STUD

The present disclosure generally relates to elongate fastening members such as bolts and studs and to apparatus for tensioning such fasteners.

BACKGROUND

Any references to methods, apparatus or documents of the prior art are not to be taken as constituting any evidence or admission that they formed, or form part of the common general knowledge.

FIG. 1 shows an elongate fastening member in the form of a stud 1 projecting from a structural member in the form of a workpiece being a flange 3a. More specifically the stud 1 is used, in conjunction with nuts 7a and 7b to join two parts, being the flange 3a and an adjacent flange 3b together. In use, the two flanges 3a and 3b are subject to a workload, indicated by arrows 8 that tends to pull the two flanges 3a and 3b apart. In order to counteract the workload 8 the stud 1 is inserted through corresponding holes 4a, 4b of each of the two flanges 3a, 3b. The stud 1 has male threaded ends 5a, 5b which are each mated with a corresponding female thread of hex nuts 7a, 7b. The hex nuts 7a, 7b are each oversized relative to holes 4a, 4b. Consequendy, torqueing the hex nuts 7a, 7b generates an axial tension in the stud 1 in the form of a preload, indicated by arrow 9, that stretches the shank 11 of the stud 1. In response a compressive clamping force, indicated by arrows 13 presses the parts 3a, 3b together. To maintain joint integrity the preload 9 (and thus the clamping force 13) must be greater than the workload 8.

It will be realized that where very high workloads are encountered, for example in nuclear reactors, steam turbines, wind turbines and the like, then the preload that must be generated in a stud or bolt must be very great too since it must exceed the foreseeable workload.

It has been found that when torqueing a conventional nut, such as nuts 7a, 7b of FIG. 1, that approximately 90% of the applied torque is absorbed by friction between the nut and the workpiece and by friction between the thread of the elongate fastening member and the nut so that only 10% of the applied torque is converted into the preload that is developed along the shank of the fastener. Consequently, in very high preload applications it has been necessary to use high power tools and/ or long handle wrenches and hammers to apply a sufficient level of torqueing to attain the desired preload.

Multi Jackbolt Tensioners (MJTs) were developed in response to the difficulties that encountered with generating sufficiently high preloads using conventional nuts.

A MJT may he used as a direct replacement for conventional nuts and holts. FIG. 2 depicts a partially cutaway nut-style MJT 20. FIG. 3 shows the MJT 100 in use. With reference to FIG. 2, the MJT 100 comprises an example of a body 22. The body 22 of the MJT 100 is formed with a threaded central hole 18 to receive a holt, shaft, or stud. A polar array of threaded jackbolt holes 17, each disposed on a circle concentric with the central hole, pass though the body 22. Corresponding jackbolts 24 traverse the jackbolt holes 17 and are threadedly received therein. The MJT 100 further includes a load bearing member in the form of a hardened washer 26 against which points 29 of the jackbolts 24 abut in use. The hardened washer 26 bears against a structural member being fastened.

With reference to FIG. 3, by torqueing the jackbolts 24 a strong axial force is generated and directed against the hardened washer 26. The thrust force of the jackbolts 24 and the opposite reaction force of the opposing nut 7b or bolt head impose a strong clamping force on the flanges 3a, 3b. The advantage of the MJT is that huge clamping forces can be generated with a fraction of the torque input that would be required if a single conventional nut were used. For example, for a fastener with a thread diameter of 160 mm approximately lOOkNm of torque is required to generate 310Mpa of bolt stress. In contrast the same amount of holt stress can be generated by torqueing jackbolts of a twenty-four jackbolt MJT to approximately lkNm of torque each. Consequently, hand tools can he used to suitably torque the jackbolts of an MJT for tensioning a stud/bolt of any diameter. Bolt-style MJTs are also available as illustrated in FIG. 4, which depicts a bolt-style MJT 200. The stud 11 is not threaded into the body 22 but rather an end of the stud 5a is integrally formed therewith so that an integrally formed shank 10 extends from the body 22 with a threaded end 5b for receiving a conventional nut 7b or for insertion into a threaded bore of a structural member. Preload accuracy using MJTs is improved over conventional bolting methods in several ways:

•Preload accuracy of ±5-10% is possible in contrast to ±40-50% for a conventional nut and bolt.

•Jackbolts generally have rolled threads to improve repeatability of the friction factor.

•Multiple jackbolts have an averaging effect, thus reducing overall scatter. •There is a large hardness spread between jackbolt and body threads.

•MJTs provide uniform gasket crush.

•MJTs eliminate leakage challenges.

Although MJTs are a great improvement over conventional nuts for high preload applications, nevertheless the Inventor has observed that for high temperature, highly loaded fastened connections, such as gas turbine, steam turbine, and centrifugal compressor flanges, the studs and nuts need to be designed to withstand the effects of creep, corrosion, and lubricant degradation. Creep, corrosion, and lubricant degradation are failure mechanisms mostly affecting the jackbolts of an MJT during operation at high temperature and high load.

Creep is mosdy experienced in the jackbolt compressive area where the pintle, i.e. the unthreaded length of the shank toward the point of the jackbolt, is compressively loaded during operation. Creep may cause load loss in the stud over time and may also contribute to mushrooming of the jackbolt pinde. To mitigate these effects, jackbolt sizes can be increased, therefore increasing the compressive areas, hence lowering the compressive stress. This mitigation is difficult to employ because larger jackbolts create larger sized tensioners. Designing larger tensioners is undesirable because often the amount of space available to install the tensioners is limited.

Corrosion occurs on all materials but more frequently on hardened parts with high stresses at high temperatures as well as in corrosive environments. Jackbolt threads in particular are susceptible due to them being hard and under high stress. When corrosion occurs at the threads of jackbolts, seizing can occur between the jackbolt and body of the MJT making the removal of the tensioner difficult or lead to jackbolt breakage. Corrosion resistant metals and high temperature coatings help minimize the effects hut come at high cost and varying reliability. Lubricant quality is essential to the proper installation of tensioners as well as to the success during removal. High temperature can take a toll on thread lubricant on the jackbolts by degrading the sliding ability between the threads at the jackbolts. Applying penetrating oil to the jackbolt threads for several hours helps to breakdown deposits and reactivate the sliding ability to the lubricant. Although this can be effective, waiting many hours is undesirable.

As discussed, many design techniques can he applied to minimize the creep, corrosion, and lubricant degradation effects of the jackbolts during operation, but these come at undesirable costs.

It is an object of the present invention to provide a method and apparatus for tensioning an elongate fastening member such as a stud or a holt that overcomes or at least ameliorates one or more of the problems that have been described.

SUMMARY

According to a first aspect of the present invention there is provided a tensioning assembly for tensioning an elongate fastening member projecting from a structural member, said assembly including: a body comprising a base having an external thread and a puller including a recess with an internal thread corresponding to the external thread of the base for engagement therewith, the base being arranged to fasten to, or being integrally formed with, the elongate fastening member for applying a tensioning force thereto; a plurality of jackbolt holes through the puller each jackbolt hole threadedly engaging a corresponding one of a plurality of jackbolts; elongate compression members located between points of the jackbolts and the structural member to apply axial force from the jackbolts to the structural member to thereby displace the base from the structural member and tension the elongate fastening member; and at least one tension retaining member arranged to maintain a displacement of the base from the structural member subsequent to unloading of the jackbolts.

In an embodiment a pusher member is located between points of the jackbolts and the elongate compression members to convey the axial force from the jackbolts to the compression members. In an embodiment the tensioning assembly includes a post end member wherein ends of the compression members distal from the structural member are coupled to the post end member.

In an embodiment the pusher member locates between the points of the jackbolts and the post end member.

In an embodiment an interface between the pusher member and the post end member is spherical for promoting alignment of the pusher member and the post end member.

In an embodiment the tension retaining member comprises a retaining ring threadedly engaged around the base whereby the retaining ring may be brought to a position in which it extends along the displacement of the base from the structural member.

In an embodiment the tension retaining member comprises one or more shims. In an embodiment the base is formed with axial base bores therethrough wherein the compression members are respectively received in the axial base bores.

In an embodiment a support member extends inwardly from an internal wall of the puller and which supports the post end member to thereby retain the post end member in the recess of the puller.

In an embodiment the support member comprises a support ring with a radially outer portion. In an embodiment the support ring is received in a corresponding peripheral groove formed around an internal wall of the puller.

In an embodiment the tensioning assembly includes a load distribution member for positioning between points of the jackbolts and the structural member in use. In an embodiment the load distribution member comprises a washer.

According to a further aspect of the present invention there is provided a method for tensioning an elongate fastening member projecting from a structural member by use of a body coupled to a plurality of jackbolts, the body being arranged to apply tension to the elongate fastening member, the method comprising: torqueing the jackbolts to force the body away from the structural member thereby loading the jackbolts and tensioning the elongate fastening member to produce a displacement of the body from the structural member; applying at least one tension retaining member between the body and the structural member to maintain the displacement; and untorqeuing the jackbolts to thereby transfer the load from the jackbolts to the tension retaining member.

In an embodiment the body is fastened to or integrally formed with an end portion of the elongate fastening member.

In an embodiment the body has an axial threaded bore for threaded fastening to a threaded end portion of the elongate fastening member.

In an embodiment the body is integrally formed with an end of the elongate fastening member. In an embodiment the applying of the tension retaining member comprises turning a retaining ring that is threadedly engaged around the body so that the retaining ring extends along the displacement from the body toward the structural member.

In an embodiment the applying of said tension retaining member comprises inserting one or more shims between the body and the structural member.

In an embodiment the body comprises a base and a puller that are operatively coupled to each other wherein the base is fastened to, forced against or integrally formed with the end of the elongate fastening member and wherein the jackbolts are engaged by the puller.

In an embodiment the method indudes conveying axial force from the jackbolts to the structural member with one or more compression members.

In an embodiment the method includes conveying the axial force from the jackbolts to the compression members with a pusher member.

In an embodiment ends of the compression members distal from the structural member are coupled to a post end member.

In an embodiment the method includes decoupling the puller from the base subsequent to transferring the load from the jackbolts to the tension retaining member.

In an embodiment a load distribution member is disposed between points of the jackbolts and the structural member.

In an embodiment the load distribution member comprises a washer.

In an embodiment the method includes attaching a cover over the body for covering holes for the compression members therethrough.

According to another aspect of the invention there is provided a non-hydraulic multi-jackbolt tensioner (MJT) including a tension retaining member, which may be comprised of a puller and a base in some embodiments, for retaining tension in a member coupled to, or integrally formed with, the MJT subsequent to untorqueing, and thus unloading, of the jackbolts to thereby transfer the load from the jackbolts to the tension retaining member . DESCRIPTION OF FIGURES

Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The embodiments described herein may be better understood by reference to the accompanying figures, in which:

FIG. 1 is a side view of a conventional preloaded stud joining two flanges.

FIG. 2 is a partially cutaway view of a prior art nut-style multi-jackholt tensioner (MJT).

FIG. 3 is a cross-sectional view of the nut-style MJT of FIG. 2.

FIG. 4 is a cross-sectional view of a prior art bolt-style MJT.

FIG. 5 is a cross-sectional view of a nut-style tensioning assembly with a body comprising a base and a puller in a first stage of operation. FIG. 6 comprises various components of the tensioning assembly of FIG. 5 spread out and in top plan view.

FIG. 6a is a view of the side and underside of a post assembly of the tensioning assembly of FIG. 5.

FIG. 7 is a cross-sectional view of the nut-style tensioning assembly of FIG. 5 in a further stage of operation.

FIG. 8 is a cross-sectional view of the nut-style tensioning assembly of FIG. 7 in a further stage of operation.

FIG. 9 is a cross-sectional view of the nut-style tensioning assembly of FIG. 8 with puller and other components removed. FIG. 10 is a cross-sectional view of the nut-style tensioning assembly of FIG. 9 with a cover installed. FIG. 11 is a cross-sectional view of a bolt-style tensioning assembly with puller and other components removed and with a cover installed.

FIG. 12 is a top front view of a nut-style tensioning assembly in use according to a further embodiment. FIG. 13 is a cross sectional view of the nut-style tensioning assembly along the line A- A' of FIG. 12.

FIG. 14 is a top front view showing a base and locking ring of the nut-style tensioning assembly with puller and other components removed.

FIG. 15 is a cross sectional view along the line B-B' of FIG. 14.

DETAILED DESCRIPTION

A nut-style MJT 115 according to an embodiment of the present invention will now be discussed with reference to FIGs. 5 to 10. FIG. 6 is a top plan view of various components of the MJT 115 spread out separately to assist in discerning the shape of each. MJT 115 comprises a two part hody 22 including a hase 22a and a puller 22h that are operatively interconnected as shown in FIG. 5 for example. The base 22a is generally cylindrical and is formed with a male thread 23 around its outside periphery. A central threaded hore 18 extends through the base 22a for engaging an elongate fastening member such as a stud 11 as shown. The puller 22b is also generally cylindrical with a diameter that is greater than that of the base 22a. An underside of the puller 22h is formed with a concentric recess 52 that complements an upper end of the base 22a. An internal wall 64 of the recess 52 is formed with a female thread 54 that mates with an upper portion of the male thread 23 of the base 22a so that the puller 22b and base 22a can be mated as shown in FIG. 5 to produce the assembled body 22.

A lower end of body base 22a initially rests upon washer 26. A plurality of axial hase hores 19 are formed through the base 22a and each receives a compression member in the form of a post 49. Ends of posts 49 are coupled to a post end member in the form of a post ring 67. The ends of the posts 49 are press fit, or screwed, into holes 69 of the post ring 67 to thereby provide a post assembly 99 comprising said posts 49 and post ring 67 as shown in FIG. 6a. In other embodiments the posts 49 may be coupled to the post ring 67 by virtue of the post ring 67 and the posts 49 being integrally formed.

The posts 49 are each longer than the axial base bores 19. Jack bolt holes, in the form of a plurality of axial puller bores 56 are formed through the puller 22b. The puller bores 56 are equi-spaced around a circle concentric with a central axis of the body 55. Each of the axial puller bores 56 is threaded.

A concentric slot 63 is formed into the internal wall 64 above the female thread 54. A radially distal portion 66 of support ring 65 is fitted into the concentric slot 63 so that a radially proximal (to centerline 55) portion 68 of the support ring 65 extends into the recess 52.

A post assembly 99, shown in FIG. 6a is provided which comprises a post ring 67 formed with holes 69 therethrough that correspond to the bores 19 that extend through the base 22a. The post assembly 99 further comprises compression members in the form of posts 49, ends of which are press fitted, or screwed, into the holes 69 of the post ring 67. The post ring 67 of the post assembly 99 supports a push ring 71.

The post ring 67 fits concentrically within the recess 52 of puller 22b and is supported at its outward edge by the radially proximal portion 68 of support ring 65. The support ring thus retains the post ring 67 and push ring 71 within the recess 52 of puller 22b. The puller 22b is able to rotate freely with respect to the post assembly 99 and push ring 71.

MJT 115 further includes a tension retaining member in the form of a retaining ring 25 which locates around a lower portion of base 22a and which has an internal thread 27 that mates with the external thread 23 of the body base 22a.

In use the washer 26 is placed over the end 5a of stud 11 so that it rests against the outside of flange 3a. The base 22a of body 22, with retaining ring 25 attached, is then turned down over the end 5a of stud 11 until it is brought against the washer 26 as shown in FIG. 5.

Posts 49 of post assembly 99 are then inserted into each of the axial base bores 19 of the base 22a. Although the bores 19 in the presently described embodiment are threaded the posts 49 are not and thus are free to slide axially The puller 22b, with post assembly 99 and push ring 71 mounted within recess 52 thereof and held in place by support ring 65 is then located over the base 22a of body 22 and turned so that thread 23 on the outside of base 22a engages with internal thread 54 of the puller 22b. As the puller 22b is turned the post assembly 99 and push ring 71 do not rotate and move axially through the bores 19 of base 22a. As the puller 22b is further turned down the outside of base 22a the posts 49 of post assembly 99 continue to move axially until the posts 49 are brought against the washer 26 and the top of the push ring 71 is brought against the points 29 of the jackbolts 24.

Jackbolts 24 are then torqued so that their points abut the pusher ring 71 as shown in FIG. 7 with the posts 49 extending between the underside of the pusher ring 71 and the upper side of washer 26. As the jackbolts 24 are further torqued the puller 22b is displaced from the pusher ring 71 and in turn displaces the body 22a from the washer 26 through a distance "h" thereby stretching and preloading shank 10 of stud 11.

Retaining ring 25 is then turned down the base 22a of body 22 so that it is brought against washer 26 as shown in FIG. 8. The jackbolts 24 are then untorqued so that the preload is transferred from the jackbolts 24 to the retaining ring 25 thereby unloading the puller 22b. Accordingly, it will be observed that a retaining member in the form of retaining ring 25 is applied between the body 22 and a structural member in the form of flange 3a, from which the elongate fastening member in the form of stud 11 projects to maintain displacement of an end of the stud under tension from the flange 3a. The retaining ring 25 rests on a force distribution member in the form of washer 26 though as previously discussed the washer 26 may not be used in other embodiments. The puller 22b can then he turned up around the body 22a and disengaged therefrom. The puller 22b, with post assembly 99, pusher ring 71, support ring 65 and jackbolts 24 can then lifted clear of the body 22a as shown in FIG. 9, leaving the stud 11 in preload tension due to the base 22a of body 22 and retaining ring 25. A cover 33 may then he installed over the body 22a as shown in FIG. 10 if desired.

FIG. 11 depicts a dissembled bolt-style MJT 215 that corresponds to the nut-style MJT 115 that has been described wherein the body 22a is integrally formed, i.e formed as a unitary piece, with the upper end of stud 11.

FIG. 12 depicts a nut-style MJT 315 according to a further embodiment of the present invention. FIG. 13 is a cross sectional view of MJT 315 along the line A- A' indicated in FIG. 12. The MJT 315 is shown attached to an elongate fastening member 311 extending from a workpiece structure 312. MJT 315 comprises a two part body 22 including a base 22a and a puller 22b that are operatively interconnected by a threaded interconnection as shown. The base 22a is generally cylindrical and is formed with a male thread 23 around its outside periphery. A central threaded bore 18 extends through the base 22a for engaging the elongate fastening member 311.

The puller 22b is also generally cylindrical with an outside diameter that is greater than that of the base 22a. An underside of the puller 22b is formed with a concentric recess 52 that complements base 22a. An internal wall of the recess 52 is formed with a female thread 54 that mates with an upper portion of the male thread 23 of the base 22a so that the puller 22b and base 22a are mated by a threaded interconnection as shown in FIG. 13 to produce the assembled body 22.

A lower end of base 22a initially rests upon workpiece 312. A washer may be inserted between the lower end of base 22a and workpiece 312 if desired. A plurality of axial base bores 19 (identified in FIG. 14 and FIG. 15) are formed through the base 22a and each receives a compression member in the form of a post 49 (FIG. 13).

A post assembly 99, similar to that shown in FIG. 6a though with eight posts, is provided which comprises a post ring 67 formed with blind holes 69 that correspond to the bores 19 that extend through the base 22a. The post assembly 99 further comprises the compression members in the form of posts 49, ends of which are press fitted to the holes 69 of the post ring 67.

Upper ends of posts 49 abut a post end member in the form of the post ring 67. The ends of the posts 49 are preferably press fit into blind holes 69 of the post ring 67. In other embodiments the posts 49 may be coupled to the post ring 67 by virtue of the post ring 67 and the posts 49 being integrally formed. Furthermore, in another embodiment the upper ends of posts 49 may simply abut the post ring 67 without being positively engaged therewith though such an embodiment is less preferred due to possible lack of stability.

The post ring 67 of the post assembly 99 supports a push ring 71. The upper side 103 of the post ring 67 and the underside 101 of the push ring 71 are formed self aligning surfaces such as a spherical surface for improving alignment therebetween similar to a pair of spherical washers. Accordingly, where the upper side 103 and the underside 101 meet a spherical interface is formed which promotes alignment of the push ring 71 and the post ring 67.

The post ring 67 and the push ring 71 fit concentrically within the recess 52 of puller 22b. Puller 22b is rotationally free with respect to the post assembly 99 and push ring 71 so that turning of the puller 22b does not in turn rotate the post assembly 99 and push ring 71.

The posts 49 are each longer than the axial base bores 19. A plurality of jackbolt holes in the form of axial puller bores 56 are formed through the puller 22b. The puller bores 56 are equi-spaced around a circle concentric with a central axis of the body 55. Each of the axial puller bores 56 is threaded and receives a threadedly engaged jackbolt 24. In contrast to earlier embodiments described with reference to FIGs. 5 to 11, the number of jackbolts 24 need not be the same as the number of posts 49. For example, in the embodiment described with reference to FIGs. 12 to 15 there are eight jackbolts and 12 posts 49. Axial force from the jackbolts is distributed to the posts 49 by the push ring 71 and the post ring 67 of the post assembly 99. MJT 315 further includes a tension retaining member in the form of a retaining ring 25 which locates around a lower portion of base 22a and which has an internal thread 27 (identified in FIG. 15) that mates with the external thread 23 of the base 22a.

In use a washer may optionally be placed over the end 5a of elongate tensioning member 311 so that it rests against the outside of flange 3a.

The base 22a of body 22, with retaining ring 25 attached, is then turned down over the end 5a of stud 11 until it is brought against the washer 26 as shown in FIG. 5.

Posts 49 of post assembly 99 are then inserted into each of the bores 19 of the base 22a and slide axially downward to abut the workpiece 312 (or optionally a washer). The push ring 71 is placed atop the post ring 67. The puller 22b is then located over the base 22a of body 22 and turned so that that the internal thread 54 of the puller 22b engages with the thread 23 of the base 22a. The jackbolts 24 are preferably previously each rotated to extend them a common distance within recess 52 of the puller 22b. As the puller 22b is further turned down the outside of base 22a the posts 49 of post platform 99 continue to move axially until the posts 49 are brought against the workpiece 312 and the points 29 of the jackbolts 24 are brought against the top of the push ring 71.

Jackbolts 24 are then torqued so that their points abut the pusher ring 71 as shown in FIG. 13 with the posts 49 extending between the pusher ring 71 and the upper side of workpiece 312. As the jackbolts 24 are further torqued the puller 22b is displaced from the pusher ring 71 and in turn displaces the body 22a from the washer 26 through a distance "h" (identified in FIG. 15) thereby stretching and preloading the elongate fastening member 311.

Retaining ring 25 is then turned down the base 22a of body 22 so that it is brought against workpiece 312. The jackbolts 24 are then untorqued so that the preload is transferred from the jackbolts 24 to the retaining ring 25 thereby unloading the puller 22b. Accordingly, it will be observed that a retaining member in the form of retaining ring 25 is applied between the body 22 and a structural member in the form of workpiece 312 from which the elongate fastening member 311 projects to maintain displacement of an end of the elongate fastening member from workpiece 312 thereby tensioning the elongate fastening member.

The puller 22b can then he turned up around the body 22a and disengaged therefrom. The puller 22b, with post platform 99, pusher ring 71, and jackbolts 24 can then lifted clear of the body 22a as shown in FIG. 14 and FIG. 15, leaving the stud 311 in preload tension due to the base 22a of body 22 and retaining ring 25. A cover 33 may then be installed over the body if desired.

To recap embodiments of the invention that have been described, a tensioning assembly (115, 215, 315) has been discussed for tensioning an elongate fastening member (11, 315) projecting from a structural member (3a, 312). The tensioning assembly includes a body (22) comprising a base (22a) having an external thread (23) and a puller (22b) including a recess (52) with an internal thread (54) corresponding to the external thread (23) of the base (22a) for engagement therewith. The base is arranged to fasten to (e.g. in embodiments 115 and 315) or is integrally formed with (e.g. in embodiment 215), the elongate fastening member (11) for applying a tensioning force thereto.

The tensioning assembly also includes a plurality of jackbolt holes (56) through the puller (22b). Each jackbolt hole 56 threadedly engages a corresponding one of a plurality of jackbolts (24). Elongate compression members (49) are located between points (29) of the jackbolts (24) and the structural member (3a, 312) to apply axial force from the jackbolts (24) to the structural member (3a, 312) to thereby displace the base from the structural member (3a, 312) and tension the elongate fastening member (11,315).

The tensioning assembly also includes at least one tension retaining member (e.g. locking ring 25 or shims 116) arranged to maintain a displacement of the base from the structural member subsequent to unloading of the jackbolts. The displacement (e.g. through a displacement "h" in FIGs. 7 and 15) may be between the base and a surface of the structural member (as in FIG. 15) or between the base and a surface of a load distribution member such as a washer (26) abutting the structural member (as in FIG. 7). The tensioning assembly is arranged so that the tension retaining member maintains the displacement of the base from the structural member so that the puller, including the jackbolts, may then he removed whilst tension due to the displacement is retained in the elongate fastening member.

The appended claims encompass embodiments in which features from one embodiment are combined with those of another, unless clearly incompatible to those skilled in the art. For example, the tensioning assembly 115 of FIG.5 is illustrated using a retaining member in the form of a retaining ring 25. It will be understood by those skilled in the art that a further embodiment includes a tensioning assembly that is similar to tensioning assembly 115 but which does not use a retaining ring but rather makes use of shims (shown as items 116 in FIG. 7) between a lower edge of body 22a and washer 26, instead of retaining ring 25.

Any documents cited herein are incorporated herein by reference, but only to the extent that the incorporated material does not conflict with existing definitions, statements, or other documents set forth herein. To the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern. The citation of any document is not to be construed as an admission that it is prior art with respect to this application.

In this specification, adjectives such as first and second, left and right, top and bottom, up and down, and the like may be used solely to distinguish one element or action from another element or action without necessarily requiring or implying any actual such relationship or order. Where the context permits, reference to an integer or a component or step (or the like) is not to be interpreted as being limited to only one of that integer, component, or step, but rather could be one or more of that integer, component, or step, etc.

Furthermore, any references to methods, apparatus or documents of the prior art are not to be taken as constituting any evidence or admission that they formed, or form part of the common general knowledge. While particular embodiments have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, numerous equivalents to the specific apparatuses and methods described herein, including alternatives, variants, additions, deletions, modifications and substitutions. This application including the appended claims is therefore intended to cover all such changes and modifications that are within the scope of this application.