Abstract:
A borescope assembly includes a first borescope plug comprising a first perimeter geometry portion. Also included is a second borescope plug comprising a second perimeter geometry portion distinct from the first perimeter geometry portion. Further included is a first borescope hole comprising a first hole geometry portion corresponding to the first perimeter geometry portion of the first borescope plug. Yet further included is a second borescope hole comprising a second hole geometry portion corresponding to the second perimeter geometry portion of the second borescope plug.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to borescope assemblies, such as those used in turbine assemblies, as well as a method of installing borescope plugs. 
         [0002]    Borescopes are used to visually inspect internal components of turbine assemblies, such as gas turbine engines, for example. They are typically inserted through borescope holes placed in locations of a static structure that lead to internal locations of interest. Such insertion occurs during an outage. When the turbine assembly is in operation, the borescope holes must be plugged and sealed to reduce or prevent hot gases from being emitted from the turbine which would result in overall system performance and/or safety issues. Plugging of the holes is done with a borescope plug. Typically, the borescope holes are similar in diameter, but vary in length. Similarly, the borescope plugs to be inserted into the borescope holes are similar in diameter, but vary in length. Maintenance personnel must use caution to ensure that a borescope plug of a given length is not inserted into a borescope hole with a distinct length. Incorrect insertion may create a leak path due to the fact that a short plug has a tendency to seal improperly. Additionally, incorrect insertion may impose a situation where a long borescope plug (relative to the borescope hole) is bent during insertion. This incorrect assembly condition may also result in leakages, disassembly issues, and delays during an outage. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0003]    According to one aspect of the invention, a borescope assembly includes a first borescope plug comprising a first perimeter geometry portion. Also included is a second borescope plug comprising a second perimeter geometry portion distinct from the first perimeter geometry portion. Further included is a first borescope hole comprising a first hole geometry portion corresponding to the first perimeter geometry portion of the first borescope plug. Yet further included is a second borescope hole comprising a second hole geometry portion corresponding to the second perimeter geometry portion of the second borescope plug. 
         [0004]    According to another aspect of the invention, a borescope assembly for a turbine assembly includes a plurality of borescope plugs each including a main plug portion and a collar disposed along the main plug portion, wherein the collar of each of the plurality of borescope plugs comprises a perimeter geometry distinct from the perimeter geometry of the remaining collars. Also included is a plurality of borescope holes each comprising a hole geometry corresponding to the perimeter geometry of the collar of one of the plurality of borescope plugs. 
         [0005]    According to yet another aspect of the invention, a gas turbine engine includes a compressor, a combustor assembly, a turbine, and a borescope assembly. The borescope assembly includes a first borescope plug comprising a first perimeter geometry portion. The borescope assembly also includes a second borescope plug comprising a second perimeter geometry portion distinct from the first perimeter geometry portion. The borescope assembly further includes a first borescope hole comprising a first hole geometry portion corresponding to the first perimeter geometry portion of the first borescope plug. The borescope assembly yet further includes a second borescope hole comprising a second hole geometry portion corresponding to the second perimeter geometry portion of the second borescope plug. 
         [0006]    These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0008]      FIG. 1  is a schematic illustration of a turbine assembly; 
           [0009]      FIG. 2  is a schematic illustration of a turbine section of the turbine assembly; 
           [0010]      FIG. 3  is a cross-sectional view of a borescope assembly; 
           [0011]      FIG. 4  is a borescope plug of the borescope assembly; 
           [0012]      FIG. 5  is a collar of the borescope plug; and 
           [0013]      FIG. 6  is a plurality of exemplary geometries used in conjunction with the borescope assembly. 
       
    
    
       [0014]    The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0015]    Referring to  FIG. 1 , a turbine assembly, such as a gas turbine engine  10  constructed in accordance with an exemplary embodiment of the invention, is schematically illustrated. The gas turbine engine  10  includes a compressor section  12  and a plurality of combustor assemblies arranged in a can annular array, one of which is indicated at  14 . As shown, the combustor  14  includes an endcover assembly  16  that seals, and at least partially defines, a combustion section  18 . In one embodiment, a plurality of nozzles  20 - 22  is supported by the endcover assembly  16  and extends into the combustion section  18 . The nozzles  20 - 22  receive fuel through a common fuel inlet (not shown) and compressed air from the compressor section  12 . It should be appreciated that this invention is independent of the details of the combustion system, and the can annular system is referenced for purposes of discussion. The fuel and compressed air are passed into the combustion section  18  and ignited to form a high temperature, high pressure combustion product or air stream that is used to drive a turbine section  24 . The turbine section  24  includes a plurality of stages  26 - 28  that are surrounded by a casing  32  and operationally connected to the compressor section  12  through a compressor/turbine shaft  30  (also referred to as a rotor). 
         [0016]    In operation, air flows into the compressor section  12  and is compressed into a high pressure gas. The high pressure gas is supplied to the combustor  14  and mixed with fuel, for example natural gas, fuel oil, process gas and/or synthetic gas (syngas), in the combustion section  18 . The fuel-air or combustible mixture ignites to form a high pressure, high temperature combustion gas stream. In any event, the combustor  14  channels the combustion gas stream to the turbine section  24  which converts thermal energy to mechanical, rotational energy. 
         [0017]    Referring to  FIG. 2 , the casing  32  of the turbine section  24  is illustrated in greater detail. The casing  32  generally refers to a structure that surrounds and at least partially defines an internal region of the turbine section  24 . The casing  32  may be a unitary structure or may be formed of multiple segments, such as a double casing that comprises an outer casing  34  and an inner casing  36 , which are operatively coupled to each other. As shown, internal components of the turbine section  24  include a plurality of nozzle vanes  38  and rotor buckets  40 , for example. The internal components are surrounded by the casing  32 , as noted above, as well as at least one shroud  42  in the illustrated embodiment. 
         [0018]    A plurality of borescope plugs  44  are disposed within a plurality of borescope holes  46  that extend through the at least one shroud  42  or through a nozzle outer side wall, as shown. Although shown and described as extending through the at least one shroud  42 , it is to be appreciated in certain embodiments, the plurality of borescope holes  46  extend through the casing  32 , or alternatively through the casing  32  and the at least one shroud  42  in combination. Regardless, it is to be understood that the plurality of borescope holes  46  extend through an outer structure to provide access for a borescope, or other inspection device, that may be employed to monitor internal components of the turbine section  24 . Although the location of the plurality of borescope holes  46  described herein are discussed in conjunction with the turbine section  24 , any portion of the gas turbine engine  10  may benefit from the use of the embodiments described herein. For example, the compressor section  12  may include the plurality of borescope holes  46  that require plugging during operation of the gas turbine engine  10 . 
         [0019]    Each of the plurality of borescope holes  46  are typically of varying lengths, as they are positioned at distinct axial locations throughout the turbine section  24 . The plurality of borescope holes  46  may be of similar diameter or perimeter, however, varying diameters and perimeter are contemplated. In order to seal the plurality of borescope holes  46  during operation of the gas turbine engine  10 , the plurality of borescope plugs  44  are inserted into the plurality of borescope holes  46 . As noted above, the plurality of borescope holes  46  extend through the casing  32  and/or the at least one shroud  42  from a first end  50  to a second end  52 , with the second end  52  exposing the internal region of the turbine section  24  that is to be inspected. A varying number of borescope holes may be included, depending on the particular application. In the exemplary embodiment, four borescope holes and associated borescope plugs are illustrated, but more or less are contemplated. For purposes of discussion, a first borescope plug  54  and a second borescope plug  56  are specifically labeled. 
         [0020]    Referring now to  FIGS. 3-5 , in conjunction with  FIG. 2 , the first borescope plug  54  and a first borescope hole  58  are illustrated in greater detail. The first borescope hole  58  extends through an outer static structure, such as the at least one shroud  42  and the first borescope plug  54  is disposed therein. In order to ensure that the proper borescope plug is being inserted into the first borescope hole  58 , uniquely shaped features are included in the overall assembly. Specifically, the first borescope plug  54  comprises a first main plug portion  55  that is typically cylindrical, but alternative cross-sectional geometries are contemplated. A collar  60  is integrally formed with, or operatively coupled to, the first main plug portion  55 . An outer surface  62  of the collar  60  comprises a first perimeter geometry portion  64 . A first insert  70  is integrally formed with, or operatively coupled to, a hole wall  72  of the first borescope hole  58 . The first insert  70  includes a cutout portion  74  that defines a first hole geometry portion  76 . The first hole geometry portion  76  and the first perimeter geometry portion  64  correspond to one another, such that it is only possible for a borescope plug having the collar  60  with the first perimeter geometry portion  64  to be inserted through the cutout portion  74  of the first insert  70 . Collars having a distinct perimeter geometry, with respect to the first hole geometry portion  76  of the cutout portion  74 , are unable to pass through the cutout portion  74  of the first insert  70  based on the mismatched geometries, thereby reducing or preventing the ability of a borescope plug other than the first borescope plug  54  to be inserted into the first borescope hole  58 . For example, the second borescope plug  56  ( FIG. 2 ) is shorter than the first borescope plug  54  and would ineffectively seal the first borescope hole  58 . Therefore, the second borescope plug  56  comprises a second collar  80  with a second perimeter geometry portion  82  that corresponds to a second hole geometry portion  84  of a second borescope hole  86 . The distinct geometries prohibit insertion of the first borescope plug  54  into the second borescope hole  86 . Conversely, the second borescope plug  56  is unable to be inserted into the first borescope hole  58 . 
         [0021]    Any number of contemplated geometries may be employed for the borescope plugs and the borescope holes. In one embodiment, the geometries are polygons  90  ( FIG. 6 ) and can range in the number of sides that define the polygons. For example, polygons with sides ranging from three to nine, however, polygons, with more sides may be suitable. The specific geometry employed may vary. The important aspect relates to the principle that each borescope plug includes a distinct outer geometry portion that corresponds to a particular borescope hole geometry. 
         [0022]    The distinct geometry portion of the respective borescope plugs and borescope holes refers to a portion of the borescope plugs and borescope holes that include the specific geometries. In the embodiments described above and illustrated, inserts are employed with cutout portions. The collars of the borescope plugs must pass through the cutout portions to become fully inserted into the borescope holes. The inserts and the collars may be operatively coupled to, or integrally formed with, the plurality of borescope holes  46  and the plurality of borescope plugs  44 , respectively. In alternative embodiments, the distinct geometries may be the borescope hole geometry and/or the borescope plug geometry. In other words, the plurality of borescope plugs  44  and/or the plurality of borescope holes  46  may comprise the distinct geometries necessary for proper insertion of the plugs into the holes. 
         [0023]    In operation, each of the plurality of borescope plugs  44  is inserted into one of the plurality of borescope holes  46 . To fully insert the borescope plug into the correct borescope hole, a perimeter geometry portion of the borescope plug must fit and slide along and/or through a hole geometry portion of the borescope hole. Use of the distinct geometries reduces the likelihood that insertion of an incorrect borescope plug is inserted into one of the borescope holes, thereby advantageously providing proper sealing of the plurality of borescope holes  46  and avoiding damage to the plugs and/or internal components of the turbine section  24 . 
         [0024]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.