the clearance spaces, the lead is not available to prevent cold flowing of the rubber packing element 46 through such spaces, resulting in failure of the well packer A to perform its sealing function against the wall of the well casing B.

The aforenoted diiculties are overcome in the devices disclosed in the drawings. The packing structure 30 disclosed in Figs. l to 5, inclusive, includes a rubber or rubber-like packing sleeve 46 that has reduced diameter end portions 47 received within pliant, inelastic annuli or lead rings 45. The lead rings have outwardly tapering inner surfaces 48 converging toward each other, and also tapering outer surfaces 49 at their inner end portions diverging outwardly from each other. The inner surfaces 48 engage companion surfaces at the end portions of the rubber packing sleeve 46, whereas the outer surfaces 49 are spaced from the outer end portions 50 of the packing sleeve to provide a substantial gap 51 therebetween. The termini 47 of the rubber packing sleeve 46 extend within the cylindrical inner surface 52 of the lead rings 45.

The outer end 53 of each lead ring is tapered in an inward direction toward the rubber packing sleeve 46, engaging a companion tapered surface 54 on a circumferentially continuous outer ring member 55 made of rigid material, such as cast iron. This outer ring member 55 snugly engages and encompasses a circumferentially continuous inner rigid ring member 56. which may also be made of cast iron, and which is slidable along the exterior of the packer body 10. The inner ring member 56 bears against a pliant, inelastic annulus, such as a lead ring 57. that engages the inner end of the expander 20 or 25, and which also slidably engages the exterior of the packer body 10.

The outer rigid ring 55 has an outer tapered surface 58 which converges in an outward direction toward its other surface 54. The ring surface 58 engages a companion tapered surface 59 onl an expansible ring 60, which may also be made of cast iron, and which is provided with a gap or split 61 (Fig. 3). This ring is of generally L-shape in cross-section. with its upwardly extending arm 62 having an upper surface 63 inclined outwardly in a direction away from the packing sleeve 46, and engaging a companion tapered surface 64 formed on the expander 20 or 25. The ring 60 itself tends to remain in a contracted position with its gap 61 substantially closed, and bearing upon the inner lead ring 57.

An outer split contractile ring 65 is nested within the recess 66 of the other split ring 60, and has an outer tapered surface 67 engaging the tapered surface 64 of the expander. The gap 68 or split of this ring 65 is preferably circumferentiallv offset with respect to the other ring, gap 61. As disclosed most clearly in Fig. 3, the gaps are displaced about 18H degrees from each other.

When the packer body 10 is moved upwardly to foreshorten the packing structure 30, the upper expander 20 is held stationary by the upper slips 18. which are anchored in the casing wall. The upper lead annulus 45 exerts an upward force on the circumferentially continuous outer thrust ring 55, causing such ring to move upwardly and exert an outward force on the split ex,

ansible rings 60, 65 which slide along the tapered surface 64 of the expander 20 in an outward direction, and into engagement with the wall of the well casing B. substantialy completely bridging the clearance gap G between the expander 20 and the well casing Wall. As the compressive force foreshortening the packing sleeve 46 increases, as a result of continued upward movement of the packer body l0, the rubber packing sleeve is moved upwardly within the lead ring 45, the coengaging tapered surfaces d3 on the sleeve and inner lower portion of the lead ring urging the latter outwardly. In view of the malleable characteristics of lead, the continuous annulus is stretched and deformed in an outward direction, at first sliding upwardly on the tapered surface 54 of the outer thrust ring 55 and across the gap between the periphery of this ring and the wall of the well casing B. When the lead ring 45 engages the inner split contractile ring 6i?, it can move upwardly to no further extent. As a result, it is then deformed in an inward direction, bridging the annular space between the packer body il] and the casing wall. packing sleeve 46 is increased to a further extent, the inner thrust ring 57 is moved by the packing sleeve and the deformed lead ring 45 toward the expander 20, foreshortening the inner lead ring 57 and causing it to expand outwardly into engagement with the inner surface of the expansible split ring ell, completely filling the ycap left by the latter ring as a result of its outward expansion against the well casing. This lead ring 57 not only fills such gap, but it also is pressed firmly against the body of the packer, completely closing the slight clearance space that exists between the inner cylindrical surface of the conical expander 20 and the exterior of the packer bod Diiring the compression of the packing structure Btl, in the manner described above, the outer lead ring 45 and inner lead ring 57, as well as the inner and outer thrust rings 56, 55 and split expansible rings 60, d5 at the lower end of the packing sleeve 4d, are also urged outwardly and caused to occupy the same general positions as the corresponding structure at the upper end of the packing sleeve. The upper and lower portions of the packing structure 3d are identical, although arranged reversely with respect to one another.

lt is, accordingly, apparent that the exnansible rings 6i), 65 form an annular bridge or barrier across the clearance space G between each expander 20 or 25 and wall of the well casing B. The adioining pliant, inelastic annulus 45 cannot pass into or be dissipated through this clearance space G. The only gap that remains is the relatively small distance 6l between the ends of the inner ring d0, and the lead material t5 can pass into this gap 6l. However7 this gap is bridged by the other expansible ring 65, and. as a result. there is no straightthrough path that can be followed bv the casing engaging lead member d5. Any tendency for the lead material to flow inwardly through the aap 61 in the exnansible ring 60 is forestalled, inasmuch as the inner lead ring 57 will have been compressed between the thrust rings 55, 56 and the expander 2li or 25. and will till such gap partially, as well as the space within the expansible ring 6ft that would otherwise result upon expansion of the split rings dll. 65 against the wall of the well casing. Here again. the inner lead ring 57 cannot pass outwardly through such gan 6l. since the upper rortion of such gap is bridged by the outer split expansible ring 65.

Accordingly, there are no paths through which the lead bridging material i5 can flow upon being subjected to extreme conditions of temperature and pressure. The lead 45 forms an additional bridge or barrier between the packer body lll and wall of the well casing B. allowing no space whatsoever through which the rubber packing material 46 can flow. However, the rubber packing material is still available for engagement with the wall of the well casing B and the packer body lll, and is capable of forming a much more efcient seal therewith than other materials, such as lead.

The beveling or tapering of the outer inner portions 49 of the lead rings has still another important advantage. Since the packing sleeve ed is more readily expandible against the casing than the lead rings d5, foreshortening of the packing sleeve 46 causes its outer portion to iirst be deformed upwardly around the tapered part 49 of each lead ring, forming a circumferential lip .7@ around each outer end portion of the packing sleeve against the tapered surface i9 of each lead ring 45 (Fig. 5). l That is, the packing material 46, in effect, becomeswedged between the exterior of the end of each lead ring and the casing,forming a wedge-shapedlip 70 projecting in As the compressive force on the a longitudinally outward direction with respect to the l packing sleeve. Any fluid under pressure that might seep or leak past a lead ring 45 would engage such lip and urge it more firmly against the casing wall. As a result, each lip 74B insures against leakage of fluid along the exterior of the packing sleeve when the latter has been compressed outwardly against the wall of the well casing.

ln the form of packing structure disclosed in Figs. 6 and 7, a lead ring 45a is provided at each end portion of the rubber packing sleeve 46a. The upper end 53a of the lead ring bears upon an L-shaped, circumerentially continuous thrust ring 71 having an outwardly directed leg 72 engaging the outer end of the lead ring and a longitudinal portion 73 slidable along the exterior of the body l0, and extending upwardly within a pocket 74 formed between an expander 2t) or 25 and the periphery of the packer body. The inner end 75 of the leg is tapered in an outward direction leading away from the expander and is engaged by a companion inner tapered end '76 of lead ring 45a. A pair of nested split, rigid rings 60a, 65a is disposed between the leg 72 and the end of the expander 2t) or 25, the opposed surfaces 77, 73 on the expander and leg diverging with respect to one another in an outward direction, the split rings 60a, 65a having companion tapered surfaces engageable with the expander and leg surfaces 77, 7. As in the other form of the invention, the split portions of the rings are angularly displaced with respect to each other.

The inner corner 79 of each circumferentially continuous thrust member 71 may be chamfered or beveled to receive a pliant, inelastic ring 8l), such as a lead ring, of generally triangular shape, which engages the beveled surface, as well as the exterior of the packer body 10.

When the packer body lll is moved upwardly, to foreshorten the packing structure 30a and expand it outwardly against the casing wall, the longitudinally directed expanding force is transmitted through each thrust ring 7l, urging it toward its companion slip expander 20 or 25 and forcing the split rigid rings 69a, 65a outwardly against the casing wall, to bridge the annular space G between an expander and the casing wall. A continuation of the longitudinally directed force on structure then foreshortens the rubber packing sleeve 46a, causing its outer portion to be deformed around the beveled corner 49 of the lead ring, to provide the lip '70 referred to in connection with the other embodiment of the invention. A continuation of the longitudinal force then deforms the lead ring 45a, causing it to bridge the space between the thrust ring 7l and casing wall and pass into engagement with the split expander bridge ring olla. The lead ring 45a may also be deformed inwardly against the packer body lll, and will exert a force upon the inner lead ring S9, wedging it against the packer body lil and sealing completely the slight clearance space existing between the thrust ring 7l and exterior of the packer body (Fig. 7).

lt is apparent that, in the form of invention disclosed in Figs. 6 and 7, the longitudinal thrust on the packing structure 3de has rst expanded the split rings 66a, 65a. against the casi B, forming a bridge or barrier against which the lead rings will engage. Each lead ring 45a also forms a bridge or barrier, precluding cold ilow of the rubber packing material @da into or through any clearance spaces between the well packer A and the casing wall B, as well through any clearance spaces around the packer body l0.

-Tn the form of invention disclosed in Figs. 8 and 9, the packing sleeve is received within pockets in pliant, inelatsic circunferentiallj. continuous lead rings 45h. These rings are received within recesses or pockets 74a formed between an expander 2li or 25 and the exterior' of the packer body l0, and they are also engageable with the split expansible rings adb that contact the expanders, and which are embraced by the outer split rings 65b which also contact the expanders, all in essentially the same fashion as in the device illustrated in Figs. 6 and 7. v

When the packing structure Sub is compressed by im posing a. longitudinally directed force thereupon, the rubber packing sleeve deb shifts each lead ring 45h longitudinally toward its associated expander 2li or Z5, causing theexpansible rings 6%, 65b to move outwardly into engagement with the easing'wall, to bridge the clearance space G between the latter and the expander. A continuation of the upward strain then deforme each lead ring 45b Atultwardly against the expanded split ring 6.01). The

the packing however, cannot ow through the annular cleareffectively stopped by the bridging action of the split rings 60h, 65b across this space. The rubber sleeve 4612 cannot ilow past the lead ring 45h, since the latter is bridging the annular space between the packer body and casing wall. As before, the lead ring 4511 and rubber 46h cooperate to form the lip seals 70 on the packing element, to preclude leakage of fluid past the rubber sleeve.

The inventors claim:

l. A packing structure,

lead ring, ance space G, since 1t 1s including an annular non-metallic packing adapted to engage a companion wall, abutment means adjacent said packing, a pliant, inelastic annulus engaging said packing and adapted to be moved by said packing against the companion Wall, and means engageable with said annulus and abutment and including a laterally movable ring-shaped structure movable against the wall in response to said movement of said annulus by said packing.

2. A packing structure, including an annular non-metallic packing adapted to engage a companion wall, abutment means adjacent said packing, a pliant, inelastic annulus engaging said packing and adapted to be moved by said packing against the companion wall, and means engageable with said annulus and abutment and including a latcrally movable split ring-shaped structure movable against the wall in response to said movement of said annulus by said packing.

3. A packing structure, including an initially retracted annular non-metallic packing adapted to engage an encompassing wall, abutment means adjacent said packing, a pliant, inelastic initially retracted annulus engaging sai packing and adapted to be expanded by said packing against the companion wall, and means engageable with said annulus and abutment and including an expansible split ring-shaped structure movable outwardly against the wall in response to said movement of said annulus by said packing.

4. A packing structure, including an annular non-metallic packing adapted to engage a companion wall, abutment means adjacent said packing, a pliant, inelastic annulus engaging said packing and adapted to be moved by said packing against the companion wall, a circumferentially continuous thrust ring engaging and movable by said annulus, and a laterally movable ring-shaped structure engaging said thrust ring and abutment and movable against the companion wall in response to said movement of said thrust ring.

5. A packing structure, including an annular non-metallic packing adapted to engage a companion Wall, abutment means adjacent said packing, a pliant, inelastic annulus engaging said packing and adapted to be moved by said packing against the companion wall, a circumferentially continuous thrust ring engaging and movable by said annulus, and a laterally movable split ring-shaped structure engaging said thrust ring and abutment and movable against the companion wall in response to said movement of said thrust ring.

6. A packing structure, including an initially retracted annular non-metallic packing adapted to engage an encompassing wall, abutment means adjacent said packing, a pliant, inelastic initially retracted annulus engaging said packing and adapted to be expanded by said packing against the companion wall, a circumferentially continuous thrust ring engaging and movable by said annulus, and an expansible split ring-shaped structure engaging said thrust ring and abutment and movable outwardly against the wall in response to movement of said thrust ring.

7. In apparatus of the character described: a supporting body; an initially retracted non-metallic packing around said body and expandible into engagement with an encompassing wall; abutment means around said body adjacent said packing' a pliant, inelastic initially retracted annulus around said body expandible by said packing against the wall; a circumferentially continuous thrust ring movable longitudinally of said body and engaging and movable by said annulus; and an expansible split ringshaped structure engaging said thrust ring and abutment and movable by said thrust ring outwardly against the wa l.

8. In apparatus of the character described: a supporting body; an initially retracted non-metallic packing around said body and expandible into engagement with an encompassing wall; abutment means around said body adjacent said packing; a pliant, inelastic initially retracted annulus around said body expandible by saidrpacking against the Wall; a circumferentially continuous thrust ring movable longitudinally of said body and engaging and movable by said annulus; and a plurality of expansible split rings mounted one upon the other and engaging said thrust ring and abutment, said split rings having their split regions circumferentially offset with respect to each other, and said split rings being movable by said thrust ring outwardly against the wall.

9. In apparatus of the character described: a supporting body; an initially retracted non-metallic packing around said body and expandible into engagement with an encompassing wall; abutment means around said body adjacent said packing; a pliant, inelastic initially retracted annulus around said body expandible by said packing against the wall; a circulnterentially continuous outer thrust ring engaging and movable by said annulus; a circumferentially continuous inner thrust ring on said body and within said outer ring and engageable by said packing; and an expansible split ring structure engaging said outer ring and abutment and movable by said outer ring outwardly against the wall.

l0. In apparatus of the character described: a supporting body; an initially retracted non-metallic packing around said body and expandible into engagement with an encompassing wall; abutment means around said body adjacent said packing; a pliant, inelastic initially retracted annulus around said body expandible by said packing against the wall; a circumferentially continuous outer thrust ring engaging and movable by said annulus; a circumferentially continuous inner thrust ring on said body and Within said outer ring and engageable by said packing', and a plurality of expansible split rings mounted one upon the other and engaging said outer ring and abutment, said split rings having their split regions circumferentially offset with respect to each other, and said split rings being movable by said outer thrust ring outwardly against the wail.

ll. In apparatus of the character described: a supporting body; an initially retracted non-metallic packing around said body and expandible into engagement with an encompassing wall; abutment means around said body adjacent said packing; a pliant, inelastic initially retracted annulus around said body expandible by said packing against the wall; a circumferentially continuous outer thrust ring engaging and movable by said annulus; a circumferentially continuous inner thrust ring on said body and within said outer ring and engageable by said packing; an expansible split ring structure engaging said outer ring and abutment and movable by said outer ring outwardly against the wall; and a pliant, inelatsic annulus within said expansible split ring structure and between said inner thrust ring and abutment.

12. in apparatus ot the character described: a supporting body; an initially retracted non-metallic packing around said body and expandible into engagement with an encompassing wall; abutment means around said body adjacent said packing; a pliant, inelastic initially retracted annulus around said body expandible by said packing against the wall; a circumferentially continuous thrust ring movable longitudinally of said body and engaging and movable by said annulus; a plurality of expansible split rings mounted one upon the other and engaging said thrust ring and abutment, said split rings having their split regions circumferentially offset with respect to each other, and said split rings being movable by said thrust ring outwardly against the wall; and a pliant, inelatsic annulus within said expansible split ring structure and between said thrust ring and abutment.

13. ln apparatus of the character described: a supporting body; an initially retracted non-metallic packing around said body expandible into engagement with an encompassing wall; abutment means around said body and adjacent said packing; a pliant, inelastic initially retracted annulus around said body engageable by said packing and expandible by said packing against the wall; and an expansible split ring structure engaging said annulus and abutment and movable by said annulus outwardly against the wall.

14. A packing structure, including an annular nonmetallic packing adapted to engage a companion wall, abutment means adjacent said packing, a pliant, inelastic annulus engaging said packing and adapted to be moved by said packing against the companion wall, and a laterally movable ring-shaped structure engaging said annulus and abutment and movable by said annulus laterally against the wall.

15. A packing structure, including an annular nonmetallic packing adapted to engage a companion Wall, a pliant, inelastic annulus engaging said packing and adapted to be moved by said packing outwardly against the companion wall, said annulus having a circumferential outer surface inclined laterally outward in a direction leading longitudinally away from said packing to form a References Cited inthe le of this patent Number 5 1,734,040 2,135,583 2,204,648 2,467,801 2,474,491

circumferential Wall engaging lip on said packing upon 10 outward expansion of said packing and annulus against the wall.

UNITED STATES PATENTS Name Date McEvoy Nov. 5, 1929 Layne Nov. 8, 1938 Baker June 18, 1940 Baker Apr. 19, 1949 Penick June 28, 1949

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