AU2002302001A1 - Tank - Google Patents

Description

T

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Tank The following statement is a full description of this invention, including the best method of performing it known to us: Freehills Carter Smith Beadle Melbourne\004173952 Printed 14 November 2002 (14:45) page 2 Freehills Carter Smith Beadle Melbourne\004173952 Printed 14 November 2002 (14:45) page 2 004173874(Copy) 1A

TANK

Background of the Invention This invention relates to tanks for transporting liquids, in particular tanks that are transported from one location to another such as those mounted on a vehicle or trailer.

Tanks used in transportation of fluids are typically elongated tubular shells with a series of internal baffles spaced longitudinally along the axis of the shell and oriented transversely to the axis. Other internal baffles may be oriented in a longitudinal direction.

Baffles come in many shapes and sizes and generally are sized to contact the internal surface of the shell, providing rigidity and strength to the tank. Baffles may also provide the necessary control for surging and wave motion of the liquid cargo, particularly when the tank undergoes a rapid acceleration or deceleration.

When the level of liquid in the tank is less than full, these forces are amplified to a much greater degree. In addition to longitudinal forces exerted by the liquid cargo, the action of turning or banking of the tank may cause lateral or transverse liquid movement, resulting in tank instability and ultimately instability of the vehicle.

Furthermore the joints securing conventional baffles to the tank shell or other internal structure may suffer cracks and early failure, primarily due to stresses induced by liquids impacting the baffle surface and stresses resulting from uneven fluid distribution inside the tank.

It is an object of the present invention to provide a tank having a baffle system which minimises the effects of surging and wave motion of the liquid cargo during transportation.

Summary of the invention Accordingly the invention provides a tank for transporting liquid having a vessel and a structural frame within the vessel, the structural frame including a plurality of baffle plates within the vessel, the baffle plates being arranged to 004173874(Copy) 2 provide at least one central baffle housing extending longitudinally and adjacent the base of the vessel.

By providing a central baffle housing which is preferably in the lower most point of the vessel, the invention provides a lower ballast of liquid in the tank in which a wave and associated surge is decreased or may not even be produced. This is particularly the case when the tank is subjected to accelerations produced by, for example, an uneven roadway or turning of the vehicle. Thus the present invention helps to decrease lateral or transverse liquid movement during turning or banking of the tanks.

It is preferable that a plurality of interconnected longitudinally extended central baffle housings are provided adjacent the base of the vessel. Lateral baffle plates are preferably provided in the vessel with the central baffle housings extending between either adjacent lateral baffle plates or lateral baffle plates and the vessel wall. In this way, substantially the full length of the vessel is provided with a central baffle housing.

By interconnecting the central baffle housings through openings formed in the lateral baffle plates, these preferred features may add an additional benefit of decreasing the surging longitudinal forces exerted by the liquid cargo during breaking. These openings also provide easy access during construction to welding joints between the vessel skin and frame during construction, thereby enabling welds to be more reliably made, simplifying construction and reducing construction time.

The central baffle housing may include inclined baffle plates extending between the lateral baffle plates. These longitudinal baffle plates inclined from the horizontal direction enable laterally or transverse forces associated with movement of the liquid cargo to be transferred or deflected towards the base of the tank. This has the effect of improving the stability of the tank during turning or banking or when travelling over uneven surfaces.

The space above the inclined baffle plates may be divided into lateral baffle zones by longitudinal baffle plates arranged vertically and extending between the 004173874(Copy) 3 lateral baffle plates. These lateral baffles are interconnected with longitudinally adjacent baffle zones and may also be connected by an opening or passage to a central baffle housing. It is preferable that at least one opening is provided into the baffle zone of the central housing through at least one opening in an inclined baffle plate. In some instances, it may be preferable for there to be provided an opening in the inclined baffle plates of alternate lateral baffle zones to enable easy maintenance and inspection access to the central baffle zone.

To enable regular maintenance and inspection of the tank in accordance with the invention, it is preferable that the top of the vessel is provided with a plurality of openings for manhole access. In the preferred form of the invention, a single access opening can be provided in the top of the vessel for each pair of adjacent lateral baffle zones.

Alternatively, a single removable opening may be provided in the top of the vessel to allow access to or of the lateral baffle zones. It would be appreciated by those skilled in the art that the cover for such an opening would be extremely large and may require the assistance of lifting machinery to remove and replace the cover.

Preferred Embodiment The features, objects and advantages of the present invention will become more apparent from the following description of the embodiment and accompanying drawings in which: Figure 1 is a perspective view of an embodiment of the present invention; Figure 2 is a perspective view of the skeletal frame of the embodiments shown in Figure 1; Figure 3 is a plan view of the frame shown in Figure 2; Figure 4 is a side view of the frame shown in Figure 2; Figure 5 is an end view of the frame shown in Figure 2; and Figure 6 is a perspective view of a second embodiment of the invention.

Referring to the drawings, the tank consists of a tank vessel formed by welding suitable material to a skeletal frame 12 (shown in Figure The frame formed from mild steel and coated after construction consists of a plurality of baffle 004173874(Copy) 4 plates 13, 14, 15 which divides the vessel into a plurality of baffle zones. The baffle plates are held together by supports 19, which combine with the baffle plates to give the vessel the necessary internal and external structural support.

A central baffle zone is created by a baffle housing consisting of inclined longitudinally extending baffle plates 14 and lower baffle plates 16. The longitudinally extending inclined baffle plates 14 extend between lateral baffle plates 13 or between lateral baffle plate 13 and end plates 18 of the vessel 11.

The central baffle zones are connected by a passage 20 formed as a cut out in lateral baffle plates 13 to allow water to flow between each of the central baffle zones in a reasonably quiescent manner. These passageways into the central buffer zone have the advantage of providing access to the area during construction for welding of the vessel skin material to the frame. This improved welding access enables more reliable welding and makes construction of the tank easier.

In order to provide maximum stability to the tank, the central baffle zone is formed at the lowest point in the tank and is positioned adjacent the base 21 of the vessel 11. In this way, the centre of gravity of the liquid contained in the central baffle zone will always be lower than the centre of gravity of the total liquid volume in the vessel with the volume of the central baffle zone being up to a third of the total volume of the vessel.

Lateral baffle zones are formed above the inclined baffle plates and separated by a longitudinal baffle plate 15 which is substantially vertical. The lateral baffle zones are interconnected with at least one adjacent lateral baffle zone by channels 23a, 23b and 23c formed in the respective baffle plates 13.

Inclined baffle plates 14 may also be provided with an opening 24 primarily as an access opening to enable inspection of the central baffle zone during routine maintenance and inspection of the tank 10. It is highly desirable that only one side of each pair of inclined baffle plates have an access opening to prevent an easy passage for lateral movement of liquid from one lateral baffle zone to the other adjacent baffle zone through the central baffle zone.

004173874(Copy) To accentuate the ballast capabilities of the central zone, wheel arches 25 are provided in the vessel 11. While these wheel arches 25 have the effect of reducing the overall volume of the vessel, the centre of gravity of the vessel when filled with liquid is lower than would be the case if the tank was simply mounted on top of a simple flat tray.

While the tank in accordance with the invention is able to be used as a separate towable trailer by the provision of wheels 25 and appropriate differential gearing (not shown), the tank may also be mounted onto a single flat bed tray.

Under these circumstances, the wheel arches 25 will not be required.

For each pair of adjacent lateral buffer zones, the top of the vessel may be provided with access hatches 30. These hatches enable easy access for maintenance workers to inspect the condition of the baffles within the lateral baffle zones and the central baffle zone through access opening 24.

In an alternative embodiment shown in Figure 6, individual access covers are replaced with a single removable top 31 which can be removed during maintenance to allow easier access by maintenance workers. It is hoped that this removable top will also avoid the occupational health and safety hazard of confined spaces thereby removing the need for maintenance workers to be fitted with breathing apparatus. The embodiment shown in Figure 6 also illustrates a version of the tank in accordance with the invention which can be used for loading onto a flat top or other suitable vehicle.

It can be seen that a significant proportion of the liquid cargo contained in the central baffle zone is effectively prevented from freely surging within the tank vessel 11 because of the limited passages in the baffle plates.

Furthermore, waves in the liquid cargo moving within the lateral baffle zones will bear against the inclined baffle plates causing the associated forces to be redirected. The generally downward redirection of these forces will help to stabilize the tank through the central baffle housing.

Claims (9)

1. A tank for transporting fluids having a vessel and a structural frame within said vessel, the structural frame including a plurality of baffle plates within the vessel, the baffle plates being arranged to provide at least one central baffle housing defining a central baffle zone extending longitudinally and adjacent the base of the vessel.

2. The tank in accordance with claim 1 wherein a plurality of interconnected longitudinally extending central baffle zones are provided adjacent the base of the vessel.

3. The tank in accordance with claim 1 wherein the plurality of baffle plates divide the space within the vessel into a plurality of interconnected baffle zones.

4. The tank in accordance with any one of claims 1 to 3 wherein the central baffle housing includes inclined baffle plates extending between lateral baffle plates.

5. The tank in accordance with claim 4 wherein the space above the inclined baffle plates are divided into lateral baffle zones by longitudinal baffle plates arranged substantially vertically and extending between the lateral baffle plates.

6. The tank in accordance with any one of the preceding claims wherein at least one opening or passage is provided into the central baffle housing through the inclined baffle plate.

7. The tank in accordance with claim 5 wherein an opening in the inclined baffle plate for access to the central baffle housing is provided in alternate lateral baffle zones. 004173874(Copy) 7

8. The tank according to claim 1 wherein the top of the vessel is provided with a fluid inlet opening.

9. The tank in accordance with claim 1 wherein the top of the vessel is provided with a plurality of openings to allow access for inspection and maintenance. The tank in accordance with claim 1 wherein the top of the vessel is removable. Anaid Nominees Pty Ltd By Freehills Carter Smith Beadle Registered Patent Attorneys for the Applicant 14 November 2002