WO1991015396A1

WO1991015396A1 - Sealing of leaks in a tank

Info

Publication number: WO1991015396A1
Application number: PCT/DK1991/000099
Authority: WO
Inventors: Lars Stub Olsen
Original assignee: Lars Stub Olsen
Priority date: 1990-04-11
Filing date: 1991-04-11
Publication date: 1991-10-17
Also published as: AU7666491A; DK92890A; DK92890D0

Abstract

A device for sealing accidentally arisen leaks in a tank, preferably in a bulk tank or hold (9) of a ship. One or more leak sealing devices in the form of sealing means (3) are filled into the tank (9). The sealing means (3) are either hose-shaped or balloon-like and are gradually filled with a fluid, for instance a mixture of oil and water, the leak of which from said tank (9) is undesirable. As a result, the sealing means (3) will gradually fill the tank (9) and eventually block the leak (5) in the tank (9). The sealing means (3) is thus guided towards the leak (5) - because of the outflow from the leak - where it wedges itself in place.

Description

Title: Sealing of Leaks in a Tank

Technical Field

The invention relates to a device for sealing accident¬ ally arisen leaks in a tank, preferably a bulk tank or hold of a ship.

Background Art

DE No. 28 27 943 discloses a sealing device for tankers, said sealing device comprising a soft closed bladder made of a resilient material. The bladder is placed permanently in the tank and is filled with the same fluid as that carried in the tank, for instance oil. Under normal condi¬ tions a circulating pump keeps the bladder afloat in the tank. The bladder is provided with controllable propul¬ sion means and fastening means. The propulsion means are adapted to guide the bladder towards the leak and the fastening means, for instance in the form of magnets or sucking discs, are adapted to fasten the bladder over the leak.

Various devices, for instance bandages, are also know which either from the outside or the inside, viewed in relation to the tank, aim at immediately stopping the inflow into the tank. Theoretically, said devices work well, but in practice they are not sufficiently tight.

Disclosure of Invention

The object of the invention is to provide a device for sealing leaks of the above type which is capable of reduc¬ ing the leak of the fluid contained in the tanks for instance of a tanker, such as oil, in such a manner that the adverse effect on the ecology is limited as much as possible in connection with an accident, for instance a grounding. It is furthermore the object of the invention to provide a device for sealing leaks which may be supplied to vessels in distress, for instance by helicopter, and which, therefore, do not need to be onboard a ship per- manently. It is moreover the object of the invention to provide a device for sealing leaks which is capable of separating the fluid originally contained in the tank from a corresponding fluid which, because it has been contaminated, contains a large amount of impurities and therefore must be treated differently from the fluid originally contained in the tank.

The inventive device for sealing accidentally arisen leaks in a tank, preferably in a bulk tank or hold of a ship is characterised in that the tank is filled with one or more hose-shaped or balloon-like sealing means gradually being filled with fluid, such as a mixture of oil and sea water, a leak of which from said tank is undesirable. As a result, the sealing means gradually fills up the tank and eventual- ly blocks the leak in the tank. The sealing means is thus guided towards the leak - because of the outflow from the leak - where it wedges itself in place. By filling the sealing means with a fluid collected on the outside of the leak, large amounts of environmentally damaging sub- stances are sucked up and filled in the sealing means, thereby causing less harm to the ecology and at the same time being separated from the fluid originally contained in the tank which has not been mixed with for instance sea water. By increasing the pressure on the sealing means, for instance by keeping the level of the fluid higher in the tank than outside, the sealing capacity of the sealing means is increased.

An embodiment of the device for sealing leaks according to the invention is characterised in that it comprises more sealing means being arranged in the tank independent of one another, and that each sealing means may be nonde- formable, reinforced, and/or balloon-like , for instance by the material being extremely resilient. As a result, sealing means with different specifications may be filled in the tank, whereby a tank which has a leak is firstly filled with sealing means capable of standing sharp objects such as torn portions of the hull and of resisting a rela¬ tively large pressure. When the leak is under control, the tank may then be filled with soft sealing means capable of holding large amounts of fluid without bursting.

Further according to the invention, the sealing means may comprise chemicals, for instance coagulants, contained in for instance blisters or in an actual double chamber system, whereby the chemicals and the fluid being filled into the sealing means together are able to form a thick, almost rigid substance of a flowability which is signifi¬ cantly poorer than the fluid, such as oil, contained in the tank. As a result, when cutting hole in the sealing means, the sharp portions of the hull will at the same time release the coagulant which in its turn will react with the oil and the sea water, thereby providing an extra sealing around the leak.

Moreover according to the invention the sealing means may be made of a material, for instance polyethylene, which may be processed, for instance burnt together with the oil without causing further harm to the environment. The tank may thereby be emptied without the sealing means, possibly comprising the coagulant, having to be actually removed.

Furthermore, according to the invention before being filled into the tank, the sealing means is rolled or wound about/ on an introducing means, for instance in the form of a tube provided with a connection, such as a hose connector connectable to a pump aboard the ship. As a result, the sealing means may be supplied as a compact unit connect¬ able to a pump, the suction end of which is placed in the sea close to the leak.

In addition according to the invention the diameter of the sealing means may correspond to or be substantially larger than the diameter of the introducing means, and the device may alternatively comprise several differing sealing means of differing diameters which may be concen¬ trically arranged on introducing means, where the first/ innermost sealing means is nondeformable , the second sealing means is comparatively less nondeformable , and the outermost sealing means is very flexible/resilient. The resulting compact unit may be supplied with a large number of sealing means to be used for completely stopping leaks .

Furthermore, according to the invention each sealing means is closed by closing means such as knots, hose clamps or cable binders. As a result, if a sealing means springs leak only a limited amount will spill.

Moreover according to the invention the introducing means may not comprise an actual hose connector, in this manner it is possible to fill the sealing means by pouring the fluid directly into the sealing means. In the case of water and oil, the fluid is heavier than the fluid con¬ tained in the tank (oil) .

According to the invention, it has been found advantageous for the reinforcement of the sealing means to consist of woven or knitted network, for instance glass fibre or stretched polyethylene.

Further according to the invention the tank of the ship may be emptied when the ship reaches port by means of a needle or cannulla-like member being inserted into the sealing means so as to perforate said means, whereafter the contents of the tank is pumped or sucked up. Brief Description of Drawings

The invention is described below with reference to the accompanying drawing in which

Fig. 1 shows a tanker into which is filled a sealing means according to the invention,

Fig. 2 shows a sealing means in the form of a hose arranged on an introducing means ,

Fig. 3 shows a nondeformable , enforced sealing means in a tank,

Fig. 4 shows a balloon-like sealing means with a canulla in the tank,

Fig. 5 shows a third embodiment of the sealing means and a second embodiment of the introducing means, and

Fig. 6 shows a third embodiment of the introducing means with different types of sealing means.

Best Mode for Carrying Out the Invention

Fig. 1 shows a tank vessel, in its entirety designated 1, in which a leak 5 has sprung. An attempt is being made at sealing said leak 5 by means of a sealing member 3 intro¬ duced by means of an introducing member. The fluid pumped into the sealing means 3 is a mixture of the fluid con¬ tained in the tank 9 and the fluid outside the tank 9, here considered oil and water, if oil is contained in the tank. The introduction of the water/oil mixture is taking place by means of the pump 11, conventionally included in the equipment of the ship, for instance a submerged pump or just a pump which is hung over the ship's side in order to minimize the height of suction. The leak may have arisen in the bottom or the side of the tank 9. Of course the leak may also extend to more tanks than the tank 9 shown in the Figure .

The sealing device 3 is intended to be used for sealing accidentally arisen leaks in the tank of a ship 9. The tank 9 may either be a bulk tank or a fuel tank, however, it applies to both tanks that their contents are something which it is undesirable to spill to the sea. To prevent the contents from leaking, one or more hose-shaped or balloon-like sealing means 3 are placed in the tank 9 and the sealing means 3 are gradually filled with a fluid, for instance a mixture of oil and sea water pumped up adjacent 6 the leak 5 of the ship 1. By pumping adjacent 6 the leak 5 a higher flow rate through the leak may be obtained, whereby the sealing means 3 is drawn towards the leak in such a manner that it closes the leak 5 of the hull. The sealing means 3 wedges into the leak 5 from the inside.

In another embodiment, as shown in Fig. 4, the device for sealing leaks may comprise more sealing means 31, 33, where for instance the sealing means 31 is reinforced 36 and where the sealing means 33 is balloon-like . Said bal¬ loon-like sealing means 33 is the result of using an ex- tremely resilient material. It is possible to use said material because possible sharp edges caused by the leak 5 are covered by the reinforced sealing means 31 which is placed in the tank firstly. The various sealing means are closed separate units, whereby a leak in one sealing means does not cause the entire contents of the tank to leak again. A reinforced 36 sealing means 31 is not only able to resist the sharp edges of the torn hull but also a relatively high pressure if the tank is filled completely, whereby the level of the fluid will exceed that of the surface of the sea.

The sealing means 3 may comprise a type of blisters 21 or an actual double chamber system 23, wherein the chambers 23 or the blisters 21 contain chemicals 25, said chemicals 25 together with the fluid filled into the sealing means 3 being able to form a thick, almost rigid substance. Said substance is of a substantially poorer flowability than the fluid, for instance oil, contained in the tank 9. Such chemicals 25 are often used in connection with oil pollution control in such a manner that the oil is caused to clot or coagulate and subsequently sink. This is, how- ever, not entirely desirable in the world seas and there¬ fore it would be more expedient to cause the chemicals to coagulate and sink in the tank 9 thereby helping in sealing the leak 5. The fact that the sealing means 3 per se comprises blisters 21 containing the chemical, causes the chemical to leak and mix with sea water and oil if a hole is torn in the sealing leak, whereby the rigid substance will appear near the leak 5. In Fig. 3 the sealing means 31 is provided with flaps, slats or webs reducing the risk of perforation of the sealing means 31. The flaps 27 may also be formed as bulges per se.

The sealing means may preferably be made of polyethylene or another material which can be processed together with the oil without causing further harm to the environment. By processing is meant for instance burning, where it may be envisaged that all the oil useable under normal condi¬ tions is removed from the tank, i.e. oil without an ex¬ cessive water content, whereupon the remainder is removed from the tank 9, the remainder comprising the polyethylene foiling, possible other reinforcement preferably also of plastic, possible coagulant and the rigid oily substance, which is all subsequently used as additive for for instance a combustion apparatus for solid matter. The sealing means 3 might also be made of entirely different materials, for instance glass fibre, or comprise a steel reinforcement whereby they will have to be destroyed in a different manner when the ship reaches port. It will, however, be advantageous to make the sealing means 3 of a material which may be processed without causing too much harm to the environment .

In Fig. 2 it is seen how a sealing means 3 has been rolled on an introducing means 7 in the form of a tube and pro¬ vided with a hose connector 8. Said hose connector may comprise a hose coupling of a commonly recognized size so as to be connectable to any given pump. When rolled on, the sealing means is retained by a retension ring 29 which may possibly also be used as a closing means 15 when the individual sealing means has been filled.

The filled sealing means may be guided towards the leak by means of the pressure from the pump, this especially applies to the nondeformable type of sealing means 31. It is possible to apply a very high pressure to the pump without the sealing means bursting, this especially applies to sealing means of the soft type.

The introducing means may comprise several branch pipes whereby it is possible to change to a new sealing means when the previous one has been used up.

Closing means 15 are provided, for instance in the form of knots, hose clamps or cable binders 16. The closing means 15 may be placed in connection with the introducing means 7 in such a manner that the individual sealing means 3 is closed in the end when introduced into the tanlO and closed when it is filled. The closing means 15 may activate a valve (not shown) stopping the flow when the individual sealing means 3 is filled. The flow may also be stopped by means of a closing means, if a sealing means should burst during the filling.

The sealing means 3 may be formed as a web which is closed to form a tube around the introducing means 7, whereby the sealing means 3 may be supplied in endless webs. The joining of the web to a tube may take place by means of a known joining process, for instance by welding or glueing.

As shown in Fig. 5, the introducing means 7 is shaped like a funnel instead of being provided with a hose con¬ nector 8 per se. This is possible because a mixture of oil and water is heavier than pure oil and therefore said funnel-shaped introducing means is suitable when filling by means of more different hoses and possibly hoses without without hose coupling.

The strength of the sealing means needs only be quite small, as it only has to be capable of absorbing forces corresponding to the difference in specific gravity between the fluid inside the sealing means 3 and the fluid outside the sealing means.

The reinforcement 36 of the sealing means 31, see Fig. 5, may comprise a woven or knitted network, of for instance glass fibre or stretched polyethylene and which may form the double chambers 23. The reinforcement 36 serves the purpose of reinforcing the sealing means 31, both to pres¬ sure and to cutting.

The sealing means 3 may be of any arbitrary material, for instance natural rubber or the like.

Fig. 4 shows how a tank 9 which has been filled with sealing means 31, 33 may be emptied by means of a cannulla- like object 19 which is inserted into the sealing means 31, 33 so as to perforate said means, whereupon the con¬ tents of the sealing means 31, 33 are sucked up. In con¬ nection with emptying the tank of the ship, it is ad- vantageous that a form of sealing has been provided on the outside of the leak 5 to prevent oil from leaking into the harbour. Tanks in ships which have to be grounded, may be filled up with sealing means prior to the grounding. As a result the leak from the tanks is limited as much as possible.

It is essential that the sealing means obtains a suitable size before being let loose inside the tank 9, so as not to be sucked out through the leak 5.

The reinforcement may for instance be formed of a network of wire or plastic-coated wire which is inflated like a football in such a manner that it is distended before being let loose in the tank 9. The hole in the tank 9 through which the sealing means 3 is inserted needs not be particularly large, it may for instance be an inspection hatch, as the sealing means 3 per se is inflated inside the tank 9.

It has proved advantageous that the first sealing means 31 inserted into the tank 9 is reinforced 36 and provided with a closing means 15 at one end and that when fully distended, the sealing means 31 is automatically provided with a closing means 15 at the other end. The introducing means 7 may contribute to closing the sealing means 3 in a manner similar to that of cable binders.

If a sealing means should slip out through the leak 5 of the hull, it will seek towards the surface, as a mixture of oil and sea water has a lower specific gravity than sea water. The sealing means 3 can then be picked up.

If the volume of contaminated fluid exceeds the capacity of the tank 9, the sealing means 3 may possibly be placed adjacent the ship 1 in the sea per se and be used as a form of spare container wherein sea water and oil can be collected and later be removed by another tank vessel. If the leak 5 is above the waterline of the ship, it is possible by pumping sea water, oil and air into the sealing means 3 inside the tank 9 to cause said means to float on the surface inside the tank 9 and thereby to come close to the leak 5 more easily.

It is an advantage when using the sealing means 3 that the level of the fluid inside the tank 9 is higher than the surface of the sea, whereby the partial pressure inside the tank 9 is higher than outside. In this manner the sealing means 3 is guided towards the leak 5 because of the constant outflow.

The invention is not limited to the above embodiments but may be modified in many ways without thereby deviating from the scope of the invention. Thus, similar sealing means may be used in connection with other leaks, for instance upset tank lorries, tank installations on the ground, chemical storage tanks or separating tanks associ- ated to power plants, and the fluids it is desired to seal need not be oil but may also be herbicides or other fluids the leak of which is undesirable, for instance water from a water reservoir.

Claims

1. A device for sealing accidentally arisen leaks in a tank, preferably in a bulk tank or hold of a ship, c h a r a c t e r i s e d in that the tank (9) is filled with one or more hose-shaped or balloon-like sealing means (3) gradually being filled with fluid, such as a mixture of oil and sea water, a leak of which from said tank (9) is undesirable.

2. A device for sealing leaks as claimed in claim 1, c h a r a c t e r i s e d in that it comprises more sealing means (31, 32, 33) being arranged in the tank (9) inde¬ pendent of one another, and that each sealing means may be nondeformable (31) , reinforced (36), and/or balloon¬ like (33) for instance in that the material is extremely resilient.

3. A device for sealing leaks as claimed in claim 1 or 2, c h a r a c t e r i s e d in that the sealing means (3) comprises chemicals (25) contained in for instance blisters (21) or in an actual double chamber system (23) , whereby the chemicals and the fluid being filled into the sealing means (3) together are able to form a thick almost rigid substance of a flowability which is significantly poorer than the fluid, such as oil, contained in the tank (9).

4. A device for sealing leaks as claimed in one or more of the preceding claims 1 to 3 , c h a r a c t e r i s e d in that the sealing means (3) is made of a material, such as polyethylene, which can be processed, for instance be burnt together with the oil without causing further harm to the environment.

5. A device for sealing leaks , c h a r a c t e r i s e d in that before being filled into the tank (9) , the sealing means (3) is rolled or wound about/on an introducing means (7) , for instance in the form of a tube provided with a connection, such as a hose connector (9) connectable to a pump (11) aboard the ship (1) .

6. A device for sealing leaks as claimed in one or more of the preceding claims 1 to 5 , c h a r a c t e r i s e d in that the diameter of the sealing means (3) corresponds to or is substantially larger than the diameter of the introducing means (7) , and that the device alternatively comprises several differing sealing means of differing diameters which may be concentrically arranged on intro¬ ducing means (71, 72, 73) , where the first/innermost sealing means (31) is nondeformable , the second sealing means (32) is comparatively less nondeformable , and the outermost sealing means (33) is very flexible/ resilient.

7. A device for sealing leaks as claimed in one or more of the preceding claims 1 to 6, c h a r a c t e r i s e d in that each sealing means (3) is closed by closing means (15) , such as knots, hose clamps or cable binders (16) .

8. A device for sealing leaks as claimed in one or more of the preceding claims 1 to 7 , c h a r a c t e r i s e d by the introducing means (7) not comprising an actual hose connector.

9. A device for sealing leaks as claimed in one or more of the preceding claims 1 to 8 , c h a r a c t e r i s e d in that the reinforcement (36) of the sealing means (31) is made of woven or knitted network of for instance glass fibre or stretched polyethylene.

10. A device for sealing leaks as claimed in one or more of the preceding claims 1 to 9 , c h a r a c t e r i s e d in that the tank (9) of the ship is emptied, for instance when the ship (1) is in port, by means of a needle or cannulla-like member (19) being inserted into the sealing means (3) so as to perforate said means, whereafter the contents of the tank is pumped or sucked up.