Fastener covers for flange joints

Abstract

A fastener cover for a flange joint, the flange joint including a first annular flange and a second annular flange extending about an axis, the fastener cover comprising: a plurality of arcuate fastener cover segments (110, 210, 310, 410, 510, 610, 710, 810, 910, 1010, 1110, 1210), the plurality of arcuate fastener cover segments arranged about the axis to form a 360-degree annulus, each fastener cover segment extending between a first circumferential end and a second circumferential end and comprising: a first radial wall, a second radial wall axially spaced from the first radial wall, an arcuate axially extending outer sidewall interconnecting the first radial wall and the second radial wall, wherein the first radial wall, the second radial wall, and the outer sidewall collectively define a cavity for receiving the first flange, the second flange, and a portion of a fastener protruding from the flanges; and an attachment structure spaced from the first radial wall and including a clearance hole (126, 226, 424) for a fastener shank.

Description

[0001] Contract Statement

[0002] The project leading to this application has received funding from the Clean Sky 2 Joint Undertaking within the European Union’s Horizon 2020 research and innovation programme, under grant agreement No CS2-LPA-GAM-2018 / 2019-01. Technical Field

[0003] The present invention relates generally to gas turbine engines and, more particularly, to flange joints in such engines. Background Art

[0004] A gas turbine engine typically includes a low-pressure compressor or supercharger, a high-pressure compressor, a combustor, a high-pressure turbine, and a low-pressure turbine in series flow communication. The combustion gases produced by the combustor are sequentially directed to the high-pressure turbine, where they are expanded to drive the high-pressure turbine, and then to the low-pressure turbine, where they are further expanded to drive the low-pressure turbine. The high-pressure turbine is drivingly connected to the high-pressure compressor via a first rotor shaft, and the low-pressure turbine is drivingly connected to the supercharger via a second rotor shaft.

[0005] Engines consist of multiple annular structures, such as a stationary casing and a rotating shaft or drum. These annular structures typically consist of two or more parts joined to one another at a flange joint, where the two flanges are clamped together by a circle of bolts.

[0006] In operation, the interaction of airflow with the exposed portion of the bolts in the flange joint can produce undesirable results such as aerodynamic drag and frictional heating. Therefore, it is known in the art to provide an arcuate cover, known as a "windage shield", over the bolts. Summary of the Invention

[0007] The present invention provides a fastener cover that provides a windage shielding function and may include a balancing feature, a sealing feature, or a damping feature.

[0008] According to one aspect of the technology described herein, a fastener cover for a flange joint is described, the flange joint comprising a first annular flange and a second annular flange extending about an axis, the fastener cover comprising: an annular axially extending inner side wall; an annular axially extending outer side wall, the outer side wall being positioned radially outward of the inner side wall; and a first radial wall, the first radial wall interconnecting the inner side wall and the outer side wall, wherein the inner side wall, the outer side wall and the first radial wall together define a cavity for receiving a portion of a fastener; at least one fastener pocket, at least one fastener pocket comprising a side wall extending axially away from the first radial wall and defining a tubular shape, the tubular shape being enclosed relative to the first radial wall by a base plate, the base plate having a clearance hole therethrough for receiving a shank of the fastener; and wherein the cover comprises a balancing weight container for receiving at least one balancing weight.

[0009] According to another aspect of the technology described herein, a fastener cover for a flange joint is described, the flange joint including a first annular flange and a second annular flange extending about an axis, the fastener cover including: a plurality of arcuate fastener cover segments arranged about the axis to form a 360-degree annulus, each fastener cover segment extending between a first circumferential end and a second circumferential end and including: a first radial wall, a second radial wall axially spaced apart from the first radial wall, an arcuate axially extending outer side wall interconnecting the first radial wall and the second radial wall, wherein the first radial wall, the second radial wall, and the outer side wall together define a cavity for receiving the first flange, the second flange, and a portion of a fastener protruding from the flange; and an attachment structure spaced apart from the first radial wall and including a clearance hole for a fastener shank. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present invention may be best understood by reference to the following description taken in conjunction with the accompanying drawings, in which:

[0011] FIG1 is a schematic diagram of a prior art gas turbine engine;

[0012] FIG2 is a cross-sectional view of a prior art rotor having a flange joint;

[0013] Figure 3 is a perspective view of a portion of a rotor having a flange joint showing a first exemplary embodiment of a fastener cover attached thereto;

[0014] Figure 4 yes Figure 3 a partial cross-sectional view of a fastener cover;

[0015] Figure 5 yes Figure 3 a front perspective view of a portion of a fastener cover;

[0016] Figure 6 yes Figure 5 A rear perspective view of the fastener cover;

[0017] Figure 7 is a perspective view of a fastener cover segment;

[0018] Figure 8 is a perspective view of a portion of a rotor having a flange joint showing a second exemplary embodiment of a fastener cover attached thereto;

[0019] Figure 9 yes Figure 8 a partial cross-sectional view of a fastener cover;

[0020] Figure 10 yes Figure 8 A perspective view of a fastener cover;

[0021] Figure 11 yes Figure 8 A perspective view of an alternative variation of a fastener cover;

[0022] Figure 12 is a perspective view of a portion of a rotor having a flange joint showing a third exemplary embodiment of a fastener cover attached thereto;

[0023] Figure 13 yes Figure 12 A perspective view of a fastener cover;

[0024] Figure 14 yes Figure 12 A perspective view of an alternative variation of a fastener cover;

[0025] Figure 15 yes Figure 12 a perspective view of the shaft showing its mating surfaces;

[0026] Figure 16 is a perspective view of an exemplary fastener cover segment having radially aligned end walls;

[0027] Figure 17 is a perspective view of an exemplary fastener cover segment having obliquely aligned end walls;

[0028] Figure 18 is a perspective view of an exemplary fastener cover segment including a balancing weight;

[0029] Figure 19 yes Figure 18 an enlarged view of a portion of a fastener cover segment;

[0030] Figure 20 yes Figure 18 an enlarged view of a portion of a fastener cover segment;

[0031] Figure 21 yes Figure 18 a cross-sectional view of a portion of a fastener cover segment;

[0032] Figure 22 is a perspective view of an exemplary fastener cover segment including an array of holes for receiving a balance weight;

[0033] Figure 23 yes Figure 22 an enlarged view of a portion of a fastener cover segment;

[0034] Figure 24 is a perspective view of an exemplary fastener cover segment including a first variation of a labyrinth seal;

[0035] Figure 25is a perspective view of an exemplary fastener cover segment including a second variation of a labyrinth seal;

[0036] Figure 26 is a perspective view of an exemplary fastener cover segment including an array of holes for receiving a balance weight; and

[0037] Figure 27 yes Figure 26 A cross-sectional view of a portion of a fastener cover segment. DETAILED DESCRIPTION

[0038] Referring to the drawings, in which like reference numerals represent like elements throughout the several views, FIG1 is a schematic diagram of a gas turbine engine 10 having a centerline or longitudinal axis 11 and including a fan assembly 12, a high-pressure compressor 14, and a combustor 16. The engine 10 also includes a high-pressure turbine 18, a low-pressure turbine 20, and a supercharger 22. The fan assembly 12 includes an array of fan blades 24 extending radially outward from a rotor disk 26. Although the illustrated engine 10 is a turbofan engine, the principles described herein are applicable to any type of engine or machine having flange joints between components.

[0039] Note that, as used herein, the terms "axial" and "longitudinal" both refer to directions parallel to the centerline axis 11, while "radial" refers to directions perpendicular to the axial direction, and "tangential" or "circumferential" refers to directions perpendicular to both the axial and radial directions. As used herein, the terms "front" or "frontward" refer to a position relatively upstream in the flow of air through or around a component, while the terms "rear" or "rearward" refer to a position relatively downstream in the flow of air through or around a component. The direction of this flow is shown by arrow "F" in FIG1 . These directional terms are used for descriptive convenience only and do not require a particular orientation of the structures described thereby.

[0040] In operation, air flows through the low-pressure compressor 22 and compressed air is supplied from the low-pressure compressor 22 to the high-pressure compressor 14. The highly compressed air is delivered to the combustor 16, where fuel is injected and combusted. The airflow from the combustor 16 drives the turbines 18 and 20 and exits the engine 10 through the nozzle. The high-pressure turbine 18 drives the high-pressure compressor 14 via a high-pressure shaft, and the low-pressure turbine 20 drives the fan assembly 12 and the supercharger 22 via a low-pressure shaft.

[0041] It should be understood that the engine 10 includes one or more flange joints therein, which include two annular components, each having flanges that abut each other and are clamped together by a plurality of fasteners. Non-limiting examples of flange joints can be found in the housing, shaft, or rotor.

[0042] FIG2 shows a rotor assembly including a first shaft 25 having an annular first flange 27 and a second shaft 28 having an annular second flange 30. This assembly is merely a representative example illustrating the structure of the flange joint. The rotor assembly or similar structure may be found in various areas within engine 10 of FIG1 , such as in a shaft interconnecting one of the turbines with one of the compressors or propulsion elements, such as a low-pressure shaft, an intermediate-pressure shaft, or a high-pressure shaft (not separately labeled in FIG1 ).

[0043] The first flange 27 includes an axially facing first mating surface 32 and an opposing first rear surface 34. A plurality of axially aligned first fastener holes 36 extend through the first flange 27. The second flange 30 includes an axially facing second mating surface 38 and an opposing second rear surface 40. A plurality of axially aligned second fastener holes 42 extend through the second flange 30.

[0044] The first and second flanges 27 , 30 are arranged so that they abut one another and each of the first fastener holes 36 is coaxial with a corresponding one of the second fastener holes 42 .

[0045] A fastener 44 having a shank 46 is inserted through each of the coaxial pairs of first and second fastener holes 36, 42 and secured. The fastener 44 is shown as a bolt 45 having a head 47, coupled to a nut 48. It will be appreciated that other types of fasteners may be used for this purpose. When torqued, the fastener 44 clamps the first and second flanges 27, 30 together, coupling the first and second shafts 25, 28 and allowing torque to be transferred therebetween. The first and second flanges 27, 30, and the fastener 44 may be collectively referred to as a "flange joint" 50.

[0046] This disclosure describes various embodiments of windage shields that may perform functions other than windage shielding, including, for example, balancing features, sealing features, or damping features.

[0047] Figure 3-6 A first exemplary embodiment of a fastener cover 100 suitable for use with the flange joint 50 of Figure 2 is shown. Two fastener covers 100 are provided, one for the first flange 27 and one for the second flange 30. These may be identical to one another in all significant respects; therefore, only one of them will be described in detail.

[0048] In this example, the fastener cover 100 is a 360° annular shape and includes arcuate, axially extending, radially spaced inner and outer sidewalls 112, 114, respectively. The inner and outer sidewalls 112, 114 are interconnected by a first radial wall 116. The inner and outer sidewalls 112, 114 and the first radial wall 116 collectively define a cavity 118 ( Figure 6), the shape and size of the cavity 118 are designed to accommodate a portion of the fastener 44 that protrudes from the second rear surface 40 of the second flange 30.

[0049] Fastener pockets 120 are formed at predetermined positions around the circumference of the fastener cover 100. Figure 5 and Figure 6 Each fastener pocket 120 includes a sidewall 122 extending in an axial direction away from the first radial wall 116, defining a short tubular shape that is closed opposite the first radial wall 116 by a base plate 124. A clearance hole 126 passes through the base plate 124 and is sized to receive the shank 46 of the fastener 44. The fastener pocket 120 is an example of an "attachment structure."

[0050] When assembled, the base 124 of the fastener cover 100 abuts the second rear surface 40 of the second flange 30. The fastener cover 100 is clamped in place by a portion of the fastener 44, such as the nut 48 or the head 47 of the bolt 45. So assembled, the fastener cover 100 provides a smooth, generally continuous surface facing in both radial and axial directions, interrupted only by the fastener pocket 120, which provides access for a tool (e.g., a socket wrench) used to install or remove the fastener 44.

[0051] In one variation, fastener cover 100 may be segmented rather than circumferentially continuous. Figure 7 An arcuate fastener cover segment 110 is shown. The structure of the fastener cover segment 110 is substantially the same as that of the fastener cover 100 described above, except that the fastener cover segment 110 extends from a first circumferential end 111 to a second circumferential end 113, and the circumferential distance between the ends 111, 113 is less than 360°. It should be understood that a plurality of such fastener cover segments 110 will be attached to the first flange 27 or the second flange 30 to form a complete 360° annulus.

[0052] Figure 8-11 A second exemplary embodiment of a fastener cover 200 suitable for use with the flange joint 50 of Figure 2 is shown. A single fastener cover 200 is provided that covers both the first flange 27 and the second flange 30.

[0053] The fastener cover 200 includes a plurality of arcuate fastener cover segments 210. A plurality of such fastener cover segments 210 will be attached to the first flange 27 and the second flange 30 to form a complete 360° annulus. The fastener cover segments 210 can be identical to each other in all important respects; therefore, only one of them will be described in detail.

[0054] In this example, the fastener cover segment 210 includes a first radial wall 216 and a second radial wall 217 spaced apart from the first radial wall 216. An arcuate, axially extending outer sidewall 214 interconnects the first and second radial walls 216, 217. The first and second radial walls 216, 217 and the outer sidewall 214 collectively define a cavity 218 shaped and sized to accommodate the first and second flanges 27, 30 and the portion of the fastener 44 projecting from the rear surfaces 34, 40 of the flanges 27, 30.

[0055] The fastener pockets 220 are formed at predetermined positions around the circumference of the fastener cover section 210. Figure 9 Each fastener pocket includes a sidewall 222 extending axially from the first radial wall 216, defining a short tubular shape that is enclosed by a base plate 224. A clearance hole 226 passes through the base plate 224 and is sized to receive the shank 46 of the fastener 44.

[0056] When assembled, the base 224 of the fastener cover segment 210 abuts the second rear surface 40 of the second flange 30. The fastener cover segment 210 is clamped in place by a portion of the fastener 44, such as the nut 48 or the head 47 of the bolt 45. So assembled, the fastener cover 200 provides a smooth, generally continuous surface facing in both radial and axial directions, interrupted only by the fastener pocket 220, which provides access for a tool (e.g., a socket wrench) used to install or remove the fastener 44.

[0057] In the circumferential direction, the first and second radial walls 216, 217 extend between the first and second circumferential ends 211, 213. Located at these ends are end edges 219, 221. The end edges 219, 221 may be oriented in the radial direction, such as Figure 10 This orientation facilitates installation or removal of fastener cover segments 210 because it does not interfere with adjacent fastener cover segments 210 . Figure 11 An alternative fastener cover segment 310 is shown having first and second end edges 319, 321 oriented in a direction oblique to the radial direction. This orientation requires that the entire ring of fastener cover segments 310 be installed or removed simultaneously.

[0058] Figure 12-15 A third exemplary embodiment of a fastener cover 400 suitable for use with the flange joint 50 of Figure 2 is shown. A single fastener cover 400 is provided that covers both the first flange 27 and the second flange 30.

[0059] The fastener cover 400 includes a plurality of arcuate fastener cover segments 410. A plurality of such fastener cover segments 410 will be attached to the first flange 27 and the second flange 30 to form a complete 360° annulus. The fastener cover segments 410 can be identical to each other in all important respects; therefore, only one of them will be described in detail.

[0060] In this example, the fastener cover segment 410 includes a first radial wall 416 and a second radial wall 417 spaced apart from the first radial wall 416. An arcuate, axially extending outer sidewall 414 interconnects the first and second radial walls 416, 417. The first and second radial walls 416, 417 and the outer sidewall 414 collectively define a cavity 418 shaped and sized to accommodate the first and second flanges 27, 30 and the portion of the fastener 44 protruding from the rear surfaces 34, 40 of the flanges 27, 30. An array of access holes 422 extends through the first and second radial walls 416, 417.

[0061] Mounting tabs 420 extend radially inwardly from outer sidewall 414 at predetermined locations around the circumference of fastener cover segment 410. Figure 13 Each mounting tab 420 includes a clearance hole 424 sized to receive the shank 46 of the fastener 44 . The mounting tab is an example of an “attachment structure.”

[0062] When assembled, the mounting tabs 420 of the fastener cover segment 410 abut the second mating surface 38 of the second flange 30. To accommodate the thickness of the mounting tabs, a recess 39 ( Figure 15 ). Fastener cover segment 410 is clamped in place between first flange 27 and second flange 30, and shank 46 of fastener 44 is passed through the mutually aligned holes of first flange 27, mounting tab 420, and second flange 30. So assembled, fastener cover 400 presents a smooth, generally continuous surface facing in both radial and axial directions, interrupted only by access hole 422, which provides access for a tool (e.g., a socket wrench) used to install or remove fastener 44.

[0063] In the circumferential direction, the first and second radial walls 416, 417 extend between the first and second end edges 419, 421. The end edges 419, 421 may be oriented in the radial direction, such as Figure 13 This orientation facilitates installation or removal of fastener cover segments 410 because it does not interfere with adjacent fastener cover segments 410 . Figure 14 An alternative fastener cover segment 510 is shown having first and second end edges 519, 521 oriented in a direction oblique to the radial direction. This orientation requires that the entire ring of fastener cover segments 510 be installed or removed simultaneously.

[0064] In addition to the function of reducing windage losses around the fastener, any of the fastener covers described above may incorporate additional structural features to perform additional functions.

[0065] A possible additional function is friction damping. To provide this function, any segmented embodiment of the fastener cover described above can be provided with end plates. Figure 16 A fastener cover segment 610 is shown that is similar to the fastener cover segments 110, 210, or 410 described above and extends between first and second circumferential ends 611, 613. At the first circumferential end 611, a pair of end walls 652 extend in the axial direction from the first and second radial walls and have a slot 654 therebetween to accommodate the passage of the first and second flanges 27, 30 ( Figure 16 A similar pair of end walls 652 are provided at the second circumferential end 613. In this example, the end walls 652 are oriented parallel to the radial direction.

[0066] In operation, the first and second flanges 27, 30 inherently experience vibrations and adopt various mode shapes, wherein different tangential locations of the flange joint 50 deflect with different dynamic displacements. In other words, the first and second flanges 27, 30 can exhibit a "wave" mode shape.

[0067] The fastener cover segments 610 in conjunction with the end walls 652 can provide frictional damping. More specifically, when installed, the end wall 652 of one fastener cover segment 610 abuts the end wall 652 of an adjacent fastener cover segment 610. Any relative movement of the adjacent fastener covers results in friction of the abutting end walls 652, thereby dissipating some of the vibration.

[0068] To increase the degree of frictional damping, end wall 652 can be provided with a predetermined surface roughness, such as protruding or recessed surface features, such as ribs or grooves (not shown). Alternatively, to increase the degree of frictional damping, end wall 652 can be provided with a friction-increasing coating or surface treatment, such as a coating embedded with sand particles or an elastomeric coating.

[0069] Figure 17 A fastener cover segment 710 is shown that is similar to the fastener cover segments 310 or 510 described above and includes an end wall 752 at a first circumferential end 711. The end wall 752 extends in an axial direction from the first and second radial walls 716, 717 and includes a slot 754 therein to accommodate the passage of the first and second flanges 27, 30 ( Figure 17 (not shown). A similar end wall 752 is provided at the second circumferential end 713. In this example, end wall 752 is oriented obliquely to the radial direction. Their function, for the purpose of frictional damping, is essentially the same as that of end wall 652 described above. Furthermore, the inclined surface increases the damping effect due to the increased damping area (i.e., a larger damping area compared to a radially oriented surface).

[0070] Another possible additional function is to provide for the installation of one or more balancing weights for the purpose of adjusting the balance of the flange joint 50 .

[0071] A structure for mounting one or more balancing weights Figure 18-21 . Fastener cover segment 810, which is most similar to fastener cover segments 210 or 410 described above, but representative of any of the previously described fastener cover embodiments, is provided with an arcuate rib 856 extending axially from second radial wall 817. An arcuate slot 858 is formed through the axial thickness of rib 856. A notch 860 is formed in a portion of slot 858. The narrow portion of slot 858 receives a threaded shank 862 of a T-bolt 864. A head 866 of T-bolt 864 is received in notch 860 and engages with notch 860 to prevent rotation of T-bolt 864.

[0072] A locking nut 868 is threaded onto the shank 862 of the T-bolt 864. The locking nut 868 can be loosened to allow the T-bolt 864 to slide to any desired position within the slot 858 and then tightened to clamp the T-bolt 864 in place. Optionally, one or more balance weights 870 can be placed on the shank 862 of the T-bolt 864 and then secured with a retaining nut 872. This arrangement allows a predetermined mass to be positioned at a desired location, thereby adjusting the balance of the flange joint 50. Optionally, the rib 856 can be provided with an extended flange 874 that covers some or all of the balance weights 870 to reduce windage losses. The slot 858 is an example of a "balance weight receptacle."

[0073] Another configuration for mounting one or more balancing weights is Figure 22 and 23 . Fastener cover segment 910, which is most similar to fastener cover segments 210 or 410 described above, but representative of any of the previously described fastener cover embodiments, is provided with an array of spaced-apart balance weight holes 956 formed through the axial thickness of second radial wall 917. Balance weight holes 956 can be threaded. One or more balance weights 970 having complementary threads can be screwed into balance weight holes 956 to affect the balance of flange joint 50. Holes 956 are an example of a "balance weight receptacle."

[0074] Figure 26 and 27Yet another configuration for mounting one or more balancing weights is shown in FIG. A fastener cover segment 1210, most similar to the fastener cover segments 210 or 410 described above, but representative of any of the previously described fastener cover embodiments, is provided with an arcuate rib 1256 extending radially from its axial wall 1214. An array of spaced-apart balancing weight holes 1258 are formed in the arcuate rib 1256. The balancing weight holes 1258 can be threaded. One or more balancing weights 1270 having complementary threads can be screwed into the balancing weight holes 1258 to affect the balance of the flange joint 50. The holes 1258 are another example of a "balancing weight receptacle." As an alternative, not shown separately, the balancing weight holes 1258 can be incorporated into an arcuate slot similar in structure and function to the slot 858 described above, but formed in the radial wall 1214.

[0075] Another possible additional function is the provision of a sealing element.

[0076] A sealing element is constructed in Figure 24 . Fastener cover segment 1010, which is most similar to fastener cover segments 310 or 510 described above, but representative of any of the previously described fastener cover embodiments, is provided with an arcuate sealing flange 1056 extending axially outward from outer sidewall 1014. A row of side-by-side sealing teeth 1076 extend radially outward from sealing flange 1056. When assembled in engine 10, sealing teeth 1076 are radially adjacent to an annular stationary sealing element (e.g., honeycomb or abradable material, not shown) and provide a tortuous flow path for leakage flow.

[0077] Figure 25 Another configuration of a sealing element is shown in FIG. Fastener cover segment 1110, which is most similar to fastener cover segments 310 or 510 described above, but representative of any of the previously described fastener cover embodiments, is provided with an arcuate sealing web 1178 extending radially outward from outer sidewall 1114. An arcuate sealing flange 1156 is disposed at the distal end of sealing web 1178, cooperating with sealing web 1178 to form a T-shape. A row of side-by-side sealing teeth 1176 extend radially outward from sealing flange 1156. When assembled in engine 10, sealing teeth 1176 are radially adjacent to an annular stationary sealing element (e.g., honeycomb or abradable material, not shown) and provide a tortuous flow path for leakage flow.

[0078] The apparatus described herein offers advantages over the prior art. For example, it can reduce windage losses. Frictional contact between the cover segments damps vibrations in the flange joint. It can also provide rotor balancing capability directly on the cover. This feature enables the application of balancing weights without disassembling the cover from the flange or removing the flange bolts. The cover can also include sealing features. Providing the cover as a separate, 360-degree component eliminates the risk of crack propagation into the primary structural rotor component (i.e., the bolted flange). Finally, the segmented embodiment is free of hoop stress and reduces the risk of crack propagation in the labyrinth seal. The fastener cover has been described previously. All features disclosed in this specification (including any accompanying claims, abstract, and drawings), and / or all steps of any method or process disclosed therein, may be combined in any combination, except where at least some of such features and / or steps are mutually exclusive.

[0079] Unless expressly stated otherwise, each feature disclosed in this specification (including any accompanying claims, abstract, and drawings) may be replaced by alternative features serving the same, equivalent, or similar purpose. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0080] The invention is not limited to the details of the foregoing embodiments. The invention extends to any novel one or any novel combination of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one or any novel combination of the steps of any method or process so disclosed.

[0081] Further aspects of the invention are provided by the subject matter of the following numbered clauses:

[0082] 1. A fastener cover for a flange joint, the flange joint comprising a first annular flange and a second annular flange extending about an axis, the fastener cover comprising: an annular axially extending inner wall; an annular axially extending outer wall, the outer wall being positioned radially outward of the inner wall; and a first radial wall, the first radial wall interconnecting the inner wall and the outer wall, wherein the inner wall, the outer wall and the first radial wall together define a cavity for receiving a portion of a fastener protruding from one of the flanges; at least one fastener pocket, the at least one fastener pocket comprising a side wall extending axially away from the first radial wall and defining a tubular shape, the tubular shape being closed relative to the first radial wall by a base plate, the base plate having a clearance hole therethrough for receiving the shank of the fastener; and wherein the cover comprises a balancing weight container for receiving at least one balancing weight.

[0083] 2. A fastener cover according to any preceding clause, wherein: the counterweight container includes an arcuate slot formed through the first radial wall, the slot including a narrow portion adjacent to the slot; the narrow portion of the slot receives a threaded shank of a T-bolt; the head of the T-bolt is received in the slot and engages with the slot to prevent rotation of the T-bolt; and a locking nut is threaded onto the shank of the T-bolt to clamp the T-bolt in the appropriate position within the slot.

[0084] 3. A fastener cover according to any preceding clause wherein one or more balancing weights are placed on the shank of the T-bolt and secured with a retaining nut.

[0085] 4. The fastener cover of any preceding clause, wherein the balancing receptacle comprises: a counterweight hole formed in the first radial wall.

[0086] 5. The fastener cover of any preceding clause, further comprising an arcuate sealing flange and at least one arcuate sealing tooth extending radially outwardly from the sealing flange.

[0087] 6. The fastener cover of any preceding clause wherein said sealing flange extends axially from said outer sidewall.

[0088] 7. A fastener cover according to any preceding clause, wherein an arcuate sealing web extends radially outwardly from said outer sidewall, and wherein said sealing flange is provided at a distal end of said sealing web to cooperate with said sealing web to form a T-shape.

[0089] 8. The fastener cover of any preceding clause, wherein the fastener cover comprises a plurality of arcuate fastener cover segments arranged about the axis to form a 360° annulus, each fastener cover segment extending between a first circumferential end and a second circumferential end.

[0090] 9. The fastener cover of any preceding clause, wherein a first end edge and a second end edge are located at the first circumferential end and the second circumferential end, respectively, and wherein the end edges are oriented in a radial orientation.

[0091] 10. The fastener cover of any preceding clause, wherein a first end edge and a second end edge are located at the first circumferential end and the second circumferential end, respectively, and wherein the end edges are oriented in a direction oblique to the radial direction.

[0092] 11. The fastener cover of any preceding clause wherein each circumferential end comprises at least one end wall.

[0093] 12. The fastener cover of any preceding clause wherein said at least one end wall is oriented in a radial direction.

[0094] 13. The fastener cover of any preceding clause wherein said at least one end wall is oriented in a direction oblique to said radial direction.

[0095] 14. A fastener cover for a flange joint, the flange joint comprising a first annular flange and a second annular flange extending around an axis, the fastener cover comprising: a plurality of arcuate fastener cover segments arranged around the axis to form a 360-degree annulus, each fastener cover segment extending between a first circumferential end and a second circumferential end and comprising: a first radial wall, a second radial wall axially spaced apart from the first radial wall, an arcuate axially extending outer side wall interconnecting the first radial wall and the second radial wall, wherein the first radial wall, the second radial wall and the outer side wall together define a cavity for receiving the first flange, the second flange and a portion of a fastener protruding from the flange; and an attachment structure spaced apart from the first radial wall and comprising a clearance hole for a fastener shank.

[0096] 15. A fastener cover according to any preceding clause, wherein the attachment structure includes at least one fastener pocket, the at least one fastener pocket including a side wall extending axially from the first radial wall and defining a tubular shape enclosed by a base plate, wherein the clearance hole passes through the base plate.

[0097] 16. The fastener cover of any preceding clause, wherein said attachment structure comprises at least one mounting tab extending radially inwardly from said outer sidewall, wherein said clearance hole passes through said mounting tab.

[0098] 17. The fastener cover of any preceding clause, wherein a first end edge and a second end edge are located at the first circumferential end and the second circumferential end, respectively, and the end edges are oriented in a radial direction.

[0099] 18. The fastener cover of any preceding clause, wherein a first end edge and a second end edge are located at the first circumferential end and the second circumferential end, respectively, and wherein the end edges are oriented in a direction oblique to the radial direction.

[0100] 19. The fastener cover of any preceding clause wherein each circumferential end comprises a pair of end walls having a slot therebetween.

[0101] 20. The fastener cover of any preceding clause wherein the pair of end walls are oriented in a radial direction.

[0102] 21. The fastener cover of any preceding clause wherein each circumferential end comprises an end wall interconnecting the first radial wall and the second radial wall, the end wall having a slot therein.

[0103] 22. A fastener cover according to any preceding clause wherein each end wall is oriented in a direction oblique to the radial direction.

[0104] 23. A fastener cover according to any preceding clause wherein the cover includes a balance weight receptacle for receiving at least one balance weight.

[0105] 24. A fastener cover according to any preceding clause, wherein: the counterweight container includes an arcuate slot formed through one of the radial walls, the slot including a narrow portion adjacent to the slot; the narrow portion of the slot receives a threaded shank of a T-bolt; the head of the T-bolt is received in the slot and engages with the slot to prevent rotation of the T-bolt; and a locking nut is threaded onto the shank of the T-bolt to clamp the T-bolt in the appropriate position within the slot.

[0106] 25. A fastener cover according to any preceding clause wherein one or more balancing weights are placed on the shank of the T-bolt and secured with a retaining nut.

[0107] 26. The fastener cover of any preceding clause wherein said balance weight receptacle comprises a balance weight aperture formed in at least one of said radial walls.

[0108] 27. The fastener cover of any preceding clause further comprising an arcuate sealing flange and at least one arcuate sealing tooth extending radially outwardly from said sealing flange.

[0109] 28. The fastener cover of any preceding clause wherein said sealing flange extends axially from said outer sidewall.

[0110] 29. The fastener cover according to any preceding clause, wherein an arcuate sealing web extends radially and axially outwardly from said outer sidewall, and said sealing flange is provided at a distal end of said sealing web to cooperate with said sealing web to form a T-shape.

Claims

1. A fastener cover for a flange joint, characterized in that: The flange joint includes a first annular flange and a second annular flange extending around an axis, and the fastener cover includes: an annular axially extending inner sidewall; an annular axially extending outer sidewall positioned radially outward of the inner sidewall; and a first radial wall interconnecting the inner sidewall and the outer sidewall, wherein the inner sidewall, the outer sidewall, and the first radial wall collectively define a cavity for receiving a portion of a fastener protruding from one of the flanges; at least one fastener pocket including a sidewall extending axially away from the first radial wall and defining a tubular shape, the tubular shape being enclosed opposite the first radial wall by a base plate having a clearance hole therethrough for receiving a shank of the fastener; and Wherein, the fastener cover includes a balance weight container for receiving at least one balance weight, the balance weight container includes an arcuate slot formed through the first radial wall, and the slot includes a narrow portion adjacent to the notch.

2. The fastener cover according to claim 1, wherein: in: The narrow portion of the slot receives a threaded shank of a T-bolt; the head of the T-bolt is received in and engages the notch to prevent rotation of the T-bolt; and A lock nut is threaded onto the shank of the T-bolt to clamp the T-bolt in place within the slot.

3. The fastener cover according to claim 2, wherein: in, One or more balancing weights are placed on the shank of the T-bolt and secured with a retaining nut.

4. The fastener cover according to claim 1, wherein: in, The balancing weight container includes a balancing weight hole formed in the first radial wall.

5. The fastener cover according to claim 1, wherein: Further included is an arcuate sealing flange and at least one arcuate sealing tooth extending radially outward from the sealing flange.

6. The fastener cover according to claim 1, wherein: in, The fastener cover includes a plurality of arcuate fastener cover segments arranged to form a 360° annulus about the axis, each fastener cover segment extending between a first circumferential end and a second circumferential end.

7. The fastener cover according to claim 6, wherein: in, The first end edge and the second end edge are located at the first circumferential end and the second circumferential end, respectively, and the first end edge and the second end edge are oriented in a direction oblique to a radial direction.

8. The fastener cover according to claim 6, wherein: in, Each circumferential end includes at least one end wall, and the end walls of adjacent fastener cover segments abut one another.

9. A fastener cover for a flange joint, characterized in that: The flange joint includes a first annular flange and a second annular flange extending around an axis, and the fastener cover includes: a plurality of arcuate fastener cover segments arranged about the axis to form a 360-degree annulus, each fastener cover segment extending between a first circumferential end and a second circumferential end and comprising: a first radial wall, a second radial wall axially spaced from the first radial wall, and an arcuate axially extending outer sidewall interconnecting the first and second radial walls, wherein the first radial wall, the second radial wall, and the outer sidewall collectively define a cavity for receiving the first annular flange, the second annular flange, and portions of fasteners protruding from the flanges; and an attachment structure spaced from the first radial wall and including a clearance hole for a fastener shank; the attachment structure including at least one fastener pocket including a sidewall extending axially from the first radial wall and defining a tubular shape enclosed by a base plate, wherein the clearance hole passes through the base plate.

10. The fastener cover according to claim 9, wherein: in, The first end edge and the second end edge are located at the first circumferential end and the second circumferential end, respectively, and the first end edge and the second end edge are oriented in a direction oblique to a radial direction.

11. The fastener cover according to claim 9, wherein: in, Each circumferential end includes a pair of end walls having a slot therebetween, with the end walls of adjacent fastener cover segments abutting one another.

12. The fastener cover according to claim 9, wherein: in, Each circumferential end includes an end wall interconnecting the first radial wall and the second radial wall, the end wall having a groove therein.

13. The fastener cover according to claim 9, wherein: in, Each end wall is oriented in a direction oblique to the radial direction.

14. The fastener cover according to claim 9, wherein: in, The cover includes a balance weight receptacle for receiving at least one balance weight.

15. The fastener cover according to claim 14, wherein: in: said counterweight receptacle including an arcuate slot formed through one of said radial walls, said slot including a narrowed portion adjacent to a notch; The narrow portion of the slot receives a threaded shank of a T-bolt; the head of the T-bolt is received in and engages the notch to prevent rotation of the T-bolt; and A lock nut is threaded onto the shank of the T-bolt to clamp the T-bolt in place within the slot.

16. The fastener cover according to claim 14, wherein: in, One or more balancing weights are placed on the shank of the T-bolt and secured with a retaining nut.

17. The fastener cover according to claim 14, wherein: in, The balance weight receptacle includes a balance weight hole formed in at least one of the first radial wall and the second radial wall.

18. The fastener cover according to claim 9, wherein: Further included is an arcuate sealing flange and at least one arcuate sealing tooth extending radially outward from the sealing flange.

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