US3874179A

US3874179A - Submarine oil storage tank system

Info

Publication number: US3874179A
Application number: US338478A
Authority: US
Inventors: Nobuo Higashihara
Original assignee: Sumitomo Shipbuilding and Machinery Co Ltd
Current assignee: Sumitomo Shipbuilding and Machinery Co Ltd
Priority date: 1972-03-06
Filing date: 1973-03-06
Publication date: 1975-04-01
Anticipated expiration: 1992-04-01
Also published as: GB1401141A; NL7303109A; FR2178598A5

Abstract

An undersea oil storage tank system and method of constructing same, which has a plurality of steel tubes driven into the ocean bottom adjacent one another. A jet lifter pipe is placed in the upper open end of the pipe to evacuate the soil or mud from the interior of the pipe. After the pipe interior has been evacuated, the bottom thereof is closed with concrete and a metal cover is welded onto the upper end of pipe. Suitable water evacuation and oil supply conduits are connected to the pipe with a control station for selectively removing the sea water from the pipes and supplying oil for storage in the undersea storage tanks.

Description

[' Apr. 1,1975

[ SUBMARINE OIL STORAGE TANK SYSTEM [75] Inventor:

[73] Assignee: Sumitomo Shipbuilding &

Machinery Co., Ltd., Tokyo, Japan 221 Filed: Mar. 6, 1973 21 Appl. No.: 338,478

Nobuo Higashihara, Tokyo, Japan [30] Foreign Application Priority Data 3,535,884 10/1970 Chaney 6l/46.5 3,552,131 l/1971 Mott et a1.

3,605,774 9/1971 Launay et a1.

3,769,803 11/1973 Finney v3,791,152 2/1974 Davis 61/46 Primary Examiner-Jacob Shapiro Attorney, Agent, or Firm--Sughrue, Rothwell, Mion, Zinn and Macpeak [57] ABSTRACT An undersea oil storage tank system and method of constructing same, which has a plurality of steel tubes driven into the ocean bottom adjacent one another. A jet lifter pipe is placed in the upper open end of the pipe to evacuate the soil or mud from the interior of the pipe. After the pipe interior has been evacuated, the bottom thereof is closed with concrete and a metal cover is welded onto the upper end of pipe. Suitable water evacuation and oil :supply conduits are connected to the pipe with a control station for selectively removing the sea water from the pipes and supplying oil for storage in the undersea storage tanks.

3 Claims, 11 Drawing Figures FU-ETENYEU APR 1 i975 FIG. 5

saw 2 ur 5 FIG. 2

I3' FILTER p gEmfgAPfi H91 5 3,874,179

SHEET 3 BF 5 FIG. 3

16 CLEANIN AGENT SUPPLYING T N '5 6L-WATER SEPARATING 6 DEVICE PATENTEU I975 3,874 l 79 SHEET 5 8F 5 FIG. 7

SUBMARINE OIL STORAGE TANK SYSTEM BACKGROUND OF THE INVENTION This invention relates generally to oil storage tanks, and more particularly to a submarine tank system made of steel tubes, and a construction method thereof.

According to the progress of modern civilization, demands for petroleum are evermore increasing year by year, and the reserved amount required in both production site and consuming areas are becoming astounding quantities.

Heretofore, crude oil has been stored in oil storage tanks provided on land. However, these tanks occupy vast spaces and are dangerous for neighbouring buildings, and to find out suitable places overcoming the security problem is becoming more and more difficult. Furthermore, it is required that the locations of these storage tanks must be selected in the proximity of harbors allowing the entrance oflarge tonnage tankers and in the neighborhood of the consumption areas. To find out and acquire such enormously wide spaces in the locations fulfilling the above described conditions are now quite difficult.

For overcoming these difficulties, various plans have been proposed for utilizing sea areas for the installation of the coil storage tanks, most of the proposals featuring in that the tanks of enormous capacities are initially built on land, towed to the required site after completion, and moored or sunk into the sea for constituting submarine tanks.

However, such towing and mooring procedures are susceptible to tidal current or stormy waves causing the installation works to be utterly unstable, and frequently the vast tanks towed or moored constitute hindrance for cruising ships.

In addition, such procedures have required largescaled operations when the tanks are towed and moored, and also in the readjustment of the sea bed on which the tanks are to be installed, whereby no submarine oil storage tanks in industrial scale have yet been installed so far as we are aware.

SUMMARY OF THE INVENTION Therefore, a primary object of the present invention is to provide an improved construction of submarine oil storage tanks wherein all of the above described drawbacks of the conventional constructions of the tanks can be substantially overcome.

Another object of the invention is to provide an improved submarine oil storage tank system wherein the construction cost is substantially economized.

Still another object of the invention is to provide an improved submarine oil storage tank system which does not require towing or mooring operation.

Still another object of the invention is to provide an improved submarine oil storage tank system which does not cause any hindrance in the sea.

Still another object of the invention is to provide an improved submarine oil storage tank system which does not cause any pollution problem.

Still another object of the invention is to provide an improved submarine oil storage tank system wherein the problem of corrosion is substantially overcome.

Still another object of the invention is to provide an improved submarine oil storage tank system wherein handling of oil is comparatively facilitated.

A further object of the invention is to provide a submarine oil storage tank system wherein the pipings for oil reception, delivery, and tank cleaning can be bundied together in an advantageous manner.

An additional object of the present invention is to provide an improved method for constructing such a submarine oil storage tank system in the site of the installation.

These and other objects of the present invention can be achieved by a steel tube type submarine oil storage tank system according to the invention, which comprises a number of tank elements driven into the sea bed at positions closely adjacent with each other, each tank element comprising a tank body made of a length of steel tube with the upper end closed with a steel lid and the lower end closed by concrete, the upper ends of a majority of the tank elements located outwardly of the tank system being located substantially in the same level with the sea bottom while the upper ends of a minor part of the tank elements located at the central portion of the system being extended above the surface of the sea water, a control platform provided near the upper ends of said minor part of the tank elements exposed in the air, an oil handling system, and a sea water piping system, both extended from said platform to each of said tank elements, whereby oil received in said oil handling system is introduced into said tank elements under a suction caused in said sea water piping system to be stored therein.

In another aspect, the platform may be provided, for instance, ashore, with both oil handling system and the sea water piping system extened from the platform to each of the tank elements which have the upper ends now substantially aligned with the surface of the sea bottom.

In still another aspect, there is provided a method for constructing the submarine oil storage tank system comprising the steps of driving a length of steel tube into the bottom of the sea until only a length is left exposed above the sea level, welding an upper lid having holes to the upper end of the steel tube, connecting an aiding tube to the upper end of the steel tube, passing ajet lifter pipe through said lid into the steel tube, driving thus extended steel tube further into the bottom of the sea with the jet lifter operated simultaneously, replace the jet lifter with a concrete placing pipe so that a concrete bottom is formed at the lower end of the steel tube, removing the aiding tube and fixing an oil pipe and a sea water pipe to said holes in the lid, and repeating the above described procedure for all of the tank elements of the oil storage tank system.

The nature, principle, and utility of the present invention will be more clearly understood from the following detailed description of the invention when read in conjunction with the accompanying drawings wherein like parts are designated like reference numerals.

BRIEF DESCRIPTION OF THE INVENTION In the drawings:

FIG. 1 is an elevational view, in a longitudinal section, of a steel tube tank constituting an element of the oil storage tank system according to the present invention;

FIGS. 2 and 3 are general views schematically showing preferred embodiments of the submarine oil storage tank system according to the invention;

FIG. 4 is a view schematically showing a steel tube tank under construction;

FIG. is a sectional view taken along the line VV in FIG. 4 for indicating a construction of ajet lifter pipe used for boring the bottom of the sea;

FIGS. 6A through 6E are explanatory elevational views showing the processes of the construction of the steel tube tank element, sequentially; and

FIG. 7 is a schematical elevational view of a work ship for piling the steel tube into the bottom of the sea.

DETAILED DESCRIPTION OF THE INVENTION Referring now to FIG. 1, there is indicated a steel tube tank constituting an element of the submarine oil storage tank system according to the present invention, which comprises a piece of steel tube 1 of, for instance,

' 3 m in diameter and from to m in length, easily available in the market. If required, several of such steel tubes may be joined together to obtain a steel tube 1 ofa length ranging from 50 to 60 m for increasing the capacity. A required number of such steel tube tanks are provided in the sea bed in a manner closely adjacent with each other. A lid 2 made of a steel plate having two holes to be used as hereinafter described is attached, for instance, by welding to the upper end of the steel tube 1. An oil inlet and outlet pipe 3 is connected to one of the two holes in the lid 2 so that it opens at the upper part of the steel tube 1. A sea water replacing pipe 4 is passed through another hole of the lid 2 to be extended to a lower portion of the steel tube 1 Although the oil inlet and outlet pipe 3 and the sea water replacing pipe 4 are provided for each of the steel tube 1, a desired number of such oil pipes 3 and sea water pipes 4 are respectively assembled together into a heavier pipe leading to a control station 5 as hereinafter described.

Referring to FIGS. 2 and 3, there are indicated preferred embodiments of the oil storage tank system according to the invention. In either one of the embodiments, a major part of the tank elements 1 are driven into the sea bottom until the upper ends of the tank elements align with the surface of the bottom of the sea. However, a minor part of centrally located tank elements 1 are extended upward so that the upper ends thereof are exposed into the air, and the above mentioned control platform 5 is constructed based on the upper portions ofthe tank elements. In the control platform 5, various operations such as storage and deliver of crude oil and cleaning of each of the tanks are carried out collectively.

It should be noted, however, that the control platform 5 is not necessarily provided on the upper part of the tank assembly, but it may also be provided ashore. In that case, the above described centrally located tank elements 1 need not be extended upward, and the upper ends of all tank elements 1 are substantially aligned with the bottom of the sea, so that any hindrance caused against ships cruising can be further eliminated.

In the embodiments shown in FIGS. 2 and 3, there are provided oil pipe lines 6 and sea water pipe lines 7. Each of the oil pipe lines 6 corresponds to the abovementioned heavier pipe line divided into oil pipe 3 in FIG. 1, and each of the sea water pipe lines 7 corresponds to the above-mentioned heavier pipe line divided into individual sea water pipe 4 in FIG. 1.

The oil pipe lines 6 are connected through corresponding valves to an oil inlet pipe 8 and an oil delivery pipe 9 provided with an oil pump 10. On the other hand, the sea-water pipe lines 7 are connected to a seawater replacing pipe 11 which is further connected in series with a sea water pump 12 and a filter 13.

In the embodiment shown in FIG. 3, all of the steel tube tank elements 1 and oil and sea

water pipe lines

6 and 7 are installed as in the embodiment shown in FIG. 2 except a cleaning pipe line 14 is installed between the sea-water replacing pipe 11 and the joined portion of the oil pipe lines 6 through a valve provided at each end of the cleaning pipe line 14. A pump 15 is further provided in the cleaning pipe line 14, and a cleaning agent supplying tank 16 is connected through a valve to an end connected to the sea-water replacing pipe 11 at a portion between the pump 15 and the valve provided at this end. A cleaning water exhaust pipe 17 is connected to the sea-water replacing pipe 11 at a portion thereof between the sea water pump 12 and a joining portion of the seawater pipe lines 7 through a valve, and an oil-water separating device 18 is provided in the cleaning water exhaust pipe 17 one end of which is opened in the sea.

When it is desired to store oil in the oil tanks 1, the

pump 12 is operated thereby to exhaust sea water filled in these tanks 1 through the sea-water replacing pipes 4, sea water pipe lines 7, sea-water replacing pipe 11 into the sea outside of the steel tube tank elements 1. Simultaneous therewith, the oil inlet pipe 8 is connected with a deliver pipe of, for instance, a tanker (not shown), and oil is drawn through the pipe 8, oil pipe lines 6, and oil inlet and outlet pipes 3 in the steel tube tank elements 1, into these tank elements 1.

When the oil is delivered from the tank system, the oil delivery pipe 9 is connected with an oil supply line, and the pump 10 is operated so that the oil stored in the tank elements 1 is picked up through the oil inlet and outlet pipes 3 in these tank elements 1, oil pipe lines 6, and the oil delivery pipe 9, to the oil supply line. Simultaneous therewith, the pump 12 is operated in the opposite direction to the above described oil storing case, whereby sea water is pumped back from the sea-water replacing pipe 11, through sea water pipe lines 7, and sea water pipes 4 in the tank elements 1, to the lower portions of the steel tube tank elements 1 to push up the oil in these tank elements.

It should be noted that, in the case of the oil being stored, the exhaust of the sea water in the tank elements must be terminated at an instant when the level of the sea water in the tank element is maintained above the opening of the sea water pipe 4 extended downwardly toward the bottom of the tank elements 1.

During the above described oil storing or oil delivering cases, all of the valves provided in the oil pipe lines and sea water pipe lines are suitably controlled so that oil is stored in or delivered out of desired blocks of the steel tube tank elements.

As described above, the embodiment shown in FIG. 3 has a cleaning pipe line. When oil is delivered after a long period of storage, deposition of sludge will be found on the bottom of the tank elements. Furthermore, a little amount of oil is contained in the replacing sea water supplied into the lower portion of the tank elements. Thus, if the replacing sea water is exhausted into the sea when the oil issubsequently stored, the sludge and the oil contained in the replacing sea water are also exhausted into the sea together with the replacing sea water, whereby the problem of sea pollution will arise.

To eliminate the above described disadvantage, whenever the interior of the steel tube oil storage tank elements is replaced by sea water, the cleaning pipe line 14 is communicated with the sea-water replacing pipe 11 and the oil pipe lines 6 by operating related valves. Simultaneously, the

pumps

12 and 15 are operated so that sea water is sent from the sea-water replacing pipe 11 through the cleaning pipe line 14, oil pipe lines 6, oil inlet and outlet pipes 3 to the interiors of the tank elements 1. On the other hand, the sea water which has replaced the interior of the tank elements is exhausted from the tank elements through sea-water replacing pipes 4, sea water pipe lines 7, and the cleaning water exhausting pipe 17 to the sea. In this case, since the oil-water separating device 18 is provided in the cleaning water exhausting pipe 17, the sludge and oil contained in the cleaning sea water and the replacing sea water are separated, and purified sea water is exhausted through the device 18 into the sea. Furthermore, a cleaning agent may be supplied from the cleaning agent supplying tank 16 suitably so that the interior of the

pipe lines

6 and 7 and the tank elements 1 can be cleaned effectively.

The submarine oil storage tank system according to the present invention is constructed as described above, and a method for constructing the oil storage tank will now be described.

Referring to FIG. 4 showing a steel tube tank under construction, there is indicated an auxiliary steel tube 19 is placed on the top of the steel tube 1 with the aid of a plurality of projecting members 20 provided circumferentially along the upper end of the steel tube 1, and by the aid of the auxiliary tube 1, the steel tube 1 is further driven into the bottom of the sea. When the steel tube 1 is sufficiently driven into the bottom of the sea, the auxiliary tube 19 is removed from the upper end of the steel tube 1. At the upper end of the steel tube 1, there is provided the lid 2 having two holes, and the sea water replacing pipe 4 is extended downwardly from one of the two holes. Flexible pipes 3' and 4' are connected through

connectors

21 and 22, respectively, to the upper side of the two holes, and a jet lifter pipe made of a flexible hose is passed through the flexible pipe 3. The jet lifter pipe 23 has a sectional configuration as shown in FIG. 5 having a centrally located suction pipe 24 for removing the soil and circumferentially arranged jet holes 25 for digging the bottom of the sea. The lower end portion 23 of the jet lifter pipe 23 is made of a metal having a cross-sectional configuration similar to that indicated in FIG. 5. The metal end portion 23 is allowed to act as a pendulum tensioning the entire jet lifter pipe 23 vertically. After completion of the driving operation, the jet lifter pipe 23 is removed, and concrete is placed into the bottom of the steel tube 1 as indicated at 26.

The method of construction of the steel tube tank element will now be described in more details with reference to FIGS. 6A through 6E. Firstly, a steel tube 1 of a required length for the final oil storage tank element is prepared, and driven into the sea bottom by means of, for instance, a vibration driver, until about two or three meters of the tube 1 is left above the sea water so that all of the operations required at that time can be carried out from the position above the surface of the sea. At this moment, the jet lifter pipe 23 is also set into the steel tube 1 as indicated in FIG. 6A, and the inside of the steel tube 1 is further dredged by the jet streams ejected from the jet holes 25 with the soil or mud thus dredged being exhausted through the central suction pipe 24 to outside of the steel tube 1 together with the sea water. Then, the jet lifter pipe 23 is removed from the steel tube 1, and a lid 2 is attached to the upper end of the steel tube 1. Through one hole of the lid 2, a sea water replacing pipe 4 is extended downwardly so that it is fixed through a connector 22 to the hole of the lid 2. A flexible pipe 4 is further connected to the upper end of the sea-water replacing pipe 4 through the connector 22, and another flexible pipe 3 is connected through a connector 21 to the other hole of the lid 2, as clearly indicated in FIG. 68. Then an auxiliary tube 19 is applied to the upper end of the steel tube 1 under guidance of a plurality of projecting members 20 provided circumferentially of the upper end. The jet lifter pipe 23 is again descended through the flexible pipe 3' to the bottom of the sea. and the steel tube 1 is again drived into the bottom of the sea by the aid of the auxiliary tube 19 and with the jet lifter pipe 23 being operated as described above (see FIG. 6C). Upon the completion of the driving and dredging operations inside of the steel tube l, the jet lifter pipe 23 is removed, and a concrete placing nozzle is inserted into the steel tube 1 through the flexible pipe 3. Concrete is thus placed at the bottom of the steel tube 1 so that a lid 26 at the bottom of the oil storage tank element is thereby formed. The concrete placing nozzle and the auxiliary tube 19 are then removed (see FIG. 6D).

In a similar manner, a large number of steel tubes 1 are driven into the sea bottom at adjacent positions with each other so that the assembly of the steel tube oil storage tank is thereby constructed. At this time, the

flexible pipes

3 and 4 are attached with buoys to be left floating on the surface of the sea. After completion of the entire oil tank elements and the oil and sea-

water pipe lines

6 and 7, the flexible pipes 3' and 4 are connected to the oil pipe line 6 and the sea-water pipe line 7, respectively, and the construction of the oil storage tank is completed (see FIG. 6E). It should be noted that each of the oil pipe lines 6 and the sea-water pipe lines 7 are connected to a plurality of oil pipes 3 and the sea-water replacing pipes 4, respectively, belonging to a block of the steel tube tank elements.

Furthermore, the lower end portion 23' of the jet lifter pipe 23 is made of metal as described before, and a plurality of jet holes 25 are arranged circumferentially of the jet lifter pipe 23. For this reason, if jet water is sent through these jet holes 25 sequentially by means of, for instance, a rotary valve or the like, or if the jet water is sent intermittedly, the lower end portion 23 of the jet lifter pipe 23 is moved inside of the steel tube 1 around its center, whereby the soil inside of the steel tube 1 can be dredged out of the steel tube substantially uniformly, and merely digging the central part of the soil is thereby prevented.

In FIG. 7, there is indicated schematically a work ship to be used for constructing the oil storage tank according to this invention. The work ship 27 is carrying thereon steel tube racks 28, a piling tower 29, a foundation 30 of the piling tower, and a device 31 for driving the steel tubes into the sea bottom. The driving device 31 is composed of a chuck for holding the steel tube 1 and a driving jack made of. for instance, a cylinder or a vibrator. Numeral 32 designates a welder for welding the steel tubes into a desired length, and also for welding the lid 2 and the projecting members 20 to the steel tube 1. On the work ship 27, there are further provided a winch 33 for hoisting the steel tubes 1, the jet lifter pipe 23 and the like, a high pressure pump 34 for ejecting jet water, a low pressure pump 35 for dredging the soil, and a concrete pump 36.

According to the present invention, since a great number of steel tubes are driven into the sea bottom in a closely adjacent relationship for obtaining a submarine oil storage tank of a required capacity, a submarine tank of not suffered by stormy waves and tidal current and operable in a stable manner can be obtained. Furthermore, since the oil storage tank according to the invention is ofa buried type into the sea bottom, no hindrance is presented for cruising ships.

In addition, steel tube piles available in the market can be used for construction of the oil storage tank, and

since the steel tubes are driven into the sea bottom by the aid of the auxiliary steel tubes, no under-water construction work is required. As a result, the construction cost of the oil storage tank according to the present invention is far cheaper than that of the conventional submarine oil storage tanks. When the position of the oil storage tank is so selected, the central part of the steel tubes rising up into the air may be used for constructing piers or auto road.

What is claimed is:

1. In a submarine oil storage tank system for a sea water installation of the type wherein underwater storage tank means receive and deliver oil to a surface vessel under pressure to replace sea water within the storage means which is pumped to and from said tank means under pressure, and said surface vessel includes respectively, oil and sea water pump means for effecting this movement, the improvement wherein:

said storage means comprises a plurality of hollow,

elongated axially driven steel tubes extending downwardly in closely adjacent positions from the bottom of the sea within the earth formation lying therebelow with their upper ends generally flush with the sea bottom, each tube including an in situ concrete bottom sealing the lower end of the tubes within the earth formation and a metal lid sealingly overlying the upper end of each tube and forming with said tube and said in situ concrete bottom, an oil storage tank,

and wherein each tank is further provided with a sea water replacing pipe extending through said lid and terminating near the bottom of said tube to permit said sea water to enter and leave the lower end of said tank and having an oil inlet and outlet connection to said lid to permit oil to enter and leave the top of said tank, and means for fluid connecting said inlet and outlet connection and said sea water replacing pipe to said surface vessel,

whereby; by controlled operation of said pumping means, oil is delivered to each tank as sea water is removed therefrom, and vice versa,

and wherein said fluid connecting means comprises an oil pipeline and a sea water pipeline extending from said lid for each tank to said vessel, and each line is provided with a valve, and connection means commonly couples respective lines to said oil and sea water pump means, and a filter is connected between said sea water pump means and the source of sea water,

whereby; sea water replaces oil within a given tank only after passing through said filter.

2. The submarine oil storage tank system as claimed in claim 1, further comprising: a cleaning agent supply tank, means for fluid coupling said cleaning agent supply tank to said oil inlet and outlet connection for each tank, and an oil-water separating device fluid coupled to said sea water replacing pipe downstream of said tanks such that sea water in passing to said oil inlet and outlet connection forces said cleaning agent to enter said tank, while the sludge and oil contained in the cleaning sea water is separated therefrom prior to being returned to the sea.

3. The submarine oil storage tank system as claimed in claim 2, wherein: said sea water replacing pipe is fluid coupled in series with said oil-water separating device at a point intermediate of said tanks and said pump, said cleaning agent supply tank is fluid coupled to said oil pipeline by means of a cleaning pipe line connected at one end to said oil pipe line and at the other end to said sea water replacing pipe and valves are operatively provided within said cleaning pipeline, said oil pipeline and said sea water pipeline, such that by operation of said valves and said pumps, said oil pipeline may receive sea water after passage through said filter and after receiving cleaning agent from said cleaning agent supply tank, and wherein sea water after oilwater separation may be delivered back to the sea water, from each tank after passage through said oil-water separating device.

Claims

1. In a submarine oil storage tank system for a sea water installation of the type wherein underwater storage tank means receive and deliver oil to a surface vessel under pressure to replace sea water within the storage means which is pumped to and from said tank means under pressure, and said surface vessel includes respectively, oil and sea water pump means for effecting this movement, the improvement wherein: said storage means comprises a plurality of hollow, elongated axially driven steel tubes extending downwardly in closely adjacent positions from the bottom of the sea within the earth formation lying therebelow with their upper ends generally flush with the sea bottom, each tube including an in situ concrete bottom sealing the lower end of the tubes within the earth formation and a metal lid sealingly overlying the upper end of each tube and forming with said tube and said in situ concrete bottom, an oil storage tank, and wherein each tank is further provided with a sea water replacing pipe extending through said lid and terminating near the bottom of said tube to permit said sea water to enter and leave the lower end of said tank and having an oil inlet and outlet connection to said lid to permit oil to enter and leave the top of said tank, and means for fluid connecting said inlet and outlet connection and said sea water replacing pipe to said surface vessel, whereby; by controlled operation of said pumping means, oil is delivered to each tank as sea water is removed therefrom, and vice versa, and wherein said fluid connecting means comprises an oil pipeline and a sea water pipeline extending from said lid for each tank to said vessel, and each line is provided with a valve, and connection means commonly couples respective lines to said oil and sea water pump means, and a filter is connected between said sea water pump means and the source of sea water, whereby; sea water replaces oil within a given tank only after passing through said filter.

3. The submarine oil storage tank system as claimed in claim 2, wherein: said sea water replacing pipe is fluid coupled in series with said oil-water separating device at a point intermediate of said tanks and said pump, said cleaning agent supply tank is fluid coupled to said oil pipeline by means of a cleaning pipe line connected at one end to said oil pipe line and at the other end to said sea water replacing pipe and valves are operatively provided within said cleaning pipeline, said oil pipeline and said sea water pipeline, such that by operation of said valves and said pumps, said oil pipeline may receive sea water after passage through said filter and after receiving cleaning agent from said cleaning agent supply tank, and wherein sea water after oil-water separation may be delivered back to the sea water, from each tank after passage through said oil-water separating device.