US20050244245A1 - Method and devices to limit a creep of mechanical fasteners - Google Patents
Method and devices to limit a creep of mechanical fasteners Download PDFInfo
- Publication number
- US20050244245A1 US20050244245A1 US10/834,955 US83495504A US2005244245A1 US 20050244245 A1 US20050244245 A1 US 20050244245A1 US 83495504 A US83495504 A US 83495504A US 2005244245 A1 US2005244245 A1 US 2005244245A1
- Authority
- US
- United States
- Prior art keywords
- shape
- creep
- memorized
- manufactured
- operating
- 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.)
- Abandoned
Links
- 238000000034 method Methods 0.000 title claims abstract description 36
- 229910001285 shape-memory alloy Inorganic materials 0.000 claims abstract description 38
- 229910000734 martensite Inorganic materials 0.000 claims abstract description 21
- 230000006835 compression Effects 0.000 claims abstract description 16
- 238000007906 compression Methods 0.000 claims abstract description 16
- 238000011084 recovery Methods 0.000 claims abstract description 15
- 230000009466 transformation Effects 0.000 claims abstract description 13
- 238000000844 transformation Methods 0.000 claims abstract description 4
- 239000000463 material Substances 0.000 claims description 17
- 238000011068 loading method Methods 0.000 claims description 8
- 230000006399 behavior Effects 0.000 claims description 7
- 229910000746 Structural steel Inorganic materials 0.000 claims description 3
- 230000008569 process Effects 0.000 abstract description 13
- 230000035882 stress Effects 0.000 description 10
- 238000013023 gasketing Methods 0.000 description 9
- 229910001000 nickel titanium Inorganic materials 0.000 description 8
- HLXZNVUGXRDIFK-UHFFFAOYSA-N nickel titanium Chemical compound [Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni] HLXZNVUGXRDIFK-UHFFFAOYSA-N 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 6
- 238000013459 approach Methods 0.000 description 5
- 229910001566 austenite Inorganic materials 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 238000007789 sealing Methods 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 230000008602 contraction Effects 0.000 description 3
- 238000013461 design Methods 0.000 description 3
- 238000011161 development Methods 0.000 description 3
- 230000018109 developmental process Effects 0.000 description 3
- 229940058401 polytetrafluoroethylene Drugs 0.000 description 3
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 3
- 239000004810 polytetrafluoroethylene Substances 0.000 description 3
- -1 aerospace Substances 0.000 description 2
- 230000032683 aging Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000002803 fossil fuel Substances 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 230000003446 memory effect Effects 0.000 description 2
- 241001250090 Capra ibex Species 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 239000013013 elastic material Substances 0.000 description 1
- 230000007717 exclusion Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 229910052733 gallium Inorganic materials 0.000 description 1
- 229910052735 hafnium Inorganic materials 0.000 description 1
- 229910000816 inconels 718 Inorganic materials 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- PWPJGUXAGUPAHP-UHFFFAOYSA-N lufenuron Chemical compound C1=C(Cl)C(OC(F)(F)C(C(F)(F)F)F)=CC(Cl)=C1NC(=O)NC(=O)C1=C(F)C=CC=C1F PWPJGUXAGUPAHP-UHFFFAOYSA-N 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000003129 oil well Substances 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000003566 sealing material Substances 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910000601 superalloy Inorganic materials 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
Images
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
- 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
- F16L23/18—Flanged joints characterised by the sealing means the sealing means being rings
- F16L23/20—Flanged joints characterised by the sealing means the sealing means being rings made exclusively of metal
-
- 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
- F16B33/00—Features common to bolt and nut
- F16B33/006—Non-metallic fasteners using screw-thread
-
- 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
- F16B2200/00—Constructional details of connections not covered for in other groups of this subclass
- F16B2200/50—Flanged connections
- F16B2200/506—Flanged connections bolted or riveted
-
- 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
- F16B2200/00—Constructional details of connections not covered for in other groups of this subclass
- F16B2200/77—Use of a shape-memory material
-
- 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
- F16B43/00—Washers or equivalent devices; Other devices for supporting bolt-heads or nuts
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S411/00—Expanded, threaded, driven, headed, tool-deformed, or locked-threaded fastener
- Y10S411/909—Fastener or fastener element composed of thermo-responsive memory material
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T403/00—Joints and connections
- Y10T403/21—Utilizing thermal characteristic, e.g., expansion or contraction, etc.
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T403/00—Joints and connections
- Y10T403/21—Utilizing thermal characteristic, e.g., expansion or contraction, etc.
- Y10T403/217—Members having different coefficients of expansion
Abstract
A method and devices to limit or to exclude operating creep of mechanical fasteners is disclosed. The method consists in use of mechanical fasteners such as bolts, gaskets, screws, washers and other power elements manufactured from shape memory alloys having temperature interval of martensitic phase transformations corresponding to the operating temperature of industrial equipment. The power elements are previously shape-memorized either to tension or to compression, flexion, torsion, or to their combinations under temperature of martensite state with suitable quantity of conserved residual shape-memorized deformation obtained during loading-unloading of the power elements. Further constrained recovery of shape-memorized deformation under operating temperature generates reactive shape-recovering forces having direction inverse to the direction of operating creep. The process of creep limitation is called “Method of “negative creep”.
Description
- Not Applicable
- Not Applicable
- Not Applicable
- This invention relates to mechanical fasteners, specifically to bolted flanged connections with gaskets that have to provide a tight and durable joint between component parts of pressure vessels, piping systems, and other industrial facilities under external and/or internal loadings and operating elevated temperatures.
- One of the most typically used means to obtain the tight and durable joint between component parts of industrial facilities is to connect their pieces with bolted fasteners. These connections have a wide applicability in petrochemical, chemical, aerospace, fossil fuel and nuclear power industries, and others.
- There are millions of bolts in critical facilities of cited industries, and the problem of structural durability and plant leakage reduction is very complex and involves many areas of applied mechanics and technological findings.
- Safe design of bolted flanged connections from structural durability point of view has been, on the whole, solved and standardized, but the plant leakage remains a principal cause of bolt damages and failure that are attributed to the high level of corrosion which is combined with high level of stresses and deformations due to alternating conditions of internal pressure, external loading, elevated temperatures, flow-induced vibrations, integral flow of neutrons, and other critical factors. Hence, the leak tightness has a greater influence on the service life of the bolted flanged connections, and highest priority in plant reliability programs is to limit or to exclude the early leakage, thus protecting critical engineering facilities from untimely degradation and failure.
- Statistic data show that, for example, piping system leakages conservatively cost each process industry hundreds of millions of dollars annually in lost profits as a result of plant shutdowns, production penalties, maintenance rework activities, and equipment repair or replacement.
- Early plant leakage is closely connected with operating creep of the fasteners and gaskets. Generally, creep is accompanying by stress relaxation, and elongation of bolted fasteners along with contraction of gaskets due to creep-relaxation is a very serious problem because it leads to bolt load and gasket compression losses that, in turn, increase the leakage rate.
- It is found that creep-relaxation of bolted fasteners and gaskets is increased with elevated temperature and load-induced stresses, although room temperature creep-relaxation can be also significant even at relatively light loads. A plant maintenance practice includes periodical retightening or replacement of the bolts and gaskets subjected to creep-relaxation to prevent leakages, and, having in mind the great quantity of bolts used in process industries, the procedure involves an expensive time-consuming process and provides only temporary effect of leak tightness because the creep-relaxation increases gradually after additional retightening, and risk of leakage event relatively increases. Nevertheless, during the development of must design procedure, little consideration has been given to the creep-relaxation of bolted fasteners and gaskets, and similar situation is observed with patent documents.
- U.S. Pat. No. 6,199,453 to Steinbock, entitled “High temperature bolting system”, offers a sophisticated apparatus for maintaining a clamping force between component parts of a steam turbine while operating at a temperatures of 800 DEG. F to 1200 DEG. F. However, the disclosed elongated stepped fastener shank manufactured from superalloy Inconel 718, having a thermal expansion coefficient similar to flange material and creep strength which is several times greater than creep strength of flanged material, can not stop a creep-relaxation process and protect proposed bolting system from creep-relaxation that is an increase of elongation and decrease of stress with time. Moreover, the high level of stresses and operating temperatures induce the high level of creep-relaxation of the fasteners.
- EP Pat. No. 352608 discloses a method of fabrication of reinforced polytetrafluoro-ethylene (PTFE) gasketing materials “characterized by high strength, excellent recovery and superior creep-relaxation resistance”. However, these super characteristics did not exclude the creep-relaxation from 20% to 30% depending on thicknesses of proposed tested materials. Moreover, the tests were carried out under standard procedure during only 22 hours at only 212 DEG. F. Thus, the proposed gasketing materials demonstrate “superior” physical and functional properties when compared to previous PTFE gasketing materials described in prior art. The most important failing, however, is the fact that proposed gasketing materials copy a typically used approach to the fabrication of sealing elements based on traditional “passive” behavior under operating conditions of all known today gasketing materials excepting those described in U.S. Pat. No. 5,226,683 to Julien et al. and U.S. Pat. No. 6,435,519 to White. These two patent documents are the first attempts to introduce the new gasketing material fabricated from NiTi (Nitinol) shape memory alloy.
- U.S. Pat. No. 5,226,683 discloses a method to use a gasket of Nitinol shape memory alloy under martensite state to fill the space between the hard flange faces having microscopic surface irregularities that can prevent the fluid leakage between the faces und will allow further to reuse the gasket.
- The Nitinol shape memory alloy of which the gasket of this invention is made “remembers” the shape, which it had when it was last formed in its austenite state. When this gasket is deformed under temperature of martensite state it fills the irregularities of flange faces under pressure exerted by hard clamping members of the flanges. The shape memory effect is used when gasket resumes its original shape after heating to austenite state during the restoration step before reuse. Although this invention has failed a main problem of plant leakage reduction by means of creep limitation, it remains a turning point from leakage problem point of view.
- U.S. Pat. No. 6,435,519 represents a next attempt to use a Nitinol shape memory alloy as a gasketing material to provide a seal between component parts of an imaginary generalized assembly. Unfortunately, this invention claims a well-known long time procedure to clamp the gasket between adjacent flange faces. As for application of gasket of shape memory alloy, this invention claims the spring forces generated by bending of the gasket when it is in super-elastic state. It is easily to observe that shape memory alloy in super-elastic state displays all mechanical properties of typical elastic material including the property of creep-relaxation while subjecting to elevated temperature and external loading. Meanwhile, this invention tries to open a real way to the application of shape memory alloys as sealing materials even though the problem of creep-relaxation remains out of consideration.
- A wide range of patent documents having relation to the present invention is dedicated to the application of shape memory alloys, mostly of the Nitinol, in design of couplings, fasteners, washers, plugs, springs and other structural components for such things as pipes, oil well casings and similar shell structures.
- U.S. Pat. Nos. 3,759,552, 4,001,928, 4,149,911, 4,198,081, 4,281,841, 4,450,616, 4,469,357, 4,501,058, 4,537,406, 5,791,847 as well as GB Pat. Nos. 1554432, 1580036, SU Pat. No. 1086282 and JP Pat. No. 62-116292 describe the means of stressing a structural members of Nitinol shape memory alloy components that provide stiffness to shell structures and tubular members as well as prestressed loadings for head bolts or other prestressed fasteners. These documents, however, did not touch the problem of creep-relaxation of mechanical fasteners and gasketing joints.
- Japanese Pat. No. 62-188764 describes a method to manufacture a bolt of Nitinol shape memory alloy that may be easily fastened and detached. This bolt is subjected to axial compression and to aging treatment under specific temperatures while holding it under compressive strain. Thus-obtained shape memory alloy bolt reversibly repeats the elongation in a length direction at a temperature of an initial temperature of martensite transformation and the contraction at a temperature of an initial temperature of inverse transformation. Owing to these characteristics, the length of bolt is arbitrary changed, so that bolt may be firmly fastened or easily detached.
- The procedure of described bolt production relates to the method known as constrained formation of shape memory effect by means of fixed deformation and following aging treatment under specific temperature above of temperature of austenite state. This procedure is very complex and the bolt's compression under elevated temperature increases a risk of bolt's buckling, and, moreover, the problem of creep-relaxation is failed too.
- None of the above-mentioned prior patent documents touch the problem of creep-relaxation of mechanical fasteners and gasketing joints from active intervention to the plant leakage reduction point of view. Accordingly, it is an object of the present invention to form a new approach to provide a bolt-flange-gasket assembly wherein there is a significant limitation or exclusion of creep-relaxation due to operating elevated temperatures and external and/or internal loadings. This invention is the first to introduce a new technological philosophy based on “active” resistance of the fasteners and gaskets to the creep-relaxation under critical operating conditions.
- It is, therefore, a primary object of the present invention to form a new idea of sealing technology based on active behavior of the fasteners and gaskets to limit or to exclude their operating creep while subjecting to the operating elevated temperature and external and/or internal loadings.
- It is another object of the present invention to provide a method and devices to limit a creep-relaxation of the fasteners and/or gaskets that are a power elements manufactured from shape memory alloys and previously shape-memorized under temperatures of martensite state.
- Active behavior of the power elements results from shape-recovering forces that appear during a recovery of previously shape-memorized deformations under operating elevated temperatures. These forces have a direction inverse to the direction of operating creep deformations of the fasteners and/or gaskets that limits or excludes the elongation of the fasteners and contraction of the gaskets due to creep. This active behavior may be called “negative creep”.
- The method consists in application of power elements such as bolts, screws, washers, gaskets, and the like manufactured from shape memory alloys and previously shape-memorized either to tension or to compression, flexion, torsion, or to their combinations. The shape-memorized deformations are obtained during loading-unloading of the power elements under temperature of martensite state when the power elements conserve the residual shape-memorized deformations upon unloading.
- The recovery of conserved shape-memorized deformations is occurred after standard tightening of the fasteners and clamping of the gasket during the operating external and/or internal loadings and variety of elevated operating temperatures including the temperatures of martensitic phase transformation of shape memory alloy. The recovery of conserved shape-memorized deformations is further stopped by rigid component parts of the assembly forming an effect of constrained recovery event, so that reactive shape-recovering forces are generated that leads to the stress of fasteners and/or gaskets at the direction inverse to the direction of creep deformations.
- The shape memory alloys on a basis of Cu, Fe, Al, Ma, Ga, Ni, Ti, In, Pd, Hf, and others have a large temperature interval of martensitic phase transformations that corresponds to the temperatures to recover the conserved shape-memorized deformations. Hence, the operating temperatures of the assembly have to be in temperature interval of martensitic phase transformations of the power elements manufactured from suitable shape memory alloy. For example, the operating temperatures of Fossil Fuel and Nuclear Power Plants' equipment such as heat exchangers, piping systems, steam generators, coolant system installations, and others vary from dozens to hundreds degrees and remain stable enough for given type of equipment, so that temperatures of martensitic phase transformation of suitable shape memory alloy have to be in the interval of operating temperatures of the assembly. The reactive shape-recovering forces may be considerable depending on quantity of conserved shape-memorized deformations and rigidity of opposed component parts of the assembly.
- A most important advantage of the present invention is a new progressive approach to the sealing technology based on active intervention in operating process by means of fasteners and gaskets manufactured from shape memory alloys and previously shape-memorized either to tension or to compression, flexion, torsion, or to their combinations.
- Another advantage of the present invention consists in use of reactive shape-recovering forces generated by fasteners and/or gaskets under operating conditions to provide a “negative creep” and to limit or to exclude the creep-relaxation of the fasteners and gaskets.
- It is next advantage of the present invention to provide a continuous automatic contact between flange faces and gasket under operating conditions. Reactive shape-recovering forces having direction inverse to the direction of the creep deformations produce this contact.
- Proposed devices provide a limitation of creep deformations excluding simultaneously a retightening of the fasteners that increases significantly a leak tightness of critical facilities and extends their service life.
- Further brief description of applied drawings and following detailed description of the invention are intended to provide a basis for understanding the nature and character of the present invention, and to explain the principles and operation of presented devices.
-
FIG. 1 represents schematically a physical basis of constrained recovery when a conserved residual shape-memorized deformation εc under temperature of martensite state below Mf tries to be recovered during the heating to temperature Af of austenite state with appearance of reactive shape-recovering stress σr. -
FIG. 2 is a bolted fastener of two component parts of a pressure vessel having a top, base, bolts with nuts and gasket. -
FIG. 3 is a similar toFIG. 2 except that the bolts have an internal axial hollow channel adapted to place and to fix firmly a shank manufactured from shape memory alloy and previously shape memorized to the compression. -
FIG. 1 is three-dimensional stress-strain-temperature diagram σ-ε-T showing a behavior of power element of shape memory alloy during the formation of shape-memorized deformation along with its constrained recovery. An initial point “O” corresponds to temperature below Mf at which the transformation of martensite finishes. The stress-induced martensite is obtained during loading-unloading of the power element that is presented at the stress-strain diagram σ-ε at the rear graph inFIG. 1 . The point K corresponds to the final stress σf before unloading, and the point S corresponds to the final strain εc after unloading. - The strain εC is a conserved residual shape-memorized deformation of the power element of shape memory alloy. This deformation tries to be recovered during the heating to the temperature Af (point Q at the front graph in
FIG. 1 corresponding to austenite state of the power element), but its shape recovery is stopped by rigid component parts of the assembly providing an effect of constrained recovery (point R at the front graph). The constrained recovery of the shape-memorized deformation generates reactive shape-recovering stress σr that is shown at the front graph inFIG. 1 . - A direction of the shape-memorized deformation coincides with direction of operating creep deformation of the fastener or gasket, and, therefore, previously compressed gasket will be shape-memorized to the tension because it will try to recover its initial elongated shape during the heating that will stopped by rigid component parts of the assembly. This constrained recovery of the gasket generates the reactive shape-recovering forces of tension having direction inverse to the direction of operating creep deformation of the gasket. This effect of “negative creep” results in active resistance of the mechanical fasteners to their operating creep that determines a new approach to the sealing technology.
- The “negative creep” provides continuous automatic contact between adjacent component parts of the assembly, because, for example, gasket from shape memory alloy being previously shape-memorized to tension will restore its initial elongated shape during the operating process under operating temperature corresponding to the temperature of martensitic phase transformation of applied shape memory alloy. It will be “active” behavior of the gasket, which will actively resist to its operating creep.
- The described process of forming of shape-memorized deformation and constrained recovery may be obtained either for tension or compression, flexion, torsion, or for their combinations.
-
FIG. 2 is a part of the cross section of a pressure vessel having a top 111 andbase 12 with flange rings 13 and 14 connected withbolts 15 andnuts 16,compliant gasket 17 manufactured from typically used material being placed between adjacent flange faces. The assembly is subjected to internal pressure “P” and operating temperature “T”. - The
bolts 15 are manufactured from shape memory alloy and previously shape-memorized to the compression under temperature of martensite state with suitable quantity of conserved residual shape-memorized deformation. The temperature of martensitic phase transformation of the shape memory alloy corresponds to operating temperature of the assembly, so that previously elongated bolts try to recover their initial length. The recovery process is stopped by resistance of rigid component parts of the assembly with simultaneous generation of reactive shape-recovering forces of compression having direction inverse to the direction of operating creep of the bolts. The reactive forces block a development of bolt elongation due to creep that excludes the bolt retightening and increases the leak tightness of bolted flanged connection. - The same
FIG. 2 shows second embodiment of the present invention except the materials of the bolts and gaskets. The bolts of second embodiment are manufactured from typically used structural steel, and the gasket is manufactured from shape memory alloy and previously shape-memorized to the tension with suitable quantity of conserved residual shape-memorized deformation. The process of generation of reactive shape-recovering forces of tension of the gasket is similar to described above, because the gasket tries to recover its initial thickness and, therefore, provides a continuous contact with adjacent flange faces. The reactive forces of the gasket have a direction inverse to the direction of operating creep of the gasket that limits creep development. - The same
FIG. 2 relates to third embodiment of the present invention except the materials of the bolts and gasket which are both manufactured from shape memory alloy and previously shape-memorized to the compression (bolts) and to the tension (gasket). Further process is similar to the one described above. -
FIG. 3 shows the same component parts of the assembly described inFIG. 2 except that the bolts are manufactured from typically used structural steel and have an internal axial hollow channel adapted to place and to fix firmly ashank 20 manufactured from shape memory alloy and previously shape-memorized to the compression. The gasket may be manufactured from shape memory alloy or from typically used material. Further process is similar to the one described above. - The present invention opens a new approach to the sealing technology based on active intervention of the fasteners and gaskets in operating process by means of creep limitation and plant leakage reduction. The power elements manufactured from shape memory alloys may be previously shape-memorized either to tension or to compression, flexion, torsion, or to their combinations that significantly increases applicability of presented method using the feature of shape memory alloys to provide a “negative creep” to limit or to exclude operating creep of the fasteners and gaskets. The real application of the present invention in plant process industries will allow to protect the fasteners and component parts of technological equipment from damages due to the corrosion, and to extend its service life.
- It will be understood that various shape memory alloys may by used for manufacturing the power elements to limit the creep of mechanical fasteners and gaskets having temperatures of martensitic phase transformation corresponding to operating temperatures of technological equipment, and various changes in details, materials, and arrangements of the parts of the fasteners and gaskets which have been described and illustrated above in order to explain the nature of this invention may be made by those skilled in the art without departing from the basic principles of the present method as recited in the applied claims.
Claims (12)
1. A method to provide an active behavior of mechanical fasteners to limit or to exclude their operating creep due to external and/or internal loadings and elevated operating temperature of industrial equipment.
2. A method according to claim 1 wherein said mechanical fasteners are the bolts, gaskets, screws, washers or other fastening power elements.
3. A method according to claim 2 wherein said bolts, gaskets or other fastening power elements are manufactured from shape memory alloys having temperature interval of martensitic phase transformations corresponding to interval of operating temperatures of industrial equipment.
4. A method according to claim 3 wherein said bolts, gaskets or other fastening power elements are previously shape-memorized either to the tension or to compression, flexion, torsion, or to their combinations obtaining conserved residual shape-memorized deformations under temperatures of martensite state during loading-unloading.
5. A method according to claim 1 wherein said mechanical fasteners interact with adjacent rigid component parts of said industrial equipment under temperatures of martensitic phase transformation to provide a constrained recovery of conserved residual shape-memorized deformation that generates a reactive shape-recovering forces having direction inverse to the direction of operating creep of said mechanical fasteners.
6. A method according to claim 1 that is called the “Method of “negative creep”.
7. A device to limit or to exclude operating creep of mechanical fasteners including bolts manufactured from shape memory alloy and previously shape-memorized to the compression.
8. A device according to claim 7 including the gasket manufactured from shape memory alloy and previously shape-memorized to the tension.
9. A device according to claim 7 including the gasket manufactured from typically used material.
10. A device including the bolts manufactured from typically used structural steel and gasket manufactured from shape memory alloy and previously shape-memorized to the tension.
11. A device according to claim 10 wherein the bolts have internal axial hollow channel adapted to place and to fix firmly a shank manufactured from shape memory alloy and previously shape-memorized to the compression.
12. A device according to claim 11 wherein the gasket is manufactured from typically used material.
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/834,955 US20050244245A1 (en) | 2004-04-30 | 2004-04-30 | Method and devices to limit a creep of mechanical fasteners |
US12/148,800 US20080199273A1 (en) | 2004-04-30 | 2008-04-23 | Method to limit a creep of bolts and gaskets of bolted flanged connections |
US12/214,741 US7699556B2 (en) | 2003-11-03 | 2008-06-23 | Bolted flanged connection on a basis of shape memory effect and inverse flexion flange design |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/834,955 US20050244245A1 (en) | 2004-04-30 | 2004-04-30 | Method and devices to limit a creep of mechanical fasteners |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/972,891 Continuation US20060017233A1 (en) | 2003-11-03 | 2004-10-26 | Flange design conception: flanges of inverse flexion |
Related Child Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/148,800 Continuation US20080199273A1 (en) | 2004-04-30 | 2008-04-23 | Method to limit a creep of bolts and gaskets of bolted flanged connections |
US12/214,741 Continuation US7699556B2 (en) | 2003-11-03 | 2008-06-23 | Bolted flanged connection on a basis of shape memory effect and inverse flexion flange design |
Publications (1)
Publication Number | Publication Date |
---|---|
US20050244245A1 true US20050244245A1 (en) | 2005-11-03 |
Family
ID=35187261
Family Applications (3)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/834,955 Abandoned US20050244245A1 (en) | 2003-11-03 | 2004-04-30 | Method and devices to limit a creep of mechanical fasteners |
US12/148,800 Abandoned US20080199273A1 (en) | 2004-04-30 | 2008-04-23 | Method to limit a creep of bolts and gaskets of bolted flanged connections |
US12/214,741 Expired - Fee Related US7699556B2 (en) | 2003-11-03 | 2008-06-23 | Bolted flanged connection on a basis of shape memory effect and inverse flexion flange design |
Family Applications After (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/148,800 Abandoned US20080199273A1 (en) | 2004-04-30 | 2008-04-23 | Method to limit a creep of bolts and gaskets of bolted flanged connections |
US12/214,741 Expired - Fee Related US7699556B2 (en) | 2003-11-03 | 2008-06-23 | Bolted flanged connection on a basis of shape memory effect and inverse flexion flange design |
Country Status (1)
Country | Link |
---|---|
US (3) | US20050244245A1 (en) |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2431606A (en) * | 2005-10-28 | 2007-05-02 | Rolls Royce Plc | A method for joining components |
US20070241516A1 (en) * | 2006-04-18 | 2007-10-18 | Anatoly Efremov | Negative creep gasket with core of shape memory alloy |
US20080199273A1 (en) * | 2004-04-30 | 2008-08-21 | Anatoly Efremov | Method to limit a creep of bolts and gaskets of bolted flanged connections |
US20100266361A1 (en) * | 2009-04-17 | 2010-10-21 | United Technologies Corporation | High Temperature Thread Locking Compound |
US20110135418A1 (en) * | 2009-12-07 | 2011-06-09 | Kirkwood Brad L | Self expanding fastener |
CN103527601A (en) * | 2013-10-29 | 2014-01-22 | 潍柴动力股份有限公司 | Connecting structure and fastening element thereof |
CN104482338A (en) * | 2014-12-09 | 2015-04-01 | 同济大学 | Water supply line K-shaped joint with emergency self-recovery capability |
CN112038158A (en) * | 2020-07-16 | 2020-12-04 | 湖南长高高压开关集团股份公司 | Method for processing abnormal temperature rise of isolating switch and isolating switch |
Families Citing this family (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2931874B1 (en) * | 2008-05-29 | 2010-06-25 | Snecma | AXIAL BLOCKING DEVICE FOR TREE GUIDE BEARING IN TURBOMACHINE. |
DE102008062917A1 (en) * | 2008-12-23 | 2010-07-01 | J. Eberspächer GmbH & Co. KG | flange |
US8579535B2 (en) | 2009-09-15 | 2013-11-12 | The United States Of America As Represented By The Secretary Of The Navy | Micro-coupling active release mechanism |
US8708322B2 (en) | 2010-11-05 | 2014-04-29 | Honeywell International Inc. | Payload launch lock mechanism |
CN103206584B (en) * | 2013-04-24 | 2015-05-06 | 山东大学 | Non-loosened seabed oil pipeline flange connection structure and connection method |
US11506238B2 (en) * | 2013-06-14 | 2022-11-22 | James Alan Monroe | Thermally stabilized fastener system and method |
CN107918721B (en) * | 2017-11-22 | 2019-06-21 | 北京千乘探索科技有限公司 | The heated length of the supply air line of satellite tank determines method and apparatus |
GB2587281B (en) | 2018-07-19 | 2022-11-23 | Halliburton Energy Services Inc | Techniques to improve wireless communications for in-situ wellbore devices |
NO20210649A1 (en) | 2018-12-26 | 2021-05-20 | Halliburton Energy Services Inc | Method and system for creating metal-to-metal seal |
US11420755B2 (en) | 2019-08-08 | 2022-08-23 | General Electric Company | Shape memory alloy isolator for a gas turbine engine |
US11828235B2 (en) | 2020-12-08 | 2023-11-28 | General Electric Company | Gearbox for a gas turbine engine utilizing shape memory alloy dampers |
Citations (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3759552A (en) * | 1970-09-08 | 1973-09-18 | Raychem Corp | Hydraulic coupling with metallic sealing member |
US4001928A (en) * | 1973-01-04 | 1977-01-11 | Raychem Corporation | Method for plugging an aperture with a heat recoverable plug |
US4149311A (en) * | 1977-09-22 | 1979-04-17 | Banner/Technical Devices Inc. | Work station for facilitating component assembly |
US4198081A (en) * | 1973-10-29 | 1980-04-15 | Raychem Corporation | Heat recoverable metallic coupling |
US4281841A (en) * | 1978-03-30 | 1981-08-04 | The United States Of America As Represented By The United States Department Of Energy | O-Ring sealing arrangements for ultra-high vacuum systems |
US4297779A (en) * | 1978-08-10 | 1981-11-03 | Bbc Brown, Boveri & Company, Limited | Method of joining structural elements |
US4450616A (en) * | 1981-07-03 | 1984-05-29 | Yamashina Seiko-Sho, Ltd. | Method of ensuring the tightness of a bolt and a nut |
US4469357A (en) * | 1975-04-09 | 1984-09-04 | Raychem Corporation | Composite coupling |
US4501058A (en) * | 1979-08-27 | 1985-02-26 | Pda Engineering | Method of pre-stressing a structural member |
US4537406A (en) * | 1983-04-27 | 1985-08-27 | L'garde, Inc. | Hostile environment joint seal and method for installation |
US4773680A (en) * | 1984-09-04 | 1988-09-27 | Beta Phase, Inc. | Pipe couplers |
US4897006A (en) * | 1987-09-04 | 1990-01-30 | Aerospatiale Societe Nationale Industrielle | Device for exerting a pressure developing in stages on a part |
US5010949A (en) * | 1988-03-22 | 1991-04-30 | Bull, S.A. | Device for fastening together under pressure two pieces, one to the other |
US5226683A (en) * | 1990-11-16 | 1993-07-13 | Julien Gerald J | Reusable metallic seal using memory metal |
US5791847A (en) * | 1993-11-30 | 1998-08-11 | Kvaerner Tamturbine Oy | Washer and method for using the washer |
US6199453B1 (en) * | 1998-04-28 | 2001-03-13 | Steinbock Machinery Co. | High temperature bolting system |
US6435519B1 (en) * | 1999-05-14 | 2002-08-20 | Patrick Michel White | Stress-induced gasket |
Family Cites Families (26)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE124715C (en) | ||||
DE64013C (en) | E. SCHWOERER in Colmar i. Elsafs | Flange seal with putty and inlaid metal ring | ||
US943461A (en) * | 1906-10-08 | 1909-12-14 | Gen Fire Extinguisher Co | Pipe-coupling. |
US2157357A (en) * | 1936-05-15 | 1939-05-09 | Smith Corp A O | Alloy-lined tubular connection for vessels |
US2412487A (en) | 1944-01-03 | 1946-12-10 | Dow Chemical Co | Thermoplastic pipe flange |
FR1024183A (en) | 1950-08-29 | 1953-03-30 | Syndicat Dauphinois D Apprenti | Autoclave flanges for superheated fluid at high pressure |
US3135538A (en) | 1959-05-18 | 1964-06-02 | Chemetron Corp | Flanged pipe joint having one flange deflectable |
DE1947306B2 (en) * | 1969-09-18 | 1972-04-20 | Schnabel, Ernst, Dr., 6250 Limburg | CONNECTION OF TWO METAL PARTS CLADED OR CLADED WITH PLASTIC |
GB1382191A (en) * | 1972-03-08 | 1975-01-29 | Doncaster Sons Ltd Daniel | Hydraulic jacking devices |
US3859802A (en) * | 1973-06-20 | 1975-01-14 | Bethlehem Steel Corp | Gasketed watertight segmented tunnel linings |
US4489964A (en) * | 1981-12-30 | 1984-12-25 | Shell Oil Company | Memory metal connector |
US4913951A (en) * | 1988-07-26 | 1990-04-03 | Garlock Inc. | Fabrication of reinforced PTFE gasketing material |
DE4228847C1 (en) * | 1992-08-29 | 1993-11-25 | Daimler Benz Ag | Metallic damping body |
CN1066806C (en) * | 1993-11-30 | 2001-06-06 | 克瓦尔纳坦姆涡轮机股份公司 | Pre-tensioning device for fastening elements and method for pretensioning fastening element |
US5536126A (en) * | 1994-06-10 | 1996-07-16 | Hughes Aircraft Company | Assembly with solid state, phase transformable locking fastener |
US5876070A (en) * | 1996-12-11 | 1999-03-02 | Kennecott Holdings Corporation | Pipe flange connection for pressure retaining, abrasive/corrosive service |
US6126371A (en) * | 1999-04-05 | 2000-10-03 | Lockheed Martin Corporation | Shape memory metal alloy preload attenuation device |
DE19934157B4 (en) * | 1999-07-21 | 2004-12-09 | Eads Deutschland Gmbh | Fastening device for a cryogenic satellite tank |
US6637995B1 (en) * | 2000-02-09 | 2003-10-28 | Patrick Michel White | Super-elastic rivet assembly |
US6688828B1 (en) * | 2000-12-01 | 2004-02-10 | Arizona Board Of Regents | Self-torquing fasteners |
US20040067122A1 (en) * | 2002-02-26 | 2004-04-08 | Arizona Board Of Regents | Self-torquing fasteners |
US6869081B1 (en) * | 2002-12-20 | 2005-03-22 | Jjenco, Inc. | Constant seating stress gasket system |
US20060017233A1 (en) * | 2003-11-03 | 2006-01-26 | Anatoly Efremov | Flange design conception: flanges of inverse flexion |
US20050244245A1 (en) * | 2004-04-30 | 2005-11-03 | Anatoly Efremov | Method and devices to limit a creep of mechanical fasteners |
US20070241516A1 (en) * | 2006-04-18 | 2007-10-18 | Anatoly Efremov | Negative creep gasket with core of shape memory alloy |
US20080075557A1 (en) * | 2006-09-22 | 2008-03-27 | Johnson A David | Constant load bolt |
-
2004
- 2004-04-30 US US10/834,955 patent/US20050244245A1/en not_active Abandoned
-
2008
- 2008-04-23 US US12/148,800 patent/US20080199273A1/en not_active Abandoned
- 2008-06-23 US US12/214,741 patent/US7699556B2/en not_active Expired - Fee Related
Patent Citations (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3759552A (en) * | 1970-09-08 | 1973-09-18 | Raychem Corp | Hydraulic coupling with metallic sealing member |
US4001928A (en) * | 1973-01-04 | 1977-01-11 | Raychem Corporation | Method for plugging an aperture with a heat recoverable plug |
US4198081A (en) * | 1973-10-29 | 1980-04-15 | Raychem Corporation | Heat recoverable metallic coupling |
US4469357A (en) * | 1975-04-09 | 1984-09-04 | Raychem Corporation | Composite coupling |
US4149311A (en) * | 1977-09-22 | 1979-04-17 | Banner/Technical Devices Inc. | Work station for facilitating component assembly |
US4281841A (en) * | 1978-03-30 | 1981-08-04 | The United States Of America As Represented By The United States Department Of Energy | O-Ring sealing arrangements for ultra-high vacuum systems |
US4297779A (en) * | 1978-08-10 | 1981-11-03 | Bbc Brown, Boveri & Company, Limited | Method of joining structural elements |
US4501058A (en) * | 1979-08-27 | 1985-02-26 | Pda Engineering | Method of pre-stressing a structural member |
US4450616A (en) * | 1981-07-03 | 1984-05-29 | Yamashina Seiko-Sho, Ltd. | Method of ensuring the tightness of a bolt and a nut |
US4537406A (en) * | 1983-04-27 | 1985-08-27 | L'garde, Inc. | Hostile environment joint seal and method for installation |
US4773680A (en) * | 1984-09-04 | 1988-09-27 | Beta Phase, Inc. | Pipe couplers |
US4897006A (en) * | 1987-09-04 | 1990-01-30 | Aerospatiale Societe Nationale Industrielle | Device for exerting a pressure developing in stages on a part |
US5010949A (en) * | 1988-03-22 | 1991-04-30 | Bull, S.A. | Device for fastening together under pressure two pieces, one to the other |
US5226683A (en) * | 1990-11-16 | 1993-07-13 | Julien Gerald J | Reusable metallic seal using memory metal |
US5791847A (en) * | 1993-11-30 | 1998-08-11 | Kvaerner Tamturbine Oy | Washer and method for using the washer |
US6199453B1 (en) * | 1998-04-28 | 2001-03-13 | Steinbock Machinery Co. | High temperature bolting system |
US6435519B1 (en) * | 1999-05-14 | 2002-08-20 | Patrick Michel White | Stress-induced gasket |
Cited By (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20080199273A1 (en) * | 2004-04-30 | 2008-08-21 | Anatoly Efremov | Method to limit a creep of bolts and gaskets of bolted flanged connections |
US7841060B2 (en) | 2005-10-28 | 2010-11-30 | Rolls-Royce Plc | Method for joining components |
GB2431606B (en) * | 2005-10-28 | 2007-12-12 | Rolls Royce Plc | Method for joining components |
US20070095442A1 (en) * | 2005-10-28 | 2007-05-03 | Daniel Clark | Method for joining components |
GB2431606A (en) * | 2005-10-28 | 2007-05-02 | Rolls Royce Plc | A method for joining components |
US20070241516A1 (en) * | 2006-04-18 | 2007-10-18 | Anatoly Efremov | Negative creep gasket with core of shape memory alloy |
US20100266361A1 (en) * | 2009-04-17 | 2010-10-21 | United Technologies Corporation | High Temperature Thread Locking Compound |
US9033631B2 (en) * | 2009-04-17 | 2015-05-19 | United Technologies Corporation | High temperature thread locking compound |
US20110135418A1 (en) * | 2009-12-07 | 2011-06-09 | Kirkwood Brad L | Self expanding fastener |
US8388292B2 (en) * | 2009-12-07 | 2013-03-05 | The Boeing Company | Self expanding fastener |
US8918978B2 (en) | 2009-12-07 | 2014-12-30 | The Boeing Company | Self expanding fastener |
CN103527601A (en) * | 2013-10-29 | 2014-01-22 | 潍柴动力股份有限公司 | Connecting structure and fastening element thereof |
CN104482338A (en) * | 2014-12-09 | 2015-04-01 | 同济大学 | Water supply line K-shaped joint with emergency self-recovery capability |
CN112038158A (en) * | 2020-07-16 | 2020-12-04 | 湖南长高高压开关集团股份公司 | Method for processing abnormal temperature rise of isolating switch and isolating switch |
Also Published As
Publication number | Publication date |
---|---|
US20080267731A1 (en) | 2008-10-30 |
US20080199273A1 (en) | 2008-08-21 |
US7699556B2 (en) | 2010-04-20 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US7699556B2 (en) | Bolted flanged connection on a basis of shape memory effect and inverse flexion flange design | |
US6199453B1 (en) | High temperature bolting system | |
US20070241516A1 (en) | Negative creep gasket with core of shape memory alloy | |
US20120286480A1 (en) | Negative creep corrugated gasket and methods of manufacturing same | |
Winter | Gasket selection—A flowchart approach | |
Walczak et al. | Tightness and material aspects of bolted flange connections with gaskets of nonlinear properties exposed to variable loads | |
Efremov | Bolted flanged connection for critical engineering applications | |
Sawa et al. | Effects of scattered bolt preload on the sealing performance of pipe flange connection with gaskets under external bending moment and internal pressure | |
Efremov | Creep Limitation of Bolted Fasteners and Gaskets | |
Krovvidi et al. | Comparison between RCC-MR and ASME section-III/NH for creep-fatigue design of bellows | |
US20060017233A1 (en) | Flange design conception: flanges of inverse flexion | |
Waterland III | Gasket selection and assembly criteria for internal sealing manways and handholes | |
Van Zyl et al. | Numerical Simulation of the Creep Failure of a Steam Reformer Outlet Manifold | |
Lassesen et al. | Compact flanged connections for high temperature applications | |
Bouzid et al. | On the strength and tightness of ASME B16. 5 and B16. 47 series a standard flanges | |
Kettler et al. | Experimental and Numerical Investigations on the Relaxation Behaviour of Power Plant Flange Connections Under Steady State and Transient Conditions | |
Currie | The Follow Up on Profiled Wire Gasket Development and Testing With Case Studies | |
Bouzid et al. | Integrity and leak tightness of ASME B. 16.5 and B. 16.47 flanges used in nuclear piping systems | |
Cooper et al. | Design criteria for high-pressure, high-temperature bolting: A state-of-the-art summary | |
Squires | Steam Inlet Expansion Joint Design & Case Study: Surface Condenser Application | |
Hau et al. | LMP and Omega Creep Testing of HPMA Centrifugally Cast Fe-Cr-Ni Alloys | |
Hantsch | Bolted High Pressure Girth Flange Connections | |
Groppi et al. | New Breech-Lock Exchanger Design to Ensure Gasket Sealing Under All Conditions | |
Yamanaka | Estimation of Bolt Creep Characteristics and Sealing Performance of Flanged Joints | |
Wesley | Interfacing Systems LOCA (ISLOCA) component pressure capacity methodology and typical plant results |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |