US2413243A - Storage tank and method of constructing same - Google Patents

Description

Dec. 24, 1946. w. NEFF 2,413,243

STORAGETANK AND METHOD OF CONSTRUCTING SAME I Filed March 7, 1944 2 Sheets-Sheet 1 @www W. NEFF Dec. 24, 1,946.V

STORAGE TANK AND METHOD OF CONSTRUCTING SAME 2 sheets-sheet 2 Filed March 7, 1944 www Patented Dec. 24, 1946 STORAGE TANK AND IWETHOD F CONSTRUCTING SAME Wallace Ne, Los Angeles, Calif.

Application March 7, 1944, Serial No. 525,475

9 Claims.

This invention relates to improvements in concrete tanks for the storage of gasoline, fuel oil, water and like liquids and the method of constructing the same.

Shortages in critical materials such as steel has limited, if not entirely prohibited, the construction of gasoline, fuel oil and water storage facilities urgently needed for civilian use in many sections of the country. Moreover, greatly increased military use of gasoline and fuel oil and the mobility of modern warfare have created serious supply and storage problems, particularly in the rapid construction of adequate storage facilities at advanced bases and under conditions of extended lines of supply. While attempts have been directed to the solution of the problems attendant to the above circumstances, such have not been entirely successful because, even where gasoline and oil storage tanks were constructed of concrete, they were of the conventional steelreinforced construction requiring shipment to the site of substantial amounts of steel necessary to their erection, and their construction moreover followed the slow methods characterizing Y the usual practices of concrete construction.

The present invention contemplates and provides improved storage tanks for gasoline, fuel oil, water and such liquids required to be stored, which may be constructed of readily available materials throughout and according to an improved method of construction which is economical, extremely fast, and capable of being carried out with a minimum of equipment by available, relatively unskilled labor. More specifically, the

invention has for an object the provision of improved concrete tanks suitable for the storage of gasoline, fuel oil and Water which are of such form and inherent structural strength as to require little or no steel reinforcement and which, moreover, can be site-fabricated substantially throughout from materials which vto a large extent are locally available, and with equipment which is sufficiently light in weight that it can be supplied by air to the erection site. The invention further proyides a novel concrete storage tank of spherical, semi-spherical or even cylindrical shape, of a type which is erected on an lnterior pneumatic form of the required shape and size and which employs the form, the latter being left in the completed structure, as a leak-proof container for the liquids to be stored, the container being in turn supported' by the concrete structure erected thereon. According to the invention, there is moreover provided a novel type of pneumatic form for the erection of structures as aforesaid which is relatively simple and inexpensive in fabrication, and which is sufficiently flexible and light in weight that it can be flown to an erection site in a small package.

Other objects will be in part ovbious and in part hereinafter pointed out in connection with the following analysis of this invention wherein are illustrated in detail selected embodiments of the invention.

In the drawings- Fig. 1 is a part elevational, part sectional view of a gasoline storage tank according to the in vention;

Fig. 2 is a detail illustrating the preferred manner of securing the form to the concrete shell erected thereon in such manner that it provides a permanent inner liner therefor; and Fig. 3 is a part elevational, part sectional view of another form of storage tank according to the invention.

Concrete storage tanks of the type to which the present invention pertains are erected generally in accordance with the methods of building construction disclosed and claimed in my prior Patents #2,270,229, dated January 20, 1942, and #2,335,500, dated November 30, 1943, and in my pending application, Serial No. 451,056, filed July 15, 1942. I'n the practice of such methods, a concrete shell is built up by applying a continuous layer of wet concrete over the exterior surface of an internal pneumatic form of size and shape such that upon ination thereof it assumes the size and shape of the interior of the desired structure and in such. manner that the so applied concrete remains in place on the form without the aid of an external form and upon setting provides a self-sustaining shell.

According to the present invention, a pneumatic form as aforesaid may be of full spherical shape, or may be of semi-spherical or cylindrical shape of either the closed or open bottom type in accordance with my prior disclosures, and is of course provided with means by which it can be suitably anchored to a foundation slab prior to inflation. Following inflation, and especially when Working with low inflation pressures of up to 2 oz. per sq. in., a preliminary shell functioning as a secondary form is preferably first built up on the pneumatic form as by spraying the exterior surface of the form with a fast-setting plastic material such as gypsum plaster or a wet mixture of gypsum, cement and sand in suitable proportions as to render it fast-setting, to a continuous layer thickness of approximately 1%; in. The ination pressure is maintained until the thin layer of plastic material has set, whereupon there is provided a self-sustaining shell capable of sustaining the load of the concrete which is thereupon applied thereover to the desired thickness. The concrete may be placed by the conventional troweling method or, when the necessary equipment is available, by the guniting method. Where it is desired that the final shell have a contour approaching that of a semisphere, but with its pole flattened and its side walls bulged outwardly, the plastic material forming the pre liminary shell may be first applied to the top portion of the form in such manner that the load thereof effects a controlled deformation of the form, according to which its pole is fiattened and its side walls bulged outwardly. As the plastic material is applied to the side portions of the pneumatic form, it follows the deformed contour thereof, with the concrete subsequently placed over the preliminary shell in turn following the contour of the latter. It is also possible to give the nal structure the shape of a peaked dome, in which case the plastic materialis applied as by spraying first the side portions of the form so that the load of the applied material has the effect of weighting-down the side portions and thereby causing the top portion of the form to deform upwardly, with the result that the top portion of the final structure is peak-shaped.

A form according to the present invention is fabricated from readily available fabric materials, among which may be noted nylon, tire cord fabric, highthreadcount cotton muslin, and cotton duck, which materials can be rendered air-tight at the relatively low iniiation pressures to which the form is inflated. The form is left in the shell after the latter has set, suitable means being provided to tie the form to the shell, thus to prevent the latter from stripping away from the shell when the inflation pressure is released. I have discovered that by coating such fabric materials with a synthetic rubber such as Thiokol or Buna, not only is the material rendered air and liquid tight but also it is rendered resistant to the solvent effects of modern high octane aromatic gasoline. Accordingly, when a form fabricated of material treated as aforesaid is left within the shell, the form acts as a leak-proof fabric container for liquids such as gasoline stored-within the same,

the container being in turn structurally supported against the load of the gasoline or other liquid by the concrete shell erected thereon according to the invention. 'I'he same or equivalent proofing substances may be employed to treat the fabric in the case of tanks designed for the storage of fuel-oil and water, for example.

In the drawings wherein are shown two forms of storage tanks selected for the purpose of illus-v trating the present invention, a shell I (Fig. 1') of semi-spherical shape is shown as erected on the pneumatic form II, in accordance with the methods of construction previously described. In the illustrated embodiment, the form II is of semi-spherical shape, having a fiat bottom I2 supported on a circular floor slab 3, a suitable waterproof membrane I4 being disposed between the iioor slab and the ground to protect the slab from the deleterious effects of moisture. Preferably, the floor slab is sloped downwardly towards its periphery to permit water collecting in the bottom of all gas tanks to be drained off from time to time. As shown, the form is provided along its periphery with a securing apron or fiap I5 which is of depth to extend below the under 4 corner of the fioor slab, the apron carrying a. tie cord for securing the apron and hence the form to the slab. Other means of anchoring the form to the iioor slab may of course be substituted.

Preferably, the form is provided with means such as buttons, keys or flap-like extensions to tie itself to the concrete which is subsequently applied thereover. In" Fig. 2, such means are shown to take the form of 1/2" or :5/4" keys I8 arranged, for example, at 14" centers each way, and being embedded in the first applied coat or layer of the concrete or plaster, the keys I8 serving also as a means of gauging the thickness thereof. Upon setting of this rst layer the keys as aforesaid provide a mechanical bond between the form and concrete shell, and thus stripping of the form under its own weight from the shell upon release of the inflation pressure is prevented.

The form may be provided at its pole with a cylindrical appendix 20 about which the concrete is built up as at 2| to provide a circular top open for a fitting 22 of the desired type. Adjacent its bottom, the form may also be provided with a similar appendix or tube 23 defining a bottom opening through the structure for a drain fitting.

As shown in the drawings, the concrete is applied to a substantially increased thickness along the base line of the structure and both along and beneath the floor slab I3, thus to provide a circular footing I6 in which the form apron I5 and its tie cord is embedded.

A shell structure erected in accordance with the foregoing provides an inner liner or container of fabric for the liquid to be stored. Pai'- ticularly where the shell-form tank is employed for the storage of high-octane aromatic gasoline, the fabric form is fabricated from a material which is resistant to the solvent effect of the gasoline, or the form following fabrication may be treated with an aromatic gasoline resistant substance such as Thiokol or Buna, and the treated form employed in erection. Or the untreated form may be shipped to the site of erection, and following the construction of the shell as aforesaid, the interior surface of the form which is retained in the structure is lined or coated with a resistant substance of the type indicated. In the case of a tank designed forthe storage'of fuel oil or Water, the form may be equivalently treated either before or after erection of the tank to render the form oilor waterproof. Accordingly, the lining or container provided by the form within the shell is impervious to the particular liquid to be stored therein. The outer surface ofthe tank may be coatedA or sprayed with a suitable waterproofing substance, thus to protect the same from the effects of weather if the tank is of the overground type, or ground moisture if the tank is built underground.

It will be understood of course that the final thickness of the concrete wall is such as to impart the structural strength'required to enable the shell to sustain not only its own weight but also the load of the gasoline or fuel oil contained within the same. Thus, in a storage tank having a iioor diameter of 22 feet, the interior cubicalspace of which providesa storage capacity ofl approximately 20,000 gal., the shell wall along'its upper portion will possess a thickness of the order of 3". At its base line, this thickness is increased, as indicated, to enable the shell to support at its base line a hoop stress of 60 lbs. per sq. in. when filled. Due to the great structural strength of a concrete Wall of substantially monolithic construction which extends along a continuous curve or arch from two spaced points of support, no structural reinforcement is required and hence storage tanks in accordance with the invention can be erected without the requirement of steel reinforcement. Moreover, as the form is treated to render it impervious to gasoline, fuel oil, water or other liquid to be stored therein, the form prevents seepage of the gasoline, oil or other liquid contained Within the concrete shell through hair cracks which may develop therein, and thus aids materially in overcoming the disadvantages incident to prior methods employed in steel and concrete tank construction.

Fig. 3 is illustrative of a spherical storage tank according to the invention and of the form employed in its erection. Reference character 30 indicates a pneumatic form of full spherical shape provided along its equator with a depending apron 3| by which the form is secured by temporary ties 32 to a foundation slab 33. The form may be provided at its top pole with an -appendix 34 and adjacent its bottom with an appendix 35 to define fitting openings, as described in connection with Fig. 1. Suitable means (not shown) are provided on the exterior of the form to anchor the latter to the concrete spherical shell erected thereon.

Upon inflation of the form, concrete is applied over the outer surface thereof in the manner -indicated in the foregoing, to a depth of approximately 3" for a shell 36 having a 9 ft. radius and a capacity of approximately 22,500 gallons, As shown, the space between the bottom pole of the shell and the slab is filled in with concrete to a thickness suitable to the formation of a foundation 38 which gives vertical stability to the final structure.

The spherical form is fabricated from materials resistant to gasoline, fuel oil, Water and like liquids, or is treated during fabrication with a substance rendering the fabric thereof resistant to such liquids as aforesaid. Alternatively, the form may be supplied untreated, and following erection of a spherical concrete tank structure thereon, the interior surface of the form is then sprayed or otherwise coated with the resistant or proofing substance.

It is also within the purview of the invention to form the tanks cylindrical on a pneumatic form having corresponding cylindrical shape upon inflation thereof.

Tanks in accordance with the foregoing may be built overground, although they may readily be erected in a construction pit, as indicated in Figs. l and 3, and thereupon covered with earth where conditions require or make advisable the provision of underground storage facilities.

The invention as above described achieves the objectives of providing concrete storage tanks for liquids such as gasoline and fuel oil, which may be erected from readily available materials, by a simple and inexpensive construction method, and with the minimum of equipment. Due to the fact that the method employed in constructing such tanks is extremely fast, the estimated construction time being approximately eight hours, it will be appreciated that the invention not only makes for the inexpensive and fast construction of permanent storage tanks but is also particularly applicable to storage tanks constructed for iii) temporary use as required, for exampleAn supplying the demands of mobile warfare. Moreover, when used for military purposes, storage tanks in accordance with the invention are capable of being readily camouflaged and may, if desired, be erected in excavations and thereupon covered or partly covered with earth to render them substantially undiscernible from the air.

As many changes could be made in carrying out the above constructions without departing from the scope ofthe invention, it is intended that all matter 'contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. A storage tank for gasoline, fuel oil and like liquids comprising a concrete shell-form structure consisting of a continuous and load-sustaining layer of set and substantially unreinforced concerete which in section extends along a continuous curve between transversely spaced points on the structure floor line, and a fabric member characterized by its prefabricated construction and a shape and size corresponding to that of the structure interior, said member being bonded to the inner Wall of said structure in the setting thereof and providing, a unitary inner container for liquid within the structure and which is supported under the load of the liquid by the concrete structure.

2. A storage tank as set forth in claim 1, wherein the fabric member carries a coating rendering it airproof and also resistant and impervious to liquid contained therein.

3. A storage tank for gasoline, fuel oil and the like comprising a concrete shell-form structure, a fabric member disposed within the structure and being characterized by its prefabricated construction and a shape and size corresponding to that of the structure interior, said fabric member carrying means on its outer surface which is bonded to the concrete shell-form structure during the setting of the concrete thereof, whereby said member is permanently secured within and against the inner face of said structure and provides a unitary inner container for liquid within the latter, which is supported under the load of the liquid by the concrete structure.

4. A storage tank as set forth in claim 3, wherein the fabric member carries a coating rendering it airproof and also resistant and impervious to liquid contained therein.

5. The method of constructing shell-form concrete storage tanks for gasoline, fuel oil and like liquids, which comprises the steps of anchoring to a suitable foundation a pneumatic form made from fabric material and of size and shape such that upon inflation it assumes the size and shape of the interior of the tank and which is provided on its external surface with bonding means, inflating the form, and applying concrete over the external surface of the form in such manner that the applied concrete embeds the bonding means and remains in place on the form during setting Without the aid of an external form, whereby to provide upon setting a self-sustaining concrete shell-form tank having a fabric lining bonded to its inner surface.

6. The method as set forth in claim 5, wherein the fabric form is treated with a substance rendering it impervious and resistant to liquid contained in the tank.

7. The method of constructing shell-form concrete storage tanks for gasoline, fuel oil and like liquids, which comprises the steps of anchoring to a suitable lfoundation a pneumatic form made from fabric material and of size and shape such. that upon inflation it assumes the size and shape of the interior of the tank and which is provided on its external surface with bonding means, inating the form, applying concrete over the external surface of the form in such manner that the applied concrete embeds the bonding means and remains in place on the form during setting without the aid of an external form, whereby to provide upon setting a self-sustaining concrete shell-form tank having a fabric 1ining bonded to its inner surface, and coating the inner surface of the lining with a substance rendering it impervious and resistant to liquid contained in the tank.

8. A pneumatic form comprising an inflatable pneumatic body of size and shape such that upon inflation it assumes the size and shape of the interior of a shell-form concrete structure adapted to be erected thereon for the storage of gasoline, fuel oil and like liquids, said fabric body carrying a substance rendering it liquid-proof and resistant to such liquids whereby when left within a structure erected thereon the fabric body is adapted to provide a liquid-proof container Within the structure, and being provided on its exterior surface with means for securing itself to the structure erected thereon.

9. The method of constructing shell-form concrete storage tanks for gasoline, fuel oil, and like liquids, which comprises the steps of anchoring to a suitable foundation a pneumatic form made from fabric material and of size and shape such that upon inflation it assumes the size and shape of the interior of the tank, inflating the form, and applying concrete over the external surface of the form in such manner that the applied concrete remains in place on the form during setting Without the aid of an external form and that the form secures itself to the concrete of the shell in the setting thereof, Whereby to provide upon setting a self-sustaining concrete shell-form tank having its inner surface lined with a fabric lining.

WALLACE NEFF.

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