WO2005002993A1

WO2005002993A1 - Tank provided with partition

Info

Publication number: WO2005002993A1
Application number: PCT/NL2004/000472
Authority: WO
Inventors: Jan Van Opstal; Frans REIJTENBAGH
Original assignee: Consani Nederland B.V.
Priority date: 2003-07-03
Filing date: 2004-07-02
Publication date: 2005-01-13
Also published as: NL1023810C2

Abstract

A tank (1) for containing a fluid comprises a peripheral wall (5) that surrounds an interior (2), which peripheral wall has a first (7) end and a second end (8) and is closed off by an end wall (6) at each end. At least one partition (10)is arranged in the interior (2), which partition is fixed to the peripheral wall. The partition is provided with at least one flexible plate-shaped element (14) that is made of a fatigue-resistant material.

Description

Title: Tank provided with partition

The invention relates to a tank for containing a fluid, comprising a peripheral wall that surrounds an interior, which peripheral wall has a first end and a second end and is closed off by an end wall at each end, wherein at least one partition is arranged in the interior, which partition is fixed to the peripheral wall. Such a tank is generally known. This tank is, for example, placed on a trailer for transport by road. In addition, it is possible that such a tank is accommodated in a standard swap tank container or a deep sea ISO tank container. A standard swap tank container is surrounded by a frame, the end walls of the tank protruding with respect to said frame. This container is widely used for transport by rail. A standard deep sea ISO tank container is likewise surrounded by a frame, but for this container the tank may not protrude with respect to said frame. This standard container is generally used especially for transport by sea. Under international legislation these containers may not be larger than maximum standard length, width and height dimensions. This applies both in respect of road transport, in respect of rail transport and in respect of transport by sea. The maximum length dimension of a standard swap tank container is 7820 mm, whilst the maximum length dimension of a standard deep sea ISO tank container is 6058 mm. In addition, there are standards for the maximum weight of a container. The weight of the container is the sum of the empty weight of the components of the container, including the tank and the partition, and the weight of the contents of the tank. During the transport of fluids, the container will be subject to stress as a consequence of sloshing of the fluid. Within current standards measures such as partitions are therefore obligatory if the degree of filling of the container is between 20 % and 80 %. The partitions reduce sloshing of the fluid. The partitions are made of the same material as the tank, such as stainless steel, carbon steel or aluminium. The partitions are fixed to the peripheral wall by means of, for example, a welded joint. The partition can be constructed as a curved disc in which a few passages for the fluid to be accommodated have been made. The curvature increases the rigidity of the partition. In addition, the thickness is chosen such that the partition as a whole is stiff and rigid. As an alternative, the partitions in a known tank can be made up of elongated partitioning sections. The shape of the sections in combination with the thickness thereof provide a rigid construction. During the production of such a tank, a ring that runs all round in the peripheral direction is welded around the inside of the peripheral wall before the end walls are fitted. This ring has holes that are positioned some distance apart in the peripheral direction. The elongated partitions are joined to the ring by bolted joints that interact with these holes. However, these known partitions are relatively heavy. As a result the maximum weight of the fluid contents of the container is restricted. The object of the present invention is to provide a tank with at least one partition where the empty weight thereof is reduced. Said object is achieved according to the invention in that the partition is provided with at least one flexible plate-shaped element that comprises a fatigue-resistant material. The tank according to the invention has a partition that is so thin that the partition is flexible. When the partition has been fitted in the tank the plate-shaped element can, for example, deform under the influence of sloshing of the fluid to be accommodated. This can give rise to fatigue cracks, in particular at the location of the fixing to the tank wall. However, because the plate-shaped element is made of a fatigue-resistant material, such as a suitable plastic, no fatigue cracks will arise. At the same time the thin plate-shaped element ensures that the empty weight of the tank with partition is reduced. A further advantage is that sloshing is more effectively counteracted because the flexible element of the partition gives to some extent during sloshing of the fluid. Preferably, the plate-shaped element is made of plastic. This plastic is, for example, polyethylene (PE), polypropylene (PP) or polytetrafluoroethylene (PTFE, Teflon). In addition, another fatigue-resistant material can be used, such as thin stainless steel. According to one embodiment of the tank according to the invention, the partition has several plate-shaped elements that are arranged adjacent to one another in the peripheral direction of the tank and wherein each element is fixed at one end thereof to the peripheral wall and at an opposing end thereof is centrally joined to other elements. This provides a lightweight construction for the partition. With this arrangement the plate-shaped elements preferably each run essentially parallel to the peripheral wall at the location of the fixing to the peripheral wall. The forces exerted on the peripheral wall by sloshing of fluid are dissipated in the axial direction into the peripheral wall. The risk of fatigue cracks is further reduced as a result. The plate-shaped elements can run essentially parallel to a cross-sectional plane through the tank at the location of the central joint between them. The plate-shaped elements are then bent through essentially an angle of 90°. So as to enable fluid communication for the fluid from the one side to the other side of the partition, adjacent plate-shaped elements can in each case enclose an opening for passage of the fluid to be accommodated in the tank through the partition. It is preferable that the fixing of the plate-shaped elements to the peripheral wall and the central fixing of the plate-shaped elements to one another can be dismantled. In this case the plate-shaped elements are separate components that can easily be fitted in and removed from the interior of the tank via a manhole in the tank. The partition according to the invention therefore does not have to be made at the same time when the tank is produced, but can be fitted in an existing tank later on. Moreover, the partition according to the invention is easily removable. For example, the fixing that can be dismantled is obtained in that the peripheral wall of the tank has at least one protruding stud provided with external screw thread and at least one plate-shaped element has a corresponding opening along the end edge thereof, the stud extending through the opening and the element being clamped between the peripheral wall and a nut. The fatigue loading on the tank wall is reduced as a result. Furthermore, the studs can easily be ground down so that the inside of the peripheral wall is smooth. This is important for cleaning the tank. To counteract the formation of fatigue cracks around the openings in the plate-shaped element, a thickening or reinforcing ring is arranged around each opening, if necessary. A second embodiment of the tank according to the invention has a partition that comprises angle sections, each of which supports a plate-shaped element, the angle sections being fixed to the peripheral wall. Preferably, the angle sections are fixed, such that they can be detached, to second angle sections that are fixed to the peripheral wall. The invention also relates to a swap tank container and a deep sea ISO tank container having a tank as described above. Furthermore, the invention relates to a partition for use in a tank as described above. The invention will now be explained in more detail with reference to the appended drawing. In the drawing: Figure 1 shows a side view in cross-section of a first embodiment of a tank according to the invention; Figure 2 shows a front view in cross-section of the tank shown in Figure 1 ; Figure 3 shows a detail of the tank shown in Figure 1 ; Figure 4 shows a perspective view of a second embodiment of a tank according to the invention. The tank shown in Figure 1 is indicated in its entirety by 1. The total length of this tank corresponds, for example, to a standard tank container. The tank 1 comprises a peripheral wall 5 that is essentially cylindrical. Two end walls 6, which are essentially convex, are arranged at the respective ends 7, 8 of the peripheral wall 5. The peripheral wall 5 and the end walls 6 together form a closed whole that surrounds an interior 2. If the tank 1 is partially filled with fluid, the fluid will start to slosh during transport. International legislation lays down that measures that counteract sloshing are needed if the tank is more than 20 % and less than 80 % filled. The tank 1 therefore has one or more partitions 10 in the interior 2. For the sake of clarity of the drawing, only one partition 10 is shown in Figure 1. The partition 10 divides the volume of the tank 1 into several compartments 11, which are in communication with one another via passages 20 in the partition 10. Sloshing is reduced in these smaller compartments 11. As shown in Figure 2, the partition 10 comprises several essentially triangular plate- shaped elements 14. The plate-shaped elements 14 are thin and consequently flexible. The weight of the thin plate-shaped elements is relatively low. As a result of the flexibility, it is possible to fix the plate-shaped elements 14 by, in each case, one end 16 thereof flat against the peripheral wall 5, while the elements 14 are joined to one another by a central joint 18 at the location of the central axis of the tank. The plate-shaped elements 14 are therefore bent through essentially an angle of 90°. There are gaps 20 between the plate-shaped elements 14. The fluid is able to flow via the gaps 20 from the one compartment 11 to the other compartment. Fixing of the plate-shaped elements 14 to the peripheral wall 5 is shown in detail in Figure 3. Several studs 21 provided with external screw thread are mounted on the peripheral wall 5, for example by welding. A spot welding gun is particularly suitable for this purpose. The ends 16 of the plate-shaped elements 14 each have one or more openings 22, in which the studs 21 are accommodated. The plate-shaped elements 14 are screwed down by means of nuts 24. This fixing enables simple cleaning of the tank. If a partition is not needed, the studs 21 can easily be ground away. The internal peripheral wall of the tank is then smooth, in contrast to a known tank where a permanent ring running all round the peripheral wall is fitted. Dirt remains behind such a ring, so that corrosion can occur. The central joint 18 is produced in that the plate-shaped elements 14 each have an opening at the end facing away from the end 16, through which opening a common bolt has been inserted. A nut clamps the plate-shaped elements 14 onto one another at the central joint 18. The flexible elements 14 are so thin and flexible that these elements 14 are able to deform under the influence of sloshing of the fluid to be accommodated in the tank. Fatigue stress occurs as a result. However, this fatigue stress does not lead to cracks in the partition or in the peripheral wall because the plate-shaped elements have been fitted flat against the peripheral wall, that is to say parallel thereto. According to the invention the forces are dissipated in the axial direction of the tank into the peripheral wall. Moreover, the elements 14 are made of a fatigue-resistant material, such as a suitable plastic. Examples of suitable plastics are polyethylene (PE) and/or polypropylene (PP) and/or polytetrafluoroethylene (PTFE, Teflon). However, the flexible elements can also be made of a metal of limited thickness, such as stainless steel. In the embodiment of the partition shown in Figure 4, the same components are indicated by the same reference numerals. The partition 10 comprises angle sections 30. The plate-shaped elements 14 are fixed to the angle sections 30 by bolted joints. The elements 14 are elongated and essentially rectangular. The gaps 20 between the plate- shaped elements 14 again form passages for fluid communication between the compartments separated by the partition 10. The angle sections 30 are in turn joined to second angle sections 32 that have been fitted on the inside of the peripheral wall 5.

Claims

1. Tank for containing a fluid, comprising a peripheral wall that surrounds an interior, which peripheral wall has a first end and a second end and is closed off by an end wall at each end, wherein at least one partition is arranged in the interior, which partition is fixed to the peripheral wall, characterised in that the partition (10) is provided with at least one flexible plate-shaped element (14) that comprises a fatigue-resistant material.

2. Tank according to Claim 1, wherein the plate-shaped element (14) comprises plastic.

3. Tank according to Claim 2, wherein the plastic comprises polyethylene (PE) and/or polypropylene (PP) and/or polytetrafluoroethylene (PTFE, Teflon).

4. Tank according to one of the preceding claims, wherein the partition (10) has several plate-shaped elements (14) that are arranged adjacent to one another in the peripheral direction of the tank (1) and wherein each element (14) is fixed at one end (16) thereof to the peripheral wall (5) and at an opposing end thereof is centrally joined to other elements by means of a central joint (18).

5. Tank according to Claim 4, wherein the plate-shaped elements (14) each run essentially parallel to the peripheral wall (5) at the location of the fixing to the peripheral wall (5).

6. Tank according to Claim 4 or 5, wherein the plate-shaped elements (14) run essentially parallel to the cross-sectional plane through the tank (1) at the location of the central joint (18) between them.

7. Tank according to one of Claims 4 - 6, wherein adjacent plate-shaped elements (14) in each case enclose an opening (20) for passage of the fluid to be accommodated in the tank through the partition (10).

8. Tank according to one of Claims 4 - 7, wherein at least one plate-shaped element (14) is essentially triangular.

9. Tank according to one of Claims 4 - 8, wherein the fixing of the plate-shaped elements (14) to the peripheral wall (5) and/or the central fixing (18) of the plate-shaped elements (14) to one another can be dismantled.

10. Tank according to Claim 9, wherein the peripheral wall (5) of the tank (1) has at least one protruding stud (21) provided with external screw thread and at least one plate-shaped element (14) has a corresponding opening (22) along the end (16) thereof, the stud (21) extending through the opening (22) and the element (14) being clamped between the peripheral wall (5) and a nut (24).

11. Tank according to Claim 10, wherein at least one opening (22) in a plate-shaped element (14) is surrounded by a thickening.

12. Tank according to one of the preceding claims, wherein the partition (10) comprises angle sections (30), each of which supports a plate-shaped element (14), the angle sections (30) being fixed to the peripheral wall (5).

13. Tank according to Claim 12, wherein the angle sections (30) are fixed, such that they can be detached, to second angle sections (32) that are fixed to the peripheral wall (5).

14. Tank according to one of the preceding claims, wherein the tank (1) has a standard length of essentially 7820 mm (swap tank container).

15. Tank according to one of the preceding claims, wherein the tank (1) has a standard length of essentially 6058 mm (deep sea ISO tank container).

16. Swap tank container having a tank according to one of the preceding claims.

17. Deep sea ISO tank container having a tank according to one of the preceding claims.

18. Partition for use with a tank according to one of the preceding claims.