Abstract:
An integral seal and sealant package includes a prefabricated seal element having multiple surfaces; a high-temperature sealant composition engaged with one or more of the multiple surfaces; and a backer material enclosing the prefabricated seal element and the high-temperature sealant composition. The backer material has composition permitting the backer material to be installed with the seal element and the sealant composition between adjacent components to be sealed.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to static seals for use in turbine machines and, specifically, to a prepackaged seal and sealant configuration for use in gas turbine seal slots. 
     In current practice, solid or cloth seals are often used in static seal arrangements in certain gas turbine components. One such cloth seal is described in commonly-owned U.S. Pat. No. 5,657,998. There has been some thought about utilizing cloth or other hard seals in combination with high temperature sealants. There is a concern, however, that application of the sealant with a caulk gun or some other uncontrolled means may well result in the sealant material being applied incorrectly, and/or in the wrong locations. It would be desirable, therefore, to devise a more reliable and effective approach to the application of seals and associated sealants that not only facilitates the installation process, but that also increases the robustness of the seals. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with a first exemplary but nonlimiting embodiment, the present invention provides an integral seal and sealant package comprising: a prefabricated seal element having multiple surfaces; a high-temperature sealant composition engaged with one or more of the multiple surfaces; and a backer material enclosing the prefabricated seal element and the high-temperature sealant composition, the backer material having a composition permitting the backer material to be installed with the seal element and the sealant composition between adjacent components to be sealed. 
     In another exemplary but nonlimiting embodiment, there is provided an integral sealant package for insertion between adjacent turbine components comprising a high-temperature sealant composition formed as an elongated strip at least partially wrapped in a film suitable for placement with the sealant composition in a sealing environment. 
     In still another exemplary but nonlimiting aspect, there is provided a method of installing an integral seal and sealant between a pair of adjacent components in a turbine machine comprising cutting a seal element to a desired size and shape; laying the seal element on a backer sheet comprised of a material that will burn away at a temperature less than a specified service temperature of the adjacent components; applying a high-temperature sealant to at least one or more sides of the seal element; wrapping the backer sheet about the seal element so as to substantially completely enclose the seal element and the high-temperature sealant, thereby forming an integral seal and sealant package; locating the integral seal and sealant package in position between the pair of adjacent components; and operating the turbine machine so that the adjacent components reach the specified service temperature, and causing the backer material to melt and/or burn away, leaving the seal element and the high-temperature sealant in place. 
     The invention will now be described in connection with the drawings identified below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic cross section illustrating alternative embodiments of a prepackaged seal and sealant assembly located within adjacent seal slots formed in adjacent gas turbine components in accordance with an exemplary but nonlimiting embodiment of the invention; 
         FIG. 2  is a perspective view of a preformed sealant composition wrapped in a thin film in accordance with another exemplary but nonlimiting embodiment of the invention; and 
         FIG. 3  is an exploded view illustrating a preformed sealant material within a seal slot prior to installation of the seal element itself. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , a seal and sealant package  10  in accordance with an exemplary but non-limiting embodiment is shown located in situ between a pair of machine components  12  and  14 . The split format of the figure is merely intended to show alternative seal materials as explained further below The components may be, for example, turbine nozzles or shrouds formed to include aligned seal slots  16 ,  18 . The seal and sealant package may include a seal element  20 , sealant material  22  and a surrounding packing membrane or enclosure  24  (also referred to herein as a backer material). 
     More specifically, the seal element  20  may be an otherwise conventional hard or cloth seal typically used in turbine applications where static seals are employed in combination with high temperature sealant. Hard seals generally refer to relatively thick metal shims (see, for example, shim  21  in  FIG. 1 ), while cloth seals may be a composite assembly of metal foil layers wrapped in overlying layers of cloth, as described, for example, in commonly-owned US Pat. No. 5,657,998. 
     The sealant material  22  may be any suitable high-temperature sealant that resists temperatures up to about 2000° F. and that is otherwise compatible with the seal slot surface material. 
     The surrounding enclosure or membrane  24  (also referred to herein as a “backer material”) may be composed of wax paper, plastic film or other suitable material with properties or characteristics that will cause the backer material to melt and/or burn away at temperatures lower than the service temperature of the sealed components. The backer material must be suitably thin, inexpensive, and leave no residue. 
     An exemplary but nonlimiting manufacturing/assembly and use of the seal and sealant package will now be described. Initially, the cloth or hard seal element  20  is prefabricated and cut to the required assembled length and width. A suitable seal element is described, for example, in commonly-owned U.S. Pat. No. 5,657,998. The seal element  20  is laid on the backer material  24 , and a line of the high temperature sealant material  22  is applied around the still exposed sides of the seal element  20 . The backer material  24  is wrapped around the sides, ends and top of the seal element  20  to completely enclose the seal element and sealant material  22 . Any openings or loose overlaps in the backer material may be sealed separately (simply by heating, for example) to protect, and to prevent escape of the sealant material  22 . At this point, depending on the application, it may be necessary to press or massage the sealant material  22  within the package into a shape that will facilitate insertion of the package into the seal slot or recess in which it is to be used (for example, the slots  16 ,  18  formed in the adjacent turbine components  12 ,  14 ) and that will locate the sealant at the required locations. In this regard, it may be sufficient to simply insure that the sealant extend along one or more edges and/or one or more sides of the seal. In other applications, it may be necessary to manipulate the package to insure sealant coverage on all sides and edges of the seals. 
     The seal and sealant package  10  can then be shipped to a machine assembly plant or field installation site where it is installed. Upon start-up of the machine, and after reaching the critical temperature (the temperature at which the backer material melts and/or burns), the backer material  22  will melt and/or burn away, leaving no residue but leaving the high-temperature sealant  20  in its design location. 
     In another exemplary but nonlimiting embodiment, the sealant material may be preformed and wrapped partially or completely in a non-stick, removable plastic (or other suitable material) film (or backer material) for later application to a seal slot with an associated seal. In  FIG. 2 , for example, a pre-rolled sealant “cylinder”  26  is wrapped in a non-stick, removable film or backer material  28 , which in turn, can be rolled into a bundle for shipment and/or storage. When ready for use, discrete strips  30  may be cut to length and pushed into the seal slots. The film  28  may be partially removed to allow the sealant to be pressed into place, followed by complete removal of the film and insertion of the seal element. Alternatively, the entire film  28  could be removed in advance of the sealant strip  30  being pressed into its respective seal slot as shown in  FIG. 3 . 
     As an additional alternative, after a non-covered strip  30  of sealant is located within a seal slot  32 , the exposed portion of the sealant may be covered with a non-stick removable film  28 . When ready to install the seal element  34 , the film  28  would be removed and the seal element  34  pressed into place directly against the sealant  30 . 
     It will be appreciated that the non-stick film  28  could also remain on the sealant strip  30  (including completely covering the sealant strip) and/or between the sealant strip  28  and the seal  20 , to be melted or burned off before the sealed components reach their service temperature. 
     The film  28  need not be of the non-stick variety in that, for some applications, it may be desirable to have a tacky film to provide some degree of adhesion to the sealant. 
     It will be appreciated that the seal and sealant package  10  could be used during initial gas turbine or other machine assembly, or incorporated as part of an up-rate package for gas turbine or other engines. 
     While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.