Abstract:
A liquid container for the above-ground storage of flammable fuels is shown having an inner tank with a bottom surface, side surfaces, and a top surface placed within an outer shell having a bottom surface, side surfaces, and an open top. The bottom surfaces of the inner tank and outer shell are spaced apart from each other by first bottom spacers which connect the two bottom surfaces. The side walls of the inner tank and outer shell are also spaced apart from each other by second side spacers which connect the tank and shell. The side spacers for connecting the tank and shell prevent the inner tank from floating within the outer shell when an insulating material, such as concrete, is added therebetween.

Description:
This application is a continuation of application Ser. No. 08/028,213, filed on Mar. 9, 1993, now abandoned, which is a continuation of application Ser. No. 07/946,026, file on Sep. 15, 1992, now U.S. Pat. No. 5,271,473, which is a continuation of application Ser. No. 07/759,703, filed on Sep. 11, 1991, now abandoned, which is a continuation of application Ser. No. 07/664,411, filed on Feb. 27, 1991, now abandoned, which is a continuation of application Ser. No. 07/452,690, filed Dec. 19, 1989, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a vaulted tank and, more particularly, to an above-ground storage tank for flammable liquids. 
     Since the 1970s, the world and the United States have been concerned with the environment and the contamination of that environment, including the earth&#39;s soil, its atmosphere and its water. The first Earth Day in 1970 resulted in the eventual creation of the Environmental Protection Agency by the United States Congress. 
     One of the many problems which the Environmental Protection Agency has addressed is the deterioration of large, underground storage tanks which result in the leakage of contaminants into the soil, such as the deterioration of gas station storage tanks and the leakage of gasoline and diesel fuel into the surrounding water table. 
     To correct this problem, the EPA has suggested that all fuel storage tanks be placed above ground. This has created a classic confrontation between governmental departments. For example, the fire departments of most major cities prefer that fuel storage tanks be placed below ground to reduce fire hazard. Most municipal codes have been drafted with this concern in mind. In more recent years, the creation of large concrete entombed tanks has been suggested as a solution to the problem. That is, a gasoline storage tank may be entombed in concrete and placed above the ground to enable its surfaces to be easily checked for deterioration and fluid leakage. By entombing the fuel tank in concrete, the tank is made impervious to impact from a vehicle that might back into it, for example, and resistant to fire due to the insulating ellect fo the concrete. One example of such an entombed tank is shown in U.S. Pat. No. 4,826,644, issued May 2, 1989 to T. R. Lindquist and R. Bambacigno. 
     The concrete entombed tank has several disadvantages including cost and convenience. For example, a 1,000-gallon concrete entombed tank weighs 18,000 pounds after it has been manufactured. Such a tank requires a large truck and crane with at least two 20-ton nylon straps to transport the tank to the site where it is to be used and to then place the tank in the desired position. The concrete entombed tank is provided with bottom supporting feet to permit the inspection of its bottom surface during its use. In California, where earthquakes represent a real concern, concrete shoes are placed on the site on either side of the bottom supporting feet to prevent the movement of the tank during an earthquake. The placement of the concrete tank between the concrete shoes can be a very dangerous procedure in view of the tank&#39;s weight. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a less expensive, lighter weight and more easily transported tank vault for the above-ground storage of liquid fuels, such as gasoline and diesel fuel. 
     This object and other objects are accomplished by providing an inner tank having a bottom surface, side surfaces, and a top surface which is placed within an outer shell having a bottom surface, side surfaces, and an open top. The bottom surface of the inner tank is spaced apart from and connected to the bottom surface of the outer shell by first, bottom spacers which do not extend to the side surfaces of either the inner tank or outer shell. The side surfaces of the inner tank and outer shell are spaced apart and attached to one another by second side spacers which do not extend to the bottom surface of either the inner tank or outer shell. The side spacers function to prevent the inner tank from floating within the outer shell when an insulating material, such as concrete, is placed therebetween. 
     The utilization of an inner tank and outer shell with appropriate bottom and side spacers for attaching the two permits the assembled tank to be shipped from the factory to the site where it is intended for use with relative ease because of its light weight. Once properly placed upon the site, the space between the inner tank and outer shell can be filled with a suitable insulation material to meet the strength and insulation requirements of the fire codes of all metropolitan areas. Spacing feet on the bottom surface of the out shell permit all surfaces of the tank vault to be inspected to assure that the tank does not deteriorate and leak. This meets the requirements of the Environmental Protection Agency. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     A better understanding of the present invention and of additional advantages and objects will be had after consideration of the following specification and drawings, wherein: 
     FIG. 1 is a side elevational view of the tank vault of the present invention; 
     FIG. 2 is a top plan view thereof; 
     FIG. 3 is a cross-sectional view taken along line  3 — 3  of FIG. 1; 
     FIG. 4 is a cross-sectional view taken along line  4 — 4  of FIG. 1; 
     FIG. 5 is a detailed view showing the inner support ribs of the inner tank; 
     FIG. 6 is a detailed view of the side spacers between the inner tank and outer shell; and 
     FIG. 7 is a cross-sectional view taken along line  7 — 7  of FIG. 2 shown in perspective after insulating material, such as concrete, has been poured between the inner tank and outer shell of the tank vault. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, a tank vault  10  is shown in all figures having an inner tank  12  including a bottom surface  14 , top surface  16  and side surfaces  18 . The inner tank may be constructed from various types of material including steel, corrosion-resistant steel, aluminum, cast iron, fiberglass, fiberglass-reinforced steel, and polyethylene. In the preferred embodiment, the inner tank is constructed from {fraction (3/16)}-inch thick steel. 
     The inner tank  12  is spaced apart from an outer shell  20  which also has a bottom surface  22  and side surfaces  24 , while the top of the outer shell  20  is open. In the preferred embodiment, the outer shell is made of 10 gauge steel. The inner tank  12  and outer shell  20  are attached in a spaced apart relationship by a first, bottom spacer  26  which, in the preferred embodiment, may be constructed from a C-shaped steel channel that is six inches long and weighs 8.2 pounds per foot (C×6×8.2). This same C-shaped channel may also be used as a second side spacer  28  which attaches and spaces the side surfaces  18  and  24  of the inner tank and outer shell. 
     The first, bottom spacer  26  may be attached to the bottom surface  14  of inner tank  12  by welding. Similarly, the second side spacers  28  may be attached to the side surfaces or walls  18  of inner tank  12  by welding. The inner tank  12  may then be lowered into the outer shell  20  and the first, bottom spacers  26  attached to the bottom surface  22  of the outer shell  20  by welding plugs which are formed by welding through small holes in the bottom surface  22  directly to the lower surface of the bottom spacers  26  to fill the holes and thus produce the welding plug for the attachment of the spacers  26 . Generally, it is not necessary to use welding plugs to attach the second, side spacers  28  to the side surfaces  24  of outer shell  20 , as seen in FIG.  6 . FIG. 6 shows an aperture  30  in the side spacer  28  which may be used to secure a hook for lifting the assembled tank vault  10  from a truck and placing it at the desired location upon the site where the tank vault  10  is to be used. It will also be seen in FIG. 6 that the upper edges of the side walls  24  of outer shell  20  are each provided with a radius which establishes a smooth rounded upper edge of the tank vault  10  once the insulating material, such as concrete, is poured between the inner tank  12  and outer shell  20 . It will also be seen in FIGS. 1,  6  and  7  that the side spacers  28  do not extend to the bottom surfaces  14  or  22  of the inner tank  12  or outer shell  20 . Similarly, the bottom spacer  26  does not extend to the side walls  24  of outer shell  20 . This permits the insulation material to flow completely between the inner tank  12  and outer shell  20 . 
     The preferred embodiment shows an inner tank  12  in the shape of a rectangular block with the outer shell  20  also shaped as a rectangular block. Other configurations are possible within the teachings of the present invention, including a cubically-shaped inner tank and outer shell or a cylindrically-shaped inner tank mounted within an outer shell in the form of a rectangular block. In this latter arrangement, the bottom surface of the inner tank is the bottom edge of the cylindrical shape while the side walls include the two side edges of the cylinder and the two flat ends thereof. 
     It has been found that the second, side supports  28  are very important in the fabrication of the inner tank  12  and outer shell  20  in that the pouring of the insulating material, such as concrete, can cause the inner tank  12  to float within the outer shell  20 . This problem has not occurred in the prior art as the prior art generally does not contemplate such large volume when fabricating the inner and outer tanks. Further, the prior art does not contemplate the problems that would be experienced when an insulating material, such as concrete, is poured to fill the space between the inner tank  12  and the outer shell  20 . Such problems include the possible bowing of either the inner side walls  14  or the outer side walls  20  of tank  12  and shell  20  and the collapse of the top surface  16  of tank  12 . To eliminate this problem, inner supports are utilized, including inner side supports  32 , shown in FIGS. 1,  3 ,  4 ,  5  and  7 , and inner top supports  34 , shown in FIGS. 1,  2  and  4 . In the preferred embodiment, the inner side supports  32  are made of 10 gauge steel sheets with a hat-shaped cross-section having a three inch crown, one inch sidewalls and a one inch brim on the outer edge of each side wall. In the preferred embodiment, the inner top supports  34  are formed from the same material and in the same shape. 
     Further support is provided to the side surfaces  18  of inner tank  12  by cross-rib supports  36  seen in FIGS. 3,  4 ,  5  and  7 . It will be seen in FIGS. 3 and 4 that the preferred embodiment may include three pairs of cross-rib supports which attach opposite side walls  18  of the inner tank  12  at the inner side supports  32 . As seen in FIG. 7, the cross-rib supports  36  are formed from a 2×2×¼-inch angle channel which is attached to the inner supports  32 , as by welding. Similarly, the inner side supports  32  and top supports  34  are attached to the side surfaces  18  and top surface  16  of the inner tank  12  by welding. 
     To complete the prefabricated assembly of the tank vault  10 , a third set of spacers or mounting feet  38 , seen in FIGS. 1,  2 ,  3 ,  4  and  7 , are attached to the bottom surface  22  of outer shell  20 , as by welding. These mounting feet  38  may be formed from the same C-shaped channel that forms the bottom and side spacers  26  and  28 . As best seen in FIGS. 2,  3  and  4 , the mounting feet  38  extend beyond the width of the outer shell  20  to form extensions  40  into which apertures  42  have been placed, as seen in FIG.  3 . These apertures receive suitable lag bolts or other fasteners which may be driven into a concrete mounting pad or other suitable mounting surface upon which the tank vault  10  is ultimately placed. The extensions  40  thus provide a convenient way for securing the tank vault  10  to the surface of its mounting site to prevent the tank  10  from walking during an earthquake. 
     As best seen in FIGS. 1 and 2, the top surface  16  of inner tank  12  is provided with several apertures into which various sized pipe fittings  44  may be attached, as by welding. The purpose of these pipe fittings  44  are many and varied. In the preferred embodiment shown in FIG. 2, they include the following: a six-inch tank bung  46  located in the center of the right-hand portion of the top surface  16  for mounting a 2.5-pound emergency vent; a two-inch tank bung  48  located in the upper, right-hand corner of the top surface  16  for a vent; a two-inch tank bung  50  located in the lower, right-hand surface of tank cover  16  to mount a sight level gauge; a four-inch tank bung  52  in the upper, left-hand corner of top surface  16  for a phase one vapor recovery device; a four-inch tank bung  54  in the center, left-hand section of the top surface  16  for filling the tank  10 ; and a two-inch tank bung  56  in the lower, left-hand corner of surface  16  for a gas pump. 
     The tank vault  10  shown in FIGS. 1-7 weighs approximately 2,400 pounds in the prefabricated state as shown in FIGS. 1-6 and holds 1,000 gallons. The reader will understand that several variations of the tank structure are possible and that the specific shape and sizes of the inner and outer tanks, the bottom spacers  26 , side spacers  28 , mounting feet  38 , side supports  32 , top supports  34 , and cross-rib supports  36  may all vary within the teachings of the present invention. Further, the inner tanks  12  may be fabricated with a double sided top, sides and bottom as shown in FIG.  7 . The size of the tank vault  10  may also vary to accommodate many volumes, such as 250, 500, 1,000 and 2,000 gallons. 
     In the present invention, it is anticipated that the 250 gallon tank vault  10  will have an inner tank  12  with a length of 80 inches, a height of 25 inches, and a width of 30 inches. The dimensions of the outer shell  20  will include a length of 92 inches, a height of 37 inches, and a width of 42 inches. This 250 gallon tank will have a single side spacer  28  that is 12 inches long and two sets of vertical inner side supports  32  with a single cross-rib support  36  between each. The 500 gallon tank  10  has an inner tank dimension of 120 inches long by 26 inches high by 37 inches wide, and an outer shell dimension of 132 inches long by 38 inches high by 49 inches wide. Along the length of the side walls  18  and  24  of the inner tank  12  and outer shell  20  are two side spacers  28 , while the inner side supports  32  number three along the long side wall with single cross-rib supports  36  therebetween. The 1,000 gallon tank has ah inner tank dimension of 120 inches long by 46 inches high by 42 inches wide with the outer shell dimensions being 132 inches by 58 inches by 54 inches. The inner supports are the same as for the 500 gallon tank except that there are two cross-rib supports  36  between each of the inner side supports  32  rather than one. A 2,000 gallon tank includes an inner tank  12  with a length of 120 inches, a height of 55 inches, and a width of 70 inches; while the outer shell measures 132 inches long by 67 inches high by 82 inches wide. The side supports  28  are twice as long as the side supports within the 1,000 gallon tank, while the inner side supports  32  and cross-rib supports are the same in number as for the 1,000 gallon tank. Each tank has the same number of bottom spacers  26  for providing a standoff between the inner tank and outer shell. The 250 gallon tank has two mounting feet  38 , while the remaining tanks have three. 
     After the tank vault  10  has been properly placed at the desired site, the space between inner tank  12  and outer shell  20  may be filled with a suitable insulating material  58 , shown in FIG.  7 . In the preferred embodiment, this insulating material is concrete. However, other materials may be used including cement, sand, gravel, a heat-resistant plastic such as polyethylene, or a fire-retardant foam. In general, the material should be fire-resistant and meet or exceed a two-hour firewall rating. In some situations, such as when the tank is intended to be used to store waste oil, for example, it may not be necessary to fill the space between the inner and outer tanks with any insulating material  48 . As the insulating material  58  is poured into the space between the inner tank  12  and outer shell  20 , the tanks are vibrated by a suitable vibrating tool to ensure that all spaces between the tank and shell are filled. The outer shell is then filled to a level equal to the upper edge of its side walls  24  so that the rounded edges thereof are flush with the upper surface of the insulating material. A T-shaped standoff  60  may be attached to the top surface  16  of inner tank  12 , as by welding. It will be seen that the standoff  60  is flush with the upper surface of the insulating material  58 . This standoff  60  thus provides a mounting platform upon which to place a nameplate or other information. Once filled with concrete  58 , for example, a gasoline pump, not shown, may be mounted to the side surface  24  of the outer shell  20  and connected to the two-inch tank bung  56 . 
     As discussed above, many shapes of the inner tank  12  and outer shell  20  are possible. The inner tank  12  may be constructed from several different materials and the space between it and the outer shell  20  may be varied and filled with several different insulating materials within the teaching of this invention. Further, the shape, number, configuration and material of the bottom spacers  26 , side spacers  28 , inner side supports  32 , inner top supports  34 , cross-rib supports  36 , and mounting feet  38  may vary within the teachings of this invention. It will also be noted that the placement of the inner side supports  32  within the inner tank  12  is usually such that they do not align themselves with the side supports  28  thereby increasing the rigidity of the side walls  18 . In view of the number of variations possible within the tank vault of the present invention, that invention should be limited only by the appended claims.