Method and device for fastening under high fluid pressure environment

Abstract

To provide a thin and long fastening member such as a bolt or a stad, and a method and device for applying a tensile force to the same.SOLUTION: Provided are: a body part formed to engage with or integrally with a thin and long fastening member, the body part having a plurality of holes provided at a position apart from an outer periphery thereof with a uniform interval from a center axis in a longitudinal direction, the body part including a side wall on which a body thread is formed; a jack bolt for engaging with the body thread at one of the holes; and a load support member for applying force to a workpiece to be fastened and arranged to position around the thin and long fastening member, the load support member having a first annular face connected to a second annular face via an inner wall and an outer wall, and a cylindrical lip projecting from the first annular face, the cylindrical lip having a wall continuous with the inner wall and being configured to form a seal with the workpiece to be fastened. The load support member further includes a second concentric projection projecting from the second annular face.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to elongated fasteners such as bolts and studs, and devices for tensioning such fasteners. [Background technology]

[0002] Any reference to prior art methods, devices, or documents is not to be construed as constituting any evidence or admission that they form part of the common general knowledge.

[0003] FIG. 1 illustrates an elongated fastener in the form of a stud 1 protruding from a structural member in the form of a workpiece, flange 3a. More specifically, stud 1, in conjunction with nuts 7a and 7b, is used to join two components, flange 3a and adjacent flange 3b. During use, the two flanges 3a and 3b are subjected to a load, indicated by arrow 8, that tends to separate the two flanges. To counteract load 8, stud 1 is inserted through corresponding holes 4a and 4b in each of the two flanges 3a and 3b. Stud 1 has externally threaded ends 5a and 5b that mate with corresponding internal threads in hex nuts 7a and 7b, respectively. The hex nuts 7a and 7b are oversized for the holes 4a and 4b, respectively. As a result, application of torque to hex nuts 7a and 7b creates axial tension in stud 1 in the form of a preload, indicated by arrow 9, stretching the shank 11 of stud 1. In response, a compressive clamping force, indicated by arrows 13, presses parts 3a, 3b together. To maintain the integrity of the joint, preload 9 (and therefore clamping force 13) must be greater than load 8.

[0004] It will be appreciated that when very high working loads are encountered, for example in nuclear reactors, steam turbines, wind turbines, etc., the preload that must be generated in the stud or bolt must be very large, as it must exceed the foreseeable working loads.

[0005] It has been found that when applying torque to conventional nuts, such as nuts 7a and 7b in Figure 1, approximately 90% of the applied torque is absorbed by friction between the nut and the workpiece and between the threads of the elongated fastener and the nut, and only 10% of the applied torque is converted into preload generated along the shank of the fastener. As a result, very high preload applications have required the use of expensive power tools and / or long-handled wrenches and hammers to apply sufficient levels of torque to achieve the desired preload.

[0006] The Multi-Jackbolt Tensioner (MJT) was developed in response to the difficulties encountered when trying to generate a sufficiently high preload using conventional nuts.

[0007] MJTs can be used as a direct replacement for traditional nuts and bolts. FIG. 2 shows a partially cut-away nut-type MJT 20. FIG. 3 shows the MJT 100 in use. The MJT 100 includes an exemplary body 22. The body 22 of the MJT 100 defines a threaded central bore 18 for receiving a bolt, shaft, or stud. A polar array of threaded jackbolt holes 19, each arranged on a circle concentric with the central bore, extends through the body 22. A corresponding jackbolt 24 traverses the jackbolt hole 19 and is threadably received therein. The MJT 100 further includes a load-bearing member in the form of a hardened washer 26 against which a tip 29 of the jackbolt 24 abuts during use. The hardened washer 26 abuts against the structural member being fastened.

[0008] Torquing the jackbolt 24 generates a strong axial force, directed toward the hardened washer 26. The thrust of the jackbolt 24 and the opposing reaction force of the opposing nut 7b or bolt head apply a strong clamping force to the flanges 3a and 3b. The advantage of the MJT is that a large clamping force can be generated with a fraction of the torque input required if a single conventional nut were used. For example, a fastener with a 160 mm thread diameter requires approximately 100 kNm of torque to generate a bolt stress of 310 MPa. In contrast, the same amount of bolt stress can be generated by torquing each of the jackbolts in a 24-piece MJT to approximately 1 kNm. Therefore, hand tools can be used to appropriately torque the jackbolts of the MJT to tension studs or bolts of any diameter. Bolt-type MJTs are also available, as shown in Figure 4, which shows the bolt-type MJT 200. The stud 11 is not threaded into the body portion 22, but rather the end of the stud 5a is integrally formed and an integrally formed shank 10 extends from the body portion 22 having a threaded end 5b for receiving a conventional nut 7b or for insertion into a threaded hole in a structural member.

[0009] Preload accuracy using MJT is improved over traditional bolting methods in several ways: · Preload accuracy of ±5-10% compared to ±40-50% for conventional nuts and bolts. Jackbolts generally have rolled threads to improve the repeatability of the coefficient of friction. Multiple jackbolts have an averaging effect, reducing variation. -There is a large difference in hardness between the jack bolt and the main body thread. MJT allows the gasket to be crushed evenly. MJT eliminates leakage problems.

[0010] Multiple MJTs can be utilized in compressing a first workpiece to a second workpiece, as shown in Figure 5. As shown, hydraulic pressure can be utilized to apply pressure to the MJTs.

[0011] Although MJTs are a significant improvement over conventional nuts for high preload applications, the inventors have nevertheless observed that for high temperature, highly loaded fastened connections such as gas turbine, steam turbine, and centrifugal compressor flanges, the studs and nuts must be designed to withstand the effects of creep, corrosion, and lubricant degradation, which are failure mechanisms that primarily affect MJT jackbolts during operation at high temperatures and loads.

[0012] It is an object of the present invention to provide a method and apparatus for tensioning elongated fasteners, such as studs or bolts, that overcomes or ameliorates at least one or more of the problems mentioned above, or at least provides consumers with a commercial alternative. Summary of the Invention

[0013] In a first aspect, although not necessarily in its broadest or indeed only aspect, the invention resides in a multi-jackbolt tensioner comprising: a body portion configured to engage or integrally formed with an elongated fastener, the body portion having a plurality of apertures uniformly spaced apart from a central longitudinal axis at spaced locations around its circumference, the apertures having sidewalls formed with body threads; jackbolts each including a body having threads in one of the body holes for engaging the body threads; and 1. A load-bearing member for applying a force to workpieces to be fastened, the load-bearing member being arranged to lie around an elongated fastener member, the load-bearing member having a first annular surface connected to a second annular surface by inner and outer walls, and a cylindrical lip projecting from the first annular surface, the cylindrical lip having a wall continuous with the inner wall.

[0014] In one embodiment, the body portion is formed with an axial opening for threaded engagement with an elongated fastener, hi one embodiment, the axial opening is closed at its end.

[0015] In one embodiment, the body portion is integrally formed with the elongate fastener.

[0016] In one embodiment, the wall projects slightly away from the plane of the inner wall.

[0017] In one embodiment, the cylindrical lip comprises a second wall. In one embodiment, the second wall projects away from the first annular surface. In certain embodiments, the second wall is sloped toward the wall. In some embodiments, the wall and the second wall are connected by a surface.

[0018] In one embodiment, the load bearing member is integrally formed.

[0019] In certain embodiments, the load-bearing member further comprises a concentric protrusion. The concentric protrusion protrudes from the first annular surface. The concentric protrusion is located between the inner wall and the outer wall. In one embodiment, the concentric protrusion has a circular shape that is substantially equidistant from the inner wall. In one embodiment, the concentric protrusion is not equidistant from both the inner wall and the outer wall.

[0020] In certain embodiments, the load-bearing member further comprises a second concentric protrusion projecting from the second annular surface. The second concentric protrusion is located between the inner wall and the outer wall. In one embodiment, the second concentric protrusion has a circular shape equidistant to the inner wall. In one embodiment, the second concentric protrusion is adjacent to the inner wall. In another embodiment, the second concentric protrusion is adjacent to the outer wall.

[0021] In certain embodiments, the load bearing member comprises a first concentric projection projecting from the first annular surface and a second concentric projection projecting from the second annular surface.

[0022] In one embodiment, the cylindrical lip is configured to form a seal with the first workpiece, the body, the jackbolt, and / or the elongated fastener. In some embodiments, the cylindrical lip is configured to form a seal with the first workpiece. In one embodiment, the cylindrical lip is configured to form a seal with the body. In several embodiments, the cylindrical lip is configured to form a seal with the jackbolt(s). In one embodiment, the cylindrical lip is configured to form a seal with the elongated fastener. In another aspect, the invention relates to a method of compressing a first workpiece and a second workpiece together, comprising: placing a load bearing member on a first workpiece, the load bearing member having a first annular surface connected to a second annular surface by inner and outer walls, and a cylindrical lip projecting from the first annular surface, the cylindrical lip having a wall continuous with the inner wall; placing a body portion on the load bearing member, the body portion engaging or integrally formed with the elongated fastener, the body portion having a plurality of holes uniformly spaced apart from the longitudinal central axis at spaced locations around its periphery, the holes having sidewalls formed with body threads; capturing the elongated fastener member on the exterior of the second workpiece; coupling a jackbolt to each of the holes in the body portion, the jackbolt including a body having threads engaging the body threads; and tensioning the jackbolt, thereby compressing the first workpiece and the second workpiece toward one another, with the cylindrical lip cooperating with the elongated fastener to form a seal therebetween.

[0023] The MJT, body and load bearing member may be substantially as described for the first embodiment.

[0024] In one embodiment, the method further includes applying hydraulic pressure to compress the first workpiece and the second workpiece, hi a further embodiment, the method further includes releasing the hydraulic pressure after tensioning the jackbolt.

[0025] In a second aspect, the present invention resides in a multi-jackbolt tensioner including: a body portion configured to engage or integrally formed with an elongated fastener, the body portion having a plurality of holes uniformly spaced apart from a central longitudinal axis at spaced locations around its circumference, the holes having sidewalls formed with body threads, and a base of the body portion including a cylindrical lip projection; jackbolts each including a body having threads in one of the body holes for engaging the body threads; and an annular load bearing member for applying a force to the workpieces to be fastened, the annular load bearing member being arranged to be disposed around the elongated fastener member; The cylindrical lip projection is configured to mate with the annular load bearing member.

[0026] In one embodiment, the body portion is formed with an axial opening for threaded engagement with an elongated fastener, hi one embodiment, the axial opening is closed at its end.

[0027] In some embodiments, the cylindrical lip is configured to form a seal with the first workpiece and / or the elongated fastener. In several embodiments, the cylindrical lip is configured to form a seal with the first workpiece. In one embodiment, the cylindrical lip is configured to form a seal with the elongated fastener.

[0028] In another aspect, the invention resides in a method of compressing together a first workpiece and a second workpiece, comprising the steps of: placing an annular load bearing member on the first workpiece; placing a body portion on a load bearing member, the body portion configured to engage or integrally formed with an elongated fastener, the body portion having a plurality of holes uniformly spaced apart from a central longitudinal axis at spaced locations around its circumference, the holes having sidewalls formed with body threads, and an underside of a base of the body portion having a cylindrical lip protrusion that abuts an annular load bearing washer; capturing the elongated fastener member on the exterior of the second workpiece; coupling a jackbolt including a body having threads engaging the body threads to each of the holes in the body; and tensioning the jackbolt, thereby compressing the first workpiece and the second workpiece toward one another, the cylindrical lip cooperating with the load bearing member and the elongated fastener member to form a seal therebetween.

[0029] The MJT, body, and load bearing member are substantially as described with respect to the second embodiment.

[0030] In one embodiment, the body portion is formed with an axial opening for threaded engagement with an elongated fastener.

[0031] In one embodiment, the body portion is integrally formed with the elongate fastener.

[0032] In one embodiment, the method further includes applying hydraulic pressure to compress the first workpiece and the second workpiece, hi a further embodiment, the method further includes releasing the hydraulic pressure after tensioning the jackbolt.

[0033] In one embodiment, the present invention resides in a method of sealing a gas turbine comprising the steps of: placing a metal insert on an adjacent surface of the gas turbine; compressing the adjacent surfaces by tensioning one or more MJTs referred to herein; This seals the gas turbine.

[0034] The method may further include sizing the metal insert to provide a tight fit between the adjacent surfaces. [Brief explanation of the drawings]

[0035] Preferred features, embodiments, and variations of the present invention can be identified from the following detailed description, which provides sufficient information for those skilled in the art to practice the invention. The Detailed Description should not be deemed to limit the scope of the above Summary of the Invention in any way. The embodiments described herein can be better understood by reference to the accompanying drawings. [Figure 1] 1 shows a prior art elongated fastening member protruding from a structural member in the form of a flange. [Figure 2] 1 shows a prior art nut-type MJT partially cut away. [Figure 3] 1 shows a prior art MJT. [Figure 4] 1 shows a prior art bolt-type MJT. [Figure 5] 1 illustrates multiple MJTs being utilized to compress a first workpiece and a second workpiece. [Figure 6] 1 shows a top view of an embodiment of an MJT. [Figure 7] 7 shows a cross-sectional view of the MJT taken along line LL shown in FIG. 6. [Figure 8] An enlarged cross-sectional view of A in FIG. 7 is shown. [Figure 9] A perspective view of the MJT shown in Figure 6 is shown. [Figure 10] 1 shows a top view of another embodiment of an MJT. [Figure 11] 11 shows a cross-sectional view of the MJT shown in FIG. 10 taken along line AA. [Figure 12] A perspective view of the MJT shown in Figure 10 is shown. [Figure 13] 1 illustrates an alternative embodiment of the MJT. [Figure 14] FIG. 2 shows a top perspective view of a load bearing member. [Figure 15]15 shows a side perspective view of the load bearing member of FIG. 14. [Figure 16] A bottom view of the metal insert is shown. [Figure 17] 17 shows a side view of the metal insert of FIG. 16. [Figure 18] 1 shows a sized metal insert welded to the surface. [Figure 19] 1 illustrates a cross section of an embodiment of a load bearing member having an exemplary MJT with little or no pressure applied by a jackbolt. [Figure 20] 19 shows the embodiment shown in FIG. 19 with pressure applied to the load bearing member by the jackbolt. DETAILED DESCRIPTION OF THE INVENTION

[0036] For ease of explanation, the present invention has been described in the context of a multi-jackbolt tensioner.

[0037] Multi-jackbolt tensioners (MJTs) can be used to tighten bolts, shafts, or studs in the oil, gas, energy, transportation, and mining industries. MJTs are suitably utilized in high-pressure environments. A non-limiting example of a high-pressure environment is turbine use. In this regard, gas turbines are generally assembled from components and are required to be substantially gas-tight; otherwise, a loss of efficiency can occur. To this end, a flange of the turbine body is typically compressed with the MJT to form a gas-tight seal therebetween.

[0038] However, the flanges and MJTs can be subjected to high pressures and temperatures, which can lead to their warping. When warping occurs, the seals between the flanges and / or MJTs no longer sealingly engage with each other, which can result in a loss of gas-tight seal. Gases within the turbine body can therefore escape between these damaged seals, resulting in a loss of efficiency or operation. The main points where gases can escape to the atmosphere are between the body of the MJT and the load-bearing member, or between the jackbolt and the jackbolt hole.

[0039] The present invention is based on the discovery that the provision of a particular load bearing member with a MJT or a particular body portion of the MJT can at least mitigate the problem of loss of the gas-tight seal.

[0040] In a first aspect, which need not be the only or indeed the broadest aspect of the invention, there is provided a multi-jackbolt tensioner comprising: a body portion configured to engage or integrally formed with an elongated fastener, the body portion having a plurality of apertures uniformly spaced apart from a central longitudinal axis at spaced locations around its circumference, the apertures having sidewalls formed with body threads; jackbolts each including a body having threads in one of the body holes for engaging the body threads; and 1. A load-bearing member for applying a force to workpieces to be fastened, the load-bearing member being arranged to lie around an elongated fastener member, the load-bearing member having a first annular surface connected to a second annular surface by inner and outer walls, and a cylindrical lip projecting from the first annular surface, the cylindrical lip having a wall continuous with the inner wall.

[0041] One drawback of currently available MJTs is that the interface between the load-bearing member and the body of the MJT can provide a gas leak point. Furthermore, if the elongated fastener is not integrally formed with the body of the MJT, the interface between the threaded central bore and the elongated fastener can also provide an additional gas leak point. Furthermore, as discussed above, creep, corrosion, and lubricant degradation can affect the jackbolt, which can lead to loss of the seal between the jackbolt and the body bore. Furthermore, the interface between the load-bearing member and the body can provide an additional gas leak point. In addition to the above, the interface between the load-bearing member and the workpiece can provide another additional gas leak point. The present invention alleviates these problems by providing an additional gas-tight seal to prevent gas leakage through these interfaces.

[0042] The present invention utilizes a load-bearing member that not only forms an airtight seal between the workpiece (e.g., a flange) and the body of the MJT, but also between the elongated fastener and the workpiece. Typically, the elongated fastener comprises a stud and a shank that extends between aligned openings in the workpiece to be compressed. This provides a seal between the workpiece, the elongated fastener, and the load-bearing member, thereby mitigating the problem of gas leaking from the volume between the elongated fastener and the workpiece.

[0043] Use of a load bearing member comprising a first annular surface connected to a second annular surface by inner and outer walls, and a cylindrical lip protruding from the first annular surface, the cylindrical lip having a wall continuous with the inner wall in the MJT, to enable a seal to be formed between the body of the MJT and a workpiece, and between the workpiece and an elongated fastener. The annular body of the load bearing member engages the body and flange of the MJT to form a seal therebetween. The cylindrical lip of the load bearing member also engages the elongated fastener to form a seal therebetween.

[0044] A cylindrical lip projecting from the first annular surface engages the elongated fastener to form a seal between the elongated fastener and the workpiece, which will be understood to provide an additional barrier between the interior volume between the elongated fastener and the workpiece and any weaknesses in the seal between the load bearing member and the body, the jackbolt and the jackbolt hole, and / or the body and the elongated fastener (where appropriate).

[0045] In one embodiment, the load bearing member is in the form of a washer. In one embodiment, the load bearing member is integrally formed; that is, the body and the cylindrical lip are formed from a single piece of material. As used herein, the term "integrally formed" refers to being formed from a single piece of material. In one embodiment, the load bearing member is formed from hardened steel.

[0046] The cylindrical lip projecting from the first annular surface also advantageously helps maintain the position of the load bearing member relative to the elongated fastener and workpiece.

[0047] 6 shows a top view of an exemplary MJT. The MJT 600 includes a body portion 620. In the illustrated embodiment, the body portion 620 is integrally formed with a locking nut 640.

[0048] Body portion 620 is formed with concentrically arranged threaded jackbolt holes 660a-660l extending therethrough. Each of threaded jackbolt holes 660a-660l receives a corresponding one of a plurality of jackbolts 662a-l. In the illustrated embodiment, there are twelve jackbolts 662a-l and twelve corresponding jackbolt holes 660a-660l. However, one skilled in the art will appreciate that any number of jackbolts and jackbolt holes may be utilized. In one embodiment, the number of jackbolts and jackbolt holes is 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12...n (n is an integer greater than 12).

[0049] FIG. 7 shows a partially cutaway cross-sectional view of MJT 600 taken through line LL. Body 620 seats on load bearing member 700. In one embodiment, the body abuts the load bearing member. Load bearing member 700 seats on flange 720a of a first workpiece. In one embodiment, the load bearing member abuts the flange of the first workpiece. Flange 720a seats on top of a flange of a second workpiece (not shown). Jackbolt 662a is inserted into threaded jackbolt hole 620a. Jackbolts 662a-l have external threads that engage with internally threaded jackbolt holes 660a-l. When jackbolt 662 is inserted into jackbolt hole 660, jackbolt 662 extends beyond the end of jackbolt hole 660. Jackbolt 662 can have a tip 661 that applies a force to load bearing member 700. Tip 661 is preferably a flat surface that abuts load bearing member 700. When jackbolt 662 is tensioned within jackbolt hole 660, tip 661 applies a force to load bearing member 700. Load bearing member 700 then applies the force to a workpiece, such as a flange. The two workpieces are then compressed together to form a seal between them.

[0050] The partially cut-away cross-sectional view of MJT 600 shown in FIG. 7 also shows an opening or jackbolt hole 620a formed therein. Opening or jackbolt hole 620a is closed at one end 620b. Female threads (not shown) are formed in the sidewall of jackbolt hole 620a. The male threaded top of stud 620c is formed to engage with the female threads of opening or jackbolt hole 620a. This embodiment is particularly useful in high pressure environments because there is no interface between the elongated fastener and the body portion through which gas can escape to the atmosphere.

[0051] The elongated fastener 650 preferably includes a stud 652 with a shank 654. The shank 654 includes an enlarged portion 655 having a larger diameter than the remainder of the shank 654. The enlarged portion 655 can abut the load bearing member 700 to form a seal therebetween, which will be discussed in more detail below. The elongated fastener 650 further includes an externally threaded portion 656. The externally threaded portion 656 is configured to receive a bolt and, optionally, a washer (not shown), which may be captured on the outside of a second workpiece.

[0052] In one embodiment, the jackbolt is subjected to a plasma bond process, which advantageously allows for efficient lubrication.

[0053] In one embodiment, the elongated fastener bolt is subjected to a Korstellarizing process. Korstellarizing is used to improve the mechanical and tribological properties of the elongated fastener. Korstellarizing improves the mechanical and wear properties without sacrificing corrosion resistance, which is particularly beneficial for the present invention. This minimizes delamination and metal debris, and improves wear resistance and fatigue strength.

[0054] Figure 8 shows an enlarged cross-sectional view (i.e., an enlarged view of Figure 7 "A") of the interface between flange 720a, load bearing member 700, and jackbolt 662a. As shown in Figure 8, load bearing member 700 is positioned between flange 720a, body portion 620, and jackbolt 662a. In this state, load bearing member 700 abuts flange 720a, body portion 620, and jackbolt 662a. Load bearing member 700 also abuts enlarged portion 655 of elongated member 650.

[0055] Load bearing member 700 comprises a first annular surface 701 connected to a second annular surface 702 by an inner wall 703 and an outer wall 704. The first annular surface 701 and the second annular surface 702 lie in substantially parallel planes. In one embodiment, the first annular surface and the second annular surface lie in parallel planes. The inner wall 703 has a smaller circumference than the outer wall 704. In one embodiment, the load bearing member has a generally annular body.

[0056] The load-bearing member 700 further comprises a cylindrical lip 710 projecting from the first annular surface 701. The cylindrical lip 710 comprises a wall 711 continuous with the inner wall 703. As shown, the wall 711 may preferably project slightly out of the plane of the inner wall 703. That is, the wall 711 extends away from the central longitudinal axis of the opening defined by the inner wall 703. The cylindrical lip 710 preferably comprises a second wall 712 projecting away from the first annular surface 701. The second wall 712 preferably is at an obtuse angle relative to the plane of the first annular surface 701 such that it is angled toward the wall 711. It is hypothesized that this slight change in orientation biases the cylindrical lip 710 toward the enlarged portion 655 in use, forming a seal therebetween. In one embodiment, a seal is formed between the load-bearing member and the elongated fastener or its stud. The wall 711 and the second wall 712 may be connected by a surface 713. It will be appreciated that wall 711 and second wall 712 may meet at an apex, however, it is preferred that wall 711 and second wall 712 be connected by surface 713 as this provides additional structural integrity to cylindrical lip 710.

[0057] A drawback of some prior art load bearing members is that they shift or move when force is applied. This shifting of the load bearing member can create a weak spot in the seal. The cylindrical lip 710 acts as a locating feature for the load bearing member 700 relative to the elongated fastener 650 (and its enlarged portion 655) and the opening in the workpiece. This mitigates the problem of the load bearing member 710 becoming offset when force is applied.

[0058] The cylindrical lip 710 is also sized and dimensioned such that it abuts the enlarged portion 655 and forms a seal therebetween. It will be appreciated that the cylindrical lip 710 extends entirely around the enlarged portion 655, providing a seal therebetween. It will be appreciated that the lip 710 forms a seal with the enlarged portion 655 around its entire circumference. The seal between the load bearing member 700 and the enlarged portion 655 provides another barrier to the escape of internal volume between any compromises in the seals between the load bearing member 700 and the body portion 620, and between the jackbolt 662 and the corresponding jackbolt hole 660.

[0059] Figure 9 is a perspective view of the MJT 600 shown in Figure 6. The MJT 600 includes the body portion 620, the load bearing member 700, and the elongated fastener 650, as described above. The distal end of the elongated member 650 is provided with an externally threaded portion 656. The externally threaded portion 656 has a larger diameter than the shank 652. The externally threaded portion 656 is configured to receive a bolt and a washer (not shown) that is captured on the outside of an optional second workpiece.

[0060] In one embodiment, the load bearing member further comprises a concentric protrusion. In one embodiment, the concentric protrusion protrudes from the first annular surface. That is, the load bearing member comprises a protrusion disposed between the inner wall and the outer wall such that a circular protrusion is formed therebetween. In certain embodiments, the concentric protrusion is not centrally disposed between the inner wall and the outer wall.

[0061] In another embodiment, a concentric protrusion projects from the second annular surface. That is, the load-bearing member includes a protrusion disposed between the inner wall and the outer wall, forming a circular protrusion therebetween. In certain embodiments, the concentric protrusion is not centrally disposed between the inner wall and the outer wall. In one embodiment, the concentric protrusion is disposed adjacent to the inner wall. In another embodiment, the concentric protrusion is disposed adjacent to the outer wall.

[0062] The concentric projections allow the load bearing member to twist slightly when the jackbolt applies pressure to it, which is hypothesized to create a tighter seal between them.

[0063] 10 shows a top view of another exemplary MJT. MJT 1000 is similar to MJT 600, except that the elongated fasteners are received in openings across the body.

[0064] The MJT 1000 includes a body portion 1020. The body portion 1020 is annular. The body portion 1020 has a circular threaded opening 1040 formed therethrough for receiving an elongated fastener (not shown). The elongated fastener preferably has a threaded body that engages with the circular threaded opening 1040. The diameter of the circular threaded opening 1040 preferably equals the diameter of the threaded body of the elongated fastener.

[0065] The body portion 1020 is formed with a concentric array of threaded jackbolt holes 1060a-l extending therethrough. Each threaded jackbolt hole 1060a-l receives a corresponding one of a plurality of jackbolts 1062a-l. In the illustrated embodiment, there are twelve jackbolts 1062a-l and twelve corresponding jackbolt holes 1060a-l.

[0066] 11 shows a partial cutaway cross-sectional view of MJT 1000 taken through line AA. Body 1020 seats on load bearing member 1100. In one embodiment, the body abuts the load bearing member. Load bearing member 1100 seats on flange 1120a of a first workpiece. Flange 1120a seats on flange 1120b of a second workpiece. In one embodiment, the load bearing member abuts the flange of the first workpiece. Jackbolts 1062a and 1062g are inserted into respective threaded jackbolt holes 1060a and 1062g in body 1020. Jackbolts 1062a and 1062g include male threads that engage with female-threaded jackbolt holes 1060a and 1060g. When the jackbolts 1062a and 1062g are inserted into their respective jackbolt holes 1060a and 1062g, the jackbolts 1062a and 1062g extend beyond the ends of the jackbolt holes 1060a and 1060g. The jackbolts 1062a and 1062g each have a respective tip 1061a and 1061g that applies a force to the load bearing member 1100. When the jackbolts 1062a and 1062g are tensioned within the jackbolt holes 1060a and 1060g, the respective tip applies a force to the load bearing member 1100. The load bearing member 1100 then applies a force to the workpiece.

[0067] Load bearing member 1100 is substantially as described for load bearing member 700 above.

[0068] The elongated fastener 1050 comprises a stud 1052 having a shank 1054. The shank 1054 comprises an enlarged portion 1055 and a threaded portion 1056. The enlarged portion 1055 has a larger diameter than the remainder of the shank 1054. The threaded portion 1056 has a larger diameter than the shank 1054. The threaded portion 1056 is configured to receive a bolt 1200 captured on the outside of the second workpiece 1120b. The elongated fastener 1050 further comprises an externally threaded body 1058 that engages with the circular, internally threaded opening 1040 in the body portion 1020. The externally threaded body 1058 is located at the distal end of the elongated fastener 1050. The threaded body 1058 is connected to the enlarged portion 1055. The diameter of the threaded body 1058 is preferably equal to the diameter of the circular, threaded opening 1040. That is, the threaded body 1058 is complementary to the circular, internally threaded opening 1040 .

[0069] As shown, the load bearing member 1100 similarly forms a seal between the first workpiece 1120a and the stud 1054. Assuming the MJT 1000 includes the elongated fastener 1050 as a separate component, this seal would further prevent gas leakage from the interface between the elongated fastener 1050 and the circular threaded opening 1040 in the body portion 1020, as well as the interface between the load bearing member 1100 and the body portion 1020, the interface between the load bearing member 1100 and the workpiece 1120a, and the interface between the jackbolt and the jackbolt hole.

[0070] Figure 12 shows a perspective view of the MJT shown in Figure 10. Note that the elongated fastening members are not shown.

[0071] Figure 14 is a top perspective view of the load support member, and Figure 15 is a side perspective view of the load support member. The load support member 1400 comprises a first annular surface 1401 connected to a second annular surface 1402 by an inner wall 1403 and an outer wall 1404. The first annular surface 1401 and the second annular surface 1402 lie in substantially parallel planes. In one embodiment, the first annular surface 1401 and the second annular surface 1402 lie in parallel planes. The inner wall 1403 has a smaller circumference than the outer wall 1404. In the illustrated embodiment, the load support member 1400 has a generally annular body.

[0072] The load bearing member 1400 further comprises a cylindrical lip 1410 projecting from the first annular surface 1401. The cylindrical lip 1410 comprises a wall 1411 continuous with the inner wall 1403. That is, the wall 1411 extends away from the central longitudinal axis of the opening defined by the inner wall 1403. In a preferred embodiment, the opening is sized and dimensioned to receive an elongated fastener as described above. The wall 1411 may project slightly away from the plane of the inner wall 1403. The cylindrical lip 1410 comprises a second wall 1412 projecting away from the first annular surface 1401. The second wall 1412 is at an obtuse angle relative to the plane of the first annular surface 1401 such that it is angled toward the wall 1411. It is hypothesized that this slight change in orientation biases the cylindrical lip 1410 toward the stud (in use) to form a seal therebetween. Wall 1411 and second wall 1412 may be connected by surface 1413. This surface 1413 is hypothesized to provide additional structural integrity to the cylindrical lip.

[0073] In use with a body portion that is not integrally formed with the elongated fastener, the cylindrical lip is configured to form a seal with the first workpiece, the body portion, the jackbolt, and / or the elongated fastener (if applicable). In some embodiments, the cylindrical lip is configured to form a seal with the first workpiece. In several embodiments, the cylindrical lip is configured to form a seal with the body portion. In one embodiment, the cylindrical lip is configured to form a seal with the jackbolt(s). In one embodiment, the cylindrical lip is configured to form a seal with the elongated fastener.

[0074] In use with an elongated fastener integrally formed with the body, the cylindrical lip is configured to form a seal with the first workpiece and / or the elongated fastener. In some embodiments, the cylindrical lip is configured to form a seal with the first workpiece. In one embodiment, the cylindrical lip is configured to form a seal with the elongated fastener.

[0075] The present invention has been described above with respect to a load bearing member having a cylindrical lip protrusion that abuts a flange. However, it will be understood that the load bearing member may be utilized in the opposite orientation, where the cylindrical lip protrusion engages the body of the MJT to form a seal therebetween. This embodiment is shown in Figures 19 and 20. In one embodiment, the cylindrical lip is configured to form a seal with the body.

[0076] Additionally, the non-centered concentric protrusion between the inner and outer walls allows for an additional seal between the flange and the load bearing member. A cross section of one embodiment of a load bearing member 1900 with an exemplary MJT is shown in Figures 19 and 20.

[0077] The load bearing member 1900 comprises a first annular surface 1901 connected to a second annular surface 1902 by an inner wall 1903 and an outer wall 1904. The first annular surface 1901 and the second annular surface 1902 lie in substantially parallel planes. In one embodiment, the first annular surface 1901 and the second annular surface 1902 lie in parallel planes. The inner wall 1903 has a smaller circumference than the outer wall 1904. In the illustrated embodiment, the load bearing member 1900 has a generally annular body.

[0078] The load bearing member 1900 further comprises a cylindrical lip 1910 projecting from the first annular surface 1901. The cylindrical lip 1910 comprises a wall 1911 continuous with the inner wall 1903. The cylindrical lip 1910 preferably comprises a second wall 1912 projecting away from the first annular surface 1901. The wall 1911 and the second wall 1912 may be connected by a surface 1913. It will be appreciated that the wall 1911 and the second wall 1912 may meet at an apex. However, it is preferred that the wall 1911 and the second wall 1912 be connected by a surface 1913 as this provides additional structural integrity to the cylindrical lip 1910. In one embodiment, the cylindrical lip 1910 is configured to form a seal with the body portion.

[0079] The load bearing member 1900 further comprises a concentric protrusion 1950. The concentric protrusion 1950 extends away from the second annular surface 1902. Preferably, the concentric protrusion is located adjacent the inner wall 1903. In another embodiment, the concentric protrusion is located adjacent the outer wall 1904.

[0080] As shown in FIG. 19 , the body portion 1920 seats on the load bearing member 1900. In one embodiment, the body portion abuts the load bearing member. The load bearing member 1900 seats on a flange 1920a of a first workpiece. In one embodiment, the load bearing member abuts the flange of the first workpiece. The flange 1920a seats on top of a flange of a second workpiece (not shown). A jackbolt 1962a is inserted through a threaded jackbolt hole in the body portion 1920. FIG. 19 shows the jackbolt 1962a in contact with the first annular surface 1901 of the load bearing member 1900. The cylindrical lip 1910 is positioned to contact the body portion 1920 to form a seal therebetween. Note that little or substantially no pressure is applied to the load bearing member 1900 by the jackbolt 1962a in FIG. 19 . As shown, concentric projection 1950 engages flange 1920a.

[0081] FIG. 20 shows the configuration of FIG. 19, except that pressure is applied to the load bearing member 1900 by a jack bolt 1962a. When pressure is applied to the load bearing member 1900, a seal is formed between the concentric projections 1950 and the flange 1920a. The applied pressure further forces the load bearing member 1900 into contact with the flange 1920a in a second position. As shown, a portion of the second annular surface 1902 adjacent the outer wall 1904 is forced into contact with the flange 1920a, forming a seal therebetween. Thus, the use of the concentric projections 1950 further enables a pair of seals to be formed, mitigating gas leakage issues.

[0082] 19 and 20, the body portion 1920 includes a recess that receives the cylindrical lip 1910. The cylindrical lip 1910 forms a seal with the recess in the body portion 1920.

[0083] It will be appreciated that if the concentric protrusion is not centered between the inner and outer walls, additional seal formation will occur. In one embodiment, the concentric protrusion is located adjacent to the inner wall. In another embodiment, the concentric protrusion is located adjacent to the outer wall.

[0084] It will be appreciated that the cylindrical lip is configured to form a seal with the first workpiece and the body. In some embodiments, the cylindrical lip is configured to form a seal with the first workpiece. In several embodiments, the cylindrical lip is configured to form a seal with the body. In one embodiment, the cylindrical lip is configured to form a seal with the elongated fastener.

[0085] In another form, the invention provides a method of compressing a first workpiece and a second workpiece together, comprising: placing a load bearing member on a first workpiece, the load bearing member having a first annular surface connected to a second annular surface by inner and outer walls, and a cylindrical lip projecting from the first annular surface, the cylindrical lip having a wall continuous with the inner wall; placing a body portion on the load bearing member, the body portion engaging or integrally formed with the elongated fastener, the body portion having a plurality of holes uniformly spaced apart from the central longitudinal axis at spaced locations around its circumference, the holes having sidewalls formed with body threads; capturing the elongated fastener member on the exterior of the second workpiece; coupling a jackbolt including a body having threads engaging the body threads to each of the holes in the body portion; tensioning the jackbolt, thereby compressing the first workpiece and the second workpiece toward one another.

[0086] The MJT, body, jackbolt, and load bearing member may be substantially as described above.

[0087] In operation, the multi-jackbolt tensioner includes a body portion configured to engage or be integrally formed with an elongated fastener. The elongated fastener typically passes through openings in the first and second workpieces (e.g., flanges). The distal end of the elongated fastener is preferably captured on the outside of the second workpiece. The elongated fastener may optionally be captured by a bolt having a washer. The elongated fastener may include a stud and / or a shank extending through the first and second workpieces.

[0088] The load-bearing member is placed on a first workpiece, and the body of the multi-jackbolt tensioner is placed on top of it. Jackbolts, each with male threads that engage with the female threads on the body, are inserted into holes in the body and connected together. When tension is applied to the jackbolts, pressure is applied to the load-bearing member and, ultimately, to the first and second workpieces. This pressure exerts compressive pressure on the first and second workpieces.

[0089] In one embodiment, the method further includes applying hydraulic pressure to compress the first workpiece and the second workpiece. The method further includes releasing the hydraulic pressure after tensioning the jackbolt.

[0090] In one embodiment, the method further includes forming a seal between the cylindrical lip and the first workpiece, the body, the jackbolt, and / or the elongated fastener. In some embodiments, the method further includes forming a seal between the cylindrical lip and the first workpiece. In certain embodiments, the method further includes forming a seal between the cylindrical lip and the jackbolt. In some embodiments, the method further includes forming a seal between the cylindrical lip and the elongated fastener. In some embodiments, the method further includes forming a seal between the cylindrical lip and the body.

[0091] It will be understood by those skilled in the art that the cylindrical lip feature may be formed on the base of the body of the MJT. In this regard, FIG. 13 illustrates an alternative embodiment of an MJT in which a cylindrical lip is formed on the base of its body. FIG. 13 illustrates a cross-sectional view of MJT 1300.

[0092] The MJT 1300 includes a body portion 1320. The body portion 1320 is preferably an annular body portion such as those described above. The body portion 1320 includes a circular threaded opening (not shown) formed therethrough to receive an elongated fastener 1350.

[0093] The body portion 1320 may be formed with a concentric array of threaded jackbolt holes extending therethrough. Each of the threaded jackbolt holes receives a corresponding one of a plurality of jackbolts. Shown in FIG. 13 are two jackbolts 1362a and 1362g inserted through the respective threaded jackbolt holes. The jackbolts 1362a and 1362g include external threads that engage with corresponding internally threaded jackbolt holes. When the jackbolts 1362a and 1362g are inserted into the jackbolt holes, the jackbolts 1362a and 1362g extend beyond the ends of the jackbolt holes. The jackbolts 1362a and 1362g preferably include tips 1361a and 1361g that apply a force to the load bearing member 1400.

[0094] In this embodiment, the load bearing member 1400 is an annular load bearing member. In another embodiment, the load bearing member 1400 is in the form of an annular washer.

[0095] The underside of the base of the body portion 1320 is provided with a cylindrical lip protrusion 1322. The cylindrical lip protrusion 1322 is sized and dimensioned to be located between the load bearing member 1400 and the enlarged portion 1355 of the shank of the elongated fastener 1350. In this regard, the cylindrical lip protrusion forms a seal with the enlarged portion and / or the load bearing member. In one embodiment, the cylindrical lip protrusion forms a seal with the enlarged portion. In one embodiment, the cylindrical lip protrusion forms a seal with the load bearing member. The cylindrical lip protrusion is sized and dimensioned to form a seal between the load bearing member 1400 and the enlarged portion 1355 in use.

[0096] The cylindrical lip protrusion 1322 forms a seal between the load bearing member 1400 and the enlarged portion 1355. It will be appreciated that the cylindrical lip protrusion 1322 performs a similar function to the load bearing members described in the previous embodiments. The cylindrical lip protrusion 1322 also helps maintain the load bearing member 1400 in a desired location / position.

[0097] It will be appreciated that the MJT described above may be utilized in conjunction with a hydraulic tensioner. In this regard, the hydraulic tensioner may be utilized to apply compressive pressure to the first and second workpieces. The jackbolt may then be tensioned to maintain the applied hydraulic pressure, and then the hydraulic pressure may be released and the hydraulic tensioner removed.

[0098] It will be appreciated that the cylindrical lip is configured to form a seal with the first workpiece and / or the elongated fastener. In some embodiments, the cylindrical lip is configured to form a seal with the first workpiece. In one embodiment, the cylindrical lip is configured to form a seal with the elongated fastener.

[0099] It will be appreciated that the cylindrical lip on either the load bearing member or the body portion provides an additional seal that mitigates pressure loss problems. In this regard, the seal formed by the cylindrical lip on either the load bearing member or the body portion (and the load bearing member or body portion, respectively) provides an additional backup against loss of seal. This is a significant advantage over prior art MJTs.

[0100] In another form, the invention provides a method of compressing a first workpiece and a second workpiece together, comprising: placing an annular load bearing member on the first workpiece; placing a body portion on the load bearing member, the body portion configured to engage or integrally formed with an elongated fastener, the body portion having a plurality of apertures uniformly spaced apart from a central longitudinal axis at spaced locations around its circumference, the apertures having sidewalls formed with body threads, and an underside of a base of the body portion having a cylindrical lip projection that abuts an annular load bearing washer; capturing the elongated fastener member on the exterior of the second workpiece; coupling a jackbolt including a body having threads engaging the body threads to each of the holes in the body; and tensioning the jackbolt, thereby compressing the first workpiece and the second workpiece toward one another.

[0101] The body, jackbolt, and load bearing member may be substantially as described above.

[0102] In one embodiment, the method further comprises forming a seal between the cylindrical lip protrusion and the enlarged portion and / or the load bearing member. In one embodiment, the method further comprises forming a seal between the cylindrical lip protrusion and the enlarged portion. In one embodiment, the method further comprises forming a seal between the cylindrical lip protrusion and the load bearing member.

[0103] As previously mentioned, the MJT described above is suitable for use in high fluid pressure environments (such as gas turbines). One problem with these high fluid pressure environments is that adjacent surfaces within the turbine are uneven. These interfaces can lead to seal loss. One solution to this problem is to seal the adjacent surfaces by installing a seal. The seal can be formed with a metal insert. The metal insert is properly installed before sealing with the MJT. The metal insert is preferably welded before tensioning the MJT. The metal insert may be sized to fit tightly between the adjacent surfaces.

[0104] In one embodiment, the present invention provides a method of sealing a gas turbine, comprising: placing a metal insert on an adjacent surface of the gas turbine; and The method includes applying tension to one or more MJTs referred to herein to compress adjacent surfaces, thereby sealing the gas turbine.

[0105] The method may further include sizing the metal insert so that it fits tightly between the adjacent surfaces.

[0106] The method can further include welding a metal insert to the adjacent surfaces. The tensioning of the one or more MJTs can be substantially as described above. In one embodiment, compressing the adjacent surfaces includes utilizing the MJTs described above.

[0107] The metal insert compresses as the MJT is tensioned, forming a tight seal between them. Preferably, the compressed metal insert forms an airtight seal between adjacent surfaces. The use of the metal insert is hypothesized to provide an additional barrier against loss of the seal in high fluid pressure environments.

[0108] 16 and 17 illustrate one embodiment of a metal insert 1600. In one embodiment, the metal insert comprises a substantially flat body portion 1610 having one or more protrusions 1620a, 1620b extending from its surface. The one or more protrusions 1620a, 1620b are preferably spaced apart. In one embodiment, the metal insert is integrally formed. Preferably, the one or more protrusions are approximately centered between the ends of the substantially flat body. This allows the metal insert to be cut or sized to fit tightly between adjacent surfaces. In one embodiment, the joints between the one or more protrusions 1620a, 1620b are reinforced at the points where they contact the substantially flat body portion 1610 (as shown).

[0109] It will be understood that gaps may exist between adjacent surfaces, and that these gaps may have different dimensions. The metal insert may accommodate these gaps by allowing a user to dimension the metal insert to provide a tight fit between the adjacent surfaces. For example, the substantially flat body portion 1610 may be cut to a desired size. Furthermore, it is assumed that the one or more protrusions will undergo some degree of flexion when inserted into the gap.

[0110] 18 illustrates an embodiment of a sized metal insert 1600 welded to at least one of adjacent surfaces 1810, 1820. As shown, the metal insert has a substantially flat body sized to a desired size. In the illustrated embodiment, the sized metal insert 1600 is welded to the adjacent surface 1820.

[0111] Any documents cited herein are incorporated by reference, but only to the extent that the incorporated material does not contradict 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 should not be construed as an admission that it is prior art with respect to the present application.

[0112] Furthermore, any reference to prior art methods, devices, or documents is not to be construed as constituting any evidence or admission that they constitute or form part of the common general knowledge.

[0113] 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 (including alternatives, variations, additions, deletions, modifications, and substitutions) to the specific devices and methods described herein.

[0114] Therefore, this application, including the appended claims, is intended to encompass all such changes and modifications that are within the scope of this application.

Claims

1. 1. A multi-jackbolt tensioner comprising: a body portion configured to engage or integrally formed with an elongated fastener, said body portion having a plurality of apertures uniformly spaced apart from a central longitudinal axis at spaced locations around its circumference, said apertures having sidewalls formed with body threads; jackbolts each including a body having threads for engaging the body threads in one of the body holes; and a load bearing member for applying a force to workpieces to be fastened, the load bearing member being arranged to rest around an elongated fastener, the load bearing member having a first annular surface connected to a second annular surface by inner and outer walls, and a cylindrical lip projecting from the first annular surface, the cylindrical lip having a wall continuous with the inner wall, the cylindrical lip being configured to form a seal with the workpieces to be fastened; Equipped with the load bearing member further comprising a second concentric projection projecting from the second annular surface.

2. 2. The multi-jackbolt tensioner of claim 1, wherein said wall projects slightly away from the plane of said inner wall.

3. 3. The multi-jackbolt tensioner of claim 1 or 2, wherein the cylindrical lip includes a second wall that projects away from the first annular surface.

4. 4. The multi-jackbolt tensioner of claim 1, wherein the load bearing member further comprises a concentric protrusion projecting from the first annular surface.

5. 5. The multi-jackbolt tensioner of claim 1, wherein the cylindrical lip is configured to form a seal with the workpiece, the body, the jackbolt, and / or the elongated fastener.

6. A multi-jackbolt tensioner as claimed in any one of claims 1 to 5, wherein the cylindrical lip is configured to form a seal with the elongated fastening member.

7. A multi-jackbolt tensioner as claimed in any preceding claim, wherein the cylindrical lip is configured to form a seal with the body portion.

8. 8. The multi-jackbolt tensioner according to claim 1, wherein the jackbolt abuts against the load bearing member.

9. 1. A method of compressing a first workpiece and a second workpiece together, comprising: placing a load bearing member on the first workpiece, the load bearing member comprising a first annular surface connected to a second annular surface by inner and outer walls, and a cylindrical lip projecting from the first annular surface, the cylindrical lip having a wall continuous with the inner wall, the cylindrical lip configured to form a seal with the first workpiece or the second workpiece, the load bearing member further comprising a second concentric protrusion projecting from the second annular surface; placing a body portion on the load bearing member, the body portion engaging or integrally formed with an elongated fastener, the body portion having a plurality of holes spaced about its periphery and uniformly spaced from its central longitudinal axis, the holes having sidewalls with body threads formed thereon; capturing the elongated fastener on an exterior of the second workpiece; coupling a jackbolt including a body having threads engaging the body threads to each of the body holes; The method includes tensioning the jackbolt, thereby compressing the first workpiece and the second workpiece toward one another.

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