GB2353306A

GB2353306A - Plough with shielded fluid jet nozzles

Info

Publication number: GB2353306A
Application number: GB0018054A
Authority: GB
Inventors: Timothy William Grinsted
Original assignee: Engineering Business Ltd
Current assignee: Engineering Business Ltd
Priority date: 1999-07-22
Filing date: 2000-07-24
Publication date: 2001-02-21
Anticipated expiration: 2020-07-24
Also published as: GB9917148D0; GB0018054D0; GB2353306B

Abstract

A plough for use in the burial of cables or pipelines in the sea bed includes nozzles for fluid jets [20] arranged on a portion of the plough so that the nozzle is at least partially shielded when ploughing. The fluid jets [20] may be located forward of the share [3] so that they can assist in its cutting operation when ploughing. The nozzles may be directed towards or away from the direction of travel of the plough, or downwards, towards the base of the plough. The fluid jet may be a liquid, such as water, or a gas, such as air.

Description

2353306 Improvements to Ploughs This invention relates to ploughs,

particularly those used to bury cable or pipe in the bed of the sea or other water.

Ploughs are a well-known method of protecting cable and pipelines underwater. The cables or pipelines are buried to protect them from damage by, for example, fishing equipment or anchors. Typically these ploughs are towed via a towrope by a vessel on the surface of the water, but may be towed by an underwater tractor. Such ploughs are fitted with a soil-engaging share that is shaped to dig into the seabed under the action of the towing force and produce a trench that the cable or pipe is placed into. Typically, the plough also places the cable or pipe into the trench. The present invention can be applied to all kinds of ploughs however. The plough of the invention can be used in trenching and in laying cable and pipeline.

Hitherto, these ploughs have been operated successfully in many types of seabed and over great distances, but sometimes experience problems in seabed conditions where excavation by water jets would be relatively easy. These conditions particularly occur with fine sands or silts. Under these circumstances the plough fails to bury the cable or pipe to the required depth to protect it. This can be a serious disadvantage resulting in a high risk of damage to the cable or pipe.

There are known methods of adding water jetting to ploughs to improve the performance. However, these suffer from disadvantages since the water jets are difficult to protect from the damaging or blocking effects of the normal operation of the plough as it is pulled through the seabed. It is the object of the present invention to provide a method of incorporating water or air jetting into a plough that alleviates these disadvantages.

According to the invention there is provided a plough comprising a fluid jet nozzle arranged on a portion of the plough so that the nozzle lies rearward of said portion in the direction of travel when ploughing whereby said portion at least partially shields the nozzle when ploughing. In this way, that portion of the share acts as a shield to the nozzle in the direction of travel of the share when ploughing.

Preferably, the plough comprises a share, in which the fluid jet nozzle lies forward of the share so that a fluid jet from the nozzle can assist in the operation of the share when ploughing.

Preferably, the share is a main share. 10 Preferably said portion comprises an auxiliary share.

Preferably said portion comprises a cutting blade.

Preferably more than one fluid jet nozzle is provided arranged on one or more shares, one or more shares at least partially shielding one or more nozzles.

Preferably one or more fluid jets assist in the cutting operation of one or more shares when ploughing.

Preferably the fluid jet nozzle lies rearward of the cutting blade of the share with respect to the direction of travel of the share when ploughing. In this way, the cutting blade acts as a shield to the nozzle in the direction of travel of the share when ploughing.

Preferably one or more nozzles are directed generally downwards towards the base of the plough.

Preferably one or more nozzles are directed away frorn the direction of travel of the 30 share when ploughing.

2 Preferably one or more nozzles are directed towards the direction of travel of the share when ploughing.

Preferably the fluid is a liquid for example water. 5 Preferably the fluid is a gas for example air.

Thus, in one embodiment the present invention provides a pipeline or cable plough with multiple soil cutting blades with fluid jets that are arranged on one or more of the cutting blades, these jets being orientated so that they assist the soil cutting process of the blade behind.

The plough can be used for trenching or for laying pipeline or cable.

The term "soil" is to be interpreted as any material to be ploughed including but not limited to soil, sand, shore, mud, and in certain circumstances rock.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 shows a plan view of a plough of a conventional type.

Figure 2 shows an elevation of the plough shown in figure 1.

Figure 3 shows an elevation of a plough according to the invention.

Figure 4 is a close up elevation of a ploughshare 11 of figure 3.

Figures 5 and 6 are cross-sectional views of shares according to the invention in which the scale across the share from side to side (vertical y-axis up the page) has been greatly exaggerated for clarity.

3 Referring to figures I and 2, a seabed cable plough of a conventional type is made up of a chassis 1, a share 3, and support skids (2 and 4). The front skids 2 support the plough on the seabed 6 and the share 3 penetrates the seabed as the plough is towed by a ship (not shown) via towrope 5. The front skids 2 are adjustable hydraulically to set the trenching depth of the plough. Cable 7 enters the plough at bellmouth 12 and exits underground at the back of the plough 8. Rear skids 4 support the back of the plough when operating in very soft seabed soils. The plough may be fitted with a control and monitoring system and a hydraulic power pack, allowing the operators on the ship to operate it effectively. Fluid jets may be fitted to assist the operation of the plough, and typical examples are indicated 9. Fluid supply pipe 10 is fitted to the share 3 and is connected to pumps, not shown, on the plough or elsewhere. The plough is fitted with an auxiliary cutting share 11.

Referring to feature 3, a cable plough according to the invention is similar to that shown in figures I and 2. Fluid jets 20 exit from nozzles 22 fitted to the back of the auxiliary cutter I I and connected to pumps via pipe or pipes 2 1. The jets 20 operate in a generally downward direction. The jets may be angled backwards 20a or forwards 20b to assist the operation of the main share -3 3.

As can be seen from the figure a shielding portion of share 11, typically the cutting blade, at least partially shields nozzles 22 in the direction of travel because these nozzles lie behind or rearwards of the portion. The nozzles can lie directly behind the shielding portion of the share along a line drawn in the direction of travel or the nozzles can lie rearwards of the portion but to one side of this line. In this case the shielding portion would offer less protection to the nozzles. In either case, the shape of the shielding portion can be adapted to provide extra protection by directing soil or other debris away from the nozzles. Also, jets 20 are typically partially shielded by share I I in the direction of travel when ploughing. The nozzles are less exposed to the material being ploughed and are therefore less likely to become blocked or suffer damage.

4 Thus, in the embodiment of figure 3 the invention provides an additional cutting blade or blades, which themselves assist in the cutting process, to shield jets 20, the jets assisting with the cutting operation of the main cutting blade 3.

Figure 4 shows fluid jets 20a and 20b directed by nozzles 22 towards the base of the plough. Fluid jets 20a are directed by nozzles 22 generally rearwards away from the direction of travel whereas fluid jet 20b points generally forwards towards the direction of travel of the plough. Thus fluid jet 20b in particular can assist in the cutting action of the main share 3. 10 Figure 5 shows in cross section an example of the location of nozzles 22 about a share 13. Nozzles 22 are shielded by cutting surface 15 in the direction of travel. In other words cutting surface 15 directs soil and other debris away from nozzles 22. 15 Figure 6 shows in cross section another example of a share 14 with nozzles 22 situated just behind a forward portion of the share. Where more than one nozzle is provided these are typically located symmetrically about the share, although this need not be the case. Also whilst it is preferred for 20 simplicity of design that the nozzles on one share are fed from the same fluid pipe more than one fluid source could be used so that the water jets from the nozzles can be controlled independently. Typically, the nozzle or nozzles are integral with the share or shares although these may be attached to it. The fluid jets may be liquid, such as water, or gas such as air.

Claims

1 A plough comprising a fluid jet nozzle arranged on a portion of the plough so that the nozzle lies rearward of said portion in the direction of travel when ploughing whereby said portion at least partially shields said portion when ploughing.

2. A plough according to claim 1 comprising a share, in which the fluid jet nozzle lies forward of the share so that a fluid jet from the nozzle can assist in the operation of the share when ploughing.

3. A plough according to claim 2 in which the share is a main share.

4. A plough according to any preceding claim in which said portion comprises an auxiliary share.

5. A plough according to any preceding claim in which said portion comprises a cutting blade.

6. A plough according to any preceding claim in which more than one fluid jet nozzle is provided arranged on one or more shares, one or more shares at least partially shielding one or more nozzles.

7. A plough according to claim 6 in which one or more fluid jets assist in the cutting operation of one or more shares when ploughing.

8. A plough according to any preceding claim in which one or more nozzles point generally downwards towards the base of the plough.

9. A plough according to any preceding claim in which one or more nozzles are directed away from the direction of travel of the share when ploughing.

6

10. A plough according to any preceding claim in which one or more nozzles are directed towards the direction of travel of the share when ploughing.

11. A plough according to any preceding claim in which the fluid is a liquid, for example, water.

12. A plough according to any preceding claim in which the fluid is a gas, for example, air. 10

13. A plough substantially described herein with reference to and/or as illustrated in figure 3, 4, 5 and/or 6.

P71532GB 7