Patent Document

CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority under 35 U.S.C. §119 of German Patent Application DE 10 2011 001 208.7 filed Mar. 10, 2011 and German Patent Application DE 10 2011 001 335.0 filed Mar. 16, 2011, the entire contents of each of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention pertains to an insulation cassette for the heat insulation of elongated elements with a multilayer insulation made of flat reflection elements, wherein each layer of the insulation has at least two flat reflection elements, which overlap at least partly at their ends, a plurality of pushing guides are arranged in an overlapping area between a first cassette part and a second cassette part, and the pushing guides have an elongated hole, in which a bolt is displaceably guided. 
     BACKGROUND OF THE INVENTION 
     Such an insulation cassette is known from DE 25 21 136 A1. The bolts extends here through the inner and outer limiting plates and all reflection plates of the cassette parts. 
     According to the introduction to the specification for the state of the art, U.S. Pat. No. 4,659,601 A also pertains to an insulation cassette, in which a bolt passes through all layers of the insulation cassette. It is disadvantageous here that a thermal bridge is formed by the passage of the bolt from the inside of the insulation cassette through all insulation layers up to the outside. 
     An insulation cassette for the heat insulation of elongated elements with a multilayer insulation made of flat reflection elements is known from EP 0 033 487 A1, wherein each layer of the insulation has at least two flat reflection elements, which overlap at least partly at their ends facing each other. 
     Insulation cassettes, which are also called reflection metal insulation or all-metal insulation, are used for the heat insulation of pipelines. In particular, such insulation cassettes are used to insulate cooling water pipes of nuclear power plants. A good insulating effect is obtained, especially at high temperatures, because of the multilayer arrangement of the flat reflection elements consisting of reflection foils. Typical areas of application of such insulation cassettes in nuclear power plants are temperature ranges of up to about 350° C. 
     However, a rather substantial problem arises due to longitudinal thermal expansion because of the comparatively great temperature gradients and the all-metal design of the insulation. Moreover, the insulation cassettes can be prefabricated in an accurately fitting manner up to a certain size only, so that adapters must be made to size on site during assembly for adaptation to the actually needed lengths. For example, insulation cassettes in a stepped fold arrangement are therefore used to compensate the longitudinal thermal expansion in order to make possible a necessary longitudinal expansion. However, the problem with these stepped fold cassettes is that open gaps do occur at times. These gaps are prone to trouble and, in addition, impair the quality of the insulation. 
     SUMMARY OF THE INVENTION 
     An underlying object of the present invention is therefore to provide an insulation cassette, with which length adjustments can be carried out without impairment of the insulating effect. 
     The object is accomplished by the bolt being rigidly connected to the shell of the second cassette part in an insulation cassette of the above-mentioned type and extending through the elongated hole associated with the first cassette part. 
     A displacement of the flat reflection elements of one layer relative to one another can take place in this manner in the present invention in the area of the overlap without a gap being able to open. A length adjustment is thus possible as a compensation for longitudinal thermal expansion of the material or for providing the desired length as an adapter in the area of the overlap, without the insulation properties of the insulation cassette being impaired due to the opening of gaps. 
     A variant of the present invention is characterized in that the flat reflection elements are metal foils, preferably foils from stainless steel, vanadium steel, especially austenitic steel. Such metal foils possess good reflection properties for radiation. In addition, stainless steel, vanadium steel, especially austenitic steel, are resistant to corrosion and resistant, and, moreover, it has a poor thermal conductivity, which improves the insulation properties. However, it is also possible to use aluminum foil if lower requirements are imposed on the material. 
     In a preferred embodiment of the present invention, the flat reflection elements are arranged concentrically, especially with a radial distance of 4 mm to 15 mm, preferably 6 mm to 10 mm. This concentric arrangement makes possible a plurality of layers of the flat reflection elements around a component to be insulated, especially a pipeline. A homogeneous insulation effect is obtained by maintaining uniform distances between the reflection elements. 
     Another embodiment of the present invention is characterized in that the flat reflection elements have spacers, preferably knobs, which are prepared especially on both sides of the reflection elements, preferably by means of controlled deformation of the reflection elements. These spacers, especially knobs, make it possible to set the distance between the reflection elements uniformly. At the same time, reflection elements that are located adjacent to each other come into contact with one another only in a punctiform manner in the area of the spacers, so that no appreciable impairment of the insulation effect occurs here relative to the surface. 
     It is advantageous in this connection if the reflection elements with spacers are arranged alternatingly with reflection elements without spacers such that they alternatingly follow each other. This leads to a simple design and simple assembly, because the reflection elements that are located adjacent to one another can be displaced in relation to one another for assembly. In addition, no problems can occur during assembly due to interlocking of spacers of two adjacent flat reflection elements. 
     Another embodiment of the present invention is characterized in that an outer shell is provided, which has a plurality of shell parts, wherein shell parts located preferably axially and/or tangentially adjacent to one another can be axially and/or tangentially displaced in relation to one another by means of a pushing guide. These shell parts, which are axially and/or tangentially displaceable in relation to one another, can cover and envelope in this manner the flat reflection elements of each layer, which are likewise displaceable axially and/or tangentially in relation to one another, so that these are well protected against damage. At the same time, a length adjustment is not hindered by this embodiment. The pushing guide may have an elongated hole and a bolt guided therein. Such a pushing guide can be manufactured in a simple manner and can be used reliably. 
     It is also possible for the shell parts to have quick-acting closures, especially toggle-type fasteners, for connecting the shell parts to one another and/or to axially and/or tangentially adjacent insulation cassettes. An element to be insulated, especially a pipeline, can be retrofitted with an insulation rapidly and in a simple manner with preassembled shell parts of an insulation system. In addition, the insulation system can be opened and reclosed at any time at any desired point for maintenance and repair purposes. 
     In an advantageous embodiment of the present invention, the second cassette part has a mount for a branching of a pipe system. A length adjustment is thus possible in a simple manner in the area of branching as well. 
     If the first cassette part and/or the second cassette part has a projection and/or fold for guiding the respective other cassette part on its shell, simple assembly and reliable guiding in relation to one another can be achieved in case of changes in length. It is especially advantageous in this case if the projection and/or the fold has a height that corresponds approximately to half the guide length of the pushing guide, and is especially slightly greater. Reliable guiding of the cassette parts in relation to one another is guaranteed in this manner during assembly or in case of changes in length over the entire or at least nearly the entire guide length of the pushing guide. 
     Another advantage of the present invention pertains to the use of an insulation cassette according to the present invention as a compensating element for compensating longitudinal thermal changes and/or as an adapter for variable length adjustment during assembly. A length adjustment can thus be performed if needed in a simple manner and without impairment of the insulation. 
     Another advantage of the present invention arises in connection with the use of an insulation cassette according to the present invention for insulating pipelines, especially cooling water pipes of nuclear power plants, preferably in the area of branching. Stable and durable insulation with long service life, good insulation properties and good adaptability to changes in length is obtained here. 
     An exemplary embodiment of the present invention will be described in more detail below on the basis of the drawings. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an insulation system with features of the present invention; 
         FIG. 2  is sectional view taken at line A-A in  FIG. 1 ; 
         FIG. 3  is a detail view according to detail z in  FIG. 1 , showing a pushing guide; 
         FIG. 4  is a sectional view of the pushing guide according to detail y in  FIG. 2 ; 
         FIG. 5  is a schematic view of the variable-length insulation cassette from  FIG. 1  with cassette parts detached from one another; 
         FIG. 6  is a front view of a cassette part from  FIG. 5 ; 
         FIG. 7  is an enlarged detail view of the cassette part from  FIG. 6 ; 
         FIG. 8  is a partly cut-away perspective view of an upper part of an insulation cassette as another exemplary embodiment of the present invention; and 
         FIG. 9  is a view similar to that in  FIG. 8  of a lower part of the insulation cassette. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings in particular,  FIG. 1  shows an insulating system  10  in a perspective view as an exemplary embodiment of the present invention. As can be seen in the figure, insulation system  10  has an insulation cassette  11 , adjacent to which an insulation cassette  12  each is arranged in the axial direction. The insulation cassettes  12  are prior-art all-metal insulation cassettes in the exemplary embodiment being shown, in which a multilayer insulation each, made of reflection metal foils, is arranged in a housing. 
     In the exemplary embodiment being shown, insulation cassette  11  has a first cassette part  13  and a second cassette part  14 , which are displaceable in relation to one another in the axial direction, as will be explained in more detail below. 
     The first cassette part  13  has two cassette part elements  15 ,  16  in the exemplary embodiment being shown, whereas the second cassette part  14  has two cassette part elements  17 ,  18  in a similar manner. 
     The respective cassette part elements  15  and  16  as well as  17  and  18  are connected to one another by means of quick-acting closures, which are toggle-type fasteners in the exemplary embodiment being shown. The cassette part elements  15  through  18  are connected to the adjoining insulation cassettes  12  in the same manner, likewise by means of quick-acting closures, namely, by means of toggle-type fasteners  19 . 
     In addition, it can be determined from the figure that a plurality of pushing guides  20  are arranged in an overlapping area between the first cassette part  13  and the second cassette part  14 . A total of four pushing guides can be seen in the figure, but only two of these pushing guides are provided with a reference number. 
       FIG. 2  shows section A-A from  FIG. 1 . As can be determined from the figure, the cassette part elements  16 ,  18  are made similarly from a plurality of layers of flat reflection elements  21 ,  22 . The flat reflection elements are specifically metal foils  21 ,  22 , namely, stainless steel foils in the exemplary embodiment being shown. The metal foils  21  have a plurality of alternatingly arranged knobs  23  and are thus made as a knobbed foil  21 . Contrary to this, the metal foils  22  are always flat. 
     The knobbed foils  21  and the flat foils  22  are arranged alternatingly adjacent to each other in the exemplary embodiment being shown. The foils  21 ,  22  of the cassette part elements  16 ,  18  overlap each other in an area  24 . As can also be determined from the figure, the foils  21 ,  22  are welded at their ends facing away from area  24  to a shell of the cassette part elements  16 ,  18  by means of a plurality of weld spots  25 , of which only two weld spots  25  are provided with a reference number in the figure for the sake of greater clarity. 
     As can also be determined from the figure, the knobs  23  are used to establish a defined air gap  26  between mutually adjacent metal foils  21 ,  22 . 
       FIG. 3  shows a pushing guide  20  according to detail z in  FIG. 1 . As can be determined from the figure, the pushing guide  20  has an elongated hole  27 , in which a bolt  28  is guided displaceably. Bolt  28  is a threaded bolt  28  in the exemplary embodiment being shown, onto which a nut  29  is screwed with a plain washer  30  placed under it. 
       FIG. 4  shows an enlarged detail view in the area of pushing guide  20  according to detail y in  FIG. 2 . As can be determined from  FIGS. 3 and 4 , bolt  28  is rigidly connected to the shell of cassette part element  18  and extends through the elongated hole  27 . Bolt  28  is secured against leaving the elongated hole  27  by means of plain washer  30  and nut  29 , and nut  29  can be reliably prevented from accidentally separating from the threaded bolt  28  by a weld spot at the connection point between nut  29  and bolt  28 . The displacement range of the maximum length adjustment of the insulation cassette  11  due to displacement of the cassette part elements  16 ,  18  in relation to one another is limited by the length of elongated hole  27 , as is indicated by a double arrow in  FIG. 3 . 
       FIG. 5  shows the cassette part elements  15 ,  16 ,  17 ,  18  in the state in which they are removed from each other in a schematic exploded view. As can be determined from the figure, the knobbed foils  21  protrude from the shell at the cassette part elements  15 ,  16 . It is ensured in this manner that no state is reached in which there is no overlap of the mutually adjacent foils any more in area  24  when the cassette part elements  15 ,  16  are displaced against the cassette part elements  17 ,  18 . In addition, simpler pushing into the cassette part elements  17 ,  18  is possible due to the protrusion of the insulating foils  21 ,  22  over the cassette part elements  15 ,  16 . As can also be determined from the figure, the cassette part elements  16 ,  18  have folds  31  at their respective ends facing the cassette part elements  15 ,  17 , which folds act as guides for the cassette part elements  15 ,  17  and, moreover, prevent the formation of a gap between the cassette part elements  15 ,  17  and the cassette part elements  16 ,  18 . 
       FIG. 6  shows a front view of cassette part element  16 . Only three metal foils  21 ,  22  are shown in the figure for the sake of greater clarity. As can be determined from the figure, folds  31  are provided on sides of the cassette part elements  16 , which sides are facing away from each other. A cassette part element  15  can thus be arranged during assembly on the cassette part element  16  and held and guided by the folds  31  reliably and securely until fastening the toggle-type fasteners  19 . It shall be pointed out here that the use of knobbed foils  21  can be eliminated for small diameters of the insulation cassette  11 . A plurality of layers of concentrically arranged metal foils  22  may also be used alone in this case, because the inherent rigidity of the metal foil  22  is sufficient for setting a defined distance between the layers. 
       FIG. 7  shows an enlarged partial view of the connection area of the metal foils  21 ,  22  with the shell of cassette part element  16 . As can be determined from the figure, the metal foils  21 ,  22  are bent over each in a U-shaped pattern at the connection-side end and connected each to the shell of the cassette part element  16 . The ends of the metal foils  21 ,  22  bent over in a U-shaped manner are used in this manner for secure fastening, on the one hand, and as spacer elements, on the other hand. 
     The mode of action of the insulation cassette  11  will be explained below on the basis of the figures. As can be determined, for example, from  FIG. 2 , the individual layers of the metal foils  21 ,  22  and of the shell are formed in area  24  such that they overlap in layers. In case of a length adjustment with the insulation cassette  11 , for example, for adjustment to the desired length during assembly or to compensate thermal expansions, the individual layers of the metal foils  21 ,  22  of the shell can thus slide on each other. The maximum adjustment is limited by the guiding of bolt  28  in elongated hole  27 . The pipeline arranged in the insulation system  10  is accessible for maintenance or repair purposes at any time by means of the toggle-type fasteners  19 . 
       FIG. 8  shows an upper part of an insulation cassette  33  in a partly cut-away perspective view as another exemplary embodiment of the present invention.  FIG. 9  shows a lower part of the insulation cassette  33  in a view similar to that in  FIG. 8 . Identical elements carry the same reference numbers as in insulation cassette  11 . 
     As can be determined from the figures, insulation cassette  33  has a first cassette part  34  and a second cassette part  35 . The design of the cassette parts  34 ,  35  corresponds essentially to that of the cassette parts  13 ,  14 . The first cassette part  34  has two cassette elements  36 ,  37  and the second cassette part  35  has two cassette elements  38 ,  39 . Cassette elements  38 ,  39  have mounts  40 ,  41  each, which together form a mount for a branch of a pipeline in the mounted state. 
     Cassette elements  36 ,  37  have a shell  42  each, which envelope the flat reflection elements, namely, the metal foils  21 ,  22 . In addition, the cassette elements  36 ,  37  have projections  43  adjoining the shell and adjacent to the cassette elements  38 ,  39 . Pushing guides  20 , which have the components already explained above and have the mode of action already explained above, are arranged in the area of the projections  43 . Pushing guides  20  are likewise arranged between the cassette elements  37 ,  39 , but these pushing guides cannot be seen in  FIG. 9 . Furthermore, the cassette elements  37 ,  39  also have folds  31 , which face the cassette elements  36 ,  38  and are adjacent to same in the mounted state. 
     The two parts of insulation cassette  33  are placed on one another in the area of the branch during assembly such that the mounts  40 ,  41  of the cassette elements  38 ,  39  together form a mount for mounting the branching pipe section. The folds  31  and the projections  43  each form a guide to facilitate the insertion of cassette element  39  into cassette element  36 . Because of the pushing guides, the dimensions of the insulation cassette do not have to be exactly coordinated with the position of the branch. Rather, it is sufficient if dimensional stability is given to the extent that the deviations are in the range of which can be compensated with pushing guide  20 . 
     Changes in the length of the main pipe or container, from which a pipe branches off, which changes occur during the operation due to temperature changes, can be compensated with the pushing guide in the manner explained above. Mutually adjacent metal foils  21 ,  22  can slide on one another in the area of their overlap, and thus likewise permit a length compensation, without weak points developing in the insulation. 
     While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles. 
     APPENDIX 
     List of Reference Numbers 
     
       
         
               
               
             
           
               
                   
               
             
             
               
                 10 
                 Insulation system 
               
               
                 11 
                 Insulation cassette 
               
               
                 12 
                 Insulation cassette 
               
               
                 13 
                 First cassette part 
               
               
                 14 
                 Second cassette part 
               
               
                 15 
                 Cassette part element 
               
               
                 16 
                 Cassette part element 
               
               
                 17 
                 Cassette part element 
               
               
                 18 
                 Cassette part element 
               
               
                 19 
                 Toggle-type fastener 
               
               
                 20 
                 Pushing guide 
               
               
                 21 
                 Knobbed foil 
               
               
                 22 
                 Foil 
               
               
                 23 
                 Knob 
               
               
                 24 
                 Area 
               
               
                 25 
                 Weld spot 
               
               
                 26 
                 Air gap 
               
               
                 27 
                 Elongated hole 
               
               
                 28 
                 Bolt 
               
               
                 29 
                 Nut 
               
               
                 30 
                 Plain washer 
               
               
                 31 
                 Fold 
               
               
                 32 
                 Weld spot 
               
               
                 33 
                 Insulation cassette 
               
               
                 33 
                 Insulation cassette 
               
               
                 34 
                 First cassette part 
               
               
                 35 
                 Second cassette part 
               
               
                 36 
                 Cassette element 
               
               
                 37 
                 Cassette element 
               
               
                 38 
                 Cassette element 
               
               
                 39 
                 Cassette element 
               
               
                 40 
                 Mount 
               
               
                 41 
                 Mount 
               
               
                 42 
                 Projection

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