GB2099533A - Split ring fastenings - Google Patents

Abstract

In devices, such as well tools, components which must support heavy loads are connected by a simple fastening device capable of transferring the heavy load from on component to the other, with the load being accepted by the fastening means in compression, and with the fastening means occupying only a small radial space. A fastening device of this type is disclosed and comprises a split ring (11) having triangular section ribs (19) presenting load- bearing surfaces (20) to a load bearing member (16), the load bearing member (16) having grooves to accommodate the ribs (19). The split ring also has an angled surface (21) parallel to and opposite the first load- bearing surfaces presenting a second load-bearing surface to a camming ring (10) supported by a second load- bearing member. Thus, a significant portion of the load transferred by ring (11) is by compression of the ring (11), little of the load being transferred by shear forces in the ring (11). <IMAGE>

Description

SPECIFICATION Fastening devices, and devices for transferring large axial loads This group of inventions relates to devices, typically but not exclusively well tools, for transferring large axial loads, and also to fastening devices which may be used in such load transfer devices.

Subject matter disclosed in the present application is also disclosed in our copending United Kingdom patent applications Nos.

8116682, 8116673 and 81 16737, all having the same date as the present application, and to which reference is directed.

In a number of arts, prior-art workers have found it necessary to provide devices for supporting heavy loads, with the nature of the device being such that the load must be transferred between two members connected together by fastening means in such manner that the fastening means transfers the load from one member to the other. Such a need is commonly met, for example, in well tools used to run, orient and land long and very heavy strings of pipe or tubing. Many types of fastening means have been employed in such devices, including screw threads, latch dogs or segments, no-lead fixed segments brought into engagement by relative rotation, and piston-actuated locking rings or segments. Such prior-art devices have achieved success and are commonly used.However, the loads to be supported continually increase, as for example with the increasing depth of oil and gas wells now being drilled, and the amount of space available for the components of the device has tended to decrease, so that there has been an increasing need for improved fastening means in well tools and like devices.

According to one of the present group of inventions, there is provided a device for transferring large axial loads comprising a first load-supporting member having a cylindrical surface, said cylindrical surface having at least one transverse annular groove, at least one side wall of said groove being frustoconical; an annular fastener comprising at least one annular rib having a first frustoconical load-bearing surface, said rib being dimensioned to be accommodated by said groove, a second frustoconical load-bearing surface parallel to and facing away from said first load-bearing surface, and a cylindrical surface spaced radially from said at least one rib and joining said second load-bearing surface in an annular corner, said annular fastener being resiliently urged to engage said rib in said groove with said first load-bearing surface in flush engagement with said frustoconical wall of said groove and said second load-bearing surface slanting away from said cylindrical surface of said first member; a second load-supporting member connected to said first member by said fastener, said second member having a cylindrical surface telescopingly engaged with said cylindrical surface of said fastener, and a frustoconical load-bearing surface in flush engagement with said second load-bearing surface of said fastener; and an additional member engaged with said second member to prevent said first and second members from being significantly moved telescopically relative to each other in a direction which would separate said frustoconical load-bearing surface from said second ioad-bearing surface of said fastener.

Thus, said one invention provides a device, such as handling tool for use in completing oil and gas wells, wherein two members which are intended to support a heavy load are connected together in an improved manner which can permit greater load-carrying capability while requiring relatively little of space for the fastening means.

The device may be used in the case wherein one of the members to be connected is tubular and has a wall which is relatively thin in the context of the heavy load to be supported, the tubular member being connected to another telescopically relates member by a simple split ring which transfers the heavy load.

According to another of the present group of inventions, there is provided a fastening device comprising an integral resilient metal split ring having an inner surface, an outer surface, a first end surface, and a second end surface, one of said inner and outer surfaces having an annular rib extending therealong and having a frustoconical load-bearing surface, the other of said inner and outer surfaces being cylindrical, and said first end surface being frustoconical, parallel to said loadbearing surface of said rib and facing away from said load-bearing surface.

Thus, this second invention provides a split ring which can simply connect two telescopically related members, the ring occupying a relatively small space and yet having a large loadsupporting capability.

Specific embodiments of the inventions will now be described, by way of example, reference being made to the accompanying drawings, in which: Figs. 1, 1 A and 1 B are vertical sectional views illustrating a handling tool for running, orienting, landing and retrieving a tubing hanger and multiple strings of tubing, the handling tool including two embodiments of the inventions; Fig. 2 is a fragmentary vertical sectional view showing relatively movable parts in different operative positions than in Fig. 1; Fig. 3 is a top plan view of a split ring fastener according to the invention and employed in the structure illustrated in Figs. 1 and 2; Fig. 4 is a fragmentary bottom plan view of the split ring of Fig. 3; Fig. 5 is a fragmentary sectional view taken generally on line 5-5, Fig. 1;; Fig. 6 is a radial sectional view taken generally on line 6-6, Fig. 3; Fig. 7 is a fragmentary side elevational view of a grooved portion of the body of the tool shown in Figs. 1-1 B; and Fig. 8 is a semi-diagrammatic view illustrating the manner in which heavy loads are transferred by the split ring of Fig. 3.

Figs. 1-1 B illustrate a multifunction handling tool, indicated generally at 1, which can be employed in conjunction with a handling string (not shown) to run, orient and land a tubing hanger 2, Fig. 1 B, in an underwater well installation in the manner described in our aforementioned applications Nos. 8116673 and 811 6637. Since the tubing hanger supports multiple strings of well tubing, which may be thousands of feet in length, the handling tool must support the very heavy load of the tubing strings during running, orienting and landing of the hanger Handling tool 1 has an elongated tubular body comprising an upper member 3 and a lower member 4, upper member 3 having an external groove 5, Fig. 1 , for attachment of the tool to the handling string (not shown). Lower member 4 carries a remotely operated hydraulically actuated coupling, indicated generally at 6, Fig. 1 B, by which tubing hanger 2 is attached to the bandling tool. Since the tubing hanger supports multiple strings of tubing disposed side-by-side, and since an upper component, typically a production upper body, must be installed after the handling tool is removed, the component having dependent stingers to engage in the multiple bores of the tubing hanger, it is necessary that the tubing hanger be oriented precisely to a predetermined rotational position before being landed. Tool 1 is therefore provided with a support collar 7, Fig. 1 A, and releasable means comprising antifriction bearing 8, thrust ring 9, camming ring 10 and a split ring fastener 11, Fig.1 , for rotatably supporting the combination of tool 1, hanger 2 and the tubing on collar 7 while the tool is rotated to cause a locator key 1 2 to engage in a coacting locator groove in the surrounding well member (not shown) which is typically the drilling upper body.

As more fully described in our aforementioned application No. 8116673, collar 7 has support segments 1 3 which are spring urged outwardly into a support groove (not shown) in the surrounding well member when the handling tool has been lowered to the proper position.

Upper body member 3 has a right cylindrical outer surface portion 14 and, in the area occupied by split ring fastener 11, a right cylindrical inner surface portion 15, these surface portions defining a tubular side wall portion 1 6 which is relatively thin when considered with reference to the great weight of the tubing strings to be supported. Outer surface portion 14 is interrupted by two transverse annular outwardly opening grooves 1 7. Grooves 1 7 are identical in size and shape, the radial cross section of each groove being in the form of an isosceles triangle having a root angle of 900.Thus, each groove 1 7 presents a frustoconical upper side wall 18, Fig. 7, which tapers downwardly and inwardly at 450. Grooves 17 are immediately adjacent to each other, so that the lower side wall of the upper groove joins the upper side wall of the lower groove in an annular corner which lies in the same right cylindrical plane as does surface portion 14.

Ring 11 is an integral resilient metal piece having two annular ribs 19 on its inner surface, ribs 1 9 being identical, the radial cross section of each rib being in the form of an isosceles triangle identical to that of grooves 1 7. Thus, as best seen in Fig. 6, each rib 1 9 presents a frustoconical upper surface 20 which slants downwardly and inwardly at 450. At its lower end, ring 11 has a frustoconical end surface 21 which tapers downwardly and inwardly at 450 and is therefore parallel to both surfaces 20. End surface 21 intersects the bottom surface of the lower one of ribs 19. Outer surface 22 of ring 11 is right cylindrical and extends upwardly from the outer edge of lower end surface 21 well beyond upper rib 19.Upper end surface 23 of the ring is a flat transverse annular face. A right cylindrical inner surface portion 24 extends from upper rib 1 9 to upper end face 23. Ribs 1 9 are immediately adjacent to each other so that the lower surface of upper rib 1 9 intersects the upper surface of lower rib 19 in an annular corner lying in the same right cylindrical plane as does surface 24.The radial distance between surfaces 22 and 24 is significantly greater than the radial height of ribs 1 9. Frustoconical surface 21 is therefore of such extent that not only will all lines passing at right angles through surface 20 of lower rib 1 9 also pass through surface 21 at right angles but all lines passing at right angles through a substantial portion of surface 20 of the upper rib 19 will pass at right angles through surface 21.

Ring 11 can be machined as a full circle of such dimensions that surface 24 has the same diameter as does surface portion 14, and the ring is completed by providing a saw cut at 25, Fig. 3.

Accordingly, the ring can be expanded, slipped over upper body member 3, and allowed to contract to bring ribs 1 9 into flush engagement with the respective grooves 17, the ribs thus being urged into and retained in the grooves by the inherent resiliency of the ring. With the ring thus installed, upper surfaces 20 of ribs 1 9 are in flush engagement with the respective upper side walls 18 of grooves 17.

Ring 11 is embraced by camming ring 10, Figs.

1 and 8. Camming ring 10 is an integral full-circle piece having an upper right cylindrical inner surface portion 27 of a diameter such as to snugly embrace outer surface 22 of fastener ring 11 when the latter is relaxed. Surface portion 27 joins a frustoconical intermediate surface portion 28 which tapers downwardly and inwardly at 450 and in turn joins a lower right cylindrical surface portion 29 of a diameter slidably to embrace outer surface portion 14 of tool body portion 3. Ring 10 has flat transverse annular bottom and top end faces 30 and 31, respectively. The lower portion of ring 10 is radially relatively thick and includes a frustoconical surface portion 32, which slants downwardly and inwardly at 450, the lower edge of surface portion 32 joining bottom end surface 30, the upper edge of surface portion 32 joining a right cylindrical outer surface portion 33.Outer surface portion 33 joins a flat transverse annular surface 34 which extends inwardly to join right cylindrical outer surface portion 35. At its upper end, ring 10 has four retainer ribs 36 which extend arcuately about the upper end of the ring and are equally spaced circumferentially. Ribs 36 project radially outwardly a short distance from surface 35.

Ring 10 cooperates with a seal ring 40, Fig. 1, comprising a main circular body 41, of rectangular radial cross section, and a dependent outer skirt 42 having four arcuate retaining ribs 43 spaced equally about the lower end of the skirt and projecting inwardly a short distance. The dimensions of skirt 42 and ribs 43 are such that ring 40 can be installed by passing ribs 43 between ribs 36 of ring 10 and then rotating one ring relative to the other to engage ribs 43 beneath ribs 36. With ring 40 thus installed, the lower end face of ring 40 engages upper end faces 23 and 31 of fastener ring 11 and ring 10, and the inner surface of the main body of ring 40 embraces surface portion 14 of tool body portion 3.A threaded radial bore is provided through one of the retainer ribs 43 of seal ring 40 to accommodate a threaded pin 44 and the tip of the pin is engaged in a bore in ring 10 to restrain the two rings against relative rotation. The main body of ring 40 is grooved to accommodate inner and outer elastomeric seals, as shown, so that a fluidtight seal is established between surface portion 1 4 of tool body portion 3 and the inner surface of skirt 45 of annular piston 46.

Thrust ring 9 is a resilient split ring having, in its relaxed condition, right cylindrical inner and outer surfaces 47 and 48, respectively, the relaxed diameter of ring 9 being such that the ring can be aligned axially with frustoconical face 32 of ring 10. Ring 9 has a flat transverse annular bottom end face 49 adapted for flush engagement with the flat transverse annular upper end face 50 of the retainer 51 of bearing 8. The upper end face of ring 9 advantageously includes a frustoconical surface 52 which tapers downwardly and inwardly at 450 so as to be capable of flush engagement with face 32 of camming ring 10.

Preparatory to use of handling tool 1 to run the tubing hanger 2 and the strings of tubing depending from the hanger, thrust ring 9 is contracted and piston 46 is moved to its lowermost position, so that skirt 45 of the piston embraces ring 9 and holds ring 9 in the position seen in Fig. 2 with face 52 of the ring in flush engagement with surface 32 of ring 10. As the tubing hanger is run into the well, segments 13 of collar 7 engage in the cooperating grooves provided, e.g., in the drilling upper body, and substantially the entire weight of the tubing strings and hanger is then supported by collar 7 via bearing 8, ring 10, fastener ring 11, and the body of handling tool 1.When the handling tool has been rotated to cause locator key 12 to engage in the copperating locator groove, piston 46 is actuated remotely to its upper position, seen in Fig. 1, freeing thrust ring 9 to expand outwardly so that the handling tool body can be lowered through ring 9, bearing 8 and collar 7 to land the tubing hanger. Thus, fastener ring 11 carries the load during rotational orientation of the handling tool but is freed of the load during the final landing operation.

During the time when piston 46 holds thrust ring 9 in its contracted position, any axial force tending to move handling tool 1 downwardly relative to support collar 7 is transferred to the combination of rings 10 and 9 via fastener ring 11 and the resulting load on ring 11 acts along the coincident normals indicated by the arrows in Fig.

8, i.e., along lines which are substantially at right angles to and substantially centered on the parallel load-bearing surfaces 18, 20, 21, 28, 32 and 52. Fastener ring 11 and camming ring 10 are thus loaded substantially entirely in compression, with substantially none of the load acting in shear.

Since load-bearing surfaces 1 8, 20, 21, 28, 32 and 52 are all mutually parallel and since ring 11 is constrained radially between cylindrical surface 27 and the grooved outer surface of body member 3, there is essentially no effective force component tending to overturn the fastening ring.

Accordingly, the dimensions of the fastening means can be minimized, so that grooves 17 in the relatively thin wall 1 6 of tool body portion 3 can, in the context of the large weight to be supported by member 3, be relatively shallow. In typical applications of the invention, the total weight to be carried by the handling tool may be as high as 300,000 Ibs (140 tonnes), and all of that weight must be transferred via fastening ring 11. Under those circumstances, if ring 11 has two ribs 19, the depth of grooves 1 7 need be only about 1/4 inch (6 mm) and the fastening means is therefore easily accommodated by the relatively thin tubular wall 16.

Fastener rings according to the invention are resilient snap rings and can be biased inwardly, as in the case of ring 11, or outwardly, as in the case of ring 55, Fig. 1 A. Ring 55 combines with a torque key 56 to secure the lower end of tool body portion 3 within the upper end portion of tool body portion 4. The lower end of portion 3 is outwardly thickened to present a right cylindrical outer surface portion 57 joined to surface portion 14 by a frustoconical shoulder 58 which tapers upwardly and inwardly. The upper end portion of tool body member 4 is tubular, presenting a right cylindrical inner surface portion 59, which slidably embraces outer surface 57, and a right cylindrical outer surface portion 60 defining the relatively thin tubular wall 61. Tool body portion 4 projects a short distance above the outer periphery of shoulder 58. At shoulder 58, the wall of body portion 3 is annularly notched to provide a short right cylindrical outer surface portion 72 joining at its lower end a frustoconical shoulder 63 which tapers upwardly and inwardly at 450. Ring 55 is essentially the same as ring 11 except that the two annular ribs 64 of ring 55 project outwardly to engage in two corresponding transverse annular inwardly opening grooves in wall 61. Since the weight of the tubing strings and hanger is suspended via tool body portion 4, the tension load is applied via the upper walls of the grooves and upper 450 fructoconical surfaces of the ribs to the body of ring 55 and thus to tool body portion 3 via the 450 frustoconical lower end face of the body of ring 55 and shoulder 63.

Torque key 56 is provided both to prevent relative rotation between tool body portions 3, 4 and to prevent relative axial movement between the two body portions in a direction which would separate shoulder 63 from its flush engagement with the lower end face of ring 55. Key 56 is rectangular, secured to body portion 3 by screws as shown, and projects outwardly through a rectangular opening in wall 61 of tool body portion 4. The dimensions and dispositions of the key and rectangular opening are such that lower end face 65 of the key is in flush engagement with lower end wall 66 of the rectangilar opening when the frustoconical lower end face of ring 55 is in flush engagement with shoulder 63. Thus, member 3 cannot move downwardly relative to member 4, nor can member 4 move upwardly relative to member 3. It will be apparent that ring 55 functions in the same manner as does ring 11 and that key 56 cooperates with ring 55 and members 3, 4 in generally the same manner as seal ring 40 cooperates with ring 11, member 3 and ring 10.

Claims (14)

1. A device for transferring large axial loads comprising a first load-supporting member having a cylindrical surface, said cylindrical surface having at least one transverse annular groove, at least one side wall of said groove being frustoconical; an annular fastener comprising at least one annular rib having a first frustoconical load-bearing surface, said rib being dimensioned to be accommodated by said groove, a second frustoconical load-bearing surface parallel to and facing away from said first load-bearing surface, and a cylindrical surface spaced radially from said at least one rib and joining said second loadbearing surface in an annular corner, said annular fastener being resiliently urged to engage said rib in said groove with said first load-bearing surface in flush engagement with said frustoconical wall of said groove and said second load-bearing surface slanting away from said cylindrical surface of said first member; a second load-supporting member connected to said first member by said fastener, said second member having a cylindrical surface telescopicaliy engaged with said cylindrical surface of said fastener, and a frustoconical load-bearing surface in flush engagement with said second load-bearing surface of said fastener; and an additional member engaged with said second member to prevent said first and second members from being significantly moved telescopically relative to each other in a direction which would separate said frustoconical load-bearing surface from said second loadbearing surface of said fastener.

2. A device as claimed in claim 1 , wherein said annular fastener is a resilient split ring.

3. A device as claimed in claim 2, wherein said split ring has an end surface opposite said loadbearing surface; and said additional member engaged with said second member comprises a ring slidably engaged with said first member and having an annular stop surface directed toward said end surface of the split ring.

4. A device as claimed in claim 2 or 3, wherein said split ring comprises two of said annular ribs; said first member is provided with two of said transverse annular grooves; and each of said ribs is engaged in different one of said grooves.

5. A device as claimed in claim 2 or 3, wherein said least one annular rib is of triangular radial cross section.

6. A device as claimed in claim 5, wherein said split ring comprises two of said annular ribs, the adjacent side walls of said ribs join in an annular corner and the opposite side wall of one of said ribs joins said second load-bearing surface in an annular corner, said annular corners lying in substantially the same right cylindrical plane, and said first member is provided with two of said transverse annular grooves, each of said grooves being of triangular radial cross section and both side walls of each of said ribs being in flush engagement with the respective side walls of a different one of said grooves.

7. A device as claimed in any one of the preceding claims, wherein said first member is a tubular member which, considering the magnitude of the load to be carried thereby, has a relatively thin wall, said cylindrical surface of the.first member being provided with a plurality of said transverse annular grooves, each of said grooves having a triangular radial cross section, corresponding walls of said grooves being mutually parallel; said annular fastener comprising a plurality of ribs equal in number to said grooves, each of said ribs being of triangular radial cross section, and each of said ribs being engaged in a different one of said grooves.

8. A device as claimed in claim 7, wherein the radial cross section of each of said grooves and ribs is an isosceles triangle having a root angle or crest angle, as the case may be, which is a right angle.

9. A device as claimed in any one of claims 7 to 9, wherein said additional member engaged with said second member comprises a stop member fixed to one of said first and second members and extending through an aperture in the other of said members.

10. A device as claimed in claim 9, wherein said first member is an outer member and the cylindrical surface of said first member is internal; said cylindrical surface of said second member is embraced by the cylindrical surface of said first member; said stop member is fixed to said second member and constitutes a key projecting outwardly through the aperture in said first member; and said key and the walls of said aperture coact to prevent relative rotation between said first and second members as well as to prevent significant relative telescopic movement tending to separate said frustoconical load-bearing surface from said second loadbearing surface of said fastener.

11. A fastening device comprising an integral resilient metal split ring having an inner surface, an outer surface, a first end surface, and a second end surface, one of said inner and outer surfaces having an annular rib extending therealong and having a frustoconical load-bearing surface, the other of said inner and outer surfaces being cylindrical, and said first end surface being frustoconical, parallel to said load-bearing surface of said rib and facing away from said load-bearing surface.

12. A device as claimed in claim 11, wherein said one of said inner and outer surfaces is provided with two of said ribs, each of said ribs being of triangular radial cross section.

13. A device as claimed in claim 12, wherein a side wall of one of said ribs joins said first end surface in an annular corner.

14. A device as claimed in any one of claims 11 to 13, wherein said second end surface is a flat annular surface lying in a plane transverse to the axis of the ring.

1 5. A fastening device substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

1 6. A device for transferring large axial loads; substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.