CA1122835A - Necked-down bolt for connecting thermal shock-stressed structural parts - Google Patents
Necked-down bolt for connecting thermal shock-stressed structural partsInfo
- Publication number
- CA1122835A CA1122835A CA341,034A CA341034A CA1122835A CA 1122835 A CA1122835 A CA 1122835A CA 341034 A CA341034 A CA 341034A CA 1122835 A CA1122835 A CA 1122835A
- Authority
- CA
- Canada
- Prior art keywords
- bolt
- packing
- necked
- structural parts
- reduced diameter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000012856 packing Methods 0.000 claims abstract description 15
- 238000005452 bending Methods 0.000 claims description 2
- 239000011148 porous material Substances 0.000 claims 1
- 238000012546 transfer Methods 0.000 abstract description 3
- 230000008642 heat stress Effects 0.000 abstract 1
- 238000013461 design Methods 0.000 description 2
- 230000035882 stress Effects 0.000 description 2
- 230000008646 thermal stress Effects 0.000 description 2
- 238000007792 addition Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000012217 deletion Methods 0.000 description 1
- 230000037430 deletion Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B5/00—Joining sheets or plates, e.g. panels, to one another or to strips or bars parallel to them
- F16B5/02—Joining sheets or plates, e.g. panels, to one another or to strips or bars parallel to them by means of fastening members using screw-thread
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
- F01D25/24—Casings; Casing parts, e.g. diaphragms, casing fastenings
- F01D25/243—Flange connections; Bolting arrangements
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B31/00—Screwed connections specially modified in view of tensile load; Break-bolts
- F16B31/04—Screwed connections specially modified in view of tensile load; Break-bolts for maintaining a tensile load
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B35/00—Screw-bolts; Stay-bolts; Screw-threaded studs; Screws; Set screws
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L23/00—Flanged joints
- F16L23/16—Flanged joints characterised by the sealing means
- F16L23/24—Flanged joints characterised by the sealing means specially adapted for unequal expansion of the parts of the joint
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Connection Of Plates (AREA)
- Pressure Vessels And Lids Thereof (AREA)
- Turbine Rotor Nozzle Sealing (AREA)
- Joining Of Building Structures In Genera (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Necked-down bolt for connecting thermal shock-stressed structural parts. A thermally conducting packing encloses the reduced diameter portion of the bolt and sub-stantially fills-up the air gap between the reduced diameter portion and a borehole wall in order to increase the heat transfer to the bolt and accordingly reduce the heat stresses in the bolt.
Necked-down bolt for connecting thermal shock-stressed structural parts. A thermally conducting packing encloses the reduced diameter portion of the bolt and sub-stantially fills-up the air gap between the reduced diameter portion and a borehole wall in order to increase the heat transfer to the bolt and accordingly reduce the heat stresses in the bolt.
Description
s BACKGROUND AND OBJECTS OF THE INVENTION
The present invention refers to a necked-down bolt for connecting thermal shock-stressed structural parts.
With conventional necked-down bolts, the threadless part of the necked-dbwn bolt features a smaller diameter than the core cross-section of the threaded ends. As a result, this necked-down bolt part in the installed state is seated with relatively great play in the borehole of at least one of the two structural parts to be connected.
With thermal shock-stressed structural parts, as perhaps with casings and similar components of high pressure and medium-pressure steam turbines, when starting from the cold state, there appears as a consequence of this great play between borehole and bolt barrel or shaft a poor heat transfer from, for.example, the casing flanges on the necked-down bolt. There can thus occur a temperature difference between the bolt and the flange parts which leads to thermal stresses owing to the differing thermal expansions of bolt and flange parts. If the thermal conductivity of the high-strength bolt barrel is relatively`low, these thermal stresses can become so great that the bolt connection is endangered and the packing strips on the casing flanges can become plastically defor~ed.
`' ` '' ~
33~i It is, therefore, an object of the present invention to provide for improved thermal conductivity to the necked-down bolt.
SUMMARY OF THE INVENTION
This object is achieved by a bolt assembly for use in connecting thermal shock-stressed structural parts.
The assembly comprises a necked-down bolt having a reduced diameter portion intermediate its ends and a threaded end for connection to one of the structural parts, and a thermal conductive packing surrounding said reduced diameter portion with essentially no play. The outer diameter of the packing is at least equal to the major thread diameter of the threaded end of the bolt.
THE DRA~ING ~ ~-Examples of preferred embod;ments of the invention are described in detail in the following with reference to the accompanying drawing wherein: ' Figure 1 is a cross~section through portions of two casing halvas depicting a stratn pin bolt according to the invention with a strain measuring pin, for inter~
connecting the casing halves~ , ~: '
The present invention refers to a necked-down bolt for connecting thermal shock-stressed structural parts.
With conventional necked-down bolts, the threadless part of the necked-dbwn bolt features a smaller diameter than the core cross-section of the threaded ends. As a result, this necked-down bolt part in the installed state is seated with relatively great play in the borehole of at least one of the two structural parts to be connected.
With thermal shock-stressed structural parts, as perhaps with casings and similar components of high pressure and medium-pressure steam turbines, when starting from the cold state, there appears as a consequence of this great play between borehole and bolt barrel or shaft a poor heat transfer from, for.example, the casing flanges on the necked-down bolt. There can thus occur a temperature difference between the bolt and the flange parts which leads to thermal stresses owing to the differing thermal expansions of bolt and flange parts. If the thermal conductivity of the high-strength bolt barrel is relatively`low, these thermal stresses can become so great that the bolt connection is endangered and the packing strips on the casing flanges can become plastically defor~ed.
`' ` '' ~
33~i It is, therefore, an object of the present invention to provide for improved thermal conductivity to the necked-down bolt.
SUMMARY OF THE INVENTION
This object is achieved by a bolt assembly for use in connecting thermal shock-stressed structural parts.
The assembly comprises a necked-down bolt having a reduced diameter portion intermediate its ends and a threaded end for connection to one of the structural parts, and a thermal conductive packing surrounding said reduced diameter portion with essentially no play. The outer diameter of the packing is at least equal to the major thread diameter of the threaded end of the bolt.
THE DRA~ING ~ ~-Examples of preferred embod;ments of the invention are described in detail in the following with reference to the accompanying drawing wherein: ' Figure 1 is a cross~section through portions of two casing halvas depicting a stratn pin bolt according to the invention with a strain measuring pin, for inter~
connecting the casing halves~ , ~: '
- 2 ~ ~
: : ..
,,~
Figuxe 2 depicts a modified form of a thermal packing according to the invention, and Figure 3 depicts a two-part form of construction of the thermal packing.
DETAILED DESCRIPTION OF A PREFERRED
EMBODIMENT OF THE INVENTION
In Figure 1, two casing halves 1, 2 of a stream turbine to be connected are depicted. The bolt used for achieving this connection is a strain pin bolt 3 whose one threaded end 4 is threaded to the casing lower half 1. A resilien~ sleeve 6 is provided between the bolt nut 5 and a contact surface of the casing upper part 2.
The necked-down bolt 3 features a measuring pin 7 which is used in the well-known manner to measure, with the aid of a dial guage 8 and a support 9, the elongation and thereby the initial stress of the bolt when tightening the nut 5.
The reduced diameter barrel part of the bolt is enclosed by a thermal packing which comprises a two-part sleeve 10 divided longitudinally and formed of a good heat-conducting material. It features essentially no play or clearance with respect to both the bolt barrel as well :
.~. .
: : ..
,,~
Figuxe 2 depicts a modified form of a thermal packing according to the invention, and Figure 3 depicts a two-part form of construction of the thermal packing.
DETAILED DESCRIPTION OF A PREFERRED
EMBODIMENT OF THE INVENTION
In Figure 1, two casing halves 1, 2 of a stream turbine to be connected are depicted. The bolt used for achieving this connection is a strain pin bolt 3 whose one threaded end 4 is threaded to the casing lower half 1. A resilien~ sleeve 6 is provided between the bolt nut 5 and a contact surface of the casing upper part 2.
The necked-down bolt 3 features a measuring pin 7 which is used in the well-known manner to measure, with the aid of a dial guage 8 and a support 9, the elongation and thereby the initial stress of the bolt when tightening the nut 5.
The reduced diameter barrel part of the bolt is enclosed by a thermal packing which comprises a two-part sleeve 10 divided longitudinally and formed of a good heat-conducting material. It features essentially no play or clearance with respect to both the bolt barrel as well :
.~. .
3 -~, . . .
: ' ' .
~, as the wall of the borehole 11. A ~light play may be provided such that, in operation, i.e,, in the heated state of the connection, the sleeve is not jammed between the bolt barrel and the borehole wall; otherwise, in the case of an eccentricity of the bolt axis with respect to the borehole axis which may be present, a bending of the bolt may occur. ~t can be stated in reference to the dimensions of the strain pin bolt 3, that the outside diameter of the sleeve is at least equal to, and preferably at least a few tenths of a millimeter larger than the diameter of the threaded part 40 As a result of the presence of the thermal packing, heat will be effectively transferred to the reduced diameter portion of the bolt 3 to avoid the afore-ment;oned problems. -Another form of sleeve used as a thermal packingis shown in Figure 2. Th~s sleeve 12 is constructed of one piece and features an ;nternal thread 13 extending over its entire length and which corresponds to the thread ends of the bolt 3. This enables the sleeve to be screwed over one of the two threaded ends of the bolt 3 in order to arr;ve at its position enveIoping the necked-down bolt barrel, ~ d~ r3~lD ~ ~
In order for design of Figure 2 to achieve a good heat transfer from the sleeve to the bolt barrel, necked-down bolts will mainly be used whose reduced shaft diameter substantially corresponds to the thread core diameter of the thread 13 so that the internal thread crests substantially contact the reduced shaft in the heated state.
For the purpose of an improved manipulation of the bolt during installation, it is possible according to an embodiment depicted in Figure 3 to hold together a two-part sleeve 14 in its position encompassing the reduced shaft by means of spring rings 15 which engage in the peripheral slots 16 of the two sleeve halves 17 and 18.
In order to hold together the two halves of a two~
part sleeve, it is naturally also possible to use other means such as hinges, set pins, pushbutton-type pin connections, etc.
The material for the thermal packing used for steam turbines should feature a good heat conductivity approximately in the order of magnitude of 40 W/m C.
In this way, a reduction of about one-third of the additional stress in the reduced diameter barrel of the bolt appearing during start-up may be achieved~
- 5 -: :
- ~ , .
3~i Here, the invention is described with application `to a strain pin bolt, and it is, however, naturally also possible to design other necked-down bolts, for example bolts with a head, possibly for large connecting and torque rods, according to the features of the invention.
Although the invention has been descriked in connec-tion with a preferred embodiment thereof, it will be appreciated by those skilled in the art that additions, modifications, substitutions, and deletions not specifically described may be made without departing from the spirit and scope of the inventlon as defined in the appended claims.
.
' :
' ; 6 ~, :: :
, ~
: ' ' .
~, as the wall of the borehole 11. A ~light play may be provided such that, in operation, i.e,, in the heated state of the connection, the sleeve is not jammed between the bolt barrel and the borehole wall; otherwise, in the case of an eccentricity of the bolt axis with respect to the borehole axis which may be present, a bending of the bolt may occur. ~t can be stated in reference to the dimensions of the strain pin bolt 3, that the outside diameter of the sleeve is at least equal to, and preferably at least a few tenths of a millimeter larger than the diameter of the threaded part 40 As a result of the presence of the thermal packing, heat will be effectively transferred to the reduced diameter portion of the bolt 3 to avoid the afore-ment;oned problems. -Another form of sleeve used as a thermal packingis shown in Figure 2. Th~s sleeve 12 is constructed of one piece and features an ;nternal thread 13 extending over its entire length and which corresponds to the thread ends of the bolt 3. This enables the sleeve to be screwed over one of the two threaded ends of the bolt 3 in order to arr;ve at its position enveIoping the necked-down bolt barrel, ~ d~ r3~lD ~ ~
In order for design of Figure 2 to achieve a good heat transfer from the sleeve to the bolt barrel, necked-down bolts will mainly be used whose reduced shaft diameter substantially corresponds to the thread core diameter of the thread 13 so that the internal thread crests substantially contact the reduced shaft in the heated state.
For the purpose of an improved manipulation of the bolt during installation, it is possible according to an embodiment depicted in Figure 3 to hold together a two-part sleeve 14 in its position encompassing the reduced shaft by means of spring rings 15 which engage in the peripheral slots 16 of the two sleeve halves 17 and 18.
In order to hold together the two halves of a two~
part sleeve, it is naturally also possible to use other means such as hinges, set pins, pushbutton-type pin connections, etc.
The material for the thermal packing used for steam turbines should feature a good heat conductivity approximately in the order of magnitude of 40 W/m C.
In this way, a reduction of about one-third of the additional stress in the reduced diameter barrel of the bolt appearing during start-up may be achieved~
- 5 -: :
- ~ , .
3~i Here, the invention is described with application `to a strain pin bolt, and it is, however, naturally also possible to design other necked-down bolts, for example bolts with a head, possibly for large connecting and torque rods, according to the features of the invention.
Although the invention has been descriked in connec-tion with a preferred embodiment thereof, it will be appreciated by those skilled in the art that additions, modifications, substitutions, and deletions not specifically described may be made without departing from the spirit and scope of the inventlon as defined in the appended claims.
.
' :
' ; 6 ~, :: :
, ~
Claims (4)
1. A bolt assembly for use in connecting thermal shock-stressed structural parts comprising a necked-down bolt having a reduced diameter portion intermediate its ends and a threaded end of larger diameter for connection to one of the structural parts, and a thermal conductive packing surrounding said reduced diameter portion, said packing comprising a one-piece member having internal threading over its entire length corresponding to the threading of said bolt to enable said packing to be inserted past said threaded end of said bolt.
2. Apparatus according to claim 1, wherein said packing has a slight play relative to said reduced diameter portion to prevent bending of the bolt.
3. Apparatus according to claim 1, wherein one axial end of said packing is free of axial compressive forces.
4. Apparatus according to claim 1, wherein said packing comprises a rigid, non-porous material.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH12296/78 | 1978-12-01 | ||
| CH1229678 | 1978-12-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1122835A true CA1122835A (en) | 1982-05-04 |
Family
ID=4381676
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA341,034A Expired CA1122835A (en) | 1978-12-01 | 1979-11-30 | Necked-down bolt for connecting thermal shock-stressed structural parts |
Country Status (6)
| Country | Link |
|---|---|
| CA (1) | CA1122835A (en) |
| DE (1) | DE2854139A1 (en) |
| DK (1) | DK506079A (en) |
| FR (1) | FR2442988A1 (en) |
| NL (1) | NL7908644A (en) |
| SE (1) | SE7909820L (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2545888B1 (en) * | 1983-05-10 | 1987-07-17 | Compair Climax Sa | CYLINDER, ESPECIALLY MICROVERIN COMPRISING A DEVICE FOR SUPPORTING EXTERNAL EXTERNAL ELEMENTS |
| DE3320460C1 (en) * | 1983-06-07 | 1984-10-18 | Thyssen Industrie Ag, 4300 Essen | Resilient mountain anchor |
| FR2577632B1 (en) * | 1985-02-19 | 1987-09-25 | Framatome Sa | ELEMENT FILTERING VARIATIONS OF CONSTRAINTS IN A BOLT ASSEMBLY |
| EP2025882A1 (en) * | 2007-08-14 | 2009-02-18 | Siemens Aktiengesellschaft | Casing assembly for a stationary turbo engine |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB417053A (en) * | 1933-03-22 | 1934-09-24 | Richard William Bailey | Improvements in and relating to flanged and like joints |
| FR1306491A (en) * | 1961-11-20 | 1962-10-13 | Ind Fernand Courtoy Bureau Et | Device for establishing a clampable joint between two elements |
-
1978
- 1978-12-14 FR FR7835161A patent/FR2442988A1/en not_active Withdrawn
- 1978-12-15 DE DE19782854139 patent/DE2854139A1/en not_active Withdrawn
-
1979
- 1979-11-28 SE SE7909820A patent/SE7909820L/en not_active Application Discontinuation
- 1979-11-28 DK DK506079A patent/DK506079A/en not_active Application Discontinuation
- 1979-11-29 NL NL7908644A patent/NL7908644A/en not_active Application Discontinuation
- 1979-11-30 CA CA341,034A patent/CA1122835A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE2854139A1 (en) | 1980-06-12 |
| SE7909820L (en) | 1980-06-02 |
| FR2442988A1 (en) | 1980-06-27 |
| DK506079A (en) | 1980-06-02 |
| NL7908644A (en) | 1980-06-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |