Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
A CLOSING DEVICE FOR AN OPENING IN THE BOTTOM OF A VESSEL
Document Type and Number:
WIPO Patent Application WO/1994/004412
Kind Code:
A1
Abstract:
A device for closing a downwardly open receiving space (3) in the bottom of a floating vessel (1), especially a space for receiving a submerged buoy for the transfer of liquid hydrocarbons, wherein the buoy is raised by means of a line means passing through the receiving space (3). The device consists of an at least bipartite shutter means (2) at the lower end of the receiving space (3) and comprises shutter elements (4) which are rotatably fastened to the bottom (5) of the vessel (1) and have a free end (6) having a central retracted edge portion (14) and a transverse edge portion (12). The two transverse edge portions (12) of the free end (6) are arranged to cause closing by mutual cooperation with at least one corresponding edge portion on at least one other shutter element, and the central retracted edge portion (14) forms a part of a sidewall (16) in a central guide opening (10) in the shutter means (2) when the free end (6) of the shutter element (4) during the closing is moved towards the corresponding free end of the other shutter element (4) or remaining shutter elements of the shutter means (2).

Inventors:
BREIVIK KAARE (NO)
SMEDAL ARNE (NO)
SYVERTSEN KAARE (NO)
Application Number:
PCT/NO1993/000127
Publication Date:
March 03, 1994
Filing Date:
August 20, 1993
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
NORSKE STATS OLJESELSKAP (NO)
BREIVIK KAARE (NO)
SMEDAL ARNE (NO)
SYVERTSEN KAARE (NO)
International Classes:
B63B19/00; B63B22/02; B63B22/04; (IPC1-7): B63B19/00; B63B21/50; B63B22/02
Domestic Patent References:
WO1987005876A11987-10-08
WO1993011032A11993-06-10
Foreign References:
GB2160166A1985-12-18
EP0396391A11990-11-07
Download PDF:
Claims:
1. P> P a t e n t C l a i m s 1 A device for closing a downwardly open receiving space (3) in the bottom of a floating vessel (1 ), especially a space for receiving a submerged buoy (32) for the transfer of liquid hydrocarbons, the buoy being raised by means of a line means (30, 39, 40) passing through the receiving space (3), characterized by an at least bipartite shutter means (2) at the lower end of the receiving space (3) and comprising shutter elements (4) of which one end is rotatably fastened to the bottom (5) of the vessel, and of which the opposite free end (6) during closing is moved towards the corresponding free end of the other shutter element (4) or remaining shutter elements of the shutter means, and that the free end (6) of the shutter elements (4) has lateral edge portions (12) arranged to cause closing by mutual cooperation with at least one corresponding edge portion on at least one other shutter element, and a retracted central edge portion (14) which, with the closing of the shutter means (2), forms a side wall (16) of a central opening (10) therein.
2. A device according to claim 1, characterized in that the shutter means (2) has two shutter elements (4) having straight lateral edge portions (12) and a curved retracted central edge portion (14) .
3. A device according to claim 1 or 2, characterized in that the shutter elements (4) are fastened to the vessel (1) by means of fastening arms (18) extending rearwards from the free end ( 6) of the shutter elements and past their rear edge (20), and that the shutter elements (4) may be turned about a horizon¬ tal axis (22) extending through the rearmost portion of each fastening arm (18) and being located in a plane at a certain distance above the horizontal plane forming the closing plane (7) of the shutter means (2) in the closed position thereof.
4. device according to claim 3, characterized in that the rear edge (20) of the shutter elements (4) is circularly curved in the horizontal plane, and in a vertical plane normal to the circularly curved contour is slanting backward/outwards to match the lower, preferably conical abutment surface (8) of the receiving space (3) .
5. A device according to any of the preceding claims, characterized in that the shutter elements (4) have protecting elements in the form of replaceable fenders on at least some of 5 their surfaces.
6. A device according to any of the preceding claims, characterized in that the shutter elements (4) at their free end (6) have flaps (24) which may be turned up and which correspond to the flaps of an aircraft wing, and/or guide elements (21) o arranged at the central opening (10).
7. A device according to claim 1, characterized in tha the shutter elements (4) are in so-called membrane panel design with a thin skin cladding having inwards curved panels and mounted on a framework. s.
8. A device according to any of the preceding claims, characterized in that the shutter elements (4) in their central edge portion (14) and at the side surface facing down in closed position have guide surfaces having a shape and/or material and surface finish adapted for sliding guidance of the line means o (39, 40) of the buoy (32) or the outer surface thereof.
Description:
A closing device for an opening in the bottom of a vessel

The invention relates to a device for closing a

5 downwardly open receiving space in the bottom of a floating vessel, especially a space for receiving a submerged buoy for the transfer of liquid hydrocarbons, the buoy being raised by means of a line means passing through the receiving space.

A vessel which is provided with a receiving space for 0 the above-mentioned purpose, for use in connection with a loading/unloading system for the transfer of e.g. oil or gas from a pipeline via a loading/unloading buoy, for example is known from the international patent application No. PCT/NO92/00055. In the vessel structure according to this patent application the s receiving space, which is arranged in the bow portion of the vessel, is open at its lower end, and at its upper end it passes into a vertical shaft which may be closed at its lower end by means of a shutter. This shutter is advantageous in order to be able to shut off the shaft against the surrounding sea water and o drain it for possible maintenance purposes when the vessel is not moored to the loading/unloading buoy. The shutter must be able to resist the normal water pressure as well as the maximum so- called "slamming pressures" which may be expected in heavy sea when the bottom of the vessel at the bow portion strikes against 5 the water surface after having been raised thereabove. Without such a lower shutter in the shaft, i.a. substantial braking actions will be able to arise because of the fact that the water level within the shaft will be raised and lowered so that water flows out and in through the opening at the bottom of the o receiving space.

The fact that the receiving space is open at its lower end implies in itself a certain braking action as a result of turbulence with movement of the vessel. In practice, this braking action will result in a reduction of the cruising speed of the 5 vessel of e.g. the order of 0,5 knots on the average.

Foreign bodies finding their way through the opening and into the receiving space thereabove, may also be a problem.

Thus, the main objective of the invention is to provide a device which, firstly, will eliminate or reduce said braking

action, and secondly will prevent foreign bodies from penetrating into the receiving space of the vessel.

A further objective of the invention is to see to it that the guiding of the buoy during the pulling-up thereof towards and into the receiving space may start as early as possible.

These objectives are achieved with a device of the introductorily stated type which, according to the invention, is characterized by an at least bipartite shutter means at the lower end of the receiving space and comprising shutter elements which are rotatably fastened to the bottom of the vessel and have a free end having a central retracted edge portion and a transver¬ sely extending edge portion on each side thereof, the two transverse edge portions of the free end being arranged to cause closing by mutual cooperation with at least one corresponding edge portion on at least one other shutter element, and the central edge portion forming a part of a side wall in a central guide opening in the shutter means when the free end of the shutter element in the closing is moved towards the corresponding free end of the other shutter element or remaining shutter elements of the shutter means.

The invention will now be further described in connec¬ tion with exemplary embodiments with reference to the drawings, wherein Fig. 1 shows a sectional side view of an embodiment of the closing device of the invention;

Fig. 2 shows a plan view of the same embodiment along the line II-II in Fig. 1:

Fig. 3 shows a sectional side view of the closing device in partly open position to make room for a buoy which is pulled up into the receiving space;

Fig. 4 corresponds to Fig. 3, but shows the situation wherein the buoy is in place and connected, and wherein the shutter elements of the closing device are completely turned-up; Fig. 5 shows a perspective view of one of the shutter elements of the device; and

Fig. 6 shows an embodiment wherein the shutter elements have flaps which may be turned up.

In Fig. 1 there is shown a section of a vessel 1,

especially a tanker, wherein a receiving space 3 is built into the vessel, the receiving space having a conical shape and is enlarged downwards towards the bottom 5 of the vessel 1, for receipt of a loading/unloading buoy (first shown in Fig. 3). In the illustrated embodiment, the main component of the device is a shutter means 2 in two-winged design, and each wing comprises one shutter element 4 which may be turned from a horizontal, closing position and up to a turned-up position wherein the shutter element is located outside the conical contour of the receiving space 3. In closed position, the underside of the shutter elements 4 are approximately flush with the underside of the bottom 5 of the vessel, and the free ends 6 of the shutter elements in this position are moved together in abutting contact or, as suggested in the Figure, with some overlap, so that the closing takes place in a closing plane 7. At the rear of the shutter elements 4, i.e. at the side which is opposite to the free end 6, the elements have an oblique surface 8a which is adapted to rest against the_lower abutment surface 8b of the receiving space 3 for the buoy. Further, Fig. 1 shows that the receiving space 3 at the top passes into a vertical shaft 9 which, at its lower end, has a space for connection of the buoy to the pipe system of the vessel for fluid transfer, here indicated by an inwards-turnable coupling unit 25. When the receiving space is not in use, the shaft 9 is air-tightly shut-off from the surrounding water by means of a shutter 26.

The device according to the invention especially is intended for use on vessels for operation in connection with a buoy of the type disclosed in e.g. the international patent application No. PCT/NO92/00056 and in Norwegian patent appli¬ cation No. 921704. Reference is made to these applications for a further description of such a buoy.

When a buoy of the current type is to be pulled up into the receiving space and connected, as indicated in Figs. 3 and 4, it is advantageous to have a centering for safe introduction of the buoy into the receiving space. Suitably, this takes place in that the pick-up line which is fastened to the upper part of the buoy, at the bottom branches off and forms a so-called lifting bridle having several lines, e.g. in a number of two or

three. A lowerable guide cylinder 11 of the type disclosed in Norwegian patent application No. 922950, in Fig. 1 is indicated in a somewhat lowered position to take care of the centering function within the receiving space 3. The guiding of the lifting bridle may take place as shown by means of guide rollers 27 which may be arranged in an approximately continuous internal ring at the lower end of the guide cylinder 11, or separate rollers may be placed in a triangle, a square or other configuration to ensure that the lines of the lifting bridle slide against a roller irrespective of the angular position of the buoy and irrespective of the number of lines included in the lifting bridle.

In addition to its main function, namely to effect a substantial closing of the bottom opening of the vessel into the receiving space 3, the closing device of the invention also has an additional function, namely to provide for an earliest possible centering and guiding of the lifting bridle of the pick¬ up line during the pulling-up of a buoy, while the closing device is still closed. The guiding and centering function is taken care of in that the shutter elements 4 of the device do not close completely in the central area, but have recesses so that, in the closed position, they form a central guide opening 10 in the closing plane 7. In the shown embodiment the opening is oval, as appears from Fig. 2. From Fig. 2 it also appears how the free end 6 of the shutter elements 4 has a central retracted edge portion 14 forming a part of a side wall 16 of the opening 10, and a transverse edge portion 12 on each side of the recess. It is along the outer edge portions 12 that the lower opening of the receiving space 3 is closed. The outer sides of the shutter elements 4 are formed by planar side surfaces 13 so that, in the closed position of the device, there will be left a relatively narrow, uncovered sector on each side of the lower circular opening of the receiving space, said sectors, in the illustrated embodiment having a two-winged shutter means 2 located diametri- cally opposite to each other.

From Figs. 1 and 2 it appears how each of the shutter elements 4 may be operated by hydraulic actuators 15 acting on an arm 17 the swinging range of which is suggested by a dot-and- dash curve on each side of the Figure. The shutter elements

consist of a main part 19 having a certain thickness to prefer¬ ably form a flushing transition from both sides of the bottom 5 and forwards to the edge portions 12, 14 of the free ends 6 of the shutter elements. Preferably, the main part is constructed

5 as a lightweight, but rigid hollow structure having a sheet covering, advantageously in the form of so-called membrane panels which are mounted on a frame and curve concavely inwards between the elements of the frame. The oblique rear surface 8a of the shutter elements 4 may be planar or somewhat curved outwards at o the bottom dependent on how the profile of the receiving space 3 is shaped at the bottom 5 of the vessel. The assembly of the shutter elements 4 to the bottom of the vessel takes place by means of over-lying fastening arms 18 extending rearwardly from the free end 6 of the shutter elements and past their rear edge s 20. At the rear, each fastening arm 18 is fixed to a horizontal shaft 21 the axis of rotation 22 of which is located in a plane at a certain distance above the closing plane 7. In this manner there is achieved that the main part 19 of the shutter elements may be turned up from its closed position and clear the abutment o surface 8b of the bottom. The hydraulic system which is connected to the shutter elements, does not need to be in operation when the elements are in the closed position, and these may be allowed of some movement upwards from the closing plane. Alternatively, they may be kept permanently down in the closing plane during 5 force influence from the hydraulic system, or they may be locked in the closing position by means of a separate locking device.

At the underside of the main part 19 of the shutter elements there may, with advantage, be mounted protective elements 28 in the form of replaceable fenders, e.g. of wood, o rubber, brass or another appropriate material.

Fig. 3 shows the pulling-up of a loading/unloading buoy 32 having an upper and a lower conical member 35 and 36, respectively. The buoy is moored by means of suggested mooring lines 29 which are fastened to a reinforced portion 34 at the 5 underside of the buoy. The Figure shows the uppermost part of the buoy sectioned in order to suggest a coupling element 37 for connection to the pipe system of the vessel. The buoy is hoisted up by means of a pick-up line 30 which, at the bottom, branches off to a lifting bridle having fastening lines 31.

In the illustrated situation, the shutter elements 4 are turned up so much as to clear the buoy, the turning-up taking place by means of the hydraulic actuators 15 (Fig. 1). It would, however, not represent any particular problem if the hydraulic system should fail and the shutter elements for this reason should be resting against the buoy, since they are so light of weight and have such a shape that they simply may be moved up and sideways when the buoy is pulled upwards by the pick-up line 30. Fig. 4 shows the situation after the buoy 32 has been moved completely into the receiving space and locked in place with a locking mechanism having locking dogs 38, and where the buoy further is connected to the pipe system and tank arrangement of the vessel by means of the inwards turnable coupling unit 25. The lower conical member 36 of the buoy at the top and bottom rests against conical abutment surfaces in the receiving space, namely the lower abutment surface 8b and an upper abutment surface 33. In the embodiment shown in Figs. 3 and 4, however, the upper abutment surface 33 is not continuous around the circumference, so that the free end 6 of each of the shutter elements 4 may be moved into a suitable recess. Alternatively, the length of the shutter elements may be shorter, so that the free end may swing in at the underside of the abutment surface 33.

Fig. 5 shows a perspective view of a shutter element 4 having three fastening arms 18 and planar side surfaces 13. Guide elements in the form of rollers 23 are suggested on each side of the central edge portion 14 to prevent the lines 31 of the lifting bridle from forcing themselves in between the transverse edge portions 12 when the buoy is centred by the opening 10 formed between two or more shutter elements 4 resting against each other.

In the Figure there is suggested that the main part 19 of the shutter element has its oblique rear surface 8a somewhat curved outwards at the bottom towards the rear edge 20, in order to match a rounded lower portion of the corresponding abutment surface 8b lowest in the bottom 5 of the vessel.

Fig. 6 shows an embodiment of the shutter element 4 wherein the free end 6 has a flap 24 mounted thereon along each of the transverse edge portions 12. The flaps 24 may correspond

to the flaps of an aircraft wing and may be turned up relative to the main part 19 of the shutter element 4 by means of a separate, e.g., hydraulic mechanism which may comprise a pivotable guide cylinder at the side of the shutter element. Alternatively, the flap may be arranged in the central edge portion 14 to close the guide opening 10 when no line is to be carried through the shutter means and the receiving space.