DESC:FIELD OF THE INVENTION
[001] The present disclosure generally relates to flexible tanks used in containers to transport non-hazardous liquid, and more specifically, relates to a reinforced flexible tank that prevents containers from bulging due to the pressure exerted by the liquid.

BACKGROUND OF THE INVENTION
[002] Flexible tank also known as flexitank is used in containers to transport non-hazardous liquid from one location to another. While transporting liquid, the trucks or lorries that carry these containers are bound to pass through patchy roads and rough terrains that causes the liquid to slosh or surge. Sloshing or surging of the liquid is the to and fro motion of the liquid within the container and can occur because of the rough roads, or sharp acceleration or deceleration of the truck. Sloshing or surging by the liquid exerts pressure on the walls of the container and can damage the walls of the container. They may result in deformation and bulging of the container making it unsuitable for further transportation.
[003] It is known that containers use bulkheads/accessories and horizontal load bars to prevent damages to the container wall. However, having bulkheads and load bars are inconvenient for transferring the liquid to and from the container. It is also known that containers use vertical bars along the container walls, to protect damage to the wall due to the pressure exerted by the liquid. Typically, the walls of the container are reinforced by placing 2” x 2” (50 x 50mm) Square, 2.0/2.2 mm thick heavy-duty box section tubes or vertical bars. The position or spacing of these vertical runners or vertical bars is crucial and depending on the severity of the containers condition the quantity of runners required is determined. Usually, the containers will have two or three runners on each side of the container and these runners absorb all the lateral forces imparted by the sloshing liquid and do not pass that on to the container walls, thereby protecting them from bulging. However, there is no fixed standard on how many runners are required to reinforce a container for higher payloads.
[004] According to the International Organization for Standardization (ISO)/Institute of International Container Lessors (IICL) recommendations, the deformation limit for sidewall panels is a maximum of 10 mm beyond the plane of the side surfaces of the corner casting fittings of the container. This limit has been exceeded in many incidents, where the pressure placed on the sidewall panels has resulted in them bulging beyond accepted ISO external dimensions and tolerances, leading to permanent deformation. Hence, many industry cargo operators have imposed limits on the quantity of liquid that may be carried in a flexitank.
[005] Another existing solution to overcome sloshing or surging is to have a two tier flexitank. Two tier flexitanks also known as double decker flexitanks, have two compartment, one upper compartment and one lower compartment. Having two compartments, damps the forces resulting from the sloshing or surging of the liquid.
[006] It is desired to have a flexitank that can accommodate high pay loads, at the same time withstand pressure arising due to sloshing of the liquid during transportation and further prevent bulging of the container wall.
BRIEF DESCRIPTION OF THE FIGURES
[007] These and other features, aspects, and advantages of the exemplary embodiments can be better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
[008] FIG. 1A, 1B, 1C and 1D illustrates various views of the reinforcement structure within a flexitank in accordance with an embodiment of the present disclosure;

[009] FIG. 2A, 2B, 2C and 2D illustrates various views of a two tier flexitank in accordance with an embodiment of the present disclosure;

[0010] FIG. 3A and 3B illustrates a view of the two tier flexitank in accordance with an embodiment of the present disclosure;

[0011] FIG. 4 illustrates the basic construction of a two-tier flexitank, in accordance with an embodiment of the present disclosure;

[0012] FIG. 5 illustrates a view of the two-tier flexitank, in accordance with an embodiment of the present discclosure;

[0013] FIG. 6 illustrates a view of the two-tier flexitank, in accordance with an embodiment of the present discclosure;

[0014] FIG. 7 illustrates the connection between the two tiers of the two-tier flexitank, in accordance with an embodiment of the present disclosure;

[0015] FIG. 8 illustrates the harness provided with the two-tier flexitank, in accordance with an embodiment of the present disclosure; and

[0016] FIG. 9 and FIG. 10 illustrates performance comparison between a container with a normal flexitank and a container with a two-tier flexitank, in accordance with an embodiment of the present disclosure.
[0017] Further, skilled artisans will appreciate that elements in the figures are illustrated for simplicity and may not have necessarily been drawn to scale. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the figures by conventional symbols, and the figures may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the figures with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.
DETAILED DESCRIPTION OF THE INVENTION
[0018] For promoting an understanding, the principles of the invention, reference will now be made to the embodiments illustrated in the figures and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
[0019] It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof.
[0020] The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion such that a process or method that comprises a list of steps does not comprise only those steps but may comprise other steps not expressly listed or inherent to such a process or a method. Similarly, one or more devices or sub-systems or elements or structures or components proceeded by "comprises... a" does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components. Appearances of the phrase “in an embodiment”, “in another embodiment” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.
[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.
[0022] In addition to the illustrative aspects, exemplary embodiments, and features described above, further aspects, exemplary embodiments of the present disclosure will become apparent by reference to the drawings and the following detailed description.
[0023] A flexitank, is a bladder, designed to fit inside a 20ft general freight container, thereby converting the freight container into a non-hazardous bulk liquid transportation unit as defined by the International Maritime Organization (IMO), the International Labour Organization (ILO) and the United Nations Economic Commission for Europe (UNECE) code of practice for packing of cargo transport units (CTU Code Reference-57). The flexitank is used for transport and or storage of a non-regulated liquid inside a CTU.
[0024] Typically, a 20 ft freight container having flexitank should generally be rated to a minimum 30,480 kg, irrespective of the size of the flexitank. The actual sidewall strength is a function of a container’s permitted payload, ie 0.6 × payload (according to ISO 1496-1 Series 1 freight containers – specification and testing). Therefore, the sidewall panels of a 30 mt container will have been tested to a greater load bearing capability than, say, a 24 mt container. The sidewall test requires a general freight container to be subjected to an internal loading uniformly distributed and arranged to allow free deflection of the sidewall and its longitudinal members. The ISO Standard requires that, upon completion of the test, the container exhibits neither permanent deformation that will render it unsuitable for use, nor any abnormality that will render it unsuitable for use, and that the dimensional requirements governing handling, securing and interchange are satisfied. Therefore, for a 30 mt container, the test load will be of the order of 16.8 mt. However, since a flexitank does not place a uniform loading over the full area of a sidewall, a gross liquid cargo weight of 24,000 kg is the recommended maximum by some flexitank operators, while some container operators maintain that there should be a lower limit for the liquid cargo weight. The problems faced by the customer today is bulging of the container walls after the flexitank is loaded. Once the bulging occurs, the customer is forced to cross stuff the product into another container. The customer faces losses in different fronts. The total loss includes (1) Container replacement, (2) New Flexitank in new container, (3) Cross stuffing expenses, (4) Transportation and (5) Loss of cargo, if any. The present disclosure solves these problems.
[0025] Embodiments of the present disclosure describes a reinforced antibulging flexitank for transportation of liquid in containers from one location to another.
[0026] FIG. 1A, 1B, 1C and 1D illustrates various views of the reinforcement structure within the flexitank in accordance with an embodiment of the present disclosure. The reinforcement structure, which is a tube of width slightly lower than the flexitank liner, is wrapped around the flexitank in the designated place. These tubes that resemble ribs help in breaking the wave formed inside the anti-bulging flexitank 100 due to the sloshing of the liquid. These tubes (Ribs) are further reinforced with a webbing 105. Webbing is inserted in the middle as the wave breaker. These additions break the wave generated by the liquid inside the tank to such an extent that its crest is significantly lower so that the center of gravity of the load is below the halfway point. In some embodiments, the tube and webbings can be replaced by a belt or a strap or any other similar structure that can provide reinforcement to the flexitank. In one embodiment, the number of ribs can be two, however one should note that the number of ribs can be increased or decreased based on the reinforcement required for the flexitank/container combination.
[0027] FIG. 1B illustrates the liner with ribs whose width is slightly lower than the liner. In one embodiment, the liner with ribs is placed anywhere between 230 cm to 400 cm.
[0028] FIG. 1C illustrates the ribs when the flexitank is being inflated. As shown in FIG. 1C, these tubes (ribs) are further reinforced with a webbing 105 running right in the middle. The ribs are strengthened with the webbing and does not stretch as much as the body of the flexitank. The body of the flexitank, by being constructed with a film tends to take the shape of the liquid inside, but the rib does not entirely take that shape, thereby breaking the wave.
[0029] Referring to FIG. 1D now, FIG. 1D depicts the dimensions of the ribs in accordance with one embodiment of the present disclosure.
[0030] It should be noted that the position of the ribs or tubes and dimensions, the webbing dimensions, the liner dimensions and stitching patten may vary and will be placed accordingly in the anti-bulging flexitank for breaking the waves of the liquid and absorb the pressure, and prevent bulging of the container.
[0031] FIG. 2A, 2B, 2C and 2D illustrates various views of a two tier flexitank in accordance with an embodiment of the present disclosure.
[0032] Though it is known that cylindrical shaped containers can prevent the effects of sloshing of the liquid while transportation, it is preferred to have containers that have a rectangular prism shape because rectangular prism shaped containers can carry non-liquid items as well as liquid items using flexitanks and are easier to manufacture. One existing solution to overcome sloshing or surging is to have a two tier flexitank. Two tier flexitank also known as dual compartment flexitanks or double decker flexitanks, have two compartments or units, one upper compartment or upper unit and one lower compartment or lower unit. Having two compartments or units, damps the forces resulting from the sloshing or surging of the liquid. However, it has been found that even with two tier flexitanks, the walls of the container can bulge due to sloshing when transporting heavy payloads. Further, heavy payloads bring about higher center of gravity and when compounded with the issue of sloshing, it results in higher stress on the container and makes the wall of the container to bulge. Hence, the dual compartment flexitanks or the two tier flexitank can be reinforced with an inbuilt webbing to prevent bulging of the container. Various embodiments of the two tier antibulging flexitank with various dimensions of the compartments is manufactured for the optimal usage of the flexitank. Further, the constructional details of the flexitank according to one embodiment is given below.

Liner details:
[0033] In one embodiment, two Layers of 7 layer, high tensile tubular film of width 2.95-3.10 m was used as liner. It should be noted that the liner can be of multiple layers, dimensions and made of various combinations of materials.
[0034] Below table shows the various dimensions of the liners.

Particulars Value Unit
Type of PE liner Rishi NA
Gauge 100 to 200 microns
Liner length 10 to 25.0 m
Liner width 2.95 to 3.50 m
No. of layers 1-5 -
No. of seals 1-4 -
Flange position 900x1100 mm

Fabric details:
[0035] Polypropylene (PP) unlaminated tubular fabric of 175 to 200 grams per square meter (GSM) is used. The fabric is tubular in nature thereby eliminating any lengthwise stitch. A tube of width 3.12m, and length 12.6 m is desired. In some embodiments, the length can range from 12.10-13.02 m and width can range from 2.95 – 3.50 m, respectively. It should be noted that the fabric can be tubular or flat and in some embodiments the fabric can be laminated or unlaminated.

Sleeves for both compartments:
[0036] If the fabric is tubular it is necessary for the sleeves to be tubular, therefore two tubular sleeves per flexitank are required. The length range between 2.5 - 3.0 m and width range between 2.95 - 3.1 m. These are prepared using unlaminated fabric and inserted over the liner. It is to be noted that the sleeve is stitched to liner first and then the sleeved liner was stitched to the body fabric for extra safety.

Side sleeves holding both compartments:
[0037] The top and the bottom half of the tanks were integrated by means of stitching a separate piece of fabric on top and bottom using a Juki machine. The two pieces can be stitched together later with the help of an over lock stitch.
Fabric : 210 GSM Laminated
Dimension : L= 185 x 70
[001] In one embodiment, the dimension of the side flap can be 1.85 x .70 m as depicted in FIG. 2D. The side flap holds the two pieces together.
[0038] FIG. 3A and 3B illustrates a view of the two tier antibulging flexitank in accordance with an embodiment of the present disclosure. Referring to FIG. 3A, FIG. 3A represents a flexitank loaded onto a container with a front flap.
Front flap:
[0039] A flap of dimension 1.87m x 1.0m is prepared to connect both the compartments at their mouth end. After preparing the sleeves the fabric is stitched with webbing which will be tied to container hooks after loading the tank. The upper and the lower half of the flexitank is connected using a single connection, of diameter 430 mm.
Valve details:
[0040] In one embodiment, the valve is positioned 90cm from stitch end and 110 cm from right end of the bottom compartment. To avoid the air getting filled in the tank, a pressure release valve (PRV) is fitted on topmost region of the tank. i.e. 3.05m x 1.55m on the upper compartment. Below table lists the details of the valve.

Particulars Description
Valve type 3” Ball Valve
Torque 21Nm
Handle position 12 ‘o’ clock

[0041] FIG. 3B is an exemplary illustration of the valve being used to load the flexitank.
Harness-Top and Bottom
[0042] A webbing running through the fabric is provided to fasten it to the container lashing points. The length of the harness is long enough to fasten it to a third lashing point. The two/dual compartment flexitank with reinforced structure prevents bulging of the container. Likewise, a single compartment flexitank with reinforced structure also prevents bulging of the container. The dual compartment reinforced anti-bulging flexitank is also a bulkhead less flexi tank and hence it is convenient to operate.

[0043] FIG. 4 illustrates the basic construction of a two-tier flexitank, in accordance with an embodiment of the present disclosure. The two-tier flexitank comprises two layers of Polyethelene (PE) Film with each layer in turn containing seven sub layers. It is wrapped around a tubular high tensile woven Polypropelene (PP) Fabric for superior mechanical properties. Tubular PP offers greater mechanical properties as there is absence of seam along the side.

[0044] FIG. 5 illustrates a view of the two-tier flexitank, in accordance with an embodiment of the present discclosure. This is a layflat top view of the flexitank construction having two layers of inner PE wrapped around with an outer layer of woven PP. The ends are joined together by way of heracle stitch.

[0045] FIG. 6 illustrates a view of the two-tier flexitank, in accordance with an embodiment of the present discclosure. FIG. 6 shows the layflat structure being folded into two, such that the end seams are almost one on top of another. This fold has now converted a single layflat structure into 2 tiered structure. The two seams are kept apart by a distance of 50 to 75.0 cms.

[0046] FIG. 7 illustrates the connection between the two tiers of the two-tier flexitank, in accordance with an embodiment of the present disclosure. The seams are integrated vide a high GSM Woven PP sewn to the individual seams of top and the bottom tier. Two Holes of dimension 43.0cms connect the two parts of the tank. These holes facilitate the movement of the cargo from lower to upper during loading and from upper to lower during unloading.

[0047] FIG. 8 illustrates the harness provided with the two-tier flexitank. There is one harness at either side and there is one harness at the top. All three harnesses hold and integrate the two tiers.

[0048] FIG. 9 and FIG. 10 illustrates performance comparison between a container with a normal flexitank and a container with a two-tier flexitank, in accordance with an embodiment of the present disclosure.

[0049] FIG. 9 shows a typical wave form within the normal flexitank. In a container, when a flexitank is loaded,the mass of the liquid and its inherent movement exerts considerable stress on the container walls as well as itself. This results in the container wall getting damaged or in some cases failure of the flexitank itself. FIG. 9 shows a normal flexitank in a standard dry container. This is filled with 24,000 ltrs of water, thereby carrying a mass of 24,000kgs. It is natural that when the container is in motion there is far greater movement of water within the container. This constant movement creates sloshing of water resulting in a wave structure of certain amplitude and wavelength as depicted in FIG. 9. The container is under constant stress due to constant shifting of the centre of gravity which is a fact due to the wave struture. Herein,the amplitude is 1 and the wavelength is 8.

[0050] Referring to FIG. 10 now, FIG. 10 illustrates an anti-bulging two tier flexitank. FIG. 10 shows the solution to the problem created by a normal flexitank. Here the flexitank is split into two tiers with an understanding that the mass is split into two components. The design is a bit like keeping one pillow of water on another, thereby mitigating or significantly reducing any scope for movement of water in the lower tier. Even if there is any movement, there is no scope of any sloshing or formations of wave in the lower tier. This leaves the upper half or upper tier of the flexitank to be prone to sloshing and wave formation. Since the volume of water involved in this tier is significantly lower (half), the wave structure that is formed also differs. The resultant amplitude is much smaller and so is the wavelength.

[0051] Refering to FIG. 9 and FIG. 10, it can be deduced that the force or energy of both wave forms differ. It is higher in a normal flexitank and lower in a anti-bulging two tier flexitank. Considering that both the tanks are filled with 24,000ltrs of liquid, thereby containing equal amount of Mass. Hence, are supposed to carry the same potential energy. Another consideration is that both the flexitanks are undergoing same conditions of acceleration, damping, breaking and deacceleration. It is a given that with these similar conditions they should carry the same dynamic load, but they don’t. Their load bearing wave structure is vastly different from each other. FIG. 9 shows higher Amplitude compared to FIG. 10. Reason being, in FIG. 10 the amplitude is lesser because the tank is divided into 2 tiers. There is hardly any internal movement of water in the lower tier. The dynamic load is offered only by the upper tier. Hence, the understanding that Amplitude will be ½ of the normal flexitank.With these factors deduced, the tank two tier tank becomes becomes much safer on the walls of the container. Not only that, since it has lesser energy within,the flexitank it is far more stable and less prone to failure in comparison to a normal flexitank.

[0052] In one embodiment, an antibulging two tier flexitank for transporting liquid includes a top tier flexitank and a bottom tier flexitank. The top tier flexitank and bottom tier flexitank are joint via a woven polypropelyne sewn to individual seams of the top tier flexitank and the bottom tier flexitank. The antibulging two tier flexitank is made of two layers of Polyethelene (PE) film with each layer in turn containing seven sub layers. The antibulging two tier flexitank includes holes to provide passage between the top tier flexitank and the bottom tier flexitank. The holes are apertures that facilitate the movement of liquid from bottom flexitank to top flexitank during loading and from top to bottom flexitank during unloading. The combined structure of the top tier flexitank and the bottom tier flexitank reduces sloshing of the liquid. In one embodiment, the antibulging two tier flexitank includes a rib reinforcement structure. The rib reinforcement structure is a tubular woven Polypropylene (PP) fabric wrapped around the inner part of the two tier flexitank. The rib reinforcement structure breaks the wave formed inside antibulging two tier tank due to sloshing of the liquid.

[0053] While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person skilled in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.
[0054] The figures and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of processes described herein may be changed and are not limited to the manner described herein. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all the acts necessarily need to be performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible.
,CLAIMS:1. An antibulging two tier flexitank for transporting liquid, the antibulging two tier flexitank comprising:
a top tier flexitank; and
a bottom tier flexitank, wherein the top tier flexitank and bottom tier flexitank are joint via a woven polypropelyne sewn to individual seams of the top tier flexitank and the bottom tier flexitank.

2. The antibulging two tier flexitank as claimed in claim 1, wherein the antibulging two tier flexitank is made of two layers of Polyethelene (PE) film with each layer in turn containing seven sub layers.

3. The antibulging two tier flexitank as claimed in claim 1, comprising holes to provide passage between the top tier flexitank and bottom tier flexitank, wherein the holes facilitate the movement of liquid from bottom to top flexitank during loading and from top to bottom flexitank during unloading.

4. The antibulging two tier flexitank as claimed in claim 1, wherein the top tier flexitank and the bottom tier flexitank reduces sloshing of the liquid.

5. The antibulging two tier flexitank as claimed in claim 1, comprising rib reinforcement structure, wherein the rib reinforcement structure breaks the wave formed inside antibulging two tier tank due to sloshing of the liquid.

6. The antibulging two tier flexitank as claimed in claim 1, wherein the rib reinforcement structure is a tubular woven Polypropylene (PP) fabric wrapped around the inner part of the two tier flexitank.