JP7005464B2 - Steam turbine cabin - Google Patents

Description

An embodiment of the present invention relates to a steam turbine casing.

The steam turbine is mainly composed of a high-pressure turbine to which the main steam is guided, a medium-pressure turbine to which the reheated steam is guided, and a low-pressure turbine to which the steam discharged from the medium-pressure turbine is guided. In steam turbines, high efficiency is required to reduce the environmental load. For example, with the increase in high temperature and high pressure of the high-pressure portion and the medium-pressure portion of the steam turbine, a double-structured passenger compartment having an internal passenger compartment and an external passenger compartment is widely adopted.

The cabin of a steam turbine is generally located in the upper half of the cabin and below the cabin on a horizontal plane that includes the centerline of the rotation axis of the turbine rotor, or near that horizontal plane, so that it can be easily disassembled and assembled during maintenance. It is divided into two halves.

Here, FIG. 8 is a cross-sectional view showing an outline of the configuration of the steam turbine 200 provided with the conventional passenger compartment 201. The cross section shown in FIG. 8 shows a cross section perpendicular to the axial direction of the turbine rotor. Further, the steam turbine 200 provided with the conventional vehicle interior 201 is, for example, a high-pressure turbine, a medium-pressure turbine, a high-medium-pressure turbine, or the like.

As shown in FIG. 8, the vehicle interior 201 of the steam turbine 200 includes an external vehicle compartment 210 and an internal vehicle compartment 220 provided in the external vehicle compartment 210. Here, an example is provided in which a steam introduction unit 205 for introducing steam into the steam turbine 200 is provided at one location on the lower half side.

The external casing 210 and the internal casing 220 are divided into upper and lower halves in a horizontal plane including the rotation axis center line O of the turbine rotor 230. Specifically, the external passenger compartment 210 is divided into two parts, an external passenger compartment upper half 211 and an external passenger compartment lower half 212. The internal passenger compartment 220 is divided into two parts, an internal passenger compartment upper half 221 and an internal passenger compartment lower half 222.

An external upper half flange portion 213 is provided on the outer side of the lower end of the outer passenger compartment upper half 211. An outer lower half flange portion 214 is provided on the outer side of the upper end of the outer passenger compartment lower half 212. An internal upper half flange portion 223 is provided on the outer side of the lower end of the inner passenger compartment upper half 221. An inner lower half flange portion 224 is provided on the outer side of the upper end of the inner passenger compartment lower half 222.

The lower end surfaces of the outer upper half flange portion 213 and the inner upper half flange portion 223 are horizontal planes and are on the same plane as the lower end surfaces of the outer passenger compartment upper half 211 and the inner passenger compartment upper half 221. The upper end surfaces of the outer lower half flange portion 214 and the inner lower half flange portion 224 are horizontal planes, and are in the same plane as the upper end surfaces of the outer passenger compartment lower half 212 and the inner passenger compartment lower half 222.

The outer upper half flange portion 213 and the outer lower half flange portion 214 are fastened to each other with bolts 240 and nuts 241. The inner upper half flange portion 223 and the inner lower half flange portion 224 are fastened to each other with bolts 250 and nuts 251.

In the steam turbine 200 shown in FIG. 8, since the steam introduction section 205 is provided in one place on the lower half side, the bolts 240 and 250 and the nuts 241, 251 as described above are fastened in the external casing 210 and the internal casing 220. Is possible.

Here, in the internal casing 220, the bolt 250 is fixed to the internal lower half flange portion 224. Specifically, the head 250a of the bolt 250 is joined to the inner lower half flange portion 224. When the upper half 221 of the internal passenger compartment is removed, a part of the bolt 250 penetrating the bolt hole 260 protrudes upward from the bolt hole 260. A screw portion 250b to be screwed with the nut 251 is formed on the tip end side of the bolt 250.

In such a steam turbine 200, when disassembling the maintenance, first, the bolt 240 and the nut 241 are removed, and the outer casing upper half 211 is removed. Subsequently, the nut 251 is removed, and the inner passenger compartment upper half 221 is removed. At this time, since the bolt 250 is joined to the inner lower half flange portion 224, it does not fall downward.

Through such a disassembly step, the state of the stationary blade and the moving blade in the internal casing 220 can be confirmed.

However, in the steam turbine, the method of introducing steam into the steam turbine is appropriately set depending on the conditions such as the layout, performance, introduction cost, and operation of the steam turbine.

For example, as a method of introducing steam into a steam turbine, there are a form in which steam is introduced from one place on the upper half side and a form in which steam is introduced from two places on the upper half side and a form in which steam is introduced from two places on each of the upper half side and the lower half side. ..

Further, for example, even when steam is introduced from one place on the upper half side, depending on the above-mentioned conditions, it may be necessary to provide a configuration for introducing steam to the nut fastening portion of the internal casing 220 shown in FIG. be. In such a case, it is difficult to adopt a nut fastening structure.

FIG. 9 is a cross-sectional view showing an outline of the configuration of a steam turbine 300 including a conventional passenger compartment 301 including a steam introduction unit 305 that introduces steam in a horizontal direction from one place on the upper half side.

The vehicle compartment 301 of the steam turbine 300 includes an external vehicle compartment 310 and an internal vehicle compartment 320 provided in the external vehicle compartment 310.

The external vehicle compartment 310 is a horizontal plane including the rotation axis center line O of the turbine rotor 330, and is divided into two parts, an external vehicle compartment upper half 311 and an external vehicle compartment lower half 312. Further, the internal passenger compartment 320 is divided into two parts, an internal passenger compartment upper half 321 and an internal passenger compartment lower half 322.

An external upper half flange portion 313 is provided on the outer side of the lower end of the outer passenger compartment upper half 311. An outer lower half flange portion 314 is provided on the outer side of the upper end of the outer passenger compartment lower half 312. An internal upper half flange portion 323 is provided on the outer side of the lower end of the inner passenger compartment upper half 321. An inner lower half flange portion 324 is provided on the outer side of the upper end of the inner passenger compartment lower half 322.

Here, the steam introduction unit 305 for introducing steam into the steam turbine 300 is formed in the outer casing upper half 311 and the inner casing upper half 321. Further, the steam introduction portion 305 is also formed in the outer upper half flange portion 313 and the inner upper half flange portion 323.

The lower end surfaces of the outer upper half flange portion 313 and the inner upper half flange portion 323 are horizontal planes as in the vehicle interior 201 shown in FIG. Further, the upper end surfaces of the outer lower half flange portion 314 and the inner lower half flange portion 324 are also horizontal surfaces as in the vehicle interior 201 shown in FIG.

As shown in FIG. 9, the outer passenger compartment upper half 311 and the outer passenger compartment lower half 312, and the inner passenger compartment upper half 321 and the inner passenger compartment lower half 322 in the portion provided with the steam introduction portion 305 are inserted from below. It is fixed by the bolt. Specifically, screw holes 315 and 325 having threads are provided on the lower surface side of the outer upper half flange portion 313 and the inner upper half flange portion 323.

Then, the bolt 340 inserted into the screw through hole 316 of the outer lower half flange portion 314 is screwed into the screw hole 315 to fix the outer casing upper half 311 and the outer casing lower half 312. Further, the bolt 350 inserted into the screw through hole 326 of the inner lower half flange portion 324 is screwed into the screw hole 325 to fix the inner casing upper half 321 and the inner casing lower half 322.

The method of fixing the upper half-cabin and the lower-half-chamber except for the portion provided with the steam introduction portion 305 is the same as the method of fixing the upper-half-chamber and the lower-half-chamber shown in FIG. That is, the outer passenger compartment upper half 311 and the external passenger compartment lower half 312 are fixed by bolts 360 and nuts 361. Further, the inner passenger compartment upper half 321 and the inner passenger compartment lower half 322 are fixed by bolts 370 and nuts 371.

In such a steam turbine 300, when disassembling the maintenance, first, the bolt 360, the nut 361 and the bolt 340 are removed, and the outer casing upper half 311 is removed.

Then, the process of removing the upper half 221 of the internal passenger compartment is started. At this time, the bolt 350 cannot be removed when the internal passenger compartment 320 is installed in the lower half 312 of the external passenger compartment.

Therefore, the turbine rotor coupling coupling portion is temporarily separated, and the turbine rotor 330 is lifted in a state of being integrated with the internal casing 320 by a jig, so that the internal casing 320 is taken out from the outer casing lower half 312. After that, the internal casing 320 is installed on a dedicated pedestal, and in that state, the bolts 350 and nuts 371 are removed from the internal casing 320, and the upper half 321 of the internal casing is removed.

The bolt 370 is joined to the inner lower half flange portion 324 in the same manner as the bolt 370 shown in FIG.

Through such a disassembling step, the state of the stationary blade and the moving blade in the internal casing 320 can be confirmed.

Japanese Unexamined Patent Publication No. 3-77367

As described above, when the vehicle has a dual structure of the external vehicle compartment 310 and the internal vehicle compartment 320 and the steam introduction unit 305 is provided on the upper half side, the steam introduction unit 305 fastens the nut of the internal vehicle compartment 320. May be located in the department.

In a steam turbine having such a structure, a bolt 350 inserted from below into the screw through hole 326 of the inner lower half flange portion 324 is screwed into the screw hole 325 to 321 the upper half of the inner casing and 322 the lower half of the inner casing. Was fixed.

Therefore, at the time of disassembly for maintenance, the internal casing 320 must be taken out from the lower half 312 of the external casing with the turbine rotor 330 integrated with the internal casing 320.

As a result, the conventional steam turbine shown in FIG. 9 is inferior in maintainability and the maintenance work period is longer than that of the conventional steam turbine shown in FIG.

The problem to be solved by the present invention is to provide an external casing and an internal casing, have a steam introduction portion on the upper half side, and fix the upper half of the internal casing and the lower half of the internal casing by fastening members from below. It is an object of the present invention to provide a steam turbine casing capable of maintenance in a state where the internal casing is provided in the lower half of the external casing in the steam turbine casing having the configuration.

The steam turbine casing of the embodiment has an external casing and an internal casing, the external casing is divided into an outer casing upper half and an external casing lower half, and the internal casing is above the internal casing. It is divided into a half and a lower half of the internal passenger compartment, and a steam introduction section that introduces steam into the steam turbine is provided on the upper half side.

The steam turbine casing includes a fastening portion having a fastening member for fixing the upper half of the internal casing and the lower half of the internal casing in the portion where the steam introduction portion is configured from the vertically lower side, and the fastening portion. It is provided in the lower half of the external passenger compartment vertically below the above, and includes an opening through which the fastening member can be taken in and out, and a lid member for closing the opening.

It is sectional drawing which shows the outline of the structure of the steam turbine provided with the vehicle interior of 1st Embodiment. It is a figure which shows the AA cross section of FIG. It is sectional drawing corresponding to the AA cross section of FIG. 1 in the process of removing a bolt in the vehicle interior of 1st Embodiment. It is a figure which enlarged and showed the cross section of the plate-shaped member and the fixing member which make up a support member in the vehicle interior of 1st Embodiment. It is a figure which enlarged and showed the cross section of the support member of another structure in the vehicle interior of 1st Embodiment. 2 is a cross-sectional view corresponding to the cross section taken along the line AA of FIG. 1 in the vehicle interior of the second embodiment. FIG. 5 is a cross-sectional view corresponding to the cross section taken along the line AA in FIG. 1 in the step of removing the nut in the vehicle interior of the second embodiment. It is sectional drawing which shows the outline of the structure of the steam turbine provided with the conventional vehicle interior. It is sectional drawing which shows the outline of the structure of the steam turbine which comprises the conventional car room which includes the steam introduction part which introduces steam in the horizontal direction from one place on the upper half side.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment)
FIG. 1 is a cross-sectional view showing an outline of the configuration of the steam turbine 1 including the vehicle interior 20 of the first embodiment. The cross section shown in FIG. 1 shows a cross section perpendicular to the axial direction of the turbine rotor. FIG. 2 is a diagram showing a cross section taken along the line AA of FIG. In the cross section shown in FIG. 2, a part of the structure is omitted. The vehicle compartment 20 functions as a steam turbine vehicle compartment.

As shown in FIG. 1, the steam turbine 1 includes a vehicle compartment 20 having a double structure having an external vehicle compartment 30 and an internal vehicle compartment 50 provided in the external vehicle compartment 30. Further, the steam turbine 1 includes a turbine rotor 10 that penetrates the internal casing 50 and the external casing 30.

Here, examples of the steam turbine 1 include, for example, a high-pressure turbine, a medium-pressure turbine, a high-medium-pressure turbine, and the like, but the steam turbine 1 is not particularly limited. The steam turbine 1 may include a vehicle compartment 20 having an external vehicle compartment 30 and an internal vehicle compartment 50.

A stationary wing 13 supported between the diaphragm outer ring 11 and the diaphragm inner ring 12 is arranged on the inner circumference of the inner casing 50. A plurality of stationary blades 13 are provided in the circumferential direction to form a stationary blade row.

Further, in the internal casing 50, a moving blade (not shown) is planted in the turbine rotor 10 in the circumferential direction. By planting a plurality of these rotor blades in the circumferential direction, a rotor blade row is formed. This moving blade row is provided so as to alternate with the stationary blade row in the axial direction of the turbine rotor 10. Then, the stationary blade row and the moving blade row immediately downstream of the stationary blade row constitute one turbine paragraph.

The external casing 30 and the internal casing 50 are divided into upper and lower halves, for example, in a horizontal plane including the rotation axis center line O of the turbine rotor 10. Specifically, the external passenger compartment 30 is divided into two parts, an external passenger compartment upper half 31 and an external passenger compartment lower half 32. The internal passenger compartment 50 is divided into two parts, an internal passenger compartment upper half 51 and an internal passenger compartment lower half 52.

Here, an example is shown in which the turbine rotor 10 is divided into an upper half and a lower half in a horizontal plane including the rotation axis center line O, but the division position is not limited to this. For example, the turbine rotor 10 may be divided into an upper half and a lower half in the horizontal plane above the horizontal plane including the rotation axis center line O of the turbine rotor 10. Further, for example, the turbine rotor 10 may be divided into an upper half and a lower half in the horizontal plane below the horizontal plane including the rotation axis center line O.

External upper half flange portions 33A and 33B are provided on the outer side of the lower end of the outer passenger compartment upper half 31. An outer lower half flange portion 34 is provided on the outer side of the upper end of the outer passenger compartment lower half 32. The inner upper half flange portions 53A and 53B are provided on the outer side of the lower end of the inner passenger compartment upper half 51. An inner lower half flange portion 54 is provided on the outer side of the upper end of the inner passenger compartment lower half 52.

Here, the outer upper half flange portion and the inner upper half flange portion in the portion where the steam introduction portion 70 described later is configured are indicated by reference numerals 33B and 53B, respectively. Further, the outer upper half flange portion and the inner upper half flange portion in the portion where the steam introduction portion 70 is not configured are indicated by reference numerals 33A and 53A, respectively.

The lower end surfaces 35 and 55 of the outer upper half flange portions 33A and 33B and the inner upper half flange portions 53A and 53B are horizontal planes and are the same as the lower end surfaces 31a and 51a of the outer casing upper half 31 and the inner casing upper half 51. It is on a plane.

The upper end surfaces 34a and 54a of the outer lower half flange portion 34 and the inner lower half flange portion 54 are horizontal planes and are on the same plane as the upper end surfaces 32a and 52a of the outer passenger compartment lower half 32 and the inner passenger compartment lower half 52. ..

As shown in FIGS. 1 and 2, the upper half 31 of the outer casing and the upper half 51 of the inner casing are provided with a steam introduction unit 70 for introducing steam into the steam turbine 1. Here, an example is shown in which the steam introduction unit 70 is provided in the horizontal direction.

The steam introduction portion 70 includes a steam passage 36 provided in the outer upper half flange portion 33B and the outer casing upper half 31, and a steam passage 56 provided in the inner upper half flange portion 53B and the inner casing upper half 51. A tubular sleeve 57 for communicating the steam passage 36 and the steam passage 56 is provided.

The sleeve 57 is provided, for example, from the inlet 36a of the steam passage 36 along the inner peripheral surface of the steam passage 36 and the inner peripheral surface of the steam passage 56. The inlet 36a of the steam passage 36 is connected to, for example, a steam pipe (not shown) that guides superheated steam heated by a boiler (not shown) or the like.

Next, regarding the fastening portion 80 of the outer casing upper half 31 and the external casing lower half 32, and the fastening portion 90 of the internal casing upper half 51 and the inner casing lower half 52 in the portion where the steam introduction portion 70 is configured. explain.

In addition, in FIG. 1 and FIG. 2, in order to clarify the structure of the bolt 91, the bolt 91 is shown in a cross-sectional view, and other bolts and nuts are not shown in a cross-sectional view.

In the portion where the steam introduction portion 70 is configured, the fastening portion 80 and the fastening portion 90 cannot be fastened with bolts 96 and nuts 97 such as the inner upper half flange portion 53A and the inner lower half flange portion 54, which will be described later. Therefore, the fastening portion 80 and the fastening portion 90 are configured as follows.

First, the fastening portion 80 of the outer passenger compartment upper half 31 and the external passenger compartment lower half 32 will be described.

The fastening portion 80 includes a bolt 81, a screw through hole 37, and a screw hole 38.

The bolt 81 has a head portion 81a on one end side and a screw portion 81b on the other end side.

The screw through hole 37 is a through hole formed in the outer lower half flange portion 34 and allows the screw portion 81b of the bolt 81 to penetrate upward from the vertically lower side.

The screw hole 38 is a hole formed on the lower end surface 35 side of the outer upper half flange portion 33B and screwed with the screw portion 81b of the bolt 81. A screw thread to be screwed with the screw portion 81b is formed on the inner peripheral surface of the screw hole 38. The screw hole 38 is not a through hole, and the tip of the screw hole 38 is closed.

Here, the screw portion 81b of the bolt 81 is inserted into the screw hole 38 from the vertically lower side via the screw through hole 37 of the outer lower half flange portion 34. Then, by screwing and tightening the screw portion 81b into the screw hole 38, the outer casing upper half 31 and the external casing lower half 32 are fastened.

Next, the fastening portion 90 of the inner passenger compartment upper half 51 and the inner passenger compartment lower half 52 will be described.

The fastening portion 90 has the same structure as the fastening portion 80, and includes a bolt 91, a screw through hole 58, and a screw hole 59.

The bolt 91 functions as a fastening member and has a head portion 91a on one end side and a screw portion 91b on the other end side.

The screw through hole 58 is formed in the inner lower half flange portion 54 and is a through hole through which the screw portion 91b of the bolt 91 is penetrated upward from the vertically lower side.

The screw hole 59 is a hole formed on the lower end surface 55 side of the inner upper half flange portion 53B and screwed with the screw portion 91b of the bolt 91. A screw thread to be screwed with the screw portion 91b is formed on the inner peripheral surface of the screw hole 59. The screw hole 59 is not a through hole, and the tip of the screw hole 59 is closed.

Here, the screw portion 91b of the bolt 91 is inserted into the screw hole 59 from the vertically lower side via the screw through hole 58 of the inner lower half flange portion 54. Then, by screwing and tightening the screw portion 91b into the screw hole 59, the upper half 51 of the internal casing and the lower half 52 of the internal casing are fastened.

The steam introduction unit 70 is not limited to being provided in the horizontal direction. The steam introduction portion 70 may be provided so as to be inclined so that the inlet side is upward and the outlet side is downward with respect to the horizontal direction. As for the configuration of the passenger compartment 20, by providing the steam introduction portion 70 in the outer passenger compartment upper half 31 and the inner passenger compartment upper half 51, as shown in FIGS. 1 and 2, the inner upper half flange portion 53B and the inner upper half flange portion 53B are provided. The structure may be such that the inner lower half flange portion 54 is fastened from below with bolts 91.

Next, in the portion where the steam introduction portion 70 is not configured, the fastening portion 85 of the outer casing upper half 31 and the external casing lower half 32, and the fastening portion 95 of the inner casing upper half 51 and the inner casing lower half 52. Will be explained.

Since the configurations of the fastening portion 85 and the fastening portion 95 are the same, the fastening portion 95 will be mainly described here.

The fastening portion 95 includes a bolt 96, screw through holes 60 and 61, and a nut 97.

The bolt 96 has a head 96a on one end side and a threaded portion 96b on the other end side.

The screw through hole 60 is a through hole formed in the inner lower half flange portion 54 and allows the screw portion 96b of the bolt 96 to penetrate upward from the vertically lower side.

The screw through hole 61 is formed in the inner upper half flange portion 53A and is a through hole through which the screw portion 96b of the bolt 96 is penetrated upward from the vertically lower side.

Here, the head 96a of the bolt 96 is joined to the inner lower half flange portion 54. Further, the screw portion 96b of the bolt 96 penetrates the screw through hole 61 and protrudes upward.

The nut 97 is screwed into the screw portion 96b protruding upward from the screw through hole 61. As a result, the upper half 51 of the internal passenger compartment and the lower half 52 of the internal passenger compartment are fastened.

Since the head 96a of the bolt 96 is joined to the inner lower half flange portion 54, the bolt 96 does not fall downward even when the nut 97 is removed.

Similar to the above-mentioned fastening portion 95, the fastening portion 85 of the outer casing upper half 31 and the outer casing lower half 32 includes bolts 86, screw through holes 39 and 40, and nuts 87.

The bolt 86 has a head portion 86a on one end side and a screw portion 86b on the other end side.

The screw through hole 39 is formed in the outer lower half flange portion 34, and the screw through hole 40 is formed in the outer upper half flange portion 33A.

The fastening method at the fastening portion 85 is the same as the fastening method at the fastening portion 95 described above.

Here, as shown in FIGS. 1 and 2, an opening 41 is formed in the outer casing lower half 32 vertically below the fastening portion 90 of the inner passenger compartment upper half 51 and the inner passenger compartment lower half 52. There is. The opening 41 is set to a size that allows the bolt 91, which is a fastening member, to be taken out to the outside of the lower half 32 of the external passenger compartment when the bolt 91 is removed.

The opening 41 is joined to, for example, an opening 42 formed in the lower half 32 of the outer casing vertically below the fastening portion 90 and the lower half 32 of the outer casing so as to surround the periphery of the opening 42, and is vertically downward. It is provided with a tubular flange 43 extending to the center.

The shape of the opening cross section (horizontal cross section) of the flange 43 is, for example, rectangular. The shape of the opening cross section of the flange 43 is not limited to this. The shape and opening size of the opening 42, the shape of the cylinder constituting the flange 43, and the opening cross-sectional size of the flange 43 may be set to such a size that the bolt 91 can be taken out to the outside of the lower half 32 of the external passenger compartment. ..

A lid member 44 for closing the opening at the lower end of the flange 43 is provided at the lower end of the flange 43. The lid member 44 is fixed to the lower end of the flange 43 by, for example, a bolt 45. A screw hole 43a to be screwed with the bolt 45 is formed on the lower surface side of the flange 43. By closing the lower end of the flange 43 with the lid member 44, the inside of the external passenger compartment 30 and the outside of the external passenger compartment 30 can be shielded from each other.

Next, the support mechanism 110 that supports the bolt 91 when the bolt 91, which is a fastening member, is removed from the fastening portion 90 will be described.

FIG. 3 is a cross-sectional view corresponding to the AA cross section of FIG. 1 in the step of removing the bolt 91 in the vehicle interior 20 of the first embodiment. In FIG. 3, the lid member 44 at the lower end of the flange 43 is removed. FIG. 4 is an enlarged view showing a cross section of a plate-shaped member 105 and a fixing member 106 constituting a support member 103 in the vehicle interior 20 of the first embodiment.

The support mechanism 110 supports the bolt 91 from the lower end to prevent the bolt 91 from falling, for example, when the bolt 91 is removed from the fastening portion 90 or when the bolt 91 is fastened to the fastening portion 90.

As shown in FIG. 3, the support mechanism 110 includes a communication passage 100, a through passage 101, and a support member 103.

The communication passage 100 is formed in the inner upper half flange portion 53B of the inner passenger compartment upper half 51, and is composed of a through hole that communicates with the fastening portion 90 from the upper side. That is, the upper end of the communication passage 100 is located above the fastening portion 90. The opening at the lower end of the communication passage 100 is located at the upper end of the screw hole 59.

The penetration passage 101 penetrates the fastening portion 90. Here, the bolt 91 is formed with a through hole 102 that penetrates along the central axis of the bolt 91. The through hole 102 is formed along the central axis of the bolt 91 from the tip of the screw portion 91b to the end of the head portion 91a.

For example, as shown in FIG. 2, in a state where the bolt 91 is attached, the through passage 101 is composed of a screw hole 59 and a through hole 102 of the bolt 91.

For example, as shown in FIG. 3, in a state where the bolt 91 is removed, the through passage 101 is composed of a screw hole 59, a screw through hole 58, and a through hole 102 of the bolt 91.

The support member 103 supports the bolt 91 at the lower end of the bolt 91.

As shown in FIG. 3, the support member 103 includes a suspension member 104, a plate-shaped member 105, and a fixing member 106.

The suspension member 104 is composed of a metal chain, a metal wire rope, or the like. One end of the suspension member 104 extends below the bolt 91 through the communication passage 100 and the through passage 101.

The suspending member 104 has a strength capable of suspending the bolt 91. Further, the passage cross section of the communication passage 100 and the penetration passage 101 is set to a shape and size that the suspension member 104 can pass through.

When the suspension member 104 is used, the outer casing upper half 31 is removed. The other end of the suspension member 104 is fixed to, for example, a crane or the like so that the bolt 91 can be suspended.

The plate-shaped member 105 is composed of, for example, a metal flat plate. The plate-shaped member 105 is formed, for example, to have the same size as the lower surface of the head 91a of the bolt 91. The plate-shaped member 105 may be formed smaller than the lower surface of the head 91a, for example.

By adjusting the size of the plate-shaped member 105 in this way, even when the plate-shaped member 105 supports the head 91a from below, a tool can be fitted to the head 91a from below to tighten the bolt 91. It can be removed.

The fixing member 106 is fixed to the center of the surface 105a on the head 91a side of the plate-shaped member 105. The fixing member 106 is inserted into the through hole 102 of the bolt 91 when the plate-shaped member 105 is brought into contact with the lower surface of the head 91a of the bolt 91.

The fixing member 106 fixes one end of the suspension member 104. The fixing member 106 is composed of, for example, a hook-shaped member. By hooking one end of the suspension member 104 on the fixing member 106, one end of the suspension member 104 is fixed to the plate-shaped member 105.

The fixing member 106 is not limited to the hook-shaped member, and may be any one that can fix one end of the suspension member 104.

Then, by pulling the suspension member 104 upward, the plate-shaped member 105 to which one end of the suspension member 104 is fixed comes into contact with the lower surface of the head 91a of the bolt 91. In this way, the plate-shaped member 105 is provided so as to support the head 91a from below.

By providing such a support mechanism 110, when the bolt 91 is rotated by a tool, the head 91a of the bolt 91 slides on the surface 105a of the plate-shaped member 105. Therefore, the suspension member 104 is not twisted even if the bolt 91 is rotated. The surface 105a of the plate-shaped member 105 is preferably configured to have excellent slidability. For example, the surface 105a of the plate-shaped member 105 may be coated with a sliding member.

Further, by providing the support mechanism 110, even when the screw portion 91b of the bolt 91 is completely removed from the screw thread of the screw hole 59, it is possible to prevent the bolt 91 from falling or lying down.

Here, regarding the disassembly process of the maintenance of the steam turbine 1, the process until the upper half 51 of the internal casing is removed will be described.

First, the bolt 86 and the nut 87 fastened to the outer upper half flange portion 33A and the outer lower half flange portion 34 shown in FIG. 1 are removed. Further, the bolt 81 of the outer upper half flange portion 33B and the outer lower half flange portion 34 is removed.

Subsequently, the sleeve 57 that connects the steam passage 36 and the steam passage 56 is removed. Then, the upper half 31 of the external passenger compartment is removed.

Next, the nut 97 that fastens the inner upper half flange portion 53A and the inner lower half flange portion 54 is removed.

Subsequently, the bolt 45 fixing the lid member 44 to the flange 43 of the opening 41 is removed, and the lid member 44 is removed.

Subsequently, the suspension member 104 is inserted into the communication passage 100 and the penetration passage 101, and one end of the suspension member 104 is passed below the bolt 91. Further, the other end of the suspension member 104 is fixed to, for example, a crane.

Subsequently, one end of the suspension member 104 is fixed to the fixing member 106 of the plate-shaped member 105. Then, the other end of the suspension member 104 is pulled up by a crane, and the plate-shaped member 105 is brought into contact with the lower surface of the head 91a of the bolt 91.

Subsequently, a tool for removing the bolt 91 via the opening 41 is inserted into the lower half 32 of the external casing. Then, the tool is fitted to the head 91a of the bolt 91 from below, and the bolt 91 is removed.

When the threaded portion 91b of the bolt 91 is completely disengaged from the thread of the screw hole 59, the bolt 91 is supported from the vertically lower side by the support mechanism 110 as shown in FIG. As a result, the bolt 91 does not fall. Further, although the bolt 91 has a predetermined length, since the suspension member 104 passes through the through hole 102 along the central axis of the bolt 91, the bolt 91 does not fall sideways.

The crane is operated to lower the suspension member 104 according to the removed state of the bolt 91. The detached bolt 91 is taken out from the opening 41 to the outside of the lower half 32 of the external passenger compartment.

Subsequently, one end of the suspension member 104 is removed from the fixing member 106 of the plate-shaped member 105, and the suspension member 104 is pulled out from the communication passage 100 and the through passage 101. Then, the upper half 51 of the internal passenger compartment is removed.

In this way, the upper half 51 of the internal passenger compartment is removed. By removing the upper half 51 of the internal passenger compartment, the condition of the stationary blades and moving blades can be confirmed.

A step of removing the nut 97 that fastens the inner upper half flange portion 53A and the inner lower half flange portion 54, and a step of removing the bolt 91 that fastens the inner upper half flange portion 53B and the inner lower half flange portion 54. May go first.

Next, regarding the maintenance assembly process of the steam turbine 1, the process up to the installation of the upper half 51 of the internal casing will be mainly described.

First, the inner passenger compartment upper half 51 is placed at a predetermined position on the inner passenger compartment lower half 52. Then, the suspension member 104 is inserted into the communication passage 100 and the through passage 101, and one end of the suspension member 104 is passed to the outside of the lower half 32 of the external passenger compartment.

Subsequently, one end of the suspension member 104 is passed through the through hole 102 of the bolt 91 taken out to the outside of the lower half 32 of the external vehicle interior to penetrate the suspension member 104.

Subsequently, one end of the suspension member 104 is fixed to the fixing member 106 of the plate-shaped member 105. Then, the other end of the suspension member 104 is pulled up by a crane, and the plate-shaped member 105 is brought into contact with the lower surface of the head 91a of the bolt 91. The other end of the suspension member 104 is further pulled up by a crane, and the screw portion 91b of the bolt 91 is inserted into the screw hole 59 via the screw through hole 58.

Subsequently, a tool for attaching the bolt 91 via the opening 41 is inserted into the lower half 32 of the external casing. Then, the tool is fitted from below to the head 91a of the bolt 91, and the bolt 91 is tightened.

Subsequently, the nut 97 is attached to and tightened to the screw portion 96b of the bolt 96 protruding above the internal upper half flange portion 53A.

In some cases, the bolt 91 and the nut 97 may be tightened once, and then the bolt 91 and the nut 97 may be tightened again to adjust the tightened state.

Subsequently, the crane is operated to lower the suspension member 104, and the plate-shaped member 105 is brought out of the lower half 32 of the external casing. Then, one end of the suspension member 104 is removed from the fixing member 106 of the plate-shaped member 105.

Subsequently, the suspension member 104 is pulled out from the communication passage 100 and the penetration passage 101. Then, the lid member 44 is fixed to the flange 43 of the opening 41 by the bolt 45.

In this way, the upper half 51 of the internal passenger compartment is attached.

After attaching the inner passenger compartment upper half 51, the external passenger compartment upper half 31 is placed at a predetermined position on the outer passenger compartment lower half 32, and each of them is fixed by bolts 86, nuts 87, and bolts 81.

As described above, in the vehicle interior 20 of the first embodiment, the steam introduction unit 70 is provided in the external vehicle interior upper half 31 and the internal vehicle interior upper half 51, and the internal upper half flange portion 53B and the inner lower half flange are provided. Even in a configuration in which the portion 54 is fastened from below with bolts 91, the inner casing upper half 51 can be removed and attached while the internal casing 50 is provided in the outer casing lower half 32.

That is, in the vehicle interior 20 of the first embodiment, the internal upper half flange portion 53B and the internal lower half flange portion 54 are fastened from below with the internal casing 50 provided in the outer casing lower half 32. The bolt 91 to be used can be removed and attached.

As described above, the vehicle interior 20 of the first embodiment is excellent in maintainability even if it has a configuration in which the inner upper half flange portion 53B and the inner lower half flange portion 54 are fastened from below. Further, in the steam turbine provided with the vehicle interior 20, the maintenance work period can be shortened.

Therefore, as in the conventional structure shown in FIG. 9, the internal casing is integrated with the turbine rotor, the turbine rotor is lifted, and the internal casing integrated with the turbine rotor is removed from the external casing for the first time. In this embodiment, the bolts that fasten the internal passenger compartment can be removed while the internal passenger compartment is attached to the lower half of the external passenger compartment. can. Therefore, in the configuration of the present embodiment, the process required for maintenance can be shortened as compared with the conventional configuration.

Here, the structure of the support member 103 is not limited to the above-mentioned structure. FIG. 5 is an enlarged view showing a cross section of a support member 103 having another structure in the vehicle interior 20 of the first embodiment.

As shown in FIG. 5, the support member 103 includes a suspension member 104, a plate-shaped member 120, and a fixing member 130.

The suspension member 104 is as described above.

The plate-shaped member 120 is made of, for example, a metal flat plate. A through hole 121 is formed in the center of the plate-shaped member 120.

The plate-shaped member 120 is formed, for example, to have the same size as the lower surface of the head 91a of the bolt 91. The plate-shaped member 120 may be formed smaller than the lower surface of the head 91a, for example. The reason for making the size of the plate-shaped member 120 in this way is as described above.

The fixing member 130 is arranged in the through hole 121 of the plate-shaped member 120. The fixing member 130 is made of a metal member and includes an upper end plate 131, an intermediate portion 132, a lower end plate 133, and a fixing portion 134.

The upper end plate 131 and the lower end plate 133 are composed of, for example, a flat plate. The outer shapes of the upper end plate 131 and the lower end plate 133 are configured to be larger than the inner diameter of the through hole 121. Therefore, the fixing member 130 does not come off from the through hole 121.

The fixing portion 134 is fixed to the surface 131a on the head 91a side of the upper end plate 131. The fixing portion 134 fixes one end of the suspension member 104. The fixing portion 134 is composed of, for example, a hook-shaped member. By hooking one end of the suspension member 104 on the fixing portion 134, one end of the suspension member 104 is fixed to the fixing member 130.

The fixing portion 134 is not limited to the hook-shaped member, and may be any one that can fix one end of the suspension member 104.

The intermediate portion 132 is composed of a columnar member, and the outer diameter of the intermediate portion 132 is formed to be smaller than the inner diameter of the through hole 121. The intermediate portion 132 is fitted in the through hole 121 so as to be rotatable around the central axis of the bolt 91 as the center of the rotation axis. In other words, the plate-shaped member 120 is configured to be rotatable around the intermediate portion 132 with the central axis of the bolt 91 as the center of the rotation axis.

The upper end plate 131 and the fixing portion 134 of the fixing member 130 are inserted into the through hole 102 of the bolt 91 when the plate-shaped member 120 is brought into contact with the lower surface of the head 91a of the bolt 91.

By providing such a support member 103, when the bolt 91 is tightened or removed, for example, even if the plate-shaped member 120 rotates together with the bolt 91, the fixing member 130 does not rotate. As a result, the suspension member 104 is not twisted even if the bolt 91 is rotated.

(Second embodiment)
In the vehicle interior 21 of the second embodiment, the configuration of the fastening portion 140 and the fastening member for fastening the internal upper half flange portion 53B and the internal lower half flange portion 54 is the vehicle interior 20 of the first embodiment. The configuration is different from that of the fastening portion 90 and the fastening member. Here, this different configuration will be mainly described.

FIG. 6 is a cross-sectional view corresponding to the AA cross section of FIG. 1 in the vehicle interior 21 of the second embodiment. In the cross section shown in FIG. 6, a part of the structure is omitted. Further, in the second embodiment, the same components as those in the first embodiment are designated by the same reference numerals, and duplicate description will be omitted or simplified.

The fastening portion 140 of the upper half 51 of the internal casing and the lower half 52 of the internal casing in the portion where the steam introduction portion 70 is configured will be described.

In FIG. 6, in order to clarify the structure of the implant bolt 150 and the nut 160, the implant bolt 150 and the nut 160 are shown in a cross-sectional view, and the other bolts and nuts are not shown in a cross-sectional view.

The fastening portion 140 of the upper half 51 of the inner passenger compartment and the lower half 52 of the inner passenger compartment will be described.

The fastening portion 140 includes an implant bolt 150, an implant bolt fixing portion 152, a screw through hole 58, and a nut 160.

The implant bolt 150 has, for example, a first screw portion 150a on one end side. The implant bolt 150 has, for example, a second screw portion 150b on the other end side.

The implant bolt fixing portion 152 fixes the implant bolt 150 to the internal upper half flange portion 53B. The implant bolt fixing portion 152 includes, for example, a screw hole 59 formed on the lower end surface 55 side of the inner upper half flange portion 53B and a second screw portion 150b on the other end side of the implant bolt 150.

In this case, the second screw portion 150b is screwed into the screw hole 59, and the implant bolt 150 is fixed to the internal upper half flange portion 53B.

The configuration of the implant bolt fixing portion 152 is not limited to this configuration. The implant bolt fixing portion 152 has a fitting hole formed on the lower end surface 55 side of the internal upper half flange portion 53B instead of the screw hole 59, and other than the implant bolt 150 instead of the second screw portion 150b. It may be composed of a columnar end portion constituting the end side.

The prismatic end is composed of a prism such as a cylinder. Further, the shape of the fitting hole is formed corresponding to the shape of the prismatic end portion, and is configured to be slightly larger than the shape of the prismatic end portion.

In this case, the prismatic end on the other end of the implant bolt 150 is inserted into the fitting hole. Then, the prismatic end portion and the internal upper half flange portion 53B are fixed by, for example, welding.

The implant bolt 150 is formed with a through hole 151 that penetrates along the central axis of the implant bolt 150. The through hole 151 is formed along the central axis of the implant bolt 150 from the tip of the second screw portion 150b to the tip of the first screw portion 150a.

The screw through hole 58 is a through hole formed in the inner lower half flange portion 54 and allows the first screw portion 150a of the implant bolt 150 to penetrate vertically downward. A first screw portion 150a projects below the screw through hole 58.

The nut 160 functions as a fastening member and is attached to a first screw portion 150a protruding vertically downward from the inner lower half flange portion 54. By screwing and tightening the nut 160 to the first screw portion 150a, the upper half 51 of the internal casing and the lower half 52 of the internal casing are fastened.

Next, a support mechanism 110 capable of supporting the nut 160 when the nut 160, which is a fastening member, is removed from the fastening portion 140 will be described.

FIG. 7 is a cross-sectional view corresponding to the AA cross section of FIG. 1 in the step of removing the nut 160 in the vehicle interior 21 of the second embodiment. In FIG. 7, the lid member 44 at the lower end of the flange 43 is removed.

The support mechanism 110 supports the nut 160 from the lower end to prevent the nut 160 from falling, for example, when the nut 160 is removed from the fastening portion 140 or when the nut 160 is fastened to the fastening portion 140.

The support mechanism 110 includes a communication passage 100, a through passage 170, and a support member 103.

Similar to the first embodiment, the communication passage 100 is formed in the inner upper half flange portion 53B of the inner passenger compartment upper half 51, and is composed of a through hole communicating with the fastening portion 140 from the upper side.

The penetration passage 170 penetrates the fastening portion 140. For example, as shown in FIG. 6, in a state where the nut 160 is attached, the through passage 170 is composed of a screw hole 59 and a through hole 151 of the implant bolt 150.

For example, as shown in FIG. 7, in a state where the nut 160 is removed, the through passage 170 is composed of a screw hole 59, a screw through hole 58, and a through hole 151 of the implant bolt 150.

The support member 103 supports the nut 160 at the lower end.

As shown in FIG. 7, the support member 103 includes a suspension member 104, a plate-shaped member 105, and a fixing member 106. The structure of the support member 103 is the same as that of the support member 103 of the first embodiment.

Here, one end of the suspension member 104 extends below the implant bolt 150 through the communication passage 100 and the penetration passage 170. The plate-shaped member 105 is formed, for example, to have the same size as the lower surface of the nut 160 or smaller than the lower surface of the nut 160.

With such a configuration, when the nut 160 is rotated by a tool, the lower surface of the nut 160 slides on the surface 105a of the plate-shaped member 105. Therefore, the suspension member 104 is not twisted even if the nut 160 is rotated.

The structure of the support member 103 may be the same as the structure shown in FIG.

By providing such a support mechanism 110, the suspension member 104 is not twisted even if the nut 160 is rotated, as in the first embodiment. Further, by providing the support mechanism 110, it is possible to prevent the nut 160 from falling even when the nut 160 is completely detached from the implant bolt 150.

Here, regarding the disassembly process of the maintenance of the steam turbine, the process until the upper half 51 of the internal passenger compartment is removed will be described.

The description of the same process as that described in the first embodiment will be omitted. Here, the process after the outer upper half 31 is removed, the nut 160 fastening the inner upper half flange portion 53A and the inner lower half flange portion 54 is removed, and the lid member 44 is removed will be described. ..

The suspension member 104 is inserted into the communication passage 100 and the through passage 170, and one end of the suspension member 104 is passed below the implant bolt 150. Further, the other end of the suspension member 104 is fixed to, for example, a crane.

Subsequently, one end of the suspension member 104 is fixed to the fixing member 106 of the plate-shaped member 105. Then, the other end of the suspension member 104 is pulled up by a crane to bring the plate-shaped member 105 into contact with the lower surface of the implant bolt 150.

Subsequently, a tool for removing the nut 160 via the opening 41 is inserted into the lower half 32 of the external casing. Then, the tool is fitted to the nut 160 from below, and the nut 160 is removed.

When the nut 160 is completely disengaged from the implant bolt 150, the nut 160 is supported from below by the support mechanism 110. As a result, the nut 160 does not fall.

The crane is operated to lower the suspension member 104 according to the removed state of the nut 160. The detached nut 160 is taken out from the opening 41 to the outside of the lower half 32 of the external passenger compartment.

The subsequent steps are the same as the steps described in the first embodiment.

Next, regarding the assembly process for maintenance of the steam turbine, the process up to the installation of the upper half 51 of the internal passenger compartment will be mainly described.

First, the inner passenger compartment upper half 51 is placed at a predetermined position on the inner passenger compartment lower half 52. Then, the suspension member 104 is inserted into the communication passage 100 and the through passage 170, and one end of the suspension member 104 is passed to the outside of the lower half 32 of the external passenger compartment.

Subsequently, one end of the suspension member 104 is passed through the inside of the nut 160 taken out to the outside of the lower half 32 of the external casing and penetrated.

Subsequently, one end of the suspension member 104 is fixed to the fixing member 106 of the plate-shaped member 105. Then, the other end of the suspension member 104 is pulled up by a crane to bring the plate-shaped member 105 into contact with the lower surface of the nut 160. The other end of the suspension member 104 is further pulled up by a crane, and the nut 160 is fitted to the first screw portion 150a of the implant bolt 150.

Subsequently, a tool for attaching the nut 160 via the opening 41 is inserted into the lower half 32 of the external casing. Then, the tool is fitted to the nut 160 from below, and the nut 160 is tightened.

The subsequent steps are the same as the steps described in the first embodiment.

As described above, in the vehicle interior 21 of the second embodiment, the steam introduction unit 70 is provided in the external vehicle interior upper half 31 and the internal vehicle interior upper half 51, and the internal upper half flange portion 53B and the inner lower half flange are provided. Even in a configuration in which the portion 54 is fastened from below with a nut 160, the inner casing upper half 51 can be removed and attached while the internal casing 50 is provided in the outer casing lower half 32.

That is, in the vehicle interior 21 of the second embodiment, the internal upper half flange portion 53B and the internal lower half flange portion 54 are fastened from below with the internal casing 50 provided in the outer casing lower half 32. The nut 160 can be removed and attached.

As described above, the vehicle interior 21 of the second embodiment is excellent in maintainability even if it has a configuration in which the inner upper half flange portion 53B and the inner lower half flange portion 54 are fastened from below. Further, in the steam turbine provided with the vehicle interior 20, the maintenance work period can be shortened.

In the above-described embodiment, the double-structured vehicle interior 20 having the external vehicle compartment 30 and the internal vehicle compartment 50 provided in the external vehicle compartment 30 has been described as an example. However, for example, the triple structure has been described. The configuration of this embodiment can also be applied to the above vehicle interiors.

According to the embodiment described above, an external vehicle compartment and an internal vehicle compartment are provided, a steam introduction portion is provided on the upper half side, and the upper half of the internal vehicle compartment and the lower half of the internal vehicle compartment are fixed by a fastening member from below. In the steam turbine cabin equipped with the above, maintenance can be performed with the internal casing provided in the lower half of the external casing.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and variations thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1 ... Steam turbine, 10 ... Turbine rotor, 11 ... Diaphragm outer ring, 12 ... Diaphragm inner ring, 13 ... Static wing, 20, 21 ... Car compartment, 30 ... External compartment, 31 ... External compartment upper half, 31a, 35, 55 ... lower end surface, 32 ... outer lower half of the passenger compartment, 32a, 34a ... upper end surface, 33A, 33B ... outer upper half flange portion, 34 ... outer lower half flange portion, 36, 56 ... steam passage, 36a ... inlet, 37 , 39, 40, 58, 60, 61 ... screw through holes, 38, 59 ... screw holes, 41 ... openings, 42 ... openings, 43 ... flanges, 44 ... lid members, 45 ... bolts, 50 ... internal casings, 51 ... Inner cabin upper half, 52 ... Internal cabin lower half, 53A, 53B ... Internal upper half flange portion, 54 ... Internal lower half flange portion, 57 ... Sleeve, 70 ... Steam introduction section, 80, 85, 90, 95, 140 ... Fastening part, 81, 86, 91, 96 ... Bolt, 81a, 86a, 91a, 96a ... Head, 81b, 86b, 91b, 96b ... Screw part, 87, 97, 160 ... Nut, 100 ... Communication Passage, 101, 170 ... Through passage, 102, 121, 151 ... Through hole, 103 ... Support member, 104 ... Suspension member, 105, 120 ... Plate-like member, 105a, 131a ... Surface, 106, 130 ... Fixing member, 110 ... Support mechanism, 131 ... Upper end plate, 132 ... Intermediate part, 133 ... Lower end plate, 134 ... Fixing part, 150 ... Implanting bolt, 150a ... First screw part, 150b ... Second screw part, 152 ... Implanting bolt fixing Department.

Claims (5)

It has an external passenger compartment and an internal passenger compartment, and the external passenger compartment is divided into an external passenger compartment upper half and an external passenger compartment lower half. Divided and
A steam turbine cabin equipped with a steam introduction section on the upper half side that introduces steam into the steam turbine.
A fastening portion having a fastening member for fixing the upper half of the internal casing and the lower half of the internal casing in the portion constituting the steam introduction portion from the vertically lower side.
An opening formed in the lower half of the external passenger compartment vertically below the fastening portion and allowing the fastening member to be taken in and out, and an opening.
A steam turbine casing comprising a lid member for closing the opening. The steam turbine casing according to claim 1, further comprising a support mechanism capable of supporting the fastening member when the fastening member is removed from the fastening portion. The support mechanism
A communication passage formed in the upper half of the internal passenger compartment and communicating with the fastening portion from above,
A through passage that penetrates the fastening portion and
2. The steam turbine cabin as described in the section. The upper half of the internal casing has an upper half flange formed on the outer side of the lower end of the upper half of the internal casing.
The lower half of the internal casing has a lower half flange formed on the outer side of the upper end of the lower half of the internal casing.
The fastening part
The fastening member composed of a bolt having a head on one end side and a threaded portion on the other end side.
A screw through hole formed in the lower half flange and allowing the threaded portion of the bolt to pass through from the vertically lower side.
The steam turbine casing according to any one of claims 1 to 3, further comprising a screw hole formed on the upper half flange and screwed with the screw portion of the bolt. The upper half of the internal casing has an upper half flange formed on the outer side of the lower end of the upper half of the internal casing.
The lower half of the internal casing has a lower half flange formed on the outer side of the upper end of the lower half of the internal casing.
The fastening part
An implant bolt whose one end side is fixed to the upper half flange and has a threaded portion on the other end side.
A screw through hole formed in the lower half flange and passing through the threaded portion of the implant bolt,
The steam turbine casing according to any one of claims 1 to 3, further comprising the fastening member composed of a nut screwed into the screw portion vertically downward from the lower half flange.

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