Patent Number: 048851221
Section: description

DETAILED DESCRIPTION Referring now to FIGS. 3 and 4, one embodiment of the clamping apparatus of the present invention is shown in plan and cross sectional views respectively. The clamping apparatus, generally designated as 30, comprises two end body members 31. Each of the end body members has an unflanged end 31U and a flanged end 31F. In the closed or assembled position, the flanged ends 31F are held together by cap screw 35. In a preferred embodiment, one of the flanged ends 31F contains an unthreaded cap screw aperture therein while the other flanged end 31F contains a threaded cap screw aperture therein. The unflanged ends 31U of the end body members 31F are connected in such a manner so as to allow the radial spacing between the flanged ends 31F to be adjustable. In this way, the present invention provides a unitary clamp having an adjustable end which is adapted to be opened in a jaw like fashion. During the assembly procedure, this feature allows the clamp, which is assembled except for the insertion of the cap screw, to be moved to an open position in which the clamp is easily placed into position over flanges 10 and 11. In one embodiment of the present invention, the means for linking the end body members so as to permit the spacing between the flanged ends of the clamp to be adjustable comprises intermediate body members 32. Means, such as link plates 33, are provided for pivotally joining the intermediate body members 32 to one another and to the unflanged ends 31U of the end body members 31. Bosses 34 extend substantially axially from each end of the intermediate body members 32 and from the unflanged ends 31U of the end body members 31. Each boss extends into an aperture in link plate 33 in known fashion. In a preferred embodiment, each boss 34 has a holding means, such as a cotter pin for example, for holding the link plates on the bosses. It is preferred that the body members be joined by a pair of link plates 33 as shown in FIG. 4. It will be appreciated by those skilled in the art that means other than those described in detail above are available for linking the unflanged ends of said end body members. For example, it may be preferable in some applications to provide more than two intermediate body members. In other applications, it may be desirable to extend the arcuate span of the end body members and link the unflanged ends 31U directly together by a link plate. The operation of an apparatus according to one embodiment of the present invention may be usefully illustrated by describing the use of the clamping apparatus shown in FIGS. 3 and 4 in connection with the instrumentation port interface shown in FIG. 1. Due in part to the articulated nature of the clamping apparatus of the present invention, the clamp may be assembled around the instrument port interface shown in FIG. 1 with a minimum of effort. With cap screw 35 removed from the clamping apparatus 30, the flanged ends 31F of the clamp are easily separated in jaw like fashion. In particular, due to the provision of at least two pivotally joined body members 31, the flanged ends 31F are easily separated a sufficient distance to allow passage of the clamp 30 around flanges 10 and 11. The flanged ends 31F are then easily rejoined by cap screw 35. As revealed by FIGS. 3 and 4, the clamp 30 according to one embodiment of the present invention is generally ring-shape when in assembled form, the inner portion of said ring-shape clamp being adapted to engage the outer portions of flanges 10 and 11. As mentioned above, it is desirable for the clamping apparatus of the present invention to exert the proper axial seating pressure on the flange interface. As best revealed in FIGS. 1 and 4, this is achieved by providing the inwardly facing portions of clamp 30 with generally flat surfaces 36 and 37 which are non-perpendicular with respect to the axis 38 of the flanges 10 and 11. In assembled form, the surfaces 36 and 37 of clamp 30 are generally parallel with respect to surfaces 39 and 40 of flanges 10 and 11 respectively. When clamp 30 is assembled around flanges 10 and 11, the internal diameter of clamp 30 tends to decrease until cap screw 35 draws flanged ends 31F together. This reduction in the internal diameter of clamp 30 in turn tends to cause opposed axially pressure on flanges 10 and 11 as a result of the engagement of surface 36 with surface 39 and surface 37 with surface 40. In order to provide the most precise application of axial pressure, the inwardly facing portions of the clamp are preferably machined, cast, and/or forged to precisely engage the surfaces 39 and 40 of flanges 11 and 10. More particularly, the spacial relationship between the surfaces 36 and 37 of clamp 30 and surfaces 39 and 40 is controlled so that the proper axial pressure is exerted when the flanged ends 31F are in contact. As mentioned above, it is critical for instrument port interface clamps of the types disclosed herein to achieve and maintain the proper uniform contact and pressure on the interface. Such uniform contact and pressure will insure a properly seated gasket 12 and will prevent gasket over overcompression. In addition this uniform contact and pressure will aid in the maintenance of a proper seal during emergency conditions. These objectives are achieved, in part, by providing a datum surface on the flanged ends 31F of the end body members. According to the present invention, the clamp 30, for example, is machined, cast, and/or forged according to methods well known in the art to exert the proper contact and pressure upon the interface between flanges 10 and 11 when datum surfaces 31D are in contact. By "preloading" the clamp of the present invention in this way, the time required to position and assemble the clamp on the instrument port interface is minimized and the need for a space limiter is eliminated. That is, once the clamp is placed around the flanges in the manner described above, the proper clamp geometry will be achieved when the cap screw is torqued sufficiently to cause intimate contact between the datum surfaces of the flanged ends. This will properly seat and compress the gasket. Further torquing of the cap screw will not overcompress the gasket and is preferred as a means for preloading the clamp flanges so that the gasket will remain seated when the pressure within the flanges increases. In particular, the clamp of the present invention will achieve these objectives upon the application of only about 60 ft/lbs. torque to the cap screw. In a preferred embodiment of the present invention, the datum surfaces are simply the flat surfaces 31D of the flanged ends 31F. It will be appreciated by those skilled in the art, however, that the use of any particular configuration or shape of datum surface is within the scope of the present invention. For example, it may be desirable to provide datum surfaces with mating portions which provide axial alignment of the flanged ends 31F. Gasket 12 is properly seated by clamping apparatus of the present invention without the need for the heretofore used axial loading device. This advantage is achieved, in part, by providing body members 31 and 32 with an arcuate span which is substantially less than the arcuate span of the body members 13A, 13B, and 13C according to heretofore used clamping apparatus. It is preferred that the body members according to the present invention span an arc no greater than about 90.degree.. Applicant has found that such a reduction in arcuate span and a decrease in the clamp inner radius increases the contact area between the clamp 30 and the flanges 10 and 11. This increased contact aids in the seating of gasket 12 as the clamp 30 is assembled. In addition, the provision of an increased number of body members having reduced arcuate span aids in the seating of the gasket 12 as the clamp 30 is assembled. Providing a clamp according to the present invention eliminates the requirement of an axial loading device and hence simplifies the assembly procedure thereof and reduces the exposure of workers to potentially hazardous conditions. Referring now to FIG. 5, another embodiment of the clamping apparatus of the present invention is shown in cross sectional view with respect to another typical instrument port interface. In this configuration, tubular members or flanges 41 and 42 cooperate in a telescoping manner to seal the interface therebetween. In the context of a nuclear reactor vessel, flange 41 comprises the upper portion of flange 10 (FIG. 1) and member 42 is the cylindrical conduit seal and carries thermocouples which pass into the interior of member 41. As with the prior interface, a gasket 12 is provided to insure a proper seal between the flanges 41 and 42. In contrast to the interface shown in FIG. 1, proper seating of gasket 12 in FIG. 5 requires application of axial pressure to each flange which is directed away from the interfacing end thereof. That is, it is necessary for the clamping apparatus to exert an upward axially pressure on cylindrical conduit 42 with respect to flange 41. Clamping apparatus heretofore used to achieve this objective are described in copending application Ser. No. 925,861. According to one embodiment of the present invention, this objective is achieved by the cooperation of positioner clamp 50 and wedge clamp 60. Although clamps 50 and 60 may have any appropriate plan view construction, it is preferred to use an articulated construction as shown in FIG. 3. As shown in FIG. 5, however, the cross sectional configuration of clamps 50 and 60, and flanges 41 and 42 is substantially different from the cross sectional configuration of clamp 30 and flanges 10 and 11 as shown in FIGS. 1 and 4. In particular, flange 42 contains an annular groove 43 on its outer surface for receiving positioner clamp 50. Positioner clamp 50 contains an inwardly extending flange 51, at least a portion of which engages groove 43. Positioner clamp 50 also contains a lower surface 52 which is nonperpendicular with respect to the central axis 44 of flanges 41 and 42. In this way, the axial distance between any portion of surface 52 and the end of flanges 41 and 42 is functionally related to the radial distance of that portion from axis 44. In particular, the distance between surface 52 and the end of flange 42 decreases with decreasing surface radius. The upper end of flange 41 contains a generally flat surface 45 which is also generally nonperpendicular with respect to axis 44. The distance between surface 45 and the interfacing end of flange 41 also decreases with decreasing surface radius. As the term is used herein, the end of a flange refers to the furthest axial extent of the flange, For example, the end of flange 41 refers to the innermost radius of surface 45. Surface 45 and surface 52 cooperate to create a wedge like opening 70 for clamp 60. The inner surface of clamp 60 provides an engaging means adapted to cooperatively engage the wedge like opening 70. In particular, clamp 60 contains an upper surface 61 and a lower surface 62, each of which are also disposed at a nonperpendicular angle with respect to axis 44. It is preferred that surface 62 be in engagement with and generally parallel to surface 45 and that surface 61 be parallel to and in engagement with surface 52, as shown in FIG. 5. Both surfaces 61 and 62 slope towards the axial center of opening 70 as the radial distance from axis 44 decreases. Due in part to the articulated nature of clamp 60 (see FIG. 3), the internal diameter of clamp 60 is reduced as the flanged ends 31F are drawn together. Due to the relationship between the axial and radial distances of the surfaces described above, this reduction in the internal diameter of the clamp 60 in turn tends to exert an upward axially pressure on flange 42 with respect to flange 41. It will be appreciated by those skilled in the art that various modifications of the clamping system shown in FIG. 5 are possible and may be desirable. In one alternative embodiment, a two-piece split ring may be substituted for positioner 50. It may be desirable in other applications to eliminate positioner 50 entirely and simply form flange 42 with the appropriate outer configuration. It should also be noted, however, that in many situations, nuclear power systems in particular, it is not practical to replace or redesign flange 42 and hence in those applications the provision of a clamp such as 50 may be desirable. Alternatively, positioner 50 and 60 may be combined into a single clamp having an inner surface similar to the combination of the clamp/positioner arrangement. It will also be appreciated by those skilled in the art that while the clamping system shown in FIG. 5 provides sloping surfaces 45, 52, 61 and 62, the provision of only one of these surfaces is sufficient to achieve the objects of the clamping apparatus disclosed therein. For example, it is possible to provide surfaces 45, 52, and 61 in a perpendicular arrangement with respect to axis 44 while maintaining surface 62 in a sloped configuration. Due to the provision of this one sloped surface, assembly of clamp 60 between surfaces 42 and 45 will tend to exert upward axial pressure on flange 42. As indicated by the foregoing description, the clamping apparatus and systems of the present invention will quickly and efficiently seal instrument port interfaces, thus reducing the exposure of nuclear power plant workers to hazardous conditions while maintaining a high degree of protection against leakage. In particular, the present invention provides a clamping apparatus which, even for relatively large instrument ports, can be easily operated by one worker. In addition, the clamps can be quickly applied to the instrument port interface since only one cap screw is required to assembly the clamp on the interface. It will be appreciated by those skilled in the art that the form of the invention shown and described above is presented by way of illustration only. For example, the clamping apparatus has been described with respect to use on the generally tubular conduits associated with instrument port interfaces. The present clamping apparatus, however, is adaptable to other conduit configurations, such as square, rectangular or triangular, for example. In addition, the present clamping apparatus may be used in other applications, such as shipping and/or storage casks, for example. Various other changes may be made in the shape, size, etc. without departing from the spirit and scope of the invention as set forth below in the claims.