Patent Publication Number: US-2009230109-A1

Title: Equipment and process for applying an external structural weld to piping and similarly shaped pressure boundary components

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a Continuation of U.S. Utility patent application Ser. No. 11/463,565, filed Aug. 9, 2006, the contents of which are incorporated by reference herein in their entirety. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a system and/or method for overlaying metal piping with a weld overlay. More specifically, a process and/or apparatus for applying a weld overlay to piping, fittings or nozzles utilizing a welding apparatus is disclosed. 
     2. General Background 
     Pipes, fittings, and nozzles are subject to degradation or material failure in a mechanical system. To prevent or fix this problem, weld overlays are often placed over theses areas to either repair damage or to prevent failure of the original boundary materials with pre-emptive reinforcement. Applying a weld overlay to a structural component will protect the integrity of the mechanical system. 
     Conventional orbital welding equipment systems that rely on either single or double weld heads typically require vertical-up application of a weld overlay that applies a weld bead only on one side of the pipe. After the first weld bead is placed on approximately half (180°) of the piping system. Then, the apparatus would need to be re-positioned, the equipment and cables being re-wrapped to the opposite side of the piping. A second weld bead would then be placed on the opposite side. Many passes on both sides of the pipe would typically be required to cover the length of the pipe section to be reinforced and to build the thickness of the weld overlay. 
     SUMMARY 
     In one embodiment of the present disclosure, an orbital welding apparatus is adapted to apply an external structural weld to a component, the apparatus comprising a mounting assembly having a plurality of magnetic foot pads, a rod attached at one end to one of the magnetic foot pads, an upper attachment pad at the opposite end of the rod, and a bottom attachment pad attached to at least one other magnetic foot pad; a travel guide, the travel guide attached to the top attachment at one end and the bottom attachment at the other end; and a head assembly attached to the travel guide by a mounting bracket, the head assembly having a track ring assembly having an inner ring and an outer ring, at least two weld heads attached to the inner ring on opposite sides of the inner ring to apply the weld overlay to the component, two wire feed drive mechanisms on the track ring on the opposite side of the track ring, the wire feed mechanisms being movable to permit placing the track ring around the component and a drive mechanism located on the outer ring of the track ring, the drive mechanism including a chain fixed to the inner ring to permit rotation of the inner ring and the weld heads around the component to be welded. 
     Another embodiment of the apparatus of the present invention includes three magnetic foot pads. In this embodiment, the lower attachment pad is located on the center of a bar attaching the two magnetic pads not attached to the tension support rod. Attaching the attachment pads to the travel guide provides a magnetically attached, cantilevered weld head assembly that remains independent of the component section to receive the weld overlay. 
     Another embodiment of the present invention is that the weld head torches are attached to a control module that monitors the weld height control programming so that the torches will adjust to follow the contours of the component transitions 
     Another embodiment of the present invention provides a system that further comprises a camera attached to each welding head to enable remote monitoring of weld bead placement and weld puddle dynamics. 
     In an additional embodiment, the disclosed apparatus and method permits use of welding equipment to apply a weld overlay on piping systems without the need to attach to the member that is to be welded. 
     In yet another embodiment of the present invention, the process relates to a method of applying an external weld overlay to a component wherein the process comprises attaching an apparatus to an adjacent structure with a mounting assembly having a plurality of magnetic foot pads, the mounting assembly attached to a travel guide; aligning a head assembly having an inner track ring and an outer track ring around a centerline axis of the component to be welded, the inner track ring including as least two weld heads placed on opposite sides of the track ring; initiating the weld torch head located at the lowest point of the weld overlay; engaging a chain drive fixed to the inner track ring and rotating inner track ring and the attached weld heads, the weld head torches rotating about 180 degrees and placing a weld bead on the component; terminating the first weld torch; and initiating the second weld torch at the lowest point of the weld overlay, engaging the chain drive to rotate the inner track ring in the reverse direction to apply a weld bead on the opposite side of the component. 
    
    
     
       DRAWINGS 
       The foregoing aspects and advantages of the present disclosure will become more readily apparent and understood with reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  illustrates an exemplary embodiment of the equipment system. In this embodiment, the system is set up for application of a structural weld overlay on a nozzle section of a pressure vessel having a hemispherical head. 
         FIG. 2  illustrates a side view of an exemplary embodiment of the equipment system for set up of the weld overlay in  FIG. 1 . 
         FIG. 3  illustrates the mounting assembly utilized to mount the equipment system to a adjacent structure or tank. 
         FIG. 4  illustrates the head assembly for the welding equipment as seen from the bottom view of the head assembly of the apparatus. 
         FIG. 5  illustrates the head assembly, particularly the chain drive actuator utilized to rotate the weld heads around the structure being welded. 
         FIG. 6  illustrates the sectional cutaway view of the weld overlay placed on a typical complex nozzle and piping spool. 
         FIG. 7  is a block flow diagram illustrating the system components for the welding system. 
     
    
    
     DETAILED DESCRIPTION 
     In one embodiment, an apparatus  10  for applying a weld overlay to a nozzle or piping spool of complex configuration is disclosed. In one example, the apparatus  10  comprises a mounting assembly  15 , a travel guide  17  and a head assembly  20 . The head assembly  20  includes a plurality of orbital weld heads for applying a weld overlay to a nozzle, piping or fitting. In another example, the apparatus  10  provides a new assembly and process that allows an easily mountable system that may operate in a smaller area and avoiding interferences and inability to mount the system. In yet another example, the welding equipment includes a plurality of different drive mechanisms to allow for application of a weld overlay on a potentially irregular surface. 
     In addition to application of a weld overlay, the welding apparatus equipment system  10  may be utilized for several other applications. For example, the system could be utilized to weld piping joints for similarly complex configurations or in interference constrained piping spools and nozzles. 
     An exemplary embodiment of the welding apparatus  10  is depicted in  FIG. 1  and  FIG. 2 . A mounting assembly  15  is attached to a structure utilizing magnetic foot pads  25 . In one example, the structure illustrated is a pressure vessel with a hemispherical head. However, the structure that the apparatus  10  is attached to may be any metallic structure. In another example, the magnetic foot pads  25  are aligned to correctly position the head portion of the apparatus  10  to apply the weld overlay to an adjacent piping, nozzle or fitting. 
     In another embodiment, attached to one of the magnetic foot pads  25  is a tension support bar. The tension support bar  60  provides support for the attached head assembly  20 . At the opposite end of the tension support bar  60  is an upper attachment pad  65 . Additionally, a lower attachment pad  70  is attached to at least one of the other magnetic foot pads  25 . 
     In an additional embodiment, the mounting assembly may comprise a 6-axis magnetically mounted robotic arm for attachment to the travel guide and head assembly. Utilization of a robotic arm rather than a fixed axis attachment provides for utilization of the welding apparatus in more confined areas. 
     In yet another embodiment, the two attachment pads are attached by a travel guide  17 . The travel guide  17  is attached at one end to the upper attachment pad  65 . The lower attachment pad  70  is attached at the other end of the travel guide  17 . The mounting assembly  15  attached to the travel guide  17  creates a magnetically attached, cantilevered base of attachment and drive for a weld head assembly  20 , all of which remain independent of the component section that is to receive the overlay. 
     In one example, the mounting assembly  15  may provide for a more versatile apparatus than previous welding systems. For example, instead of hooking onto systems with complex geometries or possible interferences, the magnetic foot pads  25  simply attach to an adjacent structure  5 . As a result this may reduce and/or eliminate the potential of being unable to apply a weld overlay due to short length of piping and the inability to attach travel or guide rings. 
     In yet another embodiment, the travel guide  17  includes a drive motor attached to a screw drive shaft  55 . A head assembly  20  is attached to the travel guide  17  by a mounting bracket. During application of the weld overlay, the drive motor  57  precisely turns the screw drive shaft  55 . As the screw drive shaft  55  is turned, the mounting bracket  45  is moved, putting the head assembly  20  in a new position to apply a subsequent weld bead. 
     In one example, utilization of a travel guide  17  may provide for a more versatile and useful apparatus. For example, in conventional systems, the travel or guide rings would typically be attached to the component that is being welded. In contrast, in one embodiment of the present invention, since the travel guide  17  may be attached to the mounting assembly  15  located on an adjacent structure  5 , less space may be utilized to provide the travel guide  17 . Accordingly, weld overlays may be applied to areas with a smaller axial envelope than with conventional welding procedures. 
     In yet another embodiment, the head assembly  20  includes a track ring  22  having an outer ring and an inner ring. The outer ring of the head assembly  20  is attached to the travel guide  17  with a mounting bracket and enable movement of the head assembly  20  to place any subsequent weld beads. The head assembly  20  includes a drive mechanism located on the outer track ring  26  that engages a chain drive fixed to the inner track ring  24 . 
     In a further embodiment, at least two weld heads are located on the inner ring. For example, the two weld heads are located on opposing sides of the track ring  22 . The opposing weld head torches are utilized to apply a weld overlay to a component. To apply a weld bead, a weld head torch is initiated and the drive mechanism is activated to rotate the inner ring about the piping or nozzle. 
     In another embodiment, to enable placement of the head assembly  20  in the proper position so as to apply the weld overlay, wire feed drive mechanisms  30  are rotated to expose an opening on the track ring  22 . By rotating the wire feed drive mechanisms  30 , the head assembly  20  may be placed around the section or component to be welded. In one example, the track ring  22  is positioned and centered around the nozzle or piping section to be overlaid and establishes a virtual center line for the overlay process. 
     In a particular embodiment, the head assembly  20  incorporates a radial self-aligning device. This device allows the head assembly to be centered automatically around the component to be welded, increasing the efficiency in utilization of the welding apparatus  10 . 
       FIG. 3  illustrates another embodiment of the mounting assembly  15  for the welding equipment. In one example, the mounting assembly  15  is attached to a metallic structure utilizing a plurality of magnetic foot pads  25 . In one specific example, the mounting assembly  15  includes three magnetic foot pads  25  that attach to the structure or pressure vessel. The magnetic foot pads  25  of the mounting assembly  15  of the welding equipment are positioned on an adjacent metallic component or structure  5 . 
     In another embodiment, attached to each metallic foot pad  25  is an actuator  32 . The actuator  32  may assist in facilitating a user of the apparatus  10  to place the metallic foot pad in a desired position. The actuator  32  may also allow a user of the apparatus to easily reposition on and remove the apparatus  10  from the adjacent structure  5 . 
     In a further embodiment, placement of the magnetic foot pads  25  is completed to maintain the alignment of the head portion of the apparatus  10  and establish the virtual center line for the overlay process. For example, utilization of metallic magnetic foot pads  25  may assist in the placement of the apparatus  10  so as to allow for different applications and types of structures. In another example, complex geometries of piping or other difficulties caused from setting up the apparatus  10  may be reduced and/or eliminated. In yet another example, the apparatus  10  may be utilized in different environments and may be utilized in areas that have a short axial length. 
     In the embodiment depicted in  FIG. 3 , the top of one of the metallic foot pads  25  is a tension support bar  60 . At the top of the tension support bar  60  is an upper attachment pad  65 . The tension support bar  60  is attached to the magnetic foot pad  25  by a hinge  62  so that the position of the support bar may be changed depending on the necessary location for the travel guide  17 . In one example, since the position of the support bar may be altered, the apparatus  10  may be utilized interchangeably with different locations and types of components that need to be welded. 
     In this embodiment, a rod extends between and is attached to the two other foot pads  25  on the mounting assembly  15 . In the middle of this rod, is a second attachment pad adapted to attach to the opposite end of the travel guide  17 . 
     In one example, the upper attachment pad  65  and lower attachment pad  70  are both utilized to connect to the travel guide  17  resulting in a magnetically attached, cantilevered weld head assembly  20  that remains independent of the component section to receive the weld overlay. 
       FIG. 4  is another embodiment and illustrates a bottom view of the head assembly  20  of the apparatus. The travel guide  17  is attached to the outer track ring  26  on the head assembly  20 . Attached to the inner ring is a plurality of program command modules  80  to control the weld head torches  75 . Extending from the command modules  80  is a bracket connecting weld head torches  75 . The weld head torches  75  are located on opposite sides of the apparatus. 
     In another example, each of the weld head torches  75  are attached through command modules  80  to the inner ring track. Suitable control modules include command or automatic height control programming so that the torches  75  will adjust to follow the contours of pipe and nozzle transitions to apply an even weld overlay to the component. 
     In one embodiment, attached to each weld head is a camera visioning module  85 . This camera  85  assists in providing for remote supervision of weld bead placement and weld puddle dynamics. As a result, the placement of the weld may be visually monitored to ensure that the weld overlay is being placed properly on the system. 
     As illustrated in  FIG. 5 , the drive mechanism  40  engages the inner track ring  24  to rotate the inner track ring about the component being welded. For example, when the drive mechanism  40  is activated, a chain drive actuator  90  rotates and moves a chain drive  95 , and thus the attached inner ring  24  and the attached weld head torches  75  rotate about the component to provide an even weld overlay. In other embodiments, in addition to a chain drive, other types of drives may be used. For example, cable, cords or wires may be utilized in the drive mechanism. 
       FIG. 6  illustrates another exemplary component wherein the weld overlay  105  had already been placed utilizing the disclosed apparatus. The shape of the nozzle  110  and piping spool  100  is an example of the type of structure that may be welded with the disclosed apparatus. In other examples, the welding apparatus  10  disclosed herein can also apply a weld overlay to various other shapes and types of nozzles, piping and fittings. For example, the weld overlay  105  depicted could be placed on this section as a repair or as a pre-emptive reinforcement of the nozzle. 
     It is understood that the disclosed apparatus  10  may be utilized to apply the weld to a variety of different shapes. After the apparatus  10  has been properly aligned on the piping or fitting, the welding operation begins. In an exemplary embodiment, a weld arc initiation using one torch located at the initial point of the design overlay is initiated. In specific examples, the initial point of application is the lowest point on the component. The drive mechanism engages the chain drive fixed to inner track ring  24  to rotate the inner track ring and the attached weld heads about the virtual center line of the weld. The virtual center line of the weld is normally aligned with the axis of the pipe or nozzle section. 
     For example, this initial weld bead application with the initial weld head torch  75  will proceed for about 170-190 degrees around the component. After the first weld head torch  75  reaches this point, a termination command ends the firing of this weld head torch. 
     In yet another embodiment, the two weld heads are fixed to be about 180 degrees opposed. After the first weld head torch  75  is terminated, the opposing weld head, the second torch  75 , will receive an initiation command and the motor drive  40  will reverse causing the weld bead to be applied on the opposite side of the first bead, applied from the lowest point and intersecting the first bead after 170-190 degrees of travel. When the second torch  75  has completed is travel, the first torch  75  is again in its original starting position. 
     The attached command module  80  monitors the height of the weld placement and will adjust weld head torch to follow the contours of the pipe and nozzle transitions. 
     In another exemplary embodiment,  FIG. 7  illustrates a box diagram illustrating the components of the welding system. The welding head apparatus  10  is attached to a welding power  145  supply via an attachment means. For example, umbilical cords may attach the different components of the system. In one specific example, the welding power supply is utilized for standard operation of the welding apparatus  10 . The welding power supply  145  measures voltage and current to monitor application of the weld overlay. Additionally, many other power supplies utilized in the welding industry may also be utilized for the power supply. 
     In another embodiment, cords attach the welding power supply  145  to a power supply control pendent  130 . Command inputs  140  are entered into the power supply control pendant  130  for the proper application of the weld overlay. The command inputs initiate the power welding supply to transmit different commands. Power, gas shielding and coolant management is transmitted  120  from the welding power supply  145  to the welding apparatus  10 . Feedback  140  is returned from the welding power supply  145  to the power supply control pendent  130  to help monitor the system. 
     In another example, electro-mechanical command inputs  125  are transmitted via an attachment cord from the welding power supply  130  to a command module  80 . The command module  80  transfers these inputs  135  to the welding head  10  to initiate the weld torch and apply the weld overlay. 
     In another embodiment, the welding head apparatus sends a video return  115  to the command module  80 . The video return  115  may be monitored remotely to remotely supervise weld bead placement and weld puddle dynamics. If any command inputs need to altered, the inputs can be changed to correctly apply the weld overly. 
     Conventional systems require a re-wrap of the attached cords to apply the weld overlay on opposing sides of the component to be welded. Since one embodiment of this apparatus may provide a plurality of weld torches fixed on the track ring about 180 degrees opposed, the re-wrap of cables in conventional systems is reduced and/or eliminated. 
     In another embodiment, the two weld heads may be concurrently managed by alternating control programs. In this embodiment, the two weld head torches are both initiated at the same time, one applying a weld bead in a vertical up weld bead placement, while the other applies a vertical down weld bead placement. 
     In yet another embodiment, to facilitate placement of a subsequent weld bead onto the component, command programming initiates an index command causing a motor drive  40  to precisely turn a screw drive shaft  55  engaging bracket  45  and repositioning the complete head assembly  20  so that the subsequent weld bead will be located with a specified overlay of the previous bead. An arc-on initiation sequence is then programmed to occur with the first torch  75  placing a bead followed by a reverse rotation of the ring drive while the second torch  75  places a bead. 
     While the above description contains many particulars, these should not be considered limitations on the scope of the disclosure, but rather a demonstration of embodiments thereof. For example, the welding apparatus  10  and process disclosed herein may include any combination of the different species or embodiments disclosed. Accordingly, it is not intended that the scope of the disclosure be limited in any way by the above description. The various elements of the claims and claims themselves may be combined in any combination, in accordance with the teachings of the present disclosure, which includes the claims.