Patent Document

FIELD AND BACKGROUND OF INVENTION 
   The present invention relates generally to the field of tube extracting devices, and more particularly to an improved tube extracting device for facilitating the removal of tubes from different types of structures, such as boilers, condensers, evaporators, and the like. 
   A typical condenser comprises a pair of parallel tube sheets, a plurality of baffle plates, and a plurality of heat exchanger tubes. The tube sheets are located at the ends of the condenser. The baffle plates are positioned between the tube sheets and generally parallel thereto. The heat exchanger tubes extend between the tube sheets and through the baffle plates and are supported by the tube sheets. The tube sheets and baffle plates have a series of aligned holes formed therein, and the heat exchanger tubes are inserted through these holes and then expanded in the areas of the tube sheets into fluid-tight pressure contact therewith. 
   Because of malfunctions or normal preventive maintenance, it may be necessary to remove one or all of the tubes from the structure. This is generally accomplished by first relieving the pressure forces between the tubes and the tube sheets and then longitudinally pulling the tubes through the baffle plates and the tube sheets. Various types of devices are used to initially relieve or break the secured connection between the tubes and tube sheets, and then another apparatus is used to withdraw the tubes from the structure. 
   In the refurbishing of a water-tube boiler and the replacing of the tubes thereof, the tubes are conventionally removed by the use of an air hammer or the like, chipping away at the tube connection to the drum, to physically force the tube from the associated opening in the boiler drum. These methods have often resulted in damage to the drum and the opening through which the tube stub section projected. 
   Another method often used for removing tubing from structures is by use of a cutting torch. This is particularly common in the case of large boilers using heavy walled tubing on the order of three inches in diameter. Errors in use of the cutting torch can, of course, damage the tube sheet requiring expensive refinishing and repair work. 
   Prior art believed to be relevant to the present invention includes U.S. Pat. No. 4,233,730 issued to Godbe, U.S. Pat. No. 4,231,246 to issued Gorenc et al., and U.S. Pat. No. 4,180,903 issued to Hannigan, Jr., as well as, U.S. Pat. No. 2,507,201 issued to Evans, U.S. Pat. No. 2,744,429 issued to Seely and U.S. Pat. No. 3,245,247 issued to Valente. 
   The Godbe patent discloses a crimping tool having a hydraulic-driven ram which drives a wedge into the outside wall of the tube to crimp the tube. The crimping operation breaks the bond between the tube and tube sheet and allows the tube to be pushed from the hole. 
   A crimping tool for crimping a boiler tube to facilitate its removal is disclosed in the Gorenc patent. 
   The Hannigan, Jr. teaches a hydraulic-driven apparatus having a plurality of arms with gripping fingers for engaging and crimping the tube. 
   The Evans patent discloses a one-piece cutter or plow-type tool for slitting the tubes from the outside of the tube sheet to break the bond between the tube and the tube sheet. 
   The Seely patent teaches a particular type of tube crimper used in reducing the cross-section of a capillary tube to provide a precise flow resistance. 
   The Valente patent teaches a complicated device for pointing the end of tubing so that the tubing may be inserted into a drawing die. 
   There is a need for a simpler device for facilitating the removal of tubing, especially heavy-walled tubing from drums and/or tube sheets without damaging the drum and/or tube sheet bonding surfaces. 
   SUMMARY OF INVENTION 
   It is an object of the present invention to provide a novel device for breaking the seal between a tube and a hole in a drum or tube sheet. 
   It is a further object of the invention to provide a simplified device for facilitating the removal of tubes from a drum or tube sheet without damaging the tube sheet bonding surfaces. 
   Accordingly, an object of the invention is to provide a tube extraction device which facilitates the removal of a tube from a tube hole in a drum. The device comprises a housing which is mounted over an exterior surface of the drum. The housing has an opening which receives a part of the tube. The device has a wedge which is slidably mounted in the housing. The wedge has a slanted face and a bottom edge. A thrusting ram is slidably mounted in the housing. The side thrusting ram laterally moves the wedge so that the slanted face indents the tube inwardly. A drive down ram is slidably mounted in the housing. The drive down ram drives the wedge down into the zone between the tube outside wall and the tube hole so that the tube collapses into the tubes hole. 
   It will be seen that use of the device is very rapid and removal of a tube from its secured connection in the boiler drum opening is materially facilitated, thereby materially reducing the costs involved in retubing a boiler or replacing a tube. The tool is light and portable enough so that a single workman utilizing the tool can readily and rapidly accomplish the job of removing the boiler tubes from a boiler. In the past, such a retubing operation normally required several workmen. 
   The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
       FIG. 1  is a front elevational view of the external tube extracting device of the invention; 
       FIG. 2  is a side elevational view of the external tube extracting device of the invention; 
       FIG. 3  is a top view of the external tube extracting device of the invention; and 
       FIG. 4  is a top view of the external tube extracting device of the invention having multiple ram assemblies. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to the drawings, in which like reference numerals are used to refer to the same or similar elements,  FIG. 1  shows a side view of the tube extracting device  100 . The device has a housing  10  preferably comprised of two parts connected by typical fasteners, such as bolts  11 . The housing  10  is supported on an external surface of a drum  200  of a typical boiler, heat exchanger or the like. The drum  200  houses conventional tube(s)  300  in tube holes  210 . The tubes  300  are typically expanded into the tube holes  210  thereby forming a joint  215  between the tube  300  and the tube hole  210 . 
   A tube stub  310  extends out of the tube hole  210 . The housing  10  has a bottom opening  12  and a top opening  14  which receive the tube stub  310 . The tube stub  310  exits the housing  10  from the top opening  14 . 
   A wedge  20  is slidably mounted in the housing  10 . The wedge  20  has a face  22  adjacent the portion of the tube stub  310 . The face  22  of the wedge  20  preferably has a curved contour  23  as illustrated in  FIG. 3 . The face  22  has a top edge  24  which is closest to the tube and a bottom edge  26  which is farthest from the tube  300 . Thus, the face  22  of the wedge  20  slants downward away from the tube  300 . The bottom edge  26  is preferably round. 
   A side thrusting ram  40  is slidably mounted in the housing  10  preferably behind the wedge  20 . The side thrusting ram  40  is connected to the wedge  20  by conventional means. The side thrusting ram  40  is a device well-known in the prior art. For example, the side thrusting ram includes control valves (not shown), spring return (not shown), a piston  500  (shown hidden) and a cylinder, which are all conventional parts of a ram. The side thrusting ram  40  is preferably coupled to a typical hydraulic pump (not shown) which powers the side thrusting ram  40 . The hydraulic pump provides pressurized hydraulic fluid to the cylinder and causes an outward extension of the side thrusting ram  40 . The spring may automatically return the side thrusting ram  40  inwardly back to its starting position upon shutting off the flow of hydraulic fluid to the power unit via the control valve. 
   A conventional drive down ram  50  is also slidably mounted in the housing  10  preferably above the wedge  20 . The drive down ram  50  is connected to the wedge  20  by means well-known in the prior art. The drive down ram  50 , preferably hydraulically powered, drives the bottom edge  26  of the wedge  20  into the indented tube whereby the tube  300  collapses into the tube hole. Tube  300 , as collapsed, is then easily removed from the hole by conventional extracting means. When the drive down ram  50  is in operation, the side thrusting ram  40  moves downward or upward along with the wedge  20 . 
   A guide means maintains the wedge  20  in operational alignment with the drive down ram  50 . The guide means generally comprises a key and carriage assembly  60 . As shown in  FIG. 2 , a key  62 , preferably a T-shaped member, is connected to the top of the wedge  20 . A carriage  64 , preferably a C-shaped member, is connected to the bottom end of the drive down ram  50 . The key  62  slidably engages the carriage  64  to connect the drive down ram  50  to the wedge  20  and allows the wedge  20  to move laterally with respect to the tube hole  210 . 
   Operation of the tube extracting device  100  for removing a tube from anchored relationship to a boiler drum is preferably as follows. In the use of the present device  100 , the device  100  is positioned down over the tube stub  310  such that the tube stub  310  may project through the housing  10 . Thereupon, the control valve for the power means is actuated to apply pressurized fluid via hose (not shown) to the cylinder, causing extension of the side thrust ram  40 , and movement of the wedge  20  into engagement with the tube stub  310 . 
   The slide thrust ram  40  laterally drives the wedge  20  into the tube stub  310 . As illustrated in  FIG. 2 , the face  22  of the wedge  20  applies a force to the wall of the tube stub  310 , indenting the tube along an area running generally lengthwise thereof. The wedge  20  moves into the tube stub  310  to a point where the bottom edge  26  is above the joint  215  formed between the tube  300  and the tube hole  210 . The face  22  of the wedge  20  applies a force to the tube stub  310 , running vertically lengthwise along the tube stub  310 , causing inward crimping lengthwise along tube stub  310  as shown for instance in  FIG. 3 . This inward crimping deforms the periphery of the tube stub  310  section inwardly, pulling the tube  300  away from the inside wall of the tube hole  210  from its attached or secured condition in the boiler drum  200 . Thus, the side thrust ram  40  creates a gap between the tube  300  and the inside wall of the tube hole  210 . When the bottom edge  26  of the wedge  20  is over such gap, the control valve shuts supply of pressurized fluid to the side thrust ram  40  and, in turn, supplies pressurized fluid to the drive down ram  50 . The drive down ram  50  drives the wedge  20  lengthwise down the tube stub  310  whereupon it collapses tube  300  downwardly into the interior of the tube hole  210 . Tube  300 , as collapsed, can then be readily removed through the tube hole  210  in the drum. 
   The device  100  will collapse the tube  300  such that the tube  300  will readily fall out of the tube hole  210  upon retraction of the device  100 . Depending on the thickness of the tube  300 , diameter of the tube hole  210  or whether there are ring grooves into which the tube  300  had been originally expanded, the collapsed tube  300  can attach to the wedge  20  and be removed upon retraction of the wedge  20  from the tube hole  210 . 
   In a preferred embodiment, a keeper plate  16  is secured to the portion of the tube stub  310  which exits the housing  10 . The keeper plate  16  is secured to the tube stub  310  by conventional methods such as welding or clamping. The wedge  20  creates a reactive force when it strikes the tube stub  310  which tends to move the device  100  away from the drum  200 . The keeper plate  16  stabilizes the device  100  and prevents the device  100  from moving away from the drum  200 . 
   In another embodiment of the present invention, as shown in  FIG. 4 , the tube extracting device  100  comprises a plurality of ram assemblies  30  each having a wedge  20 , a side thrust ram  40 , and a drive down ram  50 . This embodiment operates in the following manner. The side thrust ram  40  of the first ram assembly  30  laterally moves the wedge  20  into the tube stub  310 , followed in sequence by the side thrust rams  40  of the remaining ram assemblies  30 . Therefore, the tube stub  310  is indented at multiple angles by the wedges  20  of the ram assemblies  30 . The drive down ram  50  of the first ram assembly  30  drives the wedge  20  into the tube stub  310 . The drive down rams  50  and wedges  20  of the remaining ram assemblies  30  follow in sequence. The drive down rams  50  collapses the tube  300  into the tube hole  210 . 
   In yet another embodiment of the present invention, the tube extracting device  100  comprising a plurality of ram assemblies  30 . In this embodiment each of the side thrust ram  40  of the two or more ram assembly  30  concurrently indent the tube stub  310 . The drive down ram  50  of each of the two or more ram assemblies  30  then concurrently drive wedge  20  of the two or more ram assemblies down tube stub  310 . The drive down ram  50  of the two or more ram assemblies  30  concurrently collapses the tube  300  into the tube hole  210 . 
   While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

Technology Category: 4