WO2013095103A1

WO2013095103A1 - Dumping vessel

Info

Publication number: WO2013095103A1
Application number: PCT/NL2012/050827
Authority: WO
Inventors: Joost WIJNANDS
Original assignee: Baggermaatschappij Boskalis B.V.
Priority date: 2011-12-15
Filing date: 2012-11-21
Publication date: 2013-06-27
Also published as: EP2820191A1; NL2007973C2; EP2820191B1

Abstract

Dumping vessel for dumping sinking particles like sand, blocks, rocks or stones onto the bottom of a lake or sea, comprising a floating hull and a fall pipe pending downwards towards the bottom, wherein the fall pipe comprises a lower dumping section and a series of fall pipe sections that are stacked onto each other on the dumping section, wherein multiple fall pipe sections each comprise a tube and an upper connector and a lower connector that are joint with the tube, wherein the upper connector and the lower connector of subsequent fall pipe sections engage each other, wherein the tube comprises a circumferential wall having at least one layer of fiber reinforced plastic.

Description

Dumping vessel

BACKGROUND

The invention relates to a dumping vessel for dumping sand, stones or rocks onto the bottom of a deep sea .

A known dumping vessel comprises a floating hull and a fall pipe pending downwards towards the bottom of the sea. The fall pipe comprises a lower dumping section that is connected to two hoisting cables that are suspended from gallows on the deck of the vessel, and a series of steel fall pipe sections onto the dumping section that are coupled with the hoisting cables. The number of fall pipe sections that can be lowered is limited by the hoisting capacity of the gallows. Therefore the maximum length of the fall pipe under water is limited by the gallows as well. There is a need for a dumping vessel having a fall pipe that extends deeper without adapting the gallows or similar hoisting facilities.

SUMMARY OF THE INVENTION

The invention provides a dumping vessel for dumping sinking particles like sand, blocks, rocks or stones onto the bottom of a lake or sea, comprising a floating hull and a fall pipe pending downwards towards the bottom, wherein the fall pipe comprises a lower dumping section and a series of fall pipe sections that are stacked onto each other on the dumping section, wherein multiple fall pipe sections each comprise a tube and an upper connector and a lower connector that are joint with the tube, wherein the upper connector and the lower connector of subsequent fall pipe sections engage each other, wherein the tube comprises a circumferential wall having at least one layer of fiber reinforced plastic.

The fall pipe sections comprise a tube that is at least partly made of fiber reinforced plastic, which has a low own weight when compared to a steel tube having comparable strength. Therefore a larger number of fall pipe sections can be suspended from gallows or similar hoisting facilities when compared to full steel fall pipe sections. This enables to build up a deeper fall pipe under water.

In an embodiment the fibers are glass fibers, which provide excellent strength and stiffness properties.

In an embodiment the fibers form a sheet or fabric, whereby the fibers are preconfigured into a strengthening web.

In a cost effective embodiment the layer is fiber reinforced polyester.

Alternatively reasoned, the layer is made of a composition of a curing resin that contains fibers, wherein the layer is preferably made of a composition of a curing vinylester that contains fibers.

In an embodiment the circumferential wall comprises a laminate or multiple layers of fiber reinforced plastic that are bonded with each other. The lamination of distinguishable layers provides stiffness to the pipe.

In an embodiment the circumferential wall comprises a gel coat that forms the outer surface of the tube. In this manner projecting fibers of the fiber reinforced plastic are covered. In an embodiment the tube comprises a base portion with a first wall thickness and a shorter end portion with a second wall thickness, wherein a hollow cylindrical metal insert is joint with the end portion for joining the tube with the upper coupling or the lower coupling. The metal insert forms the actual transition between the plastic tube material and the upper or lower coupling .

In an embodiment thereof the insert comprises rims that are embedded into the fiber reinforced plastic of the tube, whereby a firm joint between the connector and the tube is provided that allows the fall pipe section to be hoisted at the connector.

In an embodiment the upper connector and/or the lower connector comprises a cylindrical metal mounting portion, wherein the insert partly projects from the tube and is accommodated in the mounting portion. The insert can be joined with the tube during manufacturing of the plastic tube. This assembly is ready to receive the connector.

In an embodiment the insert is joint with the mounting portion by means of a weld, whereby a strong joint is formed between the tube and the connector.

In an embodiment the tube comprises at the side of the upper connector and/or the lower connector an annular abutment surface that extends orthogonal to the centre line of the fall pipe section, wherein the upper connector and/or the lower connector comprise an annular abutment surface that extends orthogonal to the centre line of the fall pipe section and that is in abutment with the abutment surface of the tube along substantially its full circumference. The mutual abutment of the surfaces that extend orthogonal to the centre line of the fall pipe section ensures that the fall pipe section can bear high pressure forces in the direction of the centre line. This allows stacking of many fall pipe sections without damage.

In an embodiment the weld extends along the projecting end of the insert, spaced apart from the abutment surface of the tube. In this manner the heat that is applied during welding is kept at a distance of the plastic of the tube, whereby the integrity of the plastic remains ensured.

In an embodiment the second wall thickness is smaller than the first wall thickness.

In an embodiment the insert and the base portion have substantially the same inner diameter, whereby rocks will pass the successive bushes and tubes smoothly.

The various aspects and features described and shown in the specification can be applied, individually, wherever possible. These individual aspects, in particular the aspects and features described in the attached dependent claims, can be made subject of divisional patent applications.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be elucidated on the basis of an exemplary embodiment shown in the attached drawings, in which :

Figure 1 schematically shows a dumping vessel that is provided with a fall pipe having multiple stacked fall pipe sections according to an embodiment of the invention ;

Figure 2 an isometric view of two subsequent fall pipe sections;

Figures 3A a longitudinal section of the two fall pipe sections before stacking; and

Figures 3B and 3C a detail and a top view of the lower fall pipe section as shown in figure 3A;

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 schematically shows a dumping vessel 1 according to an embodiment of the invention for dumping sinking particles like sand, blocks, rocks or stones 9 onto the bottom 8 of a lake or sea 7 having a depth A that is typically more than 100 meter, preferably more than 1000 meter. The vessel 1 comprises a floating hull 2 having a moonpool 6 and two hoisting gallows 10 each having a sheave 11 at both sides of the moonpool 6. The hoisting gallows 10 can each swivel in direction B around a transverse axis of the hull 2 to position the sheaves 11 above the moonpool 6. The vessel 1 is provided with two winches 12 each having a hoisting cable 15 that run via the sheaves 11 through the moonpool 6 towards the bottom 8 of the deep sea 7. The vessel 1 is furthermore provided with a pipe handling crane 3 on deck.

The dumping vessel 1 is configured to dump the particles like the stones 9 onto the bottom 8 of the sea 7 with high accuracy, for example to locally cover or embed a deep sea oil pipe or an electricity line, or to build a traverse onto the sea bottom 8 in order to support crossing oil pipes. The dumping vessel 1 is therefore provided with a fall pipe 20 that is suspended from the hull 2.

The fall pipe 20 comprises a lower dumping section 21 and a series of identical fall pipe sections 31- 38 that are stacked on the dumping section 21. The dumping section 21 comprises a vertically extending, hollow tube 22 for passing the stones 9 and two couplings 23 that are connected to the lowered ends of the hoisting cables 15. The dumping section 21 can under water be engaged by a remotely operated vehicle that is known per se and therefore is not shown. The remotely operated vehicle is controlled from the deck, and is provided with multiple sideward oriented thrusters in order to move the suspended dumping section 21 in horizontal orthogonal directions E. In this manner the dumping section 21 is accurately positioned above the sea bottom 8. The fall pipe sections 31-38 have a length of about 8 meters and an inner diameter of 0,70 meters or more. Figure 2 isometrically shows by way of example only the first fall pipe section 31 that extends through the moonpool 6 and the identical second fall pipe section 32 below the moonpool 6 as indicated in figure 1. Figures 3A-3C show the second pipe 32 section and the lower part of the first fall pipe section 31 each having a centre line S in more detail. The second fall pipe section 32 comprises a steel upper connector 40 and a steel lower connector 60 that are both joined with a straight, circle cylindrical tube 70 that is made of fiber reinforced cured resin as described in much more detail hereafter. The inner surface of the tube 70 is covered and protected by a woven textile liner 78.

The upper connector 40 is shown in more detail in figures 3B and 3C. The upper connector 40 comprises a straight, circle cylindrical mounting portion 44 having a base portion 45 with a wall thickness of 30 millimeters and a thinner support portion 46 that forms a widening of the inner diameter of the base portion 45. The support portion 46 merges into a wider support flange 47 having a straight, annular abutment surface 48 that extends orthogonal to the centre line S of this fall pipe section 32. The upper connector 40 further comprises a supporting flange 50 that is welded above the mounting portion 44, and an inner circumferential wall 51 and two outer circumferential wall sections 52 that are welded onto the supporting flange 50 at a fixed distance to each other to form an annular confinement channel 53. As shown in figure 3C, a resilient seal 58 has been provided in the confinement channel 53. As best shown in figures 2 and 3C, the support flange 50 comprises two hoisting cable passages 54 at opposite sides that are accessible from outside. The fall pipe section 32 is hoisted on deck by means of a dedicated adapter 5 on the hoist cable 4 of the pipe handling crane 3.

As shown in figures 2 and 3A, the lower connector

60 comprises a straight, circle cylindrical mounting section 61 having a base portion 62 with a wall thickness of 30 millimeter and a thinner support portion 63 that forms a widening of the inner diameter of the base portion 62. The support portion 63 merges into a wider support flange 64 having a straight, annular abutment surface 65 that extends orthogonal to the centre line S of the fall pipe section 32. The lower connector 60 further comprises a supporting flange 66 with two hoisting cable passages 77 that is welded below the mounting section 61, and an inner circumferential wall 67 and two higher outer circumferential wall sections 68 that are welded on the supporting flange 66 at a fixed distance to each other to fit narrow into the confinement channel 53 of the upper connector 40, thereby abutting the resilient seal 58.

The tube 70 comprises a base portion 71 that forms the longest part of the tube, and two opposite smaller end portions 72 that form a widening of the inner diameter of the base portion 71. The end portions 72 each comprise a straight, annular abutment surface 73 that extends orthogonal to the centre line S of the second fall pipe section 32. The upper connector 40 and the lower connector 60have been joint with the opposite end portions 72 of the tube 70 by means of steel, straight, circle cylindrical and hollow inserts 80. The inner diameter of the inserts 80 is equal to the inner diameters of both the tube 70 and the base portions 45, 62 of the upper connector 40 and the lower connector 60, respectively. The inserts 80 comprise one half 81 that is provided with multiple outwardly directed rims 83 extending along the outer circumference. The rims 83 form a tooth saw pattern.

During production, the inserts 80 are supported on both sides of a cylindrical mould while a composition of a curing resin that contains fibers, preferably in the form of a sheet or fabric, is wounded multiple times around and compressed from outside after each winding, whereby a multilayered or laminated tube 70 is formed. In particular, the fibers are glass fibers and the resin is a vinylester, whereby after curing glass fiber reinforced polyester is formed, is a Only the halves 81 of the inserts 80 that are provided with the rims 83 are thereby fully covered by the multilayer composition, whereby the rims 83 are fully and tightly embedded into the composition and thereby joint therewith after curing. The smaller end portions 72 are formed by locally using a less thick composition or by locally applying more pressure there from outside. After curing a gel coat is applied to form a smooth and protecting outer surface of the tube 70. Finally, the abutment surfaces 73 are formed by means of a circumferential cut up to the inserts 70.

The support portion 46 of the upper connector 40 and the support portion 63 of the lower connector 60 are slid over the upper half 82 of the connecting bush 80 such that the annular abutment surfaces 48, 65 of the upper connector 40 and the lower connector 60 have come into firm abutment with the annular abutment surfaces 73 of the tube 70 along the full circumference thereof. The support portions 46, 63 have subsequently been joint with the insert 80 by means of a circumferentially extending first weld 84 and second weld 69, respectively. As the welds 84, 69 are applied at a distance from the tube 70 which is at least 3 times the wall thickness of the inserts 80, the cured resin of the tube 70 has not suffered from the heat that has been applied during welding.

The straight abutment surfaces 73 of the tube 70 are in abutment with the straight abutment surfaces 48, 65 of the upper connector 40 and the lower connector 60, respectively, whereby high pressure forces in the direction of the centre line S can be transferred between the connectors 40, 60 and the tube 70. In this manner the fall pipe sections 31-38 can bear the weight of many other fall pipe sections 31-38 that are stacked on it. The rims 83 ensure that each fall pipe section 31-38 can be hoisted individually while hanging on the upper connector 40 or the lower connector 60.

When the fall pipe 20 is built up and lowered via the moonpool 6 of the dumping vessel 1, the dumping section 21 that hangs on the hoisting cables 15 is lowered firstly. Subsequently the fall pipe sections 31-38 are stacked one by one while further paying out both hoisting cables 15. When the fall pipe 20 is hauled in, the fall pipe sections 31-38 are unstacked by the pipe crane 3 from above the deck .

It is to be understood that the above description is included to illustrate the operation of the preferred embodiments and is not meant to limit the scope of the invention. From the above discussion, many variations will be apparent to one skilled in the art that would yet be encompassed by the spirit and scope of the present invention .

Claims

C L A I M S

1. Dumping vessel for dumping sinking particles like sand, blocks, rocks or stones onto the bottom of a lake or sea, comprising a floating hull and a fall pipe pending downwards towards the bottom, wherein the fall pipe comprises a lower dumping section and a series of fall pipe sections that are stacked onto each other on the dumping section, wherein multiple fall pipe sections each comprise a tube and an upper connector and a lower connector that are joint with the tube, wherein the upper connector and the lower connector of subsequent fall pipe sections engage each other, wherein the tube comprises a circumferential wall having at least one layer of fiber reinforced plastic.

2. Dumping vessel according to claim 1, wherein the fibers are glass fibers.

3. Dumping vessel according to claim 1 or 2, wherein the fibers form a sheet or fabric.

4. Dumping vessel according to any one of the preceding claims, wherein the layer is fiber reinforced polyester .

5. Dumping vessel according to any one of the preceding claims, wherein the layer is made of a composition of a curing resin that contains fibers.

6. Dumping vessel according to claim 5, wherein the layer is made of a composition of a curing vinylester that contains fibers.

7. Dumping vessel according to any one of the preceding claims, wherein the circumferential wall comprises a laminate or multiple layers of fiber reinforced plastic that are bonded with each other.

8. Dumping vessel according to any one of the preceding claims, wherein the circumferential wall comprises a gel coat that forms the outer surface of the tube .

9. Dumping vessel according to any one of the preceding claims, wherein the tube comprises a base portion with a first wall thickness and a shorter end portion with a second wall thickness, wherein a hollow cylindrical metal insert is joint with the end portion for joining the tube with the upper coupling or the lower coupling.

10. Dumping vessel according to claims 9, wherein the insert comprises rims that are embedded into the fiber reinforced plastic of the tube.

11. Dumping vessel according to claim 9 or 10, wherein the upper connector and/or the lower connector comprises a cylindrical metal mounting portion, wherein the insert partly projects from the tube and is accommodated in the mounting portion.

12. Dumping vessel according to claim 11, wherein the insert is joint with the mounting portion by means of a weld.

13. Dumping vessel according to any one of the preceding claims, wherein at the side of the upper connector and/or the lower connector the tube comprises an annular abutment surface that extends orthogonal to the centre line of the fall pipe section, wherein the upper connector and/or the lower connector comprise an annular abutment surface that extends orthogonal to the centre line of the fall pipe section and that is in abutment with the abutment surface of the tube along substantially its full circumference.

14. Dumping vessel according to claims 12 and 13, wherein the weld extends along the projecting end of the insert, spaced apart from the abutment surface of the tube.

15. Dumping vessel according to any one of the claims 9-14, wherein the second wall thickness is smaller than the first wall thickness.

16. Dumping vessel according to any one of the claims 9-11, wherein the insert and the base portion have substantially the same inner diameter. o-o-o-o-o-o-o-o-

FG/HZ