Abstract:
A visual tool to enable unskilled workers to properly tighten connections flanges at a pipe joint utilizes a formed shim having opposing abutment portions defining coaxial bolt holes. When the shim is placed on connecting bolts between the flanges compression of the shims provide a visual indication of uniform tightening of the flange bolts.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to the field of joining metal pipe using raised face flanges of the ASME variety. The invention also has application to the use of such flanges in bolting piping to pumps, valves, traps, and any machinery. 
         [0002]    The bolted joint has been around for centuries, and for that time span the novice or uninformed installer often uses improper techniques in putting the joint together. Raised face flanges are commonly used in the industry and typically include an annular face, positioned adjacent the pipe to be connected, which has a thickness that is greater than the thickness of the portion of the flange circumferentially surrounding the raised face. Thus, when opposing flanges are mounted on two pipes with the raised faces abutting a gasket placed there between, a circumferential space is formed between the outer portions of the flanges. Typically, a flange connection includes two flange components with aligned circumferential bolt holes extending through the flange components parallel the axis of the pipe to be joined. Bolts are inserted through the aligned bolt holes and tightened to make the connection. The non skilled installer tends to tighten one bolt completely and work sequentially around to the other bolts. This creates a condition called “flange rotation”, wherein the first over tightened bolt creates a fulcrum effect urging the periphery of the flanges closer together adjacent the first tightened bolt and preventing proper tightening of the bolts on the opposite side of the pipe. The result is insufficient loading on the rotated side of the flange and too much load on the side over tightened adjacent the first bolt. 
       SUMMARY OF THE PRESENT INVENTION 
       [0003]    It is an object of the present invention to give the installer a visual conformation that the flanges are aligned and true, that one bolt isn&#39;t tightened more than another causing a rotated flange. 
         [0004]    The device also allows the installer a physical clue that he is starting his installation properly (i.e.: square and aligned). 
         [0005]    It is a further object of the invention to reduce the cost of routine maintenance of flange connected pipe, by providing a simple tool to enable unskilled workers to properly tighten flange bolts. 
         [0006]    These and other objects and advantages of the invention will become apparent from the following detailed description of the preferred embodiment of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    An article of manufacture for use as a visual and physical aid to determine flange perpendicularity is depicted in the accompanying drawings which form a portion of this disclosure and wherein: 
           [0008]      FIG. 1  is a plan view of a die cut for the flange shim; 
           [0009]      FIG. 2  is a perspective view of the flange shim; 
           [0010]      FIG. 3  is a second perspective view of the flange shim; and 
           [0011]      FIG. 4  is a side elevation view of a pipe connection using the flange shims. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0012]    Referring to the  FIGS. 1-4  for a clearer understanding of the invention, it may be seen that the preferred embodiment of the invention contemplates an article of manufacture which is used with raised face flanges employed to join two pipes or similar structures. Raised face flanges are commonly used in the industry and typically include a face surrounding the pipe to be connected which has a thickness that is greater than the thickness of the portion of the flange circumferentially surrounding the raised face. Thus, when opposing flanges are mounted on two pipes with the raised faces abutting a gasket placed there between, a circumferential space is formed between the outer portions of the flanges. The present invention provides the unskilled worker with a quick visual reference as to whether the flange faces have remained square or substantially parallel as he tightens flange connection. 
         [0013]    Referring to  FIG. 1 , one embodiment of the invention may be made by die cutting appropriate stainless steel shims  10  from sheet metal As shown in  FIG. 1 , the shim  10  is initially formed as a blank having a thickness appropriate for the flange connection with which it will be used. By way of example the shim  10  may be made from  304  stainless steel sheet having a 0.020 inch thickness. The blank may also be stamped from 316 stainless steel or any other suitable non-corrosive and mailable material. In the embodiment shown it will be appreciated that the blank has a generally  FIG. 8  shape, however, it is to be understood that the specific shape is not critical to the invention. The blank has a first abutment portion  11  and a second abutment portion  12  joined by a central portion  13 . Each abutment portion has an inner edge  14  and  15  respectively which defines a bolt hole on either side of central portion  13 . The bolt holes are sized appropriately to receive there through a bolt such as would be used to connect a pair of flanges. 
         [0014]    Referring to  FIGS. 2 and 3 , it will be seen that shim  10  is formed into its operative configuration by bringing abutment portions  11  and  12  into near parallel relationship and the bolt holes defined by edges  14  and  15  into coaxial alignment. The term mailable in this application means that the blank may be physically bent or deformed to bring the abutment portions and bolt holes into the described configuration where they will remain until additional forces act to alter the position. Center portion  13  has to have sufficient mass to allow the bending of the shim into this configuration. The exact curvature assumed by central portion  13  is not critical as long as portions  11  and  12  assume their intended positions, thus, the shim could be formed with two bends at the intersection of the central portion with the two abutment portions and the central portion  13 . By way of example, the shim blank may be formed from 0.020 steel and have an is overall length of about 2.25 inches. Abutment portions  11  and  12  may have an outer diameter of 1 inch and the inner edges  14  and  15  may define bolt holes which have a diameter of about 0.75 inches. It is to be understood that the specific bolt hole size will be determined by the size bolts being used in the particular flange installation. When the shim  10  is shaped to bring the abutment portions  11  and  12  into alignment, the separation between them will be about 0.25 inches or less. Other dimensions may be appropriate for particular applications however all of the shims should have a uniform separation for their specific application. 
         [0015]    Referring to  FIG. 4 , it may be seen that two pipe sections  21  and  22  are to be joined at their threaded portions by a flange connection. Each pipe  21 ,  22  carries a flange  23 ,  24  of the raised face type previously discussed. The raised faces are brought into abutment with a circumferential gasket, not shown. A plurality bolt and nut combinations  26  serve to connect the flanges. Each bolt  27  passes through one of the flanges  23  and then through both bolt holes of a shim  10  before passing through flange  24  for connection with nut  28 . Thus, each bolt  27  will have a shim  10  mounted on it intermediate flanges  23  and  24 . It should be understood that the shims are single use products that remain on the bolt  24  for as long as the joint is secured. Abutment portions  11  and  12  will abut the inner surfaces of flanges  23  and  24  and should provide uniform resistance to the compression of the gasket between the raised faces of the flanges. Thus, the user may look at the circumference of the flanges when they are in position to be tightened and note the visual uniformity of the shims. The resistance to further tightening should occur prior to or concomitantly with the faces of the flanges contacting the gasket. Thus, this product starts the flanges square, promoting better load on the gasket. Because the shim  10  is placed totally in the outer circumferential region of the flanges, it does not interfere with the gasket, placement of the gasket or compression by the flanges in any manner. As the flange bolts are tightened the shims will deform further providing a visual indication of how much the particular bolt has been tightened. By insuring that the shim deformation is uniform, the installer has a visual indicator that the flange is being properly installed. 
         [0016]    Thus the invention provides a visual medium that is readily viewed outside the flange that targets and warns of rotated flanges and “bird beak” flange conditions with its easily discernable pass/fail indication on installation. The product is usable with sizes ½″  150 # through 8″  150  ANSI raised face flanges and requires no special conditions or changing of any part of the ANSI design. 
         [0017]    It is to be understood that the form of the invention shown is a preferred embodiment thereof and that various changes and modifications may be made therein without departing from the spirit of the invention or scope as defined in the following claims.