FLEXIBLE TANKS
Flexible tanks for storage of fluids are constructed of interconnected panels of flexible material made of flexible woven and coated materials and with specific geometric panel configurations.
This application is related to U.S. provisional application No. 61/865,375 filed Aug. 13, 2013.
FIELD OF THE INVENTIONCollapsible tanks for improved field performance related to stretch, storage, displacement and minimization of leakage and utilizing flexible, high-strength coated fabrics.
BACKGROUNDTraditionally, most tanks used for the field storage of liquid fuels, JP-8, water and other liquids are based on a “pillow tank” or similar designs. Such tanks are collapsible, flexible storage bladder tanks which provide temporary or longer term liquid storage. While these containers are designed for land based operations, they can also be utilized on the decks of vessels. These sizes ranging from 100 gallons to 210,000 gallons capacities and even larger custom tanks. Of course, with each design there are limitations to the tank and concerns regarding leakage. By considering material, fabrication techniques, fluid mechanic and design geometry variables, a number of unique tank designs were developed to overcome these issues. The present invention inherently reduces the stretch and hence the stress in the tank walls and welds, both at the design volume and at elevated temperatures. In addition, the present invention minimizes the number of weld seams, overall seam length or the need for certain weld types. These changes positively impact field life by reducing areas in the tank which serve as potential leak sources.
U.S. Pat. No. 7,213,970 and U.S. Pat. No. 7,503,885 both disclose flexible storage tanks with corners designed to improve resistance to leakage. Both patents cite the rounded corners as an improvement on pressure, yet both contain a significant number of panels and even directly cite a plurality of panels in their claims.
U.S. Pat. No. 4,865,096 also discloses a tank design but again suffers from less than preferred weld placements. The present invention seeks to minimize the number of panels in the tank and minimize the use of welds and weld seams.
In one embodiment the present invention discloses a flexible canoe ends design storage tank comprising two or more panels, each panel bonded by seams with others of the panels to enclose a storage volume, a left side pocket formed by one or more panels, a right side pocket formed by one or more panels, an optional middle section formed by one or more panels and the left side pocket, right side pocket and optional middle sections being assembled in a manner to maximize the tank base and maintain a low fill height with low stretch.
In another embodiment the present invention discloses a flexible multi panel trapezoidal design storage tank comprising, four or more panels, each panel bonded by seams with others of the panels to enclose a storage volume, a large rectangular panel formed by one or more panels, a small rectangular panel formed by one or more panels, two or more side panels, and the large rectangle, small rectangle and two or more side panels being assembled in a manner to maximize the base corners contact with the surface below and have low stretch on the small rectangle.
In yet another embodiment the present invention discloses a flexible dogbone trapezoid design storage tank comprising two or more panels, each panel bonded by seams with others of the panels to enclose a storage volume, a top rounded-corner square formed by one or more panels, a bottom envelope formed by one or more panels, and the top rounded-corner square and the bottom envelope being assembled in a manner to maximize the base corners contact with the surface below and have low stretch on the top rounded-corner square.
In still yet another embodiment the present invention discloses a flexible quonset but design storage tank comprising three or more panels, each panel bonded by seams with others of the panels to enclose a storage volume, an oval shaped left end-piece formed by one or more panels, an oval shaped right end-piece formed by one or more panels, a tube piece formed by one or more panels, and the oval shaped left end-piece, the oval shaped right end-piece and the tube piece being assembled in a manner to create a tank with a rectangular footprint with a taller height.
The present invention utilizes designs to reduce the total number of “T” seams and the total seam length. Furthermore, the present invention creates designs which keeps the tank bottom on the ground, thereby reducing peripheral (“edge”) hydrostatic effects on the tanks top and welds. This is accomplished by utilizing new geometrical designs. These designs may add 5-15% more material over traditional “pillow” tank designs, but this further reduces tank stress at target volumes. These new geometries aid in offsetting the difference between warp and fill directional stretch characteristics of material. In addition, closing seams are located on the bottom of the tank where hydrostatic pressure minimizes material stretch.
In the DTT design the panels which form the top have an angled edge which interfaces with the sides. The panel geometry balances warp versus fill stretch differences by offsetting the top and bottom assemblies by 90° as illustrated in
In preferred embodiments, any of the disclosed tanks can be made of 2819 (30 gallon water prototype evaluation tanks) or 1940 PTFF MS 337 (field test tanks). In side by side field studies with JP-8, the flexible tanks of the present disclosure have been found to have fewer and less severe leaks than prior art tanks. Any of the flexible tanks of the present disclosure can utilize lapped, shingle type, alternating, bottom flap over top shear, fold over prayer weld or double butt seams.
Claims
1. A flexible tank comprising:
- A plurality of interconnected panels, each panel bonded to adjoining panels to define a tank cavity;
- a left side pocket formed by one or more panels;
- a right side pocket formed by one or more panels;
- an middle section formed by one or more panels; and
- the left side pocket, right side pocket and optional middle sections being assembled in a manner to maximize the tank base and maintain a low fill height with low stretch of the panels.
2. The tank of claim 1 further comprising:
- five panels where four of the panels are rectangular and have two rounded adjacent corners, two of the four panels are bonded to form the left side pocket and two of the four panels are bonded to form the right side pocket; and
- one of the four panels is the middle section which is a rectangle and is bonded to the left side pocket and the right side pocket and to itself.
3. A flexible multi panel trapezoidal design storage tank comprising:
- four or more panels, each panel bonded by seams with others of the panels to enclose a storage volume;
- a large rectangular panel formed by one or more panels;
- a small rectangular panel formed by one or more panels;
- two or more side panels; and
- the large rectangle, small rectangle and two or more side panels being assembled in a manner to maximize the base corners contact with the surface below and have low stretch on the small rectangle.
4. The multi panel trapezoidal design storage tank of claim 3 further comprising:
- ten panels where four of the panels are side panel trapezoids and six of the panels are rectangles; and
- three of the rectangle panels are bonded to one another to form the large rectangle, three of the rectangle panels are bonded to one another to form the small rectangle, the long parallel edges of the side trapezoids bonded to the larger rectangle and the short parallel edges of the side trapezoids bonded to the small rectangle and the non-parallel edges of the side trapezoids bonded to one another.
Type: Application
Filed: Aug 13, 2014
Publication Date: Feb 19, 2015
Inventors: Jude A. KRAL (Green, OH), Frank E. BRADENBURG (Wooster, OH)
Application Number: 14/458,920
International Classification: B65D 88/00 (20060101); B65D 88/16 (20060101);