Abstract:
Systems and methods for manufacturing a substantially impermeable concrete wall that may be used, for example, in fluid storage tanks to improve leak resistance to pressurized gases or fluids and reduce manufacturing costs.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The priority of U.S. Provisional Patent Application Ser. No. 61/791,521, filed on Mar. 15, 2013, is hereby claimed, and the specification thereof is incorporated herein by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
       [0002]    Not applicable. 
       FIELD OF THE INVENTION 
       [0003]    The present invention generally relates to systems and methods for manufacturing a substantially impermeable wall. More particularly, the present invention relates to manufacturing a substantially impermeable concrete wall that may be used, for example, in fluid storage tanks to improve leak resistance to pressurized gases or fluids and reduce manufacturing costs. 
       BACKGROUND OF THE INVENTION 
       [0004]    In facilities that process liquefied natural gas (LNG), the natural gas is typically cleaned of impurities and cooled thus, removing a substantial amount of thermal energy to bring it to a liquid state. In this state, it is easy to transport and store in large quantities. LNG type storage tanks are generally constructed onsite and may be used to store other fluids such as ammonia, propane, butane, ethylene, oxygen, argon, nitrogen, hydrogen, and helium, which are generally referred to as cryogenic or low temperature fluids. 
         [0005]    Cryogenic fluid storage tanks made of reinforced or pre-stressed concrete are often lined with a metal liner to prevent gases, liquids, or other contents from moving through the concrete bottom, wall and/or roof. For the bottom, a concrete slab has a metal liner, which is simply laid on top of a concrete surface and then welded for tightness. For the tank concrete roof, a metal liner with attached anchors may be the inside formwork, resulting in an integrated roof after pouring the concrete. Various manufacturing techniques exist for constructing the wall with a metal liner, which include using a stiffened liner. This technique uses metal stiffening welded to the metal liner to resist hydraulic forces when pouring the wet concrete. A partial cross-sectional image of an exemplary prior art system  100  using metal stiffening is illustrated in  FIG. 1 . The system  100  includes a metal liner  107  that includes a plurality of inward facing anchors  110  that are used to secure the metal liner  107  to a concrete wall (not shown) after the wet concrete is poured between the metal liner  107  and a form  116 . The form  116  includes a continuous interior surface  118  and plurality of trusses or ribs  122  that support the interior surface  118 . A plurality of tie rods  112  are secured to an interior surface of the metal liner  107  at one end and are secured to the form  116  at another end by a plurality of anchor cones  113  for structural support of the system  100  when the wet concrete is poured therein. A metal stiffener comprising a plurality of vertical sections  130  and a plurality of horizontal sections  132  is used for additional structural support, which may be welded to either side of the metal liner  107  as illustrated in  FIG. 1 . The metal stiffener, however, is often removed and discarded after each section of the concrete wall and metal liner  107  are constructed. The metal stiffener may be removed by cutting each vertical section  130  and each horizontal section  132  where they are welded to the metal liner  107 . As a result, additional material costs are incurred in addition to the expense of time spent to remove each metal stiffener from the system  100 . 
         [0006]    In order to overcome the disadvantages and delays inherent with conventional manufacturing techniques using a stiffened liner, attempts have been made to improve the manufacturing process. In U.S. Patent Application Publication No. 2008/0302804, for example, a freestanding inner steel liner is erected prior to pouring the outer concrete containment wall. Because the liner is “freestanding,” meaning that no internal or external formwork and/or stiffening is necessary, the liner is sized and configured to withstand the hydraulic forces of the concrete as the concrete wall is poured. Consequently, the liner is comprised of plates having a general thickness of more than eight millimeters. This type of cryogenic fluid storage tank can be distinguished from conventional cryogenic fluid storage tanks by the close spacing of metal rods that are required in the outer concrete wall and are attached to the liner. These metal rods are also referred to as tie rods that are used to hold the liner to the outer formwork when pouring the outer concrete wall. Because this technique is a two-step process that first requires the construction of the free standing liner followed by the construction of the outer concrete wall, construction costs may be unnecessarily high due to materials (e.g. thickness of the liner), time required for a two-step process and the inherent large volume of formwork ties that are required. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention therefore, meets the above needs and overcomes one or more deficiencies in the prior art by providing systems and methods for manufacturing a substantially impermeable concrete wall that may be used, for example, in fluid storage tanks to improve leak resistance to pressurized gases or fluids and reduce manufacturing costs. 
         [0008]    In one embodiment, the present invention includes a system for constructing a substantially impermeable wall, which comprises: 1) a form; ii) a frame; and iii) a liner positioned between the form and the frame, the liner releasably coupled to the form and releasably connected to the frame. 
         [0009]    In another embodiment, the present invention includes a substantially impermeable wall, which comprises: i) a stabilizing section; and ii) a liner connected to one side of the stabilizing section, the liner comprising a plurality of attachment lugs attached to an external side of the liner for releasably coupling the liner to a form and a plurality of lugs attached to an internal side of the liner for releasably connecting the liner to a frame. 
         [0010]    In yet another embodiment, the present invention includes a method for constructing a substantially impermeable wall, which comprises pouring a stabilizing material between a form and a liner, the liner releasably coupled to the form and releasably connected to the frame. 
         [0011]    Additional aspects, advantages and embodiments of the invention will become apparent to those skilled in the art from the following description of the various embodiments and related drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The present invention is described below with references to the accompanying drawings, in which like elements are referenced with like numerals, wherein: 
           [0013]      FIG. 1  is a partial cross-sectional view illustrating an exemplary prior art system for constructing a cryogenic fluid storage tank. 
           [0014]      FIG. 2  is a partial cross-sectional view illustrating one embodiment of a system for constructing a substantially impermeable wall. 
           [0015]      FIG. 3  is an isometric view illustrating a frame for the system in  FIG. 2 . 
           [0016]      FIG. 4  is a cross-sectional view illustrating a stabilizing base and reinforcing members to support the substantially impermeable wall. 
           [0017]      FIG. 5  is a partial cross-sectional view illustrating the cross-sectional view in  FIG. 4  with a liner. 
           [0018]      FIG. 6  is a partial cross-sectional view illustrating the cross-sectional view in  FIG. 4  before the system in  FIG. 2  is removed from a completed section of the substantially impermeable wall. 
           [0019]      FIG. 7  is a partial cross-sectional view illustrating the cross-sectional view in  FIG. 4  after the system in  FIG. 2  is removed from a completed section of the substantially impermeable wall and is repositioned as shown. 
           [0020]      FIG. 8A  is a partial cross-sectional view illustrating the application of a substantially impermeable wall in a cryogenic fluid storage tank. 
           [0021]      FIG. 8B  is an enlarged view illustrating the detail circled in  FIG. 8A . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0022]    The subject matter of the present invention is described with specificity, however, the description itself is not intended to limit the scope of the invention. The subject matter thus, might also be embodied in other ways, to include different steps or combinations of steps similar to the ones described herein, in conjunction with other present or future technologies. Moreover, although the term “step” may be used herein to describe different elements of methods employed, the term should not be interpreted as implying any particular order among or between various steps herein disclosed unless otherwise expressly limited by the description to a particular order. While the following description refers to storage tanks for cryogenic fluids, the systems and methods of the present invention are not limited thereto and may include other applications in which a substantially impermeable wall may be used to achieve similar results. 
         [0023]    Referring now to  FIG. 2 , a partial cross-sectional view of one embodiment of a system  200  for constructing a substantially impermeable wall is illustrated. The system  200  includes a metal frame  208  comprising a plurality of vertical members  215   a  typically welded or affixed to a plurality of horizontal members  215   b.  The vertical members  215   a  may be equidistantly spaced apart relative to each other. Likewise, the horizontal members  215   b  may be equidistantly spaced apart relative to each other. An isometric view of an exemplary metal frame  208  is illustrated in  FIG. 3 , which includes horizontal members  215   b  that are not equidistantly spaced apart relative to each other. The vertical, members  215   a  and the horizontal members  215   b  may be attached to each other by any permanent means such as melding or they may be made from materials other than metal that meet predetermined load requirements. The metal frame  208  may also be curved. 
         [0024]    The system  200  further includes a liner  207  that is preferably made from metal or steel, however, may be made of any other comparable composite material that resists transverse movement of fluids (i.e. substantially impermeable). The liner  207  may include one or more sections connected by a metal weld or other materials. The liner  207  also includes a plurality of attachment lugs  211  permanently attached to an external side of the liner  207  and a plurality of lugs  214  permanently attached to an internal side of the liner  207 . Each of the plurality of attachment lugs  211  is positioned opposite a respective one of the plurality of lugs  214  relative to the liner  207  for the purpose of transmitting forces through the liner  207  when a force (γC) is exerted against the liner  207 . The plurality of attachment lugs  211  may be permanently attached to the external side of the liner  207  by welding or any other means capable of permanently attaching the plurality of attachment lugs  211  to the external side of the liner  207 . Likewise, the plurality of lugs  214  may be permanently attached to the internal side of the liner  207  by welding or any other means capable of permanently attaching the plurality of lugs  214  to the internal side of the liner  207 . Each of the plurality of lugs  214  may be connected to a vertical member  215   a  or a horizontal member  215   b  in a releasable manner for releasably connecting the liner  207  to the frame. For example, each of the plurality of lugs  214  may include a respective opening  217  for receipt of a pin that passes through another opening (not shown) in the vertical member  215   a  or the horizontal member  215   b.  The liner  207  also includes a plurality of anchors  210  permanently attached to the external side of the liner  207  for connecting and integrating the liner  207  to a stabilizing section (not shown) that is preferably made of concrete. 
         [0025]    The system  200  further includes a form  216  comprising, a plurality of trusses or ribs  222  that may be vertically and/or horizontally positioned on the continuous interior surface  218 . The plurality of trusses  222  therefore, support the interior surface  218 . The form  216  and the frame  208  may be constructed in sections that are substantially similar in size and shape. The materials used to construct the form  216  may include wood, metal, any composite material or a combination thereof. The interior surface  218  of the form  216 , however, includes a plurality of removable form anchors  213  that include an attaching device for receipt of a metal tie rod  212 . Each metal tie rod  212  therefore, is connected at one end to the plurality of attachment lugs  211  and is connected at another end to the plurality of form anchors  213 . Each metal tie rod  212  may be protected by a sleeve so that each metal tie rod  212  may be removed and reused after each section of the substantially impermeable wall is completed. In this manner, the liner  207  may be releasably coupled to the form  216  to resist a force (γC ) exerted against the liner  207  by concrete or any other material poured between the liner  207  and the form  216 . The interior surface  218  of the form  216  therefore, is preferably made of any material capable of withstanding the force (γC) exerted against the liner  207  to transfer the tension load into the plurality of metal tie rods  212 , attachment lugs  211 , lugs  214  and form anchors  213 . On the inside surface of the concrete stabilizing section, the lateral force (γC) is transferred through the liner  207  into the frame  208  that in turn places the plurality of attachment lugs  211 , metal tie rods  212 , form anchors  213  and lugs  214  into tension and balances the load. 
         [0026]    Although the substantially impermeable wall may comprise a concrete section (not shown) that exerts the force (γC) illustrated in  FIG. 2 , it may comprise a similar section made from different materials for stabilizing the substantially impermeable wall. The substantially impermeable wall therefore, may comprise a stabilizing section made of concrete and the liner  207 . The liner  207  is connected to a side of the stabilizing section by the plurality of anchors  210 . Once a section of the substantially impermeable wall is completed using the system  200 , liner  207  remains connected to the stabilizing section by the plurality of anchors  210  and the plurality of attachment lugs  211  that are embedded in the stabilizing section. The plurality of metal tie rods  212 , the plurality of form anchors  213  and the form  216  may be removed and reused. Likewise, the frame  208  may be removed and reused. The plurality of lugs  214  may be optionally removed by cutting them from the external surface of the liner  207 . If each of the plurality of the metal tie rods  212  are positioned through a protective sleeve, they may be removed after the form  216  is removed leaving the plurality of form anchors  213  to be removed with the plurality of metal tie rods  212  as each metal tie rod  212  is disconnected from a respective one of the plurality of attachment lugs  211 . The form  216  and the frame  208  therefore, may be used for construction of another section of the substantially impermeable wall. 
         [0027]    Referring now to  FIGS. 4-7 , a method for manufacturing a substantially impermeable wall is illustrated. 
         [0028]    In  FIG. 4 , a cross-sectional view of a stabilizing base  402  and reinforcing members  408  is illustrated. The stabilizing base  402  may be made of concrete or any other material in which the reinforcing members  408  may be positioned and secured for construction of the substantially impermeable wall. The reinforcing members  408  may be rebar or any other rigid material that may be used to reinforce and support the substantially impermeable wall. The reinforcing members  408  are therefore, optional as well as a liner base  407  that may be used to cover the stabilizing base  402  to form a substantially impermeable base within an enclosure formed by the fully constructed substantially impermeable wall for containing fluids. The liner base  407  therefore, may be made of any substantially impermeable material such as, for example, metal or steel. 
         [0029]    In  FIG. 5 , a partial cross-sectional view of  FIG. 4  is illustrated with the liner  207  that includes a plurality of anchors  210 , attachment lugs  211  and lugs  214 . The liner  207  is preferably welded to the liner base  407  at weld  502  and forms a substantially impermeable seal in the event that the substantially impermeable wall is intended to extend to the liner base  407  for purposes of containing fluids. 
         [0030]    In  FIG. 6 , a partial cross-sectional view of  FIG. 4  is illustrated before the system  200  is removed from a completed section of the substantially impermeable wall. The system  200  remains in place while a stabilizing section  604  hardens, which is preferably concrete. Scaffolding  602  may be attached to the form  216  and frame  208  for securing another section of the liner  207  and constructing another section of the substantially impermeable wall above the previously constructed section using the system  200 . 
         [0031]    In  FIG. 7 , a partial cross-sectional view of  FIG. 4  is illustrated after the system  200  is removed from a completed section of the substantially impermeable wall and is repositioned as shown. Here, the system  200  is removed from the stabilizing section  604  in  FIG. 6  and is repositioned to construct another stabilizing section. As demonstrated by the stabilizing section  604  and the liner  207 , another stabilizing section may be constructed on top of the stabilizing section  604  wherein additional scaffolding  706  may be used for removing the plurality of form anchors  213  as the system  200  is removed and moved upward to construct another stabilizing section. The scaffolding  602  may be used to position another section of the liner  207  shown as a dashed line and then weld it to the liner  207 , which is currently connected to the another stabilizing section before the system  200  is removed with scaffolding  602  and is repositioned to construct the next section of the substantially impermeable wall. Construction joints  702  therefore, exist between each stabilizing section of the substantially impermeable wall. If a third stabilizing section is needed, bottom scaffolding (not shown) may be positioned around the stabilizing section  604  for removing the plurality of lugs  214  while the scaffolding  602  and additional scaffolding  706  are repositioned for construction of the next stabilizing section and removing the plurality of form anchors  213 , respectively. 
         [0032]    Referring now to  FIG. 8A , a partial cross-sectional view of a substantially impermeable wall in a cryogenic fluid storage tank is illustrated. The storage tank  800  includes an inner tank comprising an inner tank bottom  801   a  and an inner tank wall  801   b,  preferably made of metal. A concrete slab  802  forms the base of the storage tank  800 , which supports the inner tank and other components. A concrete wall  803  partially encloses the storage tank  800 , with the concrete wall  803  being positioned near a perimeter of the concrete slab and may be cylindrical, square or any other shape practical for the for storing cryogenic fluids. A roof  804 , preferably made of concrete, is formed with a perimeter that joins a top of the concrete wall  803  for enclosing the storage tank  800 . A deck  805  is suspended from a ceiling in the storage tank  800  for supporting a plurality of insulation  820 . Additional insulation  806  is used around the inner tank wall  801   b.  A substantially impermeable metal liner is positioned against the concrete slab  802 , the concrete wall  803  and the roof  804 , which includes a metal bottom liner  807   a,  a metal side liner  807   b  and a metal roof liner  807   c.  The substantially impermeable metal liner is used to prevent the transmission of fluids into and out of the storage tank  800 . Bottom support pads  808  include block insulation for supporting the inner tank. A thermal corner protection section includes a metal bottom  809   a  and a metal wall  809   b.  The metal bottom  809   a  is positioned below the inner tank and between the inner tank bottom  801   a  and the metal bottom liner  807   a.  The metal wall  809   b  is similarly positioned between the inner tank wall  801   b  and the metal side liner  807   b.  The metal bottom  809   a  is therefore, connected to the metal wall  809   b , which is connected to the metal side liner  807   b.  It should be understood by one of ordinary skill in the art, that an inner tank and thermal corner protection section may or may not be included in the design of storage tank  800 , where a substantially impermeable wall is manufactured and employed. 
         [0033]    Referring now to  FIG. 8B , an enlarged view of the details circled in  FIG. 8A  is illustrated. The metal side liner  807   b  and the concrete wall  803  are constructed using the system in  FIG. 2  to form a substantially impermeable wall. Once the system in  FIG. 2  is removed, the substantially impermeable wall includes a stabilizing section comprising the concrete wall  803  and the substantially impermeable metal liner, which includes the metal side liner  807   b,  a plurality of attachment lugs  811  for releasably coupling the metal side liner  807   b  to a form and a plurality of concrete anchors  810  for securing the metal side liner  807   b  to the concrete wall  803 . 
         [0034]    The systems and methods of the present invention therefore, allow for integration of a metal liner and frame as each section of the concrete wall is constructed in one step, without the need for excessive metal liner thickness, excessive metal tie rods or conventional stiffening welded to the liner. 
         [0035]    While the present invention has been described in connection with presently preferred embodiments, it will be understood by those skilled in the art that it is not intended to limit the invention to those embodiments. It is therefore, contemplated that various alternative embodiments and modifications may be made to the disclosed embodiments without departing from the spirit and scope of the invention defined by the appended claims and equivalents thereof.