GB2128141A

GB2128141A - Tanker ship

Info

Publication number: GB2128141A
Application number: GB08325669A
Authority: GB
Inventors: Shoji Yoshida; Kuniaki Ishida; Tadashi Shibue
Original assignee: IHI Corp; Ishikawajima Harima Heavy Industries Co Ltd
Current assignee: IHI Corp
Priority date: 1982-09-30
Filing date: 1983-09-26
Publication date: 1984-04-26
Also published as: FR2533878A1; NO833403L; JPS5959588A; GB8325669D0; ES526025A0; FR2533878B1; GB2128141B; KR880000805B1; KR840005994A; ES8406960A1

Abstract

An oil tanker ship contains an elongate oil tank 1 extending in the direction of the length of the ship, the tank containing a plurality of bulkheads 10 dividing it into a plurality of tank sections 12. The bulkheads 10 are spaced apart in the direction of the length of the ship. The bulkheads may be double walls with reinforcing members in the intermediate spaces. The cross-section of the tank is circular or is formed of different arcuate surfaces optimally with some straight sides. <IMAGE>

Description

SPECIFICATION Tanker ship The present invention relates to tanker ships or vessels, that is to say ships of the type including a tank for the bulk storage or transport of fluids, in particular oil tankers.

The oil tanks of an oil tanker must be periodically cleaned to prevent the tanks being progressively filled and corroded by sludge. To this end, a Butterworth cleaning system is generally employed which sprays hot water at high pressure against every surface of the oil tank thereby removing the sludge.

Conventional oil tanks are generally in the form of a box and comprise flat panels, e.g. bottom plates, side shells, upper deck plates and longitudinal and transverse bulkheads. The oil tanks are reinforced by reinforcing members such as longitudinal and transverse girders, webs and stiffeners. These reinforcing members extend inwardly from the panels or inner surfaces of the oil tank so that certain portions of the inner surface of the tank are inevitably not sprayed with hot water when the oil tank is cleaned. Thus high pressure hot water cannot readily be sprayed over all the inner surfaces of the oil tank and the surfaces of the reinforcing members so that cleaning of the oil tank is a lengthy procedure. Furthermore, it is found that the sludge cannot be completely removed with the result that the corrosion of the ship's hull is accelerated by the accumulated sludge.

While the oil tanks of oil tankers are generally in the form of a box, onshore oil storage tanks with a large capacity are always in the form of a cylinder.

The wall thickness of the cylindrical tanks is less than that of the box-shaped oil tanks of oil tanker vessels.

Furthermore, onshore oil storage tanks are not provided with any reinforcing members because of their shape. The advantages of cylindrical onshore oil storage tanks may be obtained if the oil tanks of oil tanker vessels are in the form of a cylinder.

It is an object of the present invention to provide a tanker ship in which all the inner surfaces of the or each tank may be simply and rapidly cleaned and in particular in which sludge may be completely removed so that corrosion of the ship's hull due to the accumulation of sludge is avoided.

According to the present invention a tanker ship includes an elongate tank extending in the direction of the length of the ship, the tank containing a plurality of bulkheads dividing it into a plurality of tank sections, the bulkheads being spaced apart in the direction of the length of the ship.

Each tank section may be separated from the or each adjacent tank section by two spaced bulkheads, reinforcing members being provided in the space defined by the said two bulkheads.

The tank may have a circular cross-section or a cross-section defined by two or more intersecting or smoothly merging arcs. It may have a cross-section whose top portion, which may extend above the deck of the ship, is defined by an arc, e.g. a semi-circular arc, and whose side and bottom portions are respectively defined by arcs with a radius of curvature greater than that of the arc defining the top portion. In one construction the side and bottom portions are defined by two straight lines.

In an aiternative construction the tank has a cross section whose top portion extends above the deck of the ship and is defined by an arc and whose remainder is defined by another arc, the radius of curvature of the first arc being greater than that of the second arc.

Further features and advantages of the present invention will be apparent from the following description of certain preferred embodiments which is given by way of example with reference to the accompanying drawings, in which Figure 1 is a diagrammatic side elevation, partly broken away, of a first embodiment of a tanker ship in accordance with the present invention; Figure 2 is a sectional view on an enlarged scale on the line ll-ll in Figure 1; Figures 3 to 7 are sectional views similar to Figure 2 of second to sixth embodiments respectively of the present invention.

The same reference numerals are used to designate similar parts throughout the figures.

In the embodiment of Figures 1 and 2 the ship includes a single integral elongate cylindrical tank 1 extending in the axial or longitudinal direction (indicated by the arrow a) of the ship's hull 2 substantially horizontally or inclined at an angle to facilitate the cleaning operation. The cylindrical tank 1 is supported by supports 3 affording a part-circular recess which are disposed transversely of the length of the ship's hull 2 and in which apertures are formed. The upper portion of the cylindrical tank 1 extends upwardly beyond the ship's deck 4. The space defined by the cylindrical tank 1 and the bottom side shells 5 and 6 respectively of the ship constitutes a ballast tank 7. The stability of the tanker ship is thus ensured and the cylindrical tank 1 may have a large capacity.

The front and rear ends of the cylindrical tank 1 are closed by front and rear end bulkheads 8. Spaced pairs of adjacent but spaced intermediate bulkheads 10 are provided with the spacing between bulkheads of each pair and of adjacent pairs being in the axial direction. Each pair of bulkheads 10 defines a water-tight space or compartment 11, there being three such water-tight spaces or compartments 11 in the embodiment of Figure 1. Adjacent pairs of bulkheads 10 define an oil tank section 12, there being four such sections 12 in the embodiment of Figure 1. The front and rear end bulkheads 8 are shaped in the manner of a dome or the like so that no additional reinforcement is needed.

It is preferable that the transverse supports 3, the front and rear end bulkheads 8 and the intermediate bulkheads 10 lie in parallel planes and that reinforcing members (not shown) for the bulkheads 10 are disposed in such a way that they do not extend into the oil tank sections 12, thereby facilitating cleaning of the inner surfaces of the oil tank sections 12.

No reinforcing members are disposed within the oil tank sections 12 because a cylindrical oil tank has greater transverse strength than a box-shaped oil tank and the cylindrical tank 1 is reinforced by the bulkheads 8 and 10. Therefore, cleaning of the tank can be effected both rapidly and efficiently.

In the embodiment of Figure 3, the elongate tank la, which also extends in the axial direction of the ship, has a tunnel-like cross sectional configuration.

This tunnel-like cross section is advantageous as compared to a circular section as shown in Figure 2 in that the capacity of the tank is increased. Apart from the cross sectional shape, the second embodiment is substantially similar in construction to the first embodiment described with reference to Figures 1 and 2.

The tunnel-shaped cross section is defined by six successive merging arcs. Thus, an upper portion 13 is defined by an arc with a radius of curvature R1; a bottom portion 14 and two side portions 15 are defined by arcs with a radius of curvature R2; and the corner portions between the bottom portion 14 and the side portions 15 are defined by arcs with a radius of curvature R3. The top curve R1 merges smoothly with the side curves R2 which in turn merge smoothly with the corner curves R3 which in turn merge smoothly with the bottom curve R2. 'Merge smoothly' means that the tangents of two curves at their point of intersection are parallel.

The third embodiment of the present invention shown in Figure 4 is again substantially similar in construction to the first embodiment except as regards the cross sectional configuration of the tank 1 a. The top portion 13a of the tank is defined by a semicircle with radius R1; the bottom and side portions 14a and 1 spa are defined by straight lines; and corner portions 1 spa between the side and bottom portions are defined by arcs with a small radius of curvature. The third embodiment is advantageous as compared to the second embodiment in that its capacity is further increased.

The fourth embodiment of the present invention shown in Figure 5 is again substantially similar in construction to the first embodiment except as regards the cross sectional configuration of the tank 1 b. Thus the upper portion 18 of the tank extends upwardly beyond the deck 4 and is defined by an arc with a radius of curvature R4 while the lower portion 19 which is disposed bellow the deck 4 is defined by an arc with a radius of curvature R5which is smaller than R4. If the radius of curvature R4 of the upper portion 18 is increased, the height h or vertical distance between the deck 4 and the top or vertex of the upper portion 18 is decreased so that the width of the deck 4 is increased.

The fifth embodiment of the present invention shown in Figure 6 is again substantially similar in construction to the first embodiment except as regards the cross sectional configuration of the tank 1 c which is defined by four successive merging arcs.

The top portion 18 is defined by an arc with a radius of curvature R4; side portions 20 are defined by arcs with a radius of curvature Rg; and the bottom portion 21 is defined by an arc with a radius-of curvature R7.

The height h by which the tank extends above the upper deck 4 can be decreased and the capacity of the tank can be increased.

The sixth embodiment of the present invention which is also substantially similar in construction to the first embodiment except as regards the cross section of the tank 1 d. The upper portion 18 which extends above the upper deck 4 is defined by an arc with a radius of curvature R4. The upper corner portions 24, which connect the domed upper portion 18 and the two straight side portions 22, are defined by arcs with a radius of curvature R8. Lower corner portions 25, which connect the straight side portions 22 to the straight bottom portion 23 are defined by arcs with a radius of curvature Rg. The height h of the tank above the upper deck 4 can be decreased and the capacity of the tank can be increased. The capacity of the tank is larger than that of the fifth embodiment.

Referring again to Figure 1, the tank 1 is divided into a plurality of sections 12 by the compartments 11, each being defined by two axially spaced intermediate bulkheads 10, but it will be understood that the tank may be divided by single intermediate bulkheads into a plurality of sections, without a water-tight space or compartment between adjacent sections. In this case also, a minimum number of reinforcing members need be attached to the intermediate bulkheads 10 thereby facilitating cleaning of the oil tank.

The effects and advantages of the present invention may be summarised as follows: Instead of a box-shaped tank comprising flat panels whose transverse strength is weak, the ship includes a cylindrical or other elongate tank extending in the axial direction of the ship which is divided into a plurality of tank sections by transverse bulkheads. The tank therefore has sufficient transverse strength that it is not necessary to provide reinforcing members within the tank sections. The reinforcing members can be attached to the bulkheads in such a way that they do not extend into the tank sections. Even when adjacent tank sections are not separated by pairs of bulkheads defining a water-tight space or compartment and single intermediate bulkheads are provided, the number of reinforcing members attached thereto may be reduced to a minimum.As a result, cleaning of the tank is much facilitated, that is to say, cleaning may be accomplished efficiently and rapidly.

The cost of cleaning the tank is substantially reduced so the operational cost of the tanker ship is reduced accordingly. Since no sludge remains in the tank, the ship's hull can be prevented from being corroded so that the service life of the ship is increased.

The reinforcing members which are essential to the construction of a box-shaped oil tank comprisng a plurality of flat panels may be reduced in number and the weight of the reinforcing members, which is a substantiai portion of the weight of each flat panel, is reduced. Furthermore, the positions of the intermediate bulkheads can be aligned or in registry with those of the transverse supports, which may be substantially planar and which support the tank so that the design of the ship can be substantially rationalised and the weight of the ship can be reduced. As a result, the cost of construction of a ship in accordance with the invention can be considerably decreased as compared to that of a conven tional tanker ship.

Claims

1. Atankership including an elongate tank extending in the direction of the length of the ship, the tank containing a plurality of bulkheads dividing it into a plurality of tank sections, the bulkheads being spaced apart in the direction of the length of the ship.

2. A ship as claimed in Claim 1 in which each tank section is separated from the or each adjacent tank section by two spaced bulkheads, reinforcing members being provided in the space defined by the said two bulkheads.

3. A ship as claimed in Claim 2 in which no reinforcing members extend substantially into the tank sections.

4. A ship as claimed in any one of the preceding claims in which the tank has a circular cross section.

5. A ship as claimed in any one of Claims 1 to 3 in which the tank has a cross section whose top portion is defined by a semicircular arc and whose side and bottom portions are respectively defined by arcs with a radius of curvature greater than that of the said semicircular arc.

6. A ship as claimed in Claim 5 in which the side and bottom portions of the cross section of the tank are respectively defined by straight lines.

7. A ship as claimed in any one of Claims 1 to 3 in which the tank has a cross section whose top portion extends above an upper deck of the ship and is defined by an arc and whose remainder is defined by another arc, the radius of curvature of the first arc being greater than that of the second arc.

8. A ship as claimed in any one of Claims 1 to 3 in which the tank has a cross section which is defined by four successive arcs.

9, A ship as claimed in any one of Claims 1 to 3 in which the tank has a cross section whose top portion extends above an upper deck of the ship and is defined by an arc and whose side and bottom portions are defined by straight lines.

10. Atankership including an elongate tank substantially as specifically herein described with reference to Figures 1 and 2 or any one of Figures 3 to 7 of the accompanying drawings.