Abstract:
A tool for supporting and centering a flat circular orifice plate flow meter between two pipe flanges that have circumferentially spaced apart circular flange bolt holes that lie on a bolt circle and receive circular flange bolts for interconnecting the flanges, comprising a flat plate having a first edge which includes at least two points that lie on a line of curvature having a radius equal to the radius of the circular orifice plate, and at least one set of at least two tool holes sized to receive two of the bolts that interconnect the flanges.

Description:
[0001]    This application claims the benefit of U.S. Provisional Application No. 60/761,658 filed on Jan. 24, 2006. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Circular orifice plate fluid flow meters and flow conditioning plates are traditionally designed with a diameter that is compatible with the size and dimension of the specific pipe coupling flanges between which the orifice plate will be installed. Standard ANSI, DIN and JIS pipe flanges are designed with a variety of pressure ratings. For example ANSI standard flanges are classified as 150, 300, 600, 900, 1500 and 2500. For each of these ratings the flanges will have different dimensions and different number of bolt holes as well as different spacing and size of the holes comprising the bolt hole circle. Accordingly, for a given pipe line size, prior art orifice plates have had to be sized to fit the particular pressure rated flange pair being used in the application. 
         [0003]    The requirement for centering an orifice plate so that its center is coaxial with the longitudinal center line of the pipes carrying the attachment flanges is well known. It is also acknowledged that visually performed alignment of a flow meter within its compressive mounting pipe flanges is time consuming and unreliable. Various alignment and centering devices have been proposed, including various gauges and installing tools. Such attempts are represented by U.S. Pat. No. 4,345,464 for Centering Device for Flowmeters Interposed in Flow Line and U.S. Pat. No. 5,632,632 for Flowmeter Alignment Device. The &#39;464 patent discloses a pair of rectangular plates acting as camming devices that take advantage of the normal play present in a bolted pipe flange arrangement, The &#39;632 patent discloses both a closed ring and an arc that are designed to mate with an edge of the raised face of a pipe flange. While adequate for a single pipe size and a single pressure rated pipe flange and flow meter, one of these devices of the prior art is not adapted for use with a large number of different pipe flanges. 
         [0004]    It is therefore the primary object of the present invention to provide a selection of arcuate appliances that center and permanently support a single size of orifice plate within any one of a plurality of different pressure rated flange pairs that interconnect pipes of the same size. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention provides one or more flat arcuate plates that function as tools to align the center of a flat circular orifice plate with the longitudinal axis of congruent pipe connecting flanges between which the orifice plate is to be compressively mounted. The flat plate comprises a first edge which includes at least two points that lie on a line of curvature having a radius equal to the radius of the circular orifice plate. The plate also has at least one set of at least two holes whose centers correspond to two adjacent bolt holes in the pipe flanges. The centers of the holes in the flat plate are spaced from the line of curvature of the plate&#39;s first edge a distance such that when the first edge of the plate is placed in contact with the outside edge of the orifice plate and the plate is sandwiched between the flanges and secured in place by the flange connecting bolts that pass through an appropriate set of bolt holes of the alignment plate the orifice plate will be centered within the fluid conducting pipe, that is, its center will be in alignment, or coaxial with, the longitudinal axis of the pipe. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0006]      FIGS. 1-3  are end views of pipe flanges having respectively three different pressure ratings such as, for example, ANSI 150, 300 and 600 class. Different pressure rated flanges are shown attached to the ends of same sized pipes with same sized orifice plates centered within the circle of each pipe flange. Shown in plan view and placed on the respective flanges is the single flat plate alignment tool of the present invention that centers the orifice plate within the various sized flanges. 
           [0007]      FIG. 4  is a perspective view of the alignment appliance shown in  FIGS. 1-3 . 
           [0008]      FIG. 5  is an end view of a pipe flange having a greater pressure rating than the flanges shown in  FIGS. 1-3 , for example ANSI 900 class. The flange is attached to the end of a pipe having the same line size as the pipes shown in  FIGS. 1-3 . An orifice plate of the same size as that shown in  FIGS. 1-3  is centered within the circle defined by the pipe flange. The alignment tool of the present invention is shown positioned on the flange and in contact with an orifice plate of the same size as the orifice plate of  FIGS. 1-3 . The alignment tool illustrated in this Figure has two sets of bolt holes and is thereby adapted for use on two different pressure rated flanges. 
           [0009]      FIG. 6  is a perspective view of the alignment device shown in  FIG. 5 . 
           [0010]      FIG. 7  is an end view of a pipe flange having a greater pressure rating than the flange shown in  FIGS. 1-5 . The flange is attached to the end of a pipe of similar size to the pipe shown in  FIG. 5  with a same sized orifice plate as that shown in  FIG. 5 . The orifice plate is centered within the circle of the flange. An alignment tool designed only for this particular rated flange is shown with its bolt holes positioned over two adjacent holes in the bolt circle of the flange. 
           [0011]      FIG. 8  is a perspective view of the alignment appliance shown in  FIG. 7 . 
           [0012]      FIG. 9  is an end view of a pipe flange attached to a larger pipe than that shown in  FIGS. 1-8  and supporting a larger orifice plate, illustrating that a larger diameter orifice plate may require the use of more than one flat plate alignment tool. 
           [0013]      FIG. 10  is a perspective view of the alignment device shown in  FIG. 9 . 
           [0014]      FIG. 11  is a cross sectional view of typical bolt connected pipe flanges where an orifice plate is compressively supported between the flanges. The alignment tool of the present invention is shown in cross section as it would appear compressed between a pair of mating pipe flanges, one of which is shown in  FIG. 7 , for example. 
           [0015]      FIG. 12  is a perspective view of the widened double plate alignment tool for use with thicker orifice plates. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    The most basic form of the flat plate alignment appliance of the present invention is shown in  FIGS. 7 and 8 . Only one of the pair of mating pipe flanges  4  is shown. Each of the pair of pipe flanges  4  is attached by welding or similar means to the end of a pipe or conduit  6 . For purposes of comparative explanation the flange of  FIG. 7  and the flanges of  FIG. 11  will be considered high pressure rated flanges. An orifice plate fluid flow meter or flow conditioner  10  having an outside diameter D, larger than the inside diameter of the pipe  6 , is centered within the circle formed by the flanges  4  and more specifically centered within the bolt circle  18 . When so centered the center  5  of orifice plate  10  will be aligned with and on the longitudinal axis  22  of the pipe  6 , which is the desirable placement of the orifice plate. 
         [0017]    The centering alignment is accomplished by abutting the arcuate inner edge  11  of the flat plate  12  against the outside circumferential edge  13  of the orifice plate  10 . The tool  12  is secured in place by sandwiching the plate between the flanges  4  and passing two adjacent flange connecting bolts  16  through the holes  14  in the plate  12 . The line of curvature of the arcuate inner edge  11  of the plate  12  preferably matches the curvature of the circumferential edge  13  of the orifice plate  10 . However, contacting the circumferential edge of the orifice plate with two widely spaced points on the inside edge of the alignment tool would be sufficient provided the points lie on a line a curvature that emulates the curvature of the orifice plate&#39;s edge. 
         [0018]      FIG. 11  is a cross sectional view taken along lines  11 - 11  of  FIG. 7 , illustrating the completed assembly of a pair of pipe flanges and the orifice plate and alignment tool sandwiched there between. As shown, the pipe flanges  4  are interconnected by bolts  16  that pass through bolt holes  17  of the flanges. Between the flanges is positioned an orifice plate  10  on either side of which are disposed sealing gaskets  15  and  19  that abut against the faces of the flanges  4 . At a selected position on the circumference of the flanges two adjacent connecting bolts  16  pass through the holes  14  in the flat plate tool  12 , securing it in place while it centers the orifice plate  10  within the flange circle and simultaneously aligns the center  5  of the orifice plate with the longitudinal axis  22  of the interconnected fluid carrying pipes  6 . 
         [0019]    Alignment of the center of the orifice plate with the centers of the flange pairs is achieved by sizing and dimensioning the flat plate appliance  12  and its bolt receiving holes  14 . Traditionally, the diameter of flange bolt holes is somewhat larger than the diameter of the bolts intended to interconnect the flanges. This mismatch provides some leeway in interconnecting flanges that are not exactly perpendicular to the longitudinal axis of the pipes being connected. 
         [0020]    Sizing and placement of the holes  14  in the alignment tool has three criteria. First, the diameter of the holes is the same as the diameter of the bolt that is intended to pass through the hole. Second, the location of each hole must be such that the holes correspond to the position of adjacent holes in the bolt hole circle of the flanges to the extent that adjacent bolts which interconnect the flanges can be passed through the appropriate holes  14  in the tool. Third, the holes in the tool must be placed so that when the interconnecting flange blots are placed through the flanges and the holes of the sandwiched tool and tightened, the tool will properly center the orifice plate with the center of the connected pipes. This third requirement demands that the holes in the tool be placed a precise distance from a reference point on the tool. The reference point may be a point lying on the edge of the tool and on a line that interconnects the center of the orifice plate  10  and the center of the proposed hole in the tool. To determine the distance from the reference point on the tool&#39;s edge to the center of the proposed hole several measurements must be taken into consideration, including accommodating the difference between the diameter of the flange bolt holes  17  and the smaller diameter of the connecting bolts  16 . As seen in  FIG. 7 , that difference is equal to the distance between the center  16   c  of the bolt  16  and the center  17   c  of the flange bolt hole  17 . Accordingly, the formula for placing the holes  14  in the flat plate is as follows: The distance B from the inside edge  11  of the flat plate to the center  16   c  of a bolt hole in the plate, measured on a line interconnecting the center  5  of the orifice plate  10  and the center  16   c  of a bolt hole in the plate  12  is equal to the difference between (a) the radius R b  of the bolt hole circle  18  and (b) the radius R o  of the orifice plate  10  plus (c) the difference between the diameter of the flange bolt hole D 17  and the diameter of the connecting bolt D 16 . Expressed more simply, B=R b −R o +D 17 −D 16 . Thus when the inside edge  11  of the tool  12  is placed in abutting relation with the circumferential edge of the orifice plate  10  and two of the bolts  16  that interconnect the flanges are passed through the holes  14  and tightened the bolts  16  at the bottom portion of the flanges will move to a position where they contact the bottom edges of the flange bolt holes, as seen in  FIG. 7 . In this position the orifice plate  10  will be centered. 
         [0021]    The concept of the alignment device of the present invention allows a single tool  12   a , such as the one illustrated in  FIGS. 5 and 6 , to accommodate more than one flange size. For example, the tool shown in  FIGS. 5 and 6  has two sets of holes. The first set comprises holes  14   a  and  14   b  while the second set includes holes  14   c  and  14   d . The first set accommodates flanges rated in the ANSI 900 class, for example. The second set is designed to accommodate another size of flanges, for example ones in the ANSI 1,500 class. 
         [0022]    Similarly,  FIGS. 1-4  illustrate an alignment tool for flanges of lower pressure ratings where a single tool  12   b  may contain three sets of holes. The first set comprises holes  14   e  and  14   f  which, for example, may match the bolt holes in an ANSI 150 class flange, as shown in  FIG. 1 . The second set includes holes  14   g  and  14   h  that accommodate the bolt holes in a higher rated flange pair, such as the one shown in  FIG. 2 . A third set of holes  14   i  and  14   j  match the bolt holes in a still higher rated pair of flanges such ones in the ANSI 600 class, for example, shown in  FIG. 3 . 
         [0023]    In each of the above referenced cases the holes in the alignment tool are sized and dimensioned as described for the single flange size alignment tool of  FIG. 7 . Accordingly, one to three or more different sizes of alignment tools can center a single sized orifice plate within a large selection of pressure rated flanges. 
         [0024]    A large orifice plate, such as the one shown in  FIG. 9  may require more that one alignment device  12   c  because of the reduced contact area between the edge  11  of the alignment devices and the circumferential edge of the orifice plate  10   a.    
         [0025]    The thickness of the tool  12  is preferably the same or substantially the same thickness as the material of the orifice plate  10  in order to maintain a proper seal with the gaskets  19 .  FIG. 12  illustrates another embodiment  25  of the alignment tool for use with an orifice plate having greater thickness than the orifice plate illustrated in  FIGS. 1-11 . A preferred form of such a modified tool includes two flat plates of the above described configuration that are interconnected with rods  32 . In all other respects, the tool of  FIG. 12  is similar in its design and theory of operation as the tools described in connection with  FIGS. 1-11 .