Abstract:
A method and apparatus for lifting and supporting a storage tank uses a series of lifting devices on piles spaced around the periphery of the tank. Each lifting device includes a lower threaded bar with a coupler that engages the upper end of a pile. A lifting bracket is inserted under or attached to the tank, and includes a tube that slides along the lower threaded bar. A plurality of upper threaded bars extend upward from the lifting bracket and pass through a horizontal beam that can slide vertically on them. Upward movement of the horizontal beam is limited by nuts on the upper threaded bars. A jack is placed between the horizontal beam and the lower threaded bar to raise the lifting bracket by exerting upward force on the horizontal beam. The lifting bracket can be held in this raised position by a nut on the lower threaded bar.

Description:
RELATED APPLICATION 
       [0001]    The present application is based on and claims priority to the Applicant&#39;s U.S. Provisional Patent Application 62/026,808, entitled “Method and Apparatus for Lifting and Supporting Storage Tanks,” filed on Jul. 21, 2014. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to the field of systems for lifting and supporting storage tanks. More specifically, the present invention discloses a method and apparatus for lifting and supporting storage tanks using piles. 
         [0004]    2. Statement of the Problem 
         [0005]    Large above-ground storage tanks have been used for many years in a variety of industries for holding water, petroleum, chemicals and other fluids. In the oil and gas industry, storage tanks are widely used at the well head, at pumping and storage facilities, at refineries and processing facilities, and at shipping locations. These storage tanks are typically made of relatively thin sheet metal and are designed for handling structural loads normally associated with fluid storage. However, most storage tanks are not particularly well-designed to handle the much larger stresses that can be encountered in lifting or repositioning a tank after its initial construction (e.g., during maintenance or repair of the tank). This renders many storage tanks susceptible to structural damage when lifted for repair or maintenance unless great care is take during the lifting operation. 
         [0006]    In addition, storage tanks in the oil and gas industry are often deployed in remote locations, and are commonly constructed on a rudimentary pad with little or no foundation supporting the tank. This can result in the excessive or uneven settling of the tank over time, that typically requires the tank be lifted, repositioned or leveled. There is also often a need to increase the size of an existing storage tank after it has been installed in the field. This augmentation process is typically done by lifting the existing tank and adding to the structure around the bottom of the tank. 
         [0007]    The most common conventional technique for lifting a large storage tank employs a series of jacks placed beneath tank around intervals around its circumference. The jacks are actuated to lift the entire tank a short vertical distance so that wooden cribbing (e.g., railroad ties) can be inserted under the tank for temporary support. The jacks are then removed and repositioned on the cribbing, so they can lift the tank again, after which additional cribbing is inserted, etc. This process of jacking and cribbing can be repeated until the tank has been lifted to a desired elevation. An example of this general technique is described in U.S. Pat. Nos. 4,930,750 and 4,807,851 (De Castro). 
         [0008]    There are many drawbacks associated with this conventional approach. The wooden cribbing must be stacked directly beneath the storage tank, which often requires heavy manual labor and can be dangerous if the cribbing, jacks, or tank structure give way. In addition, this approach is relatively slow due to the manual labor required and the incremental process of actuating each jack and inserting individual timbers beneath the tank. 
         [0009]    Solution to the Problem. The present invention provides a method and apparatus for use with piles in lifting and supporting storage tanks in the field. This approach is much safer, faster, less labor-intensive and more efficient than previous methods using conventional jacks and cribbing. In addition, the piles and lifting devices are generally located slightly outside the periphery of tank, with only a small portion of the lifting devices extending directly under the tank to increase safety. Furthermore, the piles used in the present invention remain in place after the lifting operation is complete, and can be incorporated into a permanent foundation for the storage tank. 
       SUMMARY OF THE INVENTION 
       [0010]    This invention provides a method and apparatus for lifting and supporting a storage tank using a series of lifting devices on piles spaced around the periphery of the tank. Each lifting device includes a lower threaded bar with a coupler that engages the upper end of a pile. A lifting bracket is inserted under the tank and includes a tube that slides along the lower threaded bar. Two upper threaded bars extend upward from the lifting bracket and pass through a horizontal beam that can slide vertically on these upper threaded bars. Upward movement of the horizontal beam is limited by two nuts on the upper threaded bars. A jack is placed between the horizontal beam and upper end of the lower threaded bar. The jack can be used to raise the lifting bracket by exerting upward force on the horizontal beam, which lifts the two upper threaded bars and the lifting bracket. The lifting bracket can be held in this raised position by moving a nut on the lower threaded bar upward against the bottom of the lifting bracket. An hydraulic control system can be employed to simultaneously actuate the jacks of all of the lifting devices in a coordinated manner to lift a storage tank. 
         [0011]    These and other advantages, features, and objects of the present invention will be more readily understood in view of the following detailed description and the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The present invention can be more readily understood in conjunction with the accompanying drawings, in which: 
           [0013]      FIG. 1  is a left side view of an embodiment of the lifting device  30  on a storage tank  10 . 
           [0014]      FIG. 2  is a front view of the lifting device  30  and storage tank  10  corresponding to  FIG. 1 . 
           [0015]      FIG. 3  is a top view showing a plurality of lifting devices  30   a - 30   f  spaced around the circumference of a storage tank  10 . 
           [0016]      FIG. 4  is a detail cross-sectional view of the lower portion of the lifting device attached to the upper end of a pile  20  in a pit  16  in the ground  15  adjacent to a storage tank  10 . 
           [0017]      FIG. 5  is a front view of the lifting device  30  with the jack  40  lowered. 
           [0018]      FIG. 6  is a front view of the lifting device  30  corresponding to  FIG. 5  after the jack  40  has been raised. 
           [0019]      FIG. 7  is a front view of the lifting device  30  corresponding to the  FIGS. 5 and 6  after the lower nut  28  has been threaded upward against the bottom of the lifting bracket. 
           [0020]      FIG. 8  is a left side view of an alternative embodiment of the lifting device  30  on a storage tank  10 . 
           [0021]      FIG. 9  is a top view corresponding to  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]      FIGS. 1 and 2  show corresponding side and front views of an embodiment of the present lifting device  30  used for lifting and supporting a storage tank  10  on a pile  20 . The pile  20  can be a conventional helical pile with one or more helical blades mounted on the lower end of a shaft. Only the upper end of the shaft of the pile  20  is shown in  FIGS. 1 and 2 . 
         [0023]    The primary components of the lifting device  30  include a lower threaded bar  25  with a coupler  22  on its lower end to engage the upper end of the a pile  20 . A vertical tube  33  slides freely over the threaded bar  25  and is attached to the front of a vertical plate  31 . This vertical plate  31 , together with a horizontal plate  32  extending from its rear surface, form an L-shaped lifting bracket for lifting a tank  10  as illustrated in  FIG. 1 . In other words, the vertical tube  33  and plates  31 ,  32  define a lifting bracket that slides vertically on the lower threaded bar  25  to lift the tank  10 . A nut  28  threaded on the lower threaded bar  25  serves as an adjustable downward limit on the elevation of the lifting bracket on the lower threaded bar  25 . 
         [0024]    A plurality of upper threaded bars  42  and  44  extend upward from the lifting bracket. Preferably, there are two upper threaded bars  42 ,  44  extending upward from the left and right sides of the lifting bracket, as shown  FIG. 2 . These upper threaded bars  42 ,  44  are generally parallel to, but laterally offset from the lower threaded bar  25  as also depicted in  FIG. 2 . The lower ends of the upper threaded bars  42 ,  44  are adjustably secured to the lifting bracket by two nuts  37  and  38 . 
         [0025]    A horizontal beam  50  extends between the upper threaded bars  42 ,  44 , with vertical holes adjacent to either end that allow the horizontal member  50  to slide freely on the upper threaded bars  42 ,  44 . Two nuts  52 ,  54  on the upper threaded bars  42 ,  44  adjustable limit upward motion of the horizontal beam  50  on the upper threaded bars  42 ,  44 . Preferably, the horizontal beam  50  has a hollow structural section (HSS), although other cross-sections could be used. 
         [0026]    A cap  26  is placed on the upper end of the lower threaded bar  25  to support a jack  40  between horizontal beam  50  and the upper end of the lower threaded bar  25  that is coupled to the pile  20 . Preferably, the jack  40  is hydraulically or pneumatically actuated. This enables an array of jacks spaced about the periphery of a tank  10  to be simultaneously operated in a coordinated manner by a control system  45 , as shown in  FIG. 3 . 
         [0027]    The following is a description of the method by which the present invention can be used to lift a storage tank  10 . First, the appropriate number and spacing of piles  20  and lifting devices  30   a - 30   f  should be selected based on size, weight, configuration, structural properties and condition of the particular storage tank to be lifted, as well as local geological conditions. Typically, a plurality of piles  20  and lifting devices are installed at intervals around the periphery of the storage tank  10 , as shown in the top view provided in  FIG. 3 . The piles  20  should have a suitable capacity with appropriate spacing to transfer the tank loads to the subsurface soils. 
         [0028]    A pit  16  is excavated at the intended location for each lifting device  30   a - 30   f  adjacent to the periphery of the tank  10 , as shown for example in  FIG. 4 . For example, the pit can be roughly 24 inches by 24 inches in area and extend approximately one foot below the bottom  12  of the tank  10 . The centerline of the pit  16  can be located in vertical alignment with the intended location of the pile  20  and the lifting device  30 , which is typically about 2 to 2½ inches outboard of the outer side of the tank wall  14 . It should be understood that the various dimensions and tolerances specified in this disclosure are only for the purposes of example, and should not be construed as limiting the scope of the present invention. 
         [0029]    If a chime exists below the tank wall, it should be removed at least from the regions of the tank that will be in contact with the lifting devices  30   a - 30   f.    
         [0030]    For a typical lifting device, this would entail a region of about 13 inches of chime removal for each lifting device. 
         [0031]    A pile  20  is then installed at each location where a lifting device  30   a - 30   f  is to be placed. For example, the pile  20  can be a conventional helical pile that is installed by threading the helical blade of the helical pile into the ground beneath the pit  16  until the top of the helical pile  20  is about 7-9 inches below the bottom  12  of the tank  10 . The lifting device  30  is placed on top of the pile  20  with the coupler  22  on the lower end of the lower threaded bar  25  engaging the upper end of the shaft of the pile  20 . 
         [0032]    Using the lower nut  28 , the lifting device  30  is secured tightly under the tank  10 , with the vertical plate  31  of the lifting bracket flush against the tank side wall  14  and the horizontal plate  32  of the lifting bracket tight against the tank bottom  12 . If desired, the vertical plate  31  may be welded to the tank wall  14  around the edges of the vertical plate  31 . 
         [0033]    A jack  40  (e.g., an hydraulic jack) is removably inserted into the space between the cap  26  and the underside of the horizontal beam  50 , as shown in  FIGS. 1 ,  2  and  5 . To hold the jack  40  in place, the upper nuts  52 ,  54  are screwed downward tightly against the top of the horizontal beam  50  on the upper threaded bars  42  and  44 , and the lower nuts  37 ,  38  are screwed upward tightly against the lifting plates near the top of the vertical plate  31 , as shown in  FIG. 5 . It is important to leave a sufficient length of threaded bar  25  between the top of the tube  33  and the cap  26  to accommodate the amount of tank lift required in each phase of the procedure. 
         [0034]    Next, the tank  10  is lifted to its desired new vertical position by jacking against the underside of the horizontal beam  50 , as shown in  FIG. 6 . A hydraulic control system  45  shown in  FIG. 3  can be employed to simultaneously actuate a plurality of jacks  40  associated with an array of lifting devices  30   a - 30   f  spaced around the circumference of a tank  10  to ensure that the tank  10  is raised evenly in a predetermined manner to avoid excessive localized stress. For example, the control system can be used to actuate the jacks  40  in a coordinated manner to maintain the tank  10  in a substantially level orientation as it is raised. When the tank  10  is in its new vertical position, the lower nut  28  is screwed upward tightly against the bottom of the vertical tube  33  of each lifting device  30   a - 30   f  as shown in  FIG. 7 . The lower nut  28  can be hand-tightened. The steps illustrated in  FIGS. 5-7  can be repeated as necessary depending on the desired elevation. 
         [0035]    The present system can also be employed to lower the tank  10  after tank augmentation, repair or foundation work has been completed. This is done by moving the lower nuts  28  downward on the lower threaded bar  25  of each lifting device  30 , so that the vertical tube  33  can slide downward to a desired elevation. The jacks  40  are then actuated to lower the horizontal beam  50 , upper threaded bars  42 ,  44  and lifting bracket  31 ,  32 , and thereby lower the storage tank  10  to its desired elevation. 
         [0036]    At that point, the jack  40  and the upper portions of the lifting device  30  (i.e., nuts  37 ,  38 ,  52  and  54 , upper threaded bars  42 ,  44 , horizontal beam  50 , and cap  26 ) can be released and removed. This leaves the tank  10  being supported by the remaining lower portions of the lifting device  30  (i.e., the horizontal plate  32 , vertical plate  31 , vertical tube  33 , lower nut  28 , lower threaded bar  25  and coupler  22 ) on the pile  20 . Tank augmentation, repair or foundation work can now be accomplished. The present lift support system can be used to re-position the tank as required during this process. 
         [0037]    After this work has been completed, the remaining components of the lifting devices  30  and the piles  20  can be left place. These components can be embedded in concrete as parts of the foundation for the tank. The pit  16  can be backfilled as appropriate. Alternatively, the lifting devices  30  can be removed entirely after the work has been completed, although the piles  20  are typically left in place in the ground  15 . If desired, the upper ends of the piles  20  can be embedded in concrete to provide a foundation for the tank  10 . In this embodiment, the foundation is at least partially supported by the piles  20 . If the lower portions of the lifting device  30  (i.e., lifting bracket  31 ,  32 ,  33 , lower threaded bar  25  and coupler  22 ) are left in place on upper end of each pile  20 , some or all of these remaining components can also be embedded in the concrete foundation for the tank  10 . 
         [0038]      FIGS. 8 and 9  show an alternative embodiment of a lifting device  30  welded to the side wall  14  of a tank  10 . In particular, the L-shaped lifting bracket  31 ,  32  in  FIG. 1  has been replaced by a vertical plate  31  with two vertical side plates  34  that can be welded directly to the side wall  14  of the tank  10 . As shown in  FIG. 8 , the tank floor  12  sometimes extends outward beyond the tank wall  14 . This embodiment eliminates having to cut the chine ring or floor  12  extending beyond the tank wall  14  to fully seat an L-shaped lifting bracket. In addition, this embodiment also has the safety advantage that nothing projects under the tank wall  14  or floor  12 . 
         [0039]    The above disclosure sets forth a number of embodiments of the present invention described in detail with respect to the accompanying drawings. Those skilled in this art will appreciate that various changes, modifications, other structural arrangements, and other embodiments could be practiced under the teachings of the present invention without departing from the scope of this invention as set forth in the following claims.