WO1992008640A1

WO1992008640A1 - Tankers

Info

Publication number: WO1992008640A1
Application number: PCT/GB1991/002005
Authority: WO
Inventors: John Brian Lund
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-11-13
Filing date: 1991-11-13
Publication date: 1992-05-29
Anticipated expiration: 1993-05-13
Also published as: GB9024624D0; AU8903091A

Abstract

A pipe system (30) interconnects the upper portions of load carrying compartments of an oil tanker, and includes a pipe (36) having an exit port (38) in a bottom portion of an evacuation compartment (18). When the oil tanker is running, the load carrying compartments are normally closed, whilst the evacuation compartment (18) may be open to atmosphere. In the event of the rupture of one of the load carrying compartments, sea water (50) may enter through a hole (60), displacing oil (40) through the pipe system (30) and into the evacuation compartment (18), where it may be held. Thus, escape of oil from a damaged compartment may be reduced or avoided.

Description

TANKERS

This invention relates to tankers and is concerned particularly, although not exclusively, with oil tankers.

In the context of this specification, the term "tanker" refers to a water- borne vessel adapted to carry bulk fluids.

In recent years, a number of natural disasters have occurred where large oil tankers have run aground. Usually, what happens is that the load carrying compartments become ruptured around the lower region of the hull, and the oil gradually seeps out and/or is washed out by the action of the sea.

Preferred embodiments of the present invention aim to provide tankers which may be improved in this respect.

More generally, according to a first aspect of the invention, there is provided a tanker comprising at least one load carrying compartment, access means for charging and/or discharging a load to and/or from the or each load carrying compartment, an evacuation compartment, venting means for selectively venting an upper part of the evacuation compartment, and communication means providing communication between an upper part of the or each load carrying compartment and the evacuation compartment.

Preferably, the communication means provides communication between an upper part of the or each load carrying compartment and a lower part of the evacuation compartment. The communication means may be provided with at least one valve means for selectively opening and closing communication between a respective said load carrying compartment and the evacuation compartment.

Such a tanker may have a plurality of load carrying compartments and a plurality of said valve means, each for selectively isolating a respective one of the load carrying compartments from the other load carrying compartments and the evacuation compartment.

Such a tanker may include pressuris ng means for maintaining the load in at least one said load carrying compartment under pressure.

Said communication means may comprise a pipe system having a respective port opening into the or each load carrying compartment.

A tanker according to any of the preceding aspects of the invention may include a load of oil in at least one said load carrying compartment.

According to a further aspect of the present invention, there is provided a method of running a tanker in accordance with any of the preceding aspects of the invention, comprising the steps of charging the or each load carrying compartment via said access means, with the venting means of the evacuation compartment closed, sealing said access means to close off said load carrying compartment(s) except for said communication means, and running the tanker with the venting means of the evacuation compartment open. For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which:

Figure 1 is a top plan view illustrating the layout of compartments in an oil tanker;

Figure 2 is a first longitudinal sectional view of the tanker as shown in Figure 1 , when in a normal running condition; and

Figure 3 is a longitudinal sectional view similar to Figure 2, but showing one of the centre compartments holed.

The tanker 10 that is illustrated diagrammatically in Figure 1 has a layout of compartments which, in plan view, is fairly conventional. Thus, a plurality of load carrying compartments comprises a forward compartment 12, a series of side compartments 14, running from behind the forward compartment 12 to the stern, a plurality of central compartments 16 surrounded by the forward and side compartments 12, 14, and a spare compartment 18, situated between two of the centre compartments 16.

In a conventional manner, a!! of the compartments 12 - 18 are separated from one another by vertical bulkheads. In the example of Figure 1, every load carrying compartment has its own respective access point 20, via which oil may be loaded into and discharged from the respective compartment. The spare compartment has its own vent 22, which may be selectively opened and closed, to allow air to enter or escape from the compartment 18 and also, when appropriate, to allow oil, water, or any other liquid accumulated in the compartment 18 to be evacuated.

A respective valve 11 is included in the pipe system 30 that leads to the forward compartment 12 and the foremost two side compartments 14.

Optional use of the valves 11 will be described later in the specification. For the time being, it may be assumed that the valves 11 are permanently open.

The spare compartment 18 is often referred to a "slop tank" . In use, fluids remaining after washing out of compartments may be discharged by a suitable pump into such a slop tank. Oil separating out in the tank can, if desired, be burnt off in the ship^'s engine system.

The tanker illustrated in Figure 1 differs from a conventional tanker in that all of the compartments are interconnected by a pipe system 30. This system 30 has a plurality of ports 32 each of which opens into the upper portion of a respective one of the forward and side compartments 12. 14, and a plurality of ports 34 each of which opens into a respective one of the centre compartments 16. In the spare compartment 18, the pipe system 30 comprises a downwardly extending pipe 36 which terminates in a port 38 in the lower portion of the compartment 18, adjacent the floor thereof.

The configuration described above is illustrated also in Figure 2. which shows the tanker 10 in a normal, fully laden state. In this condition, all of the load carrying compartments are full of oil 40. As may be seen in Figure 2, the pipe system 30 is generally at the level of the surface of the sea water 50 - e.g. at substantially the level of the plimsol line. The spare compartment 18 is substantially empty. To load the tanker in this way, the following procedure may be followed.

Firstly, the vent 22 on the spare compartment 18 is closed, to seal the compartment 18 completely, except for the communication via the port 38 of the pipe 36. One or more of the access points 20 of the load carrying compartments 12 - 16 is opened and oil is supplied into the compartments via each open access point. Since all of the load carrying compartments are interconnected by the pipe system 30, the oil in them automatically comes to substantially the same level, once the compartments are approaching full, and the oil is up to the level of the pipe system 30. During the loading process, a small amount of oil 40 will enter the spare compartment 18 via the pipe 36. However, as soon as the level of oil in that compartment rises above that of the port 38, the compartment 18 becomes fully sealed, the air space above the oil level quickly becomes pressurised, and no more oil can then enter the compartment 18.

When all of the load carrying compartments are substantially full of oil. all of the access points 20 are closed in a sealing manner. The vent 22 on the spare compartment 18 is then opened. This releases the pressure in the compartment 18, and allows a very small additional amount of oil to enter the compartment via the pipe 36. However, since the load carrying compartments are all now sealed, they are very quickly placed under vacuum conditions, thereby preventing the flow of any further oil into the compartment 18.

The tanker 10 is then in a condition ready to run, as illustrated in Figure 2. In Figure 3. one of the centre load carrying compartments 16 has been ruptured, forming a hole 60 in the bottom of the hull. As soon as this hole

60 is formed, the vacuum condition in the compartment 16 is released, and sea water 50 can enter the compartment 16. As it does so, it displaces oil out of the compartment 16, through the pipe system 30, and into the spare compartment 18, via the pipe 36. This action continues until the level of oil 40 in the spare compartment 18 is substantially at the level of the sea water around the tanker. The liquids in the tanker are then in a substantially stable condition. Since oil is lighter than water, the oil 40 in the ruptured compartment 16 tends to stay above the level of the hole 60. Thus, there is no tendency for oil to escape from anywhere, even when the tanker is subjected to a washing action by the sea water. The oil 40 in all of the undamaged compartments remains quite safe since, as it is held under vacuum conditions, there is no tendency for it to escape anywhere.

Although the rupturing of a centre compartment 16 has been described, exactly the same result will obtain, if any other of the forward, side or centre compartments 12 -16 is ruptured.

Experience has shown that the worst oil pollution disasters tend to occur when a large tanker runs aground, when damage typically occurs to the lowermost parts of the hull. In such circumstances, the above described embodiment of the present invention may be most useful in limiting pollution and the loss of the load.

In the illustrated embodiment, all of the load carrying compartments are interconnected, so that they will inevitably carry the same fuel. In alternative embodiments, however, load carrying compartments may be arranged in groups, the compartments of each group being interconnected, but the separate groups being isolated from one another so that they may carry different liquids, or liquids of differing grades. Each group of compartments may have its own spare, evacuation compartment, or all groups may connect with a common evacuation compartment such as 18.

The illustrated embodiment is adapted to work with a liquid. Alternative embodiments may be adapted to work with a gas or liquified gas. In such an arrangement, it may be unsafe to vent the contents of the spare compartment 18 directly to atmosphere. However, moving seals may be located above the exit port 38 of the pipe 36, so that gas and/or liquified gas may expand into the compartment 18. whilst being isolated from atmosphere.

The forward compartment 12 and the foremost two side components 14 may be individually sealed off from the rest of the compartments and the pipe system 30, by operation of the valves 11. The valves 11 are preferably on/off valves, and may be actuated mechanically, electromechanially or in any suitable manner.

If the valves 11 are closed during normal running, then the contents of the respective compartments may be contained under pressure, rather than under a partial vacuum. This may be advantageous for the carriage of hazardous and/or volatile loads.

If the ship is run with the valves 11 closed, then, in the event of an accident causing rupture of one of the relevant compartments, the respective valve 11 may be opened, to allow free passage of the contents into the evacuation compartment 18. Any pressurisation of the contents of the ruptured compartment may help to expel the contents through the pipe system 30.

Actuation of the or each valve 11 may be carried out manually. Alternatively, automatic sensors may be provided to detect rupturing of a compartment, causing an alarm to be triggered, and/or the respective valve 11 to be opened automatically.

The illustrated embodiment is shown with just three valves 11 in Figure 1, for the purposes of illustration. If free communication between the various compartments is acceptable, then no valves 11 at all may be provided.

Alternatively, a respective valve such as 11 may be provided for some or all of the load carrying compartments.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings , or to any novel one, or any novel combination, of the steps of any methoα or process so disclosed.

Claims

1. A tanker comprising at least one load carrying compartment, access means for charging and/or discharging a load to and/or from the or each load carrying compartment, an evacuation compartment, venting means for selectively venting an upper part of the evacuation compartment, and communication means providing communication between an upper part of the or each load carrying compartment and the evacuation compartment.

2. A tanker according to claim 1. wherein the communication means provides communication between an upper part of the or each load carrying compartment and a lower part of the evacuation compartment.

3. A tanker according to claim 1 or 2, wherein the communication means is provided with at least one valve means for selectively opening and closing communication between a respective said load carrying compartment and the evacuation compartment.

4. A tanker according to claim 3. having a plurality of load carrying compartments and a plurality of said valve means, each for selectively isolating a respective one of the load carrying compartments from the other load carrying compartments and the evacuation compartment.

5. A tanker according to claim 3 or 4. including pressurising means for maintaining the load in at least one said load carrying compartment under pressure.

6. A tanker according to any of the preceding claims, wherein said communication means comprises a pipe system having a respective port opening into the or each load carrying compartment.

7. A tanker according to any of the preceding claims, including a load of oil in at least one said load carrying compartment.

8. A tanker substantially as hereinbefore described with reference to the accompanying drawings.

9. A method of running a tanker in accordance with any of the preceding claims, comprising the steps of charging the or each load carrying compartment via said access means, with the venting means of the evacuation compartment closed, sealing said access means to close off said load carrying compartment(s) except for said communication means, and running the tanker with the venting means of the evacuation compartment open.