DK154443B - DEVICE FOR UNDERGRADING A WIRE IN THE SEA - Google Patents

Description

DK 154443 B

The present invention relates to an apparatus for burying a conduit, e.g. a cable or a pipeline in the seabed, and consisting of a number of rearwardly directed (calculated in the direction of gravity) nozzles which are connected to a common pressure-fluid-carrying hose and located on both 5 sides of the center line of the hose.

Several different types of excavators are known for burying a conduit in the seabed using nozzles. Examples of this are shown in U.S. Patent Nos. 3,217,499 and 3,505,826.

10

The apparatus disclosed in these patents is operated by a kind of sledge which is pulled over the seabed by means of a med on each side of the pipe or cable carrying an assembly of pressurized liquid nozzles which detach the seabed on both sides of the cable. 15 or the tube, and suction tubes for suction of the loosened material. A considerably less complicated apparatus is known from US Patent No. 2 755 632.

According to this patent, pipe hoses with pressurized fluid are lowered on both sides of the pipe or cable to be buried. The pipe hoses are provided on the underside with nozzles which can be rotated so that the pressurized fluid from the nozzles can be released to release the material into the seabed along the sides of the pipe or cable to be buried or to release the seabed material below it. Also, this apparatus must have suction pipes that open behind the nozzles to remove the loosened material that would otherwise remain. These suction pipes not only mean a significant increase in weight, but also necessitate a more complicated machinery, since the vessel which pulls the excavator over the seabed must, in addition to high-pressure fluid pumps, have pumps that have sufficient capacity to pump the released material up to the sea surface in at the same rate as it is detached by the pressure fluid nozzles.

DK 154443B

2

The invention relates, as mentioned above, to an apparatus for burying a conduit, e.g. a cable or pipeline in the seabed, which is in principle the same as that of US Patent No. 2 755 632 5, and consisting of a number of rear nozzles (calculated in the direction of gravity) which are connected to a common pressurized fluid hose and are arranged on both sides of the center line of the hose, and the object of the invention is to produce such an apparatus in which the suction pipes are avoided, and the weight of which is thereby reduced to a minimum.

This is achieved by the invention in that the nozzles two and two are arranged in pairs and that one nozzle in each pair is directed obliquely downwards and the other obliquely upwards. Thereby, the suction pipes and the associated pumping system are superfluous, the ejector action of the upstream nozzles generating a flow of water which removes the material which is detached and fluidized by the downstream nozzles.

The abducted material eventually deposits on the buried wire behind the apparatus.

In a preferred embodiment of the invention, the sum of the angles between a plane parallel to the pressurized fluid hose and the two nozzles is at least approximately right. This usually results in the most advantageous removal of the detached material. Under certain conditions, it may be convenient to make the angle between said plane and the downward nozzle somewhat smaller than the angle between the same plane and the upside down.

The invention will now be explained in greater detail with reference to the drawing, in which: 1 schematically shows the apparatus according to the invention in use, 3

DK 154443 B

FIG. 2 is a side view of the apparatus, and FIG. 3 shows a longitudinal section along the line 111 - 111 of FIG.

2nd

As will be apparent from the drawings, the apparatus according to the invention can be designed extremely simply. In principle, it consists of a pressurized hose 1 to which nozzle devices 2 are connected on both sides of the center line of the hose. The nozzles are arranged as nozzle pairs 3 with a nozzle 4 directed upward / backward and a nozzle 5, 10 directed backward / downward. Each nozzle pair 3 is disposed on the end of a downwardly extending tubing member 7 from a hollow-shaped holding member 6. The hollow-shaped holding member 6 is readily interconnected with the hose 1. In this way, it is easy to extend the entire excavator assembly by connecting one or more hose pieces and one or more holding parts 6 with arms 7 and nozzle pairs 3. The length of the unit, ie the number of nozzle pairs depends on the ground in which the gutter 8 is to be dug. If it is a light mass, almost like a duvet, one or two holders with 20 arms and nozzle pairs can be satisfied. The length of the unit, ie the number of nozzle pairs, must be increased if a harder ground is to be worked.

As shown in FIG. 2 is the sum of the angle α which the nozzle 4 forms with a conceived plane parallel to the hose 25 1, and the angle β which the nozzle 3 forms with the same plane is approximately right. As may be seen, it may also be appropriate that the angle α be somewhat larger than the angle β.

As will be seen from the drawing and description above, the apparatus is very simple and robust. It consists quite simply of a pressurized fluid-carrying hose with attached holders for pipe nozzle 7 with nozzle pairs 3. If you are going to start an excavation, you must first dig in another way

DK 154443 B

4 is such a long piece of a gutter that one can get a piece of the conduit 9 down into the bottom of the gutter at the depth you want the conduit. Then the apparatus according to the invention is laid down with arms 7 on both sides of the conduit 5 in the gutter and pressure water is supplied to the conduit 1.

The pressurized water supply, e.g. a powerful pump unit can be in a boat or it can be transported on a sled directly in front of the excavator. The whole thing can be controlled by a diver or with the help of a television 10 camera. The inclined downward nozzles 5 will flush the pulp loose at the bottom and flush it backwards. Due to vortex formation, a fluidized mass is obtained which is swirled upwards towards the region of the nozzles 4, which ensures that the fluidized mass is moved further upwards and backwards. The mass will then float in the water until the conduit 9 is brought down to the predetermined depth, and only when the mass has been outside the scope of the rear nozzles will it settle and sink into the gutter again, filling it up. In the case of a light mass, part of the swirled mass can be carried away due to current conditions, so that the gutter is not immediately filled. However, the ditch of the same water streams will fill up relatively quickly.

The apparatus according to the invention is inexpensive to manufacture, easy to transport and rig in place, reliable and efficient during use and easy to regulate for different types of material in the seabed.

A test apparatus according to the invention has been tested by the burial of electric cables in the northern Norwegian fjords, and the result has been very good.

Claims (3)

1. Device for burying a conduit (9) e.g. a cable or pipeline, in the seabed and consisting of a plurality of rearwardly directed nozzles (calculated in the direction of gravity), which are connected to a common pressure fluid-carrying hose and arranged on both sides of the center line of the hose, characterized in that the nozzles (4,5) and two are arranged in pairs (3), and one of the nozzles (5) in each pair (3) is directed obliquely downward and the other obliquely upward. Apparatus according to Claim 1, characterized in that the sum of the angles (a and β) between a plane parallel to the pressurized fluid hose and the two nozzles (4,5) is at least approximately equal. Apparatus according to claim 1, characterized in that the angle (β) between the plane parallel to the pressurized hose (1) and the downwardly directed nozzle (5) is smaller than the angle (a) between the same plane and the inclined upwardly nozzle ( 4).