Fall pipe

Abstract: The invention concerns a fall pipe for dumping materials onto a bottom situated under water, characterised in that it is mainly composed of a series of tubular elements (1) supported by at least two cables, which elements (1) are provided at both ends with a flange (3, 4) defining together with a flange (4, 3) of an adjacent tubular element (1') an annular space (5) wherein at least one resilient sealing ring (6) is applied between said flanges (3, 4).

Description: This invention concerns a fall pipe for dumping materials, in particular but not exclusively stones, onto a bottom situated under water. It is known to equip ships with a fall pipe and different structures have been suggested therefor. Dumping quarry stones at high depths (300 to 600 m) onto the seabottom is done regularly nowadays. The problems which arise upon dumping stones and similar materials at such depths and after all also at relatively small depths are i.a. the consequences of currents, movements of the ship upon violent wind etc. It has already been proposed to construct a fall pipe to be used for this object with water permeable elements, i.a. by using a steel network. Examples thereof are described in the following patents or published applications : NL 7904516 and NL 188938. Possibly, it could also be considered to use slightly conical elements sliding into one another for constructing the fall pipe. Finally, it has also been proposed to use a fall pipe consisting of elements having a specific weight equal to or less than that of the water. In this respect see Norwegian application 773352. All of these structures offer only partially a solution to the set requirements. Steel networks are easily damaged by the falling material and smaller material can be lost through these networks. The use of elements sliding into one another does not offer the desired solution either, i.a. namely since an uncontrolled water inflow in the fall pipe occurs between these elements. Light-weight fall pipes with a specific weight as mentioned hereinabove are difficult to reinforce when they reach large lengths. The invention has therefore as object to provide a new and original fall pipe, offering simultaneously the required strength and flexibility so that the stones can be dumped under good circumstances at the required place onto the bottom and at the desired depth. In order to enable this in conformity with the invention, the fall pipe according to the invention is mainly composed of a series of tubular elements piled up onto one another and supported by at least two cables, said tubular elements being arranged at both ends to fit against a corresponding tubular end of an adjacent tubular element of said series, each of said elements comprising two flanges, one of said flanges being arranged at the end of the tubular element whereas the other is at a small distance of the opposite end of the same tubular element so as to allow forming with an adjacent element an annular space wherein at least one resilient sealing ring is applied between said flanges. The sealing ring or rings between both flanges provide for a waterproof sealing between two successive tubular elements so that there is no uncontrolled water inflow in the fall pipe. Such an inflow can now, if desired, occur in a controllable way at the top of the fall pipe. Of course, in this way no fine material can further escape between two successive elements in the fall pipe according to the invention. The fall pipe according to the invention further also allows a limited flexion, which is required to permit the outlet of the fall pipe to be positioned correctly. Still according to the invention, said flanges are provided with at least one raised edge directed towards the adjacent tubular element, with said raised edges of the flanges which are situated at two ends fitting against one another, sliding fittingly into one another. These raised edges permit the different elements of the fall pipe to be put quickly and easily accurately onto one another and prevent these elements from displacing laterally with respect to each other. The invention further relates to a tubular element for constructing a fall pipe according to the invention and which shows more particularly the characteristics as indicated in claim 12. Other details and advantages of the invention will become apparent from the following description of a fall pipe according to the invention. This description is only given by way of example and does not limit the invention. The reference numerals relate to the figures annexed hereto. Figure 1 is a longitudinal section in the area of the connection between two tubular elements. Figure 2 is a perspective view, on a smaller scale, of two elements and two cables pertaining thereto. Figure 3 is a top view, on a larger scale, of a tubular element. Figure 4 is a section according to line IV-IV in Figure 5 and shows a locking plate in top view. Figure 5 is a section according to line V-V in Figure 4. Figure 6 is a section according to line VI-VI in Figure 4. Figure 7 shows schematically the lower end of the fall pipe. The fall pipe shown in these figures, is composed of a series of tubular, more particularly cylindrical elements 1 piled up onto one another and supported by two or possibly more cables 2. Both ends of the cylindrical elements 1 are arranged to fit against a corresponding end of an adjacent cylindrical element 1'. Each cylindrical element 1 shows at its two ends a outwardly directed flange. For the clarity of the description and supposing that the drawings show the fall pipe in vertical position, these flanges are represented as upper flange 3 and lower flange 4. In the annular space 5 which is defined by the flanges 3 and 4 of two adjacent elements 1, 1', a resilient seal is provided which consists in the here represented example of three rubber rings 6 which are mutually separated by steel rings 7 having a rectangular cross section. As a result thereof, the middle rubber ring 6 is caught between two steel rings 7 while the upper and the lower rubber rings 6 are each caught between a steel ring 7 and a portion of the flanges 3, respectively 4. The steel rings 7 show a rectangular cross section so that the rubber rings 6 remain always in contact with the large flat side of these steel rings 7. In the preferred embodiment shown in the figures, the flanges 3, 4 of a cylindrical element 1, 1' are provided with a raised edge 8, 9 directed towards the adjacent cylindrical element 1' and 1 respectively, and sliding fittingly into one another. Due to these edges 8, 9, it is easy to position the cylindrical elements 1, 1' correctly with respect to one another and a mutual displacement of these elements 1, 1' is further avoided. The edges 8, 9 do not necessarily have to extend over the entire circumference of the elements 1, 1'. When the fall pipe is flexed locally or over its entire length, the different cylindrical elements 1 composing this fall pipe can each form two by two an angle, as shown by Figure 1. On one side the rubber rings 6 will be compressed (at the left in Figure 1) and on the opposite side (at the right in the same figure) they will be released. In order to permit the different cylindrical elements 1 to move in this way with respect to one another, at least one of the raised edges 8, 9 sliding fittingly into one another shows a bevelled contact surface with the other raised edge. Such bevelled contact surfaces makes sliding these edges into one another further easier. Due to the bevelled contact surfaces, the cylindrical elements (1, 1') will not be clamped at their flanges 3 and 4 upon flexion of the fall pipe as represented in Figure 1. Although according to Figure 1, the inner surface of the raised edge 9 of the upper flange 3 of an element 1' which is situated at the bottom is bevelled, the same effect could be achieved by bevelling the outer surface of the raised edge 8 of a lower flange 4. Vice versa, the raised edge 8 of the lower flange 4 could also be situated at the outer side of the raised edge 9 of the upper flange 3. The upper flanges 3 are locally supported by knee pieces 20. The entire fall pipe structure is thus formed by different cylindrical elements 1, 1'. These elements are caught over the entire length of the fall pipe between two cables 2, which are more particularly fixed to the lowermost element of the fall pipe. As a result of the own weight of the different elements, these elements lie onto one another so that heavy connections between the different elements are not required. In order to position the different cylindrical elements 1, 1' with respect to said cables 2, each of the flanges 3 and 4 show a notch 10 at the passage of the cables 2. The cables 2 are fixed in the notches 10 of the flanges 3 and 4 by making use of locking plates 11 (Figures 2, 4, 5 and 6). Considered in top view, the locking plates 11 show an inner rounding 12 having a radius adapted to the diameter of the cables 2. This ensures a correct and technically reliable positioning of the different cylindrical elements 1 composing the fall pipe over the entire length of these cables 2. As it appears from Figures 4, 5 and 6, the locking plates 11 are provided with pins 13 which are applied in holes 14 provided in the upper flanges 3 for fixing these plates 11 onto the upper flanges 3. In this way, applying such a locking plate 11 can be done easily and quickly, after the cable 2 has been pushed in the notch 10. For blocking the pins 13, use could possibly be made of split pins. In the preferred embodiment according to the figures, this is however not required but the pins 13 are automatically blocked in the holes 14 by applying a further cylindrical element 1. As it appears from Figure 6, the locking plate 11 is more particularly blocked by the raised edge 8 of the lower flange 4 of the upper element 1. The shape of this raised edge 8 in the area of the locking plate 11 is adapted to the shape of this plate 11. Due to the own weight of the usually metal cylindrical elements 1, which clearly have a larger specific weight than water, no further mutual fixing of the different elements 1, 1' is required. All of the cylindrical elements 1, 1' are internally provided with a protective layer 15. This layer may consist of natural or synthetic rubber or a technically equivalent material. The thickness of the protective layer is nearly twice the thickness of the wall of the steel cylindrical elements 1, 1'. Preferably, the resilient lining layer 15 protrudes out of the cylindrical element 1 and fits resiliently against the corresponding lining layer of an adjacent element 1' whereby a bulge may be formed locally. In this way, a good connection is obtained between both elements 1, 1'. The lowermost end of the fall pipe is shown in Figure 7, which end is more particularly provided with a so-called "remote operated vehicle". This remote controllable unit comprises a central shute which is mounted telescopically with respect to the lowermost elements of the fall pipe. By means of the cables 17, the heaving movements of the ship can be compensated for in such a manner that the device is situated at a constant distance from the bottom. On the unit are provided folding supporting arms 18 for all kinds of sensors and/or cameras. For the control of the unit, and thus for the correct positioning of the lowermost end of the fall pipe, thrusters are provided on the unit, as already known per se. From the description of the fall pipe according to the invention, it clearly appears that a fall pipe structure which is adaptable to all depths and working circumstances is made feasible. This fall pipe offers the required flexibility and from a lifting structure with winches for the cables mounted on the ship, cylindrical elements can be added to or removed from the fall pipe. The invention is not limited to the embodiment described herein by way of example and modifications could be applied hereto, provided they fall within the scope of the claims.

Claims: A fall pipe for dumping materials, in particular stones, onto a bottom situated under water, characterised in that it is mainly composed of a series of tubular elements (1, 1') piled up onto one another and supported by at least two cables (2), said tubular elements (1) being arranged at both ends to fit against a corresponding tubular end of an adjacent tubular element (1') of said series, each of said elements (1, 1') comprising two flanges (3, 4), one of said flanges being arranged at the end of the tubular element (1) whereas the other is at a small distance of the opposite end of the tubular element (1') so as to allow forming an annular space (5) wherein at least one resilient sealing ring (6) is applied between said flanges (3, 4). A fall pipe according to claim 1, characterized in that said flanges (3, 4) are provided with at least one raised edge (9, 8) directed towards the adjacent tubular element (1, 1'), with said raised edges (9, 8) of the flanges (3, 4) which are situated at two ends fitting against one another, sliding fittingly into one another. A fall pipe according to claim 2, characterised in that at least one of the raised edges (8, 9) sliding fittingly into one another has a bevelled contact surface. A fall pipe according to any one of the claims 1 to 3, characterised in that notches are provided in the flanges (3, 4) for said cables (2), with means (11) being provided on the flange (3) of each of said elements, which is situated at the top in the use position for locking the cables (2) in said notches (10). A fall pipe according to claim 4, characterised in that said locking means comprise a locking plate (11) with pins (13) for fixing this plate (11) around the respective cable (2) on said upper flange (3). A fall pipe according to claim 5, characterised in that said locking plate (11) is blocked between two adjacent flanges (3, 4) of two adjacent elements (1, 1'), in particular between said upper flange (3) and said raised edge (8) directed towards said upper flange (3) of a flange (4) of the adjacent tubular element (1) cooperating with this upper flange (3). A fall pipe according to any one of the claims 1 to 6, characterised in that said tubular elements (1, 1') have an inner wall lined with a resilient protective material (15). A fall pipe according to claim 7, characterised in that said resilient protective material (15) is natural or synthetic rubber. A fall pipe according to claim 7 or 8, characterised in that said lining (15) protrudes out of the tubular element (1) and fits resiliently against the corresponding lining (15) of an adjacent tubular element (1'). A fall pipe according to any one of the claims 1 to 9, characterised in that said tubular elements (1, 1') are mainly cylindrical. A fall pipe according to any one of the claims 1 to 10, characterised in that it comprises at the bottom a remote controllable unit with a central shute (16) which is mounted telescopically with respect to the lower elements of the fall pipe. A tubular element for a fall pipe according to any one of the claims 1 to 11, characterised in that it comprises two flanges (3, 4), one of said flanges being arranged at the end of the tubular element whereas the other is at a small distance of the opposite end of the tubular element.

Inventors: LAER MARCEL VAN, VAN LAER, MARCEL
Applicants: DREDGING INT, RODA SHIPPING LIMITED, TIDEWAY B V, "DREDGING INTERNATIONAL", TIDEWAY B.V.
Application year: 1995
Main classification: B63B35
IPC codes: B63B27, B63B35