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(11) | EP 0 079 846 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Segmented elevator link |
| (57) A segmented elevator link (11) is shown of the kind used to support a derrick elevator
from a derrick hook. The elevator link has two or more shank portions (15, 22) having
ends which are joined together by a split collar. The shank ends are upset, being
joined to the shanks at tapered surfaces which correspond to matching tapers (63,
65) in an interior bore of the split collar which releasably engages the link ends.
A plurality of bolts passing through aligned bores (51) in the split collar and link
ends wedge the ends together and serve to maintain the link eyelets in alignment. |
[0001] The present invention relates generally to hoisting equipment of the kind used in oil and gas drilling and workover operations and specifically to an improved elevator link by which the derrick elevator is supported from the derrick hook.
[0002] The typical rotary earth drilling rig of the kind used in drilling oil and gas wells includes a drawworks on the rig floor, a crown block, and a traveling block suspended from the crown block by a series of cables running to the drawworks. A derrick hook carried by the traveling block is used to support a derrick elevator by means of connecting links. The derrick elevator has a generally flat upper surface and a pipe receiving bore and supports drill pipe, casing, and tubing when the same is being raised and lowered into or out of the well bore.
[0003] Many servicing rigs, especially those located in the North Sea, are not equipped with motion compensators. The operation being undertaken often requires that the work string be suspended from slips located at the well head which is located on the ocean floor. Because of the wave action present, the top of the work string moves up and down with respect to the derrick as the rig heaves with the waves. The derrick elevator remains latched around the work string and slides up and down the top joint of the string as the rig heaves. If elevator links of sufficient length are not used, the top of the work string can strike the bottom of the hook. This can result in damage to the work string or hook and could cause injury to rig personnel.
[0004] Elevator links of sufficient length to overcome the above problem can be manufactured as one piece but would be difficult to transport, especially by helicopter to an offshore rig. Such links would also be relatively fragile because of their long length thus increasing the possibility of damage during transit.
[0005] The segmented elevator link of the present invention has a hook shank having an eyelet at one end thereof for engaging a derrick hook and having an opposite end.
[0006] The link also has an elevator shank having an eyelet at one end thereof for engaging a derrick elevator and having an other end. Connecting means releasably engage the opposite end and the other end so that the hook shank eyelet and the elevator shank eyelet are maintained in alignment.
[0007] Preferably, the hook shank opposite end and the elevator shank other end are upset, being of greater external diameter than the remaining length of the shanks. The upset ends are joined to the remaining shank lengths by tapered surfaces. The opposite upset end and other upset end have flat exterior contacting surfaces at the outermost extent thereof. A split collar releasably engages the opposite end and the other end. The split collar has an interior bore having a mating taper at each end thereof corresponding to the tapered surfaces on the opposite end and the other end. The split collar includes a pair of matching halves and each half has a plurality of bores transverse to the plane of the split. Preferably, the bores are located between the mating tapers. The opposite end and the other end have corresponding bores in the upset portions thereof. Wedging means pass through the bores in the split collar halves and through the bores in the opposite end and other end to wedge the flat exterior contacting surfaces of the ends together when the collar engages the ends.
[0008] Additional objects, features, and advantages will be apparent in the written description which follows:
Fig. 1 is a perspective view of the segmented elevator link supporting a derrick elevator from a derrick hook.
Fig. 2 is a side view of the elevator link of Fig. 1 partially broken away.
Fig. 3 is a partial sectional view of the elevator link of Fig. 1.
Fig. 4 is a side view of an elevator link having one intermediate section.
[0009] Turning now to Fig. 1, there is shown a segmen ted elevator link designated as 11 in place on a derrick hook 13. The elevator link 11 has a hook shank 15 having an eyelet 17 at one end thereof for engaging the derrick hook 13 and having an opposite end 19 (Fig. 3). The elevator link 11 also has an elevator shank 21 having an eyelet 23 at one end thereof for engaging a derrick elevator 25 and having an other end 27 (Fig. 3).
[0010] A stand of pipe 29 extends from a hole 31 in the rig floor 33 and has an upset portion or tool joint 35 having a collar 37 adapted to be supported on a mating surface 39 of the derrick elevator 25. As shown in Fig. 1, the tool joint 35 can rise above upper surface 39, especially in an offshore rig where wave action acts on the pipe string. The hook shank 15 and elevator shank 21 are releasably engaged by a connecting means, in this case split collar 41, so that the hook shank eyelet 17 and the elevator shank eyelet 23 are maintained in alignment. By "in alignment" is meant that eyelet 17 and eyelet 23 are in the same vertical plane with respect to elevator ears 43 and hook ears 45.
[0011] As shown in Fig. 3, segmented elevator link 11 has a hook shank 15 formed in the shape of an elongated rod. The opposite end 19 of rod shaped hook shank 15 is of greater relative external diameter than the remaining length of shank 15 and forms an upset with respect to shank 15. Opposite end 19 is joined to the remaining length of shank 15 by a tapered surface 47 and is preferably tapered in the range of about 45 to 75 degrees with respect to the longitudinal axis of the remaining length of shank 15. Opposite end 19 has a flat exterior contacting surface 49 at the outermost extent thereof. Opposite end 19 is generally cylindrical in shape and has a plurality of bores 51 preferably located between tapered surface 47 and flat exterior surface 49. As shown in Fig. 3, elevator shank 21 is a mirror image of hook shank 15, differing only in the size of eyelet 23 which is generally smaller than hook eyelet 15. Hook shank 15 and elevator shank 21 can be bent gradually at the outer extents 53, 55, respectively, so that eyelets 17, 23, are offset slightly with respect to the vertical plane of shanks 15, 21.
[0012] As shown in Fig. 2, a split collar 41 having matching halves 57, 59 is provided for releasably engaging the opposite end 19 and other end 27 so that the hook shank eyelet 17 and elevator shank eyelet 23 are maintained in alignment. As shown in Fig. 3, the split collar halves 57, 59 have interior bores 61 having inwardly slanting tapers 63, 65 at each end thereof corresponding to the tapered surfaces 47 on the opposite end 19 and other end 27. The inwardly slanting tapers 63, 65 are spaced-apart approximately twice the distance from the tapered surfaces 47 to the flat contacting surfaces 49 of the opposite end 19 and other end 27, respectively.
[0013] Each of the split collar halves 57, 59 has a plurality of bores 67 transverse to the plane of the split 69 between the halves 57, 59 when the split collar 41 releasably engages the opposite end 19 and other end 27. The bores 67 in split collar halves 57, 59 are located between mating tapers 63, 65 and are adapted to be aligned with the bores 51 in opposite end 19 and other end 27 when halves 57, 59 are in place about ends 19, 27. Wedging means, in this case bolts 71 can be inserted through bores 67, in halves 57, 59 and bores 51 in the upset portions of ends 19, 27 where they are secured by nuts 73 to wedge the ends 19, 27 together when the collar 41 engages the ends.
[0014] The operation of the segmented elevator link will now be described. The hook shank 15 and elevator shank 21 can be flown to a remote location such as an offshore rig as separate components. Preferably the length of shanks 15, 21 will each be less than about 10 feet to enable the disassembled link to be transported by helicopter. On the rig, the link 11 is assembled by aligning the bores 51 in the ends 19, 27 with the bores 67 in the split collar halves 57, 59 and bolts 71 are inserted through the bores and nuts 73 are threaded onto the bolts. The bolts and nuts are then tightened to securely clamp the too split collar halves 57, 59 about the ends 19, 27. As bolts 71 are tightened, the flat contacting surfaces 49 at the outermost extents of ends 19, 27 are brought into a full 360 degrees contact due to the wedging action of the inwardly slanting tapers 63, 65 on the tapered surfaces 47 of the ends 19, 27. To provide adequate fatigue strength in the connection, the clamping action must produce sufficient compressive stress within the ends 19, 27 of the shanks 15, 21 to assure that the flat contacting surfaces 49 maintain full 360 degree contact under any bending moment at the section generated by a load on the assembled link 11. The split collar halves 57, 59 are selectively sized so that when the two upset ends 19, 27 of the link 11 are butted face to face against each other, the two halves 57, 59 of the split collar 41 are spaced-apart by a gap of approximately 1/16 to 1/8 inch.
[0015] The segmented link 11 can be provided with one or more intermediate sections 71, 73 (see Fig. 4) having upset portions at either end thereof which are adapted to be inserted between the hook shank opposite end 19 and the elevator shank other end 27 (see Fig. 3). A split collar 75, 77 would then be provided for releasably engaging each intermediate section end to the appropriate hook shank and elevator shank end respectively. In this way, the intermediate sections of shank would provide the overall length of the assembled link required for operational purposes while, at the same time, keeping the length of each element to ten feet or less for ease of transportation.
[0016] The present elevator link can be provided in the lengths necessary to separate the derrick hook from the derrick elevator where the pipe stand being supported is subject to sliding up and down in the elevator due to wave motion. In this way, the possibility of damage to the work string or derrick hook as well as to rig personnel is greatly reduced. The present link can be disassembled for ease of transportation and can easily be reassembled. The split collar arrangement for joining the link segments wedges the segment ends to assure adequate fatigue strength in the connection. The aligned bores in the split collar and segment ends assure alignment of the link eyelets.
a hook shank having an eyelet at one end thereof for engaging a derrick hook and having an opposite end;
an elevator shank having an eyelet at one end thereof for engaging a derrick elevator and having an other end; and
connecting means for releasably engaging said opposite end and said other end so that said hook shank eyelet and said elevator shank eyelet are maintained in alignment.
a hook shank formed in the shape of an elongated rod, said hook shank having an eyelet at one end thereof for engaging a derrick hook and having an opposite upset end of greater external diameter than the remaining length of said rod;
an elevator shank formed in the shape of an elongated rod, said elevator shank having an eyelet and having an other upset end of greater external diameter than the remaining length of said rod;
connecting means for releasably engaging said opposite end and said other end so that said hook shank eyelet and said elevator shank eyelet are maintained in alignment.
a hook shank formed in the shape of an elongated rod, said hook shank having an eyelet at one end thereof for engaging a derrick hook and having an opposite upset end of greater external diameter than the remaining length of said rod;
an elevator shank formed in the shape of an elongated rod, said elevator shank having an eyelet at one end thereof for engaging a derrick elevator and having an other upset end of greater external diameter than the remaining length of said rod;
a split collar for releasably engaging said opposite end and said other end so that said hook shank eyelet and said elevator shank eyelet are maintained in alignment.
a hook shank formed in the shape of an elongated rod, said hook shank having an eyelet at one end thereof for engaging a derrick hook and having an opposite upset end of greater external diameter than the remaining length of said rod, said opposite upset end being joined to said remaining length by a tapered surface;
an elevator shank formed in the shape of an elongated rod, said elevator shank having an eyelet at one end thereof for engaging a derrick elevator and having an other upset end of greater external diameter than the remaining length of said rod, said other upset end being joined to said remaining length by a tapered surface;
a split collar having an interior bore for releasably engaging said opposite end and said other end so that said hook shank eyelet and said elevator shank eyelet are maintained in alignment, said split collar interior bore having mating tapers at each end thereof corresponding to the tapered surfaces on said opposite upset end and said other upset end.
a hook shank formed in the shape of an elongated rod, said hook shank having an eyelet at one end thereof for engaging a derrick hook and having an opposite upset end of greater external diameter than the remaining length of said rod, said opposite end being joined to said remaining length by a tapered surface;
an elevator shank formed in the shape of an elongated rod, said elevator shank having an eyelet at one end thereof for engaging a derrick hook and having an other upset end of greater external diameter than the remaining length of said rod, said other upset end being joined to said remaining length by a tdpered surface;
at least one intermediate section having upset portions on either end thereof adapted to be inserted between said hook shank opposite end and said elevator shank other end; and
a pair of split collars for releasably engaging said intermediate section ends to said hook shank and said elevator shank other end respectively.