Abstract:
A method for marking a specific tube in a shell and tube heat exchanger includes inserting a marker into a second tube adjacent to the tube to be marked and directing a directional pointer on the marker toward the tube to be marked.

Description:
This application is a continuation-in-part of U.S. patent application Ser. No. 12/882,694, filed Sep. 15, 2010, which claims priority from U.S. Provisional Patent Application Ser. No. 61/245,079, filed Sep. 23, 2009, and it is a continuation-in-part of U.S. patent application Ser. No. 12/248,281, filed Oct. 9, 2008, which claims priority from U.S. Provisional Patent Application Ser. No. 60/979,191, filed Oct. 11, 2007, all of which are hereby incorporated herein by reference. 
    
    
     BACKGROUND 
     The present invention relates to shell and tube heat exchangers and, in particular, to an arrangement for marking specific tubes, for example tubes that need to be repaired, serviced differently than other tubes, left alone or otherwise corrected. Shell and tube heat exchangers that are used as chemical reactors may have many thousands of open-ended tubes. Various methods have been used in the past to mark tubes. Usually, a marker cap has been inserted into the open end of the tube being marked, but those markers can come loose when people walk on top of the tube sheet, and they require the marker to be removed in order to treat the tube. Also, when the marker is removed in order to treat the tube, the location of the tube may be lost. Other methods of marking tubes have included using paint, tape, and permanent markers on the tube sheet. However paint, tape and ink can rub off as people walk along the tube sheet. 
     One or more of the tubes in the chemical reactor may have thermocouples to monitor the reaction temperature during operation. The catalyst in these thermocouple tubes is loaded separately with special attention to the thermocouples and their electrical leads. It is useful to be able to temporarily seal a thermocouple tube to prevent catalyst loading in that tube while the other tubes are being loaded. Once the other tubes are loaded with catalyst, it is useful to be able to readily identify the thermocouple tubes to be separately loaded with catalyst but without obstructing the thermocouple tube to be loaded. 
     SUMMARY 
     One embodiment of the present invention provides an arrangement by which one or more directional pointers are inserted into the open ends of one or more tubes adjacent to the tube that needs to be corrected, with the pointers being directed toward the tube that needs to be corrected. The directional pointer may be secured in place by a mechanism that requires the use of a special tool in order to reduce the opportunity for it to be removed accidentally or to be removed by someone who does not have authorization. It also may include an indicator to indicate the condition of the tube, such as the type of action that needs to be taken for the tube it is marking. 
     Another embodiment allows easy identification of thermocouple tubes on the top tube sheet of the chemical reactor. Another embodiment is better suited for the identification of thermocouple tubes on the bottom tube sheet of the chemical reactor. Another embodiment allows the installation or removal of the device for marking the location of a thermocouple tube while the electrical leads or wires of the thermocouple extend through the marking device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a broken away, schematic top view of a tube sheet in which a directional pointer has been inserted into a tube adjacent to a specific tube being marked; 
         FIG. 1A  is the same view as  FIG. 1  but with three directional pointers inserted adjacent to the specific tube being marked; 
         FIG. 2  is a front section view of the directional pointer of  FIG. 1  in an expanded condition; 
         FIG. 2A  is a front section view of an alternate embodiment of the directional pointer of  FIG. 2 ; 
         FIG. 2B  is a front section view of two of the directional pointers of  FIG. 2  inserted into tubes in a tubesheet, one directional pointer in an expanded condition and the other in a non-expanded condition; 
         FIG. 3  is a front section view of the directional pointer of  FIG. 2  in a non-expanded condition, before it is inserted into the tube; 
         FIG. 4  is a top view of the toothed plate of the directional pointer of  FIG. 2 ; 
         FIG. 5  is a top view of the rubber cylinder of  FIG. 3 ; 
         FIG. 6  is a top view of an alternate directional pointer plate for the directional pointer of  FIG. 2 ; 
         FIG. 7  is a top view of the directional pointer plate of  FIG. 2 ; 
         FIG. 8  is a top view of another alternative directional pointer plate; 
         FIG. 9  is a top view of another alternative directional pointer plate; 
         FIG. 10  is a top view of another alternative directional pointer plate; 
         FIG. 11  is a top view of another alternative directional pointer plate; 
         FIG. 12  is a top view of the directional pointer plate of  FIG. 7  on an assembled directional pointer; 
         FIG. 13  is a top view of another alternative directional pointer plate; 
         FIG. 14  is a top view of another alternative directional pointer plate; 
         FIG. 15  is a front section view of another alternative directional pointer; 
         FIG. 16  is a bottom view of the directional pointer of  FIG. 15 ; 
         FIG. 17  is a front view of the cap of the directional pointer of  FIG. 15 ; 
         FIG. 18  is a schematic view showing the directional pointers of  FIG. 15  being used on the bottom of a vertical tube shell and tube heat exchanger; 
         FIG. 19  is a broken away, plan view, similar to  FIG. 1 , but for another embodiment of a device for marking a tube installed in the tube sheet; 
         FIG. 20A  is a plan view of the flange of the device of  FIG. 19 ; 
         FIG. 20B  is a plan view of a second embodiment of a flange to replace the flange of  20 A; 
         FIG. 21  is a section view of a securing mechanism which is part of the device for marking a tube of  FIG. 19 ; 
         FIG. 22  is a section view along line  22 - 22  of  FIG. 19 ; 
         FIG. 23  is a section view, similar to  FIG. 22 , but for another embodiment of a device for marking a tube, in this instance installed in a bottom tube sheet; 
         FIG. 24  shows an alternate directional pointer; and 
         FIG. 25  shows still another alternate directional pointer. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a broken-away, schematic top view of the horizontal top tube sheet  10  of a vertical tube shell and tube heat exchanger, showing the top openings of a plurality of vertical tubes  12 . In this case, the tube  12 A needs to be marked, because it requires some type of attention. For example, it may have been found in a back pressure test to have a back pressure that is too high or too low, indicating some type of problem with the catalyst loading that needs to be corrected. A directional pointer  14  has been inserted into the tube  12 B, which is adjacent to the tube  12 A that needs to be corrected. That directional pointer  14  includes a directional indicator  16 , pointing to the tube  12 A. In this case, the directional indicator  16  is a small hole in the plate  26  that is offset in a radial direction from the longitudinal axis of the plate  26  (which is the same as the longitudinal axis of the directional pointer  14  and of the bolt  18 ). 
     As explained later, especially with respect to  FIGS. 2-2B , it can be seen that the directional pointer  14  is secured in place by the radial expansion of a compressible cylindrical member  21 , which is deformed due to compression exerted by a nut  22  threading up onto a bolt  18 . This causes the cylindrical member  21  to compress in the axial direction and expand in the radial direction. The bolt  18  has a head  18 A with a hexagonal-shaped recess  18 B for receiving an Allen wrench having a hexagonal cross-section. Also, the directional pointer  14  includes a plate or flange  20 , having a diameter that is larger than the inside diameter of the tube  12 B, so the plate  20  rests on the top surface of the tube sheet  10  and prevents the directional pointer  14  from falling into the tube  12 B. All the open tubes  12 ,  12 A,  12 B have the same diameter, and there may be thousands of tubes  12  secured to the tube sheet  10 . 
       FIGS. 2 ,  2 B, and  3  show the directional pointer  14  in more detail.  FIG. 2  and the left side of  FIG. 2B  show the cylindrical member  21  in an expanded condition, in which it exerts a radially outwardly-directed force against the inner surface of the wall of the tube  12 B. This secures the directional pointer  14  in the tube  12 B so it cannot be rotated or pulled out by hand.  FIG. 3  and the right side of  FIG. 2B  show the cylindrical member  21  in a non-expanded condition, before it has been secured in the tube  12 B. 
     The cylindrical compressible member  21  (made of rubber or a flexible, rubbery type of material) defines an axial hole  23  (See also  FIG. 5 ) extending from one end to the other. A cap bolt  18  extends through a directional indicator plate  26 , through the plate or flange  20 , and through the axial hole  23  and has a threaded end  18 C onto which a nut  22  has been threaded. As was explained earlier, the head  18 A of the bolt  18  has a hexagonal-shaped recess  18 B (shown in  FIG. 1 ). The directional indicator plate  26  has an outside diameter that is somewhat less than the outside diameter of the flange  20 . At the other end of the bolt  18  is a toothed plate  28  with upwardly projecting teeth  30  that dig into the compressible member  21 . The nut  22  is fixed to the toothed plate  28  (or alternatively there is sufficient friction between the nut  22  and the bottom surface of the toothed plate  28 ) so the nut  22  does not rotate relative to the toothed plate  28  when the bolt  18  is being rotated, and since the toothed plate  28  digs into the compressible member  21 , the toothed plate  28  and nut  22  also do not rotate relative to the compressible member  21 . This enables the user to tighten the nut  22  up onto the bolt  18  just by rotating the head of the bolt  18 . At first, the loose fit between the bolt  18  and the inner surface of the compressible member  21  at the opening  23  and the mass of the compressible member  21  prevent the compressible member  21  from rotating as the bolt is tightened, and then, as the compressible member  21  moves to its expanded state, in which it presses against the inner wall of the tube  12 , the friction between the compressible member  21  and the inner wall of the tube  12  prevents the compressible member  21  (and the toothed plate  28  and the nut  22 ) from rotating. 
     When the bolt  18  is tightened (threaded into the nut  22 ), it causes the compressible member  21  to shorten axially and expand radially, so it presses against the inner wall of the tube  12 B, causing the directional pointer  14  to be secured within the tube  12 B. 
     If desired, the flange  20  may be secured to the compressible member  21 , which would allow the worker to prevent the compressible member  21  from rotating while he is rotating the bolt  18  simply by holding the flange  20  with one hand as he rotates the bolt  18  with the other hand. 
     The directional indicator plate  26  may have a variety of configurations. It may have a small hole  16  offset from the axis to serve as a directional indicator as shown in 
       FIGS. 1 ,  7  and  9 . The hole  16  is offset radially from the axis of the directional indicator plate  26 , indicating a direction from the axis to the hole  16  which serves as a pointer that can be used to point toward the tube  12 A that needs correction, as illustrated in  FIG. 1 . Instead of a hole  16 , the directional indicator plate  26 ″ may have a small nick or indentation  16 ″ as shown in  FIG. 8 , or may bear some other reference mark, such as an arrow (not shown). 
     The directional indicator plates  26  also may be made in various colors, with each color indicating a different type of condition within the tube  12 A to be corrected. For example, red may indicate that the pressure in the tube was too high, and yellow may indicate that the pressure in the tube was too low, violet may indicate that the height of catalyst in the tube was too low, and so forth. 
     Instead of using color to indicate the type of correction that is needed, the directional indicator plate  26 ″ may be textured, as shown in  FIG. 8 , or may have a certain pattern to indicate the type of correction, as shown in  FIG. 9 . 
     The plate  26 ′, shown in  FIG. 6 , does not have a hole to serve as a directional indicator or pointer but instead has markings  24  on its top surface that may serve both as a pointer and as an indication of the type of correction that is needed. Those markings may be engraved, printed, cut through the plate, or even hand-applied using a pencil, an indelible pen, a piece of tape, or the like. As explained earlier, ink or tape are not preferred for use where they can be worn off due to foot traffic, but they may be preferred for use on the bottom tube sheet, where people do not walk. 
       FIGS. 10 ,  11 ,  13  and  14  show various directional indicator plates  26 A-D that have different shapes to indicate the type of correction that is needed. 
     One example of how these directional pointers  14  may be used is after a vertical tube chemical reactor has been loaded with catalyst and has been pressure tested. These directional pointers  14  may then be installed to indicate which tubes had a back pressure that was too high, which tubes had a back pressure that was too low, which tubes need to be plugged, and so forth. The directional pointers  14  also may be used on heat exchangers with horizontal tubes. The directional pointers  14  are installed by a person who has the special tool that can fit into the hex recess of the head of the bolt  18 . This tool usually is L-shaped and has a cross-section that matches the hexagonal recess, with both legs of the L being long enough that the tool cannot fall into one of the tubes  12 . Also, the directional pointers  14  are made so they will not come apart so there will be no loose parts that could fall into one of the tubes  12 . The tool alternatively can be installed in a battery powered drill. 
     When using the directional pointers  14 , the installer installs the directional pointer  14  in a tube  12 B that is adjacent to the tube  12 A that is being marked for correction, and he installs it with the pointer  16  directed toward the tube  12 A that needs correction, so that the tube  12 A becomes the “marked tube”, that is, the tube toward which the pointer on the directional pointer  14  is pointing. He tightens the directional pointer  14  with the special tool so the pointer  16  cannot be rotated relative to the tube  12 B, and the directional pointer  14  cannot be removed from the tube  12 B by someone who does not have authorization to carry one of the special tools. This means that the directional indicator  16  will be directed toward the tube  12 A until an authorized person comes with the special tool to rotate the bolt  18  in the opposite direction, moving the compressible member  21  to a less expanded condition, and allowing the directional pointer  14  to be removed from the tube  12 B. (While a hexagonal recess is shown here, there are various known types of driving arrangements that require special tools that could be used instead, such as star-shaped, and so forth.) 
     The directional pointer  14  would remain in place (such as in tube  12 B in  FIG. 1 ) as the corrections are being made so the person making the corrections does not lose track of the tube  12 A being corrected. The directional pointer  14  may also be used to help a worker find the corrected tubes so they can be re-tested. 
     After the tubes have been corrected and retested or had the desired treatment, a person with authorization to carry the special tool would then go around and remove the directional pointers  14 . 
     It should be noted that it also would be possible to use the directional pointer  14  to provide further indication of activities that have occurred relating to the marked tube  12 A. For example, a worker may use an indelible pen to mark on top of the plate  26  to indicate that the marked tube has been corrected or that it has been retested. The marking may be a symbol such as a check-mark “√” or a number sign, “#”, a letter, such as “C” for “corrected” and “R” for “retested”, a shape, such as an unfilled-in triangle or a filled-in square, or different colors, such as a blue mark to indicate that a correction has been done and a green mark to indicate that the tube has been retested, or anything else that will tell the workers what has been done to the marked tube. 
     While  FIG. 1  shows the directional pointers  14  being used on the top tube sheet  10  to mark the tops of the tubes  12 , it also may be helpful to mark the bottom of the tubes  12  at the bottom tube sheet  10 B, as shown in  FIG. 18 . In that case, the directional indicator plate  126  may be used in a directional pointer  114  that is otherwise very similar to the directional pointer  14 . This directional indicator plate  126  differs from the original directional indicator plate  26  in that it has a cylindrical shape so it projects axially beyond the washer  20  and therefore can be seen more easily by a worker walking along the ground or on a platform below the reactor. This directional indicator plate  126  also has a hole  116  through the side wall which serves as a directional indicator or pointer. The directional indicator plate  126  may also have identification markings  124  as shown in  FIG. 17  instead of, or in addition to the opening  116 . It also may be made in a color or have a texture or marking or other indication of the type of correction that needs to be made. In general, it may have all the same features as the directional indicator plate that is used on the top of the tubesheet  10 . 
     These directional pointers  114  are inserted into the bottom of the tubes  12 B and point toward the adjacent tubes  12 A that need to be corrected. A flag, streamer, or tag (not shown) may be tied to the directional pointer  114 , for example by threading a streamer through the opening  116 , to make the directional pointer  114  easier to see. The markings  124  may refer to the condition of the tube  12 A to be corrected, or to some other characteristic of interest, such as the location of the tube  12 B or of the tube  12 A to be corrected. 
     Referring back briefly to  FIG. 6 , a line  32  (or some other reference mark) may be added by the user onto the directional indicator plate  26 ′, either before or after the directional pointer  14  has been installed in the tube  12 B. The line  32  may be added to the plate  26 ′ by the user with a pencil, pen, decal, or other mechanism after the directional pointer has been installed and secured in the reactor tube. In this instance, there is no need to align the directional indicator of the directional pointer  14  with the tube  12 A to be corrected before tightening the directional pointer  14 ′ in place, since the line  32  is used instead as the directional indicator and this line  32  can be applied after the directional pointer is installed in the tube  12 B. It also should be noted that it may be desirable for the directional indicator plate  26 ′ to be the same as the flange or plate  20  that rests on the tubesheet rather than using a separate plate. 
       FIG. 19  is a plan view of an alternative directional pointer  38 . This directional pointer  38  includes a flange  40 , a securing member  42 , and an anti-rotation member  44 , as explained below. The flange  40  defines an opening  46 , which, as described below, is aligned with the tube to be marked. 
     Referring to  FIGS. 19 ,  20 A and  22 , the flange  40  is an oval shaped, substantially flat plate sized to span across three adjacent reactor tubes  12 . The circular, middle opening  46  preferably is at least as large as, and in this embodiment slightly larger than, the inside diameter of the reactor tubes  12 . However, the middle opening  46  could be smaller than the inside diameter of the tubes  12 , if desired.  FIG. 20B  shows an alternative embodiment of a flange  40 *, which defines a slot  82 * extending from the outer edge to the central opening  46 * and can be used to permit a thermocouple lead wire to pass through the central opening  46 * in the flange  40 * as will be described later. 
     As shown in  FIG. 19 , the opening  46  is aligned with the reactor tube  12 A that is being marked. The flange  40  also defines another circular opening  48  to one side of the middle opening  46 , and a slotted opening  50  on the other side of the middle opening  46 . Referring to  FIG. 22 , it can be seen that the securing member  42  is secured in place by the radial expansion of a compressible cylindrical member  52 , which is deformed due to compression exerted by a nut  54  threading up onto a bolt  56 . This causes the cylindrical member  52  to compress in the axial direction and expand in the radial direction to secure the securing member  42  against the inner surface of the tube  12 , as was described earlier with respect to the directional pointer of  FIG. 1 . The bolt  56  has a head  58  with a hexagonal-shaped recess  58 B for receiving an Allen® wrench having a hexagonal cross-section. Also, the securing member  42  includes a plate  60 , having a diameter that is larger than the diameter of the opening  48  in the flange  40 , so the plate  60  rests on the top surface of the flange  40  and prevents the securing member  42  from falling into the tube  12 . The plate  60  may have various indicators on its top surface to indicate the condition of the tube  12 A, as desired. In this embodiment, it has the letters A, B, C, D spaced apart at  90  degree intervals. It also could include an indicator  26  or  126  as shown in  FIGS. 3-18  and described earlier. 
     The anti-rotation member  44  (See  FIGS. 19 and 22 ) is similar to the securing member  42  except that it does not have a compressible member to expand axially to secure against the wall of the tube  12 . While the plug  70  of the anti-rotation member  44  could be made out of a compressible material, similar to that of the compressible member  52 , in this particular embodiment, the plug  70  is made from a non-compressible material, such as metal, wood, or a hard plastic, such as Nylon® (DuPont). Other than this difference, the anti-rotation member  44  is similar to the securing member  42 , including a bolt  72  with a hex head  74 , a lower washer  76 , a nut  78  threaded onto the threaded end of the bolt  72 , and an upper washer  80 . The upper washer  80  or plate has a larger diameter than the width of the slot  50  in the flange  40  and may have indicators on its top surface to indicate the condition of the tube  12 A. In this example, the numbers  1 ,  2 ,  3 ,  4  are located at 90 degree intervals on the washer  80 . The plug  70  has a diameter which is substantially smaller than the inside diameter of the tube  12 . This allows the anti-rotation member  44  to slide along the slotted opening  50  in the bridging flange  40  (as shown in phantom in  FIG. 22 ) to adjust to any changes in pitch (center to center distance) of the tubes  12 . 
     Once assembled onto the flange  40 , the anti-rotation member  44  need not be removed. However, the bolt  72  may be loosened slightly from the nut  78  to allow the anti-rotation member  44  to slide along the slotted opening  50  of the bridging flange  40  in order to snug up the anti-rotation member  44  against the inner wall of the tube  12 , which helps secure the directional pointer  38  in position, ensuring that the opening  46  in the flange  40  remains aligned with the tube  12 A (See  FIG. 19 ). Also, the bolt  72  may be loosened slightly to allow the user to rotate the washer  80  so a different indicator is directed toward the marked tube  12 A to indicate a change in the condition of the marked tube  12 A, and then the bolt  72  may be tightened again. 
     One example of how the directional pointer  38  may be used is explained below. Initially it is desirable to load all the tubes  12  with catalyst except the tube  12 A which will house a thermocouple. This tube  12 A should be kept empty so that a thermocouple (not shown) may be installed later. Therefore, the securing member  42  shown in  FIG. 21  is installed in the tube  12 A. The plate  60  covers the opening of the tube  12 A to prevent any catalyst particles from entering the tube  12 A. 
     Once the chemical reactor has been satisfactorily loaded with catalyst, the sealing member  42  is removed from the tube  12 A in preparation for installing a thermocouple in the tube  12 A. However, all the tubes  12  and  12 A look identical when standing on top of the upper tube sheet  10 . To prevent losing track of the thermocouple tube  12 A, the directional pointer  38  is installed, with its opening  46  placed over the marked tube  12 A , as seen in  FIG. 19 , prior to removing the securing member  42  that is in the marked tube  12 A. In this situation, the flange  40 * of  FIG. 20B  would be used. 
     The directional pointer  38  provides unhindered access to the marked tube  12 A to allow for the placement of a thermocouple inside the marked tube  12 A and for the loading of catalyst after the thermocouple has been installed, while providing a visual indication of the location of the marked tube  12 A, and does so with substantially only the hex heads  58 ,  74 , of the securing member  42  and anti-rotation member  44  respectively, projecting above the upper tube sheet  10 . This allows the personnel working on the upper tube sheet  10  to have full access to the complete upper tubesheet  10  and to the thermocouple tube  12 A with essentially no tripping hazard. 
     The indicators on the plate  60  or  80  may be used to indicate the condition of the tube  12 A during the process. For example, one of the indicators may be rotated to a first position to indicate that the marked tube  12 A is empty, and the other indicator may be rotated to a first position to indicate that a thermocouple needs to be installed in the marked tube  12 A. Then, the second indicator may be rotated to indicate that the thermocouple has been installed, and, finally, the first indicator may be rotated to a second position to indicate when the marked tube is loaded with catalyst. After the thermocouple has been installed and the tube has been loaded with catalyst, it may be back-pressure tested, and then the directional pointer would be removed. 
     It is common for electrical leads to extend upwardly from the thermowell out of the top of the tube  12 A, and the slot  82 * facilitates the removal of the directional pointer  38  from the tube sheet  10  by allowing the electrical wire to pass out of the opening  46 * and through the slot  82 *. Other types of sensors or other devices may project out of the top or bottom of the reactor tube, and they also may be accommodated by using the slot  82 *. 
       FIG. 23  shows another embodiment of a directional pointer  38 *, preferably for use on the lower tubesheet  11  of a chemical reactor. A comparison with the directional pointer  38  of  FIG. 22  shows that these two devices  38 ,  38 * are essentially identical except for the anti-rotation member  44 * which has a second plug  70 * located between the washer  80  and the flange  40 . This second plug  70 *, the washer  80  and the head  74  of the bolt  72  project from the bottom of the lower tubesheet  11  to make it easier for personnel to spot the directional pointer  38 *. The circumferential surface of the second plug  70 * may be used to further identify the tube  12 A by placing, for instance, an inscription (not shown) on the surface, such as T 1  (Thermocouple  1 ). Other than this difference, the directional pointer  38 * operates in substantially the same manner as the directional pointer  38  described earlier. 
       FIGS. 24 and 25  show two alternative types of securing members that may be used instead of the securing member  42 . 
     In  FIG. 24 , the securing member  42 ′ uses O-rings  100  to press against the inner surface of the wall of the tube  12 . 
     In  FIG. 25 , the securing member  42 ″ uses a wedging arrangement to expand against the inner surface of the tube  12 . As the bolt  102  is tightened, the wedge elements are pressed together and slide relative to each other to expand the diameter of the securing member  42 ″ and press against the inner surface of the tube  12 . 
     It will be obvious to those skilled in the art that various modifications may be made to the embodiments described above without departing from the scope of the present invention as claimed.