US3238734A - Apparatus for burying and recovering pipe in underwater locations - Google Patents

Description

March 8, 1966 R. F. RHODES 3,238,734

APPARATUS FOR BURYING AND RECOVERING PIPE IN UNDERWATER LOCATIONS Filed April 25, 1963 5 Sheets-Sheet 1 Fuel FIG. 2

RAYMOND F. RHODES k INVENTOR.

Ki BY (BN2, W,

R. F. RHODES 3,238,734 APPARATUS FOR BURYING AND RECOVERING PIPE IN I March 8, 1966 UNDERWATER LOCATIONS 5 Sheets-Sheet 2 Filed April 25, 1963 OOODGOO RAYMOND F. RHODES INVENTOR.

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\ QOODQOD R. F. RHODES 3,238,734 URYING AND RECOVERING PIPE IN March 8, 1966 APPARATUS FOR B UNDERWATER LOCATIONS 5 Sheets-Sheet 5 Filed April 25, 1963 RAYMOND E RHODE$ I INVENTOR.

R. F. RHODES 3,238,734 APPARATUS FOR BURYING AND RECOVERING PIPE IN March 8, 1966 UNDERWATER LOCATIONS 5 Sheets-Sheet 4 Filed April 25, 1963 RAYMOND F. RHODES INVENTOR.

March 8, 1966 R. F. RHODES 3,238,734

APPARATUS FOR BURYING AND REGOVERING PIPE IN UNDERWATER LOCATIONS Filed April 25, 1965 5 Sheets-Sheet 5 LL 9. LL.

RAYMOND E R HODES INVENTOR.

United States Patent 3,238,734 APPARATUS FOR BURYING AND RECOVERING PEPE IN UNDERWATER LOCATIONS Raymond F. Rhodes, 800 E. Park Ave., Houma, La. Filed Apr. 25, 1963, Ser. No. 275,762 1 Claim. (Cl. 61-724) This application is a continuation-in-part of my copending application, Ser. No. 150,290 filed Nov. 6, 1961 and now abandoned.

This invention relates to the art of burying and retrieving pipelines or cables in underwater locations. It is particularly directed to improvements in apparatus for digging trenches in underwater locations and burying or recovering pipe or cables from such trenches.

When pipelines, especially those carrying crude oil, gas or petroleum products, traverse the bottom of bodies of water such as rivers, lakes and oceans, it is customary to bury the pipelines to prevent damage from anchors or other navigational equipment or from aquatic life. Some harbor regulations, for example, require the pipelines to be buried in the earth at the bottom of the harbor to a depth of eight feet, although most underwater lines are covered to a lesser depth. Several types of apparatus have been proposed for this use. These may be classified as of hydraulic, plow or mechanical ditcher types as typified by US. Patents 2,755,632, 2,610,415 and 737,021, respectively.

Hydraulic type trenching apparatus which excavates a trench by the action of jets of water expelled at high velocity is probably the type most widely used at present. Trenching apparatus of this type is excellent when bottom conditions are right for its use, but in some areas, such as the gulf coast of Texas and Louisiana where many offshore oil and gas wells are located, the bottom often consists of extensive beds of stiff, gummy clay interspersed with sand and shell beds. When jets of water are directed at high velocity upon clay of this type, the jets do not cut out a uniform trench but merely cut the gummy clay up into separate pieces which topple into the excavation and do not disintegrate, so that the resulting trench, when formed, is not uniform. When a hydraulic jet is drawn across a shell bed which has different degrees of compactness at various locations therein, there is a resulting lack of uniformity in any trench washed out.

Plow type diggers can be used only when the depth of the trench is to be quite shallow as otherwise the resistance would be so great that a tug or self-propelled barge could not pull the trenching device across the body of water. The mechanical ditchers that have been proposed are very diflicult to get on and off an underwater pipeline, and frequently require divers to work for hours in placing the equipment on the line or removing it. At locations where squalls and storms frequently arise, ease and speed in detaching the apparatus from the underwater pipe are essential.

It is an object of this invention to provide an improved apparatus for burying and uncovering pipe or cables in underwater locations which is easily and quickly detachable from the pipe or cable.

Another object is to provide an improved pipe burying apparatus which may cut a uniform trench in clay, sand or shell bottoms.

Another object is to provide apparatus of the above type which does not require excessive power for moving along a pipeline or cable on the bottom of a body of water.

Another object is to provide a digging assembly of the above type which is easily movable between a position above the surface of a body of water, where it is available for maintenance and repair, and an effective digging position at the bottom of the body of water.

. 3,238,734 Patented Mar. 8, 1966 "ice Another object is to provide apparatus of the above type in which the digging conditions may be easily sensed by an operator.

Other objects, advantages and features of the invention will be apparent to one skilled in the art upon consideration of the claims and attached drawings.

The present invention includes a digging assembly comprising a pair of cutting heads, preferably including cutters of endless chain type, laterally spaced from each other at a distance suitable to receive a pipe between them. The cutting heads are carried on a support by a connection providing for substantially vertical arcuate motion from substantially vertical positions to positions with lower parts of the cutting heads substantially converging beneath a pipe to be buried or recovered. A means for tilting the cutting heads into converging positions, bringing lower effective parts of the cutters directly beneath the pipe, is provided. This tilting means preferably includes hydraulic cylinders, a screw jack, rack and pinion, or other mechanical device arranged to move the upper part of the cutting heads outward and inward. It is preferred that this tilting means be controlled from a boat or floating carrier upon the surface of the body of water above the pipe.

A means, connected to the carrier and digging assembly, for moving the digging assembly between a position above the surface of a body of water and an efiective digging position at the bottom of said body of water is provided. When the body of water is of shallow depth and high waves are not normally expected, it is preferred that this means include a boom, preferably of open work type, pivoted at a point adjacent one end thereof on the floating carrier for movement in a substantially vertical arc, and attached to the digging assembly at its outboard end. A pair of vertically movable, preferably extensible or telescoping type, studs may be substituted for the boom if desired.

When greater depths are to be encountered or when waves of sufiicient height to impart a substantial rocking motion to the floating carrier are to be normally expected, as is the case when work is performed under open ocean locations, it is preferred that the means for moving the digging assembly between above surface and bottom positions include a bridle suspending the digging assembly upon at least one cable. It will be seen that a flexible cable or bridle of this type is effective for reducing the rocking motion imparted by the carrier to the digging assembly when in operating position upon an underwater pipe, so that the cutting heads are not tilted from their normal position on the pipe as a result of wave action.

A means for driving the cutting heads, or for rotating peripheral endless chains thereon carrying cutter members, is provided. This means includes at least one motor operatively connected to drive the cutting heads. When the boom arrangement is used, the motor preferably is located upon the floating carrier and drives the cutting heads through a long drive shaft paralleling and supported by the boom although the motor may be of hydraulic or waterproof electric type and located on the support in the digging assembly, if desired. When the bridle arrangement connecting the carrier and digging assembly is used, it is preferred that the motor be of hydraulic or waterproof electric type and be mounted on a support included in the digging assembly. When a hydraulic motor is used, hydraulic fluid under pressure is supplied from the floating carrier through a suitable line to drive the motor, and when a waterproof electric type motor is used, an electric line for energizing the motor from a suitable source of electric current, such as a generator carried upon the carrier, is provided. In any case, the power supply preferably is located on the carrier where it may be conveniently controlled by an operator.

The flexible nature of a hydraulic line or electric cable supplying power to a motor in this manner permits the digging assembly to remain in proper digging position upon the pipe being covered when the floating carrier is rocked by Wave action. The digging assembly can be further stabilized against rocking by wave motion imparted to the carrier, if desired, by providing it with a pair of lateral stabilizing members, such as skids, wheels or crawler tracks attached to opposite sides of the digging assembly at a level where they will come in contact with the earth at the bottom of the body of water.

A suction line is attached to the digging assembly to carry away cuttings resulting from movement of the cutting heads through the earth. This suction line preferably is divided into a Y at its lower end and is connected to flow ways provided in a supporting member in each cutting head, although a separate suction line for cuttings can be used, if desired.

A means is provided for moving the carrier and digging assembly attached thereto in paths corresponding to a course of an underwater pipe. This means may include a tugboat for drawing the carrier across a body of Water, motor driven screws or paddle wheels for propelling a barge used as the carrier and may include one or more kedge anchors and connecting lines.

It is preferred that all controls or all motors, boom or bridle, suction line pump and means for moving the carrier and digging assembly be located in a small area on the floating carrier where they can be operated by a single operator. It has been found that this arrangement of controls enables the single operator to sense by sight, sound and feeling the manner in which digging is progressing and provides improved efliciency in operation.

It is believed that the construction and operation of this device can be best appreciated from consideration of the attached drawings wherein like reference numerals refer to like parts:

FIG. 1 is a diagrammatic plan view of a preferred type of floating carrier equipped with a boom and digging assembly;

FIG. 2 is an elevation of the device of FIG. 1;

FIG. 3 is an enlarged end elevation of the digging assembly of FIG. 2;

FIG. 4 is an enlarged end elevation of the device of FIG. 2 illustrating diagrammatically the relationship between the digging assembly and floating carrier;

FIG. 5 is an elevation of a pair of alignment studs shown in FIG. 2;

FIG. 6 is an enlarged side elevation of one cutting head partly broken away;

FIG. 7 is a detail of one type of means for tilting the cutting heads;

FIG. 8 is an enlarged detail of another device for tilting the cutting heads; and

FIG. 9 illustrates diagrammatically one preferred type of bridle suspension of the digging assembly.

In FIGS. 1 and 2, the reference numeral 1 designates generally a floating carrier, illustrated as a barge having a cut-out section 2 in an end thereof. A boom of open framework type, designated generally as 3, is pivoted at 4 and 4a for vertical arcuate movement of its outboard end from a level above the surface of water to a level adjacent to the bottom of a body of water 5. A means for raising and lowering boom 3 is illustrated as a pair of posts 6 and 6a carrying pulleys 7 and 7a over which run lines 8 and 8a controlled by a compound winch 9. A digging assembly, designated generally as 10, is supported by boom 3 adjacent the outboard end thereof so that the boom forms a means connected to the carrier and digging assembly for moving the digging assembly between a level above the surface of the Water 5 and an effective digging position at the bottom of the body of water.

The digging assembly comprises a pair of cutting heads designated generally in FIG. 3 as 11 and 11a. Since these cutting heads are substantially identical, the construction of only one will be described.

Each cutting head comprises a peripheral endless chain 12 having cutting members 13 thereon. The endless chain moves over a driven sprocket 14 and idler sprockets 15, 16, 17 and 18. The sprocket is supported upon a central member 19 while the sprockets 16, 17 and 18, respectively, are supported upon side supports 20 attached to the central member. The member 19 preferably is constructed to provide a flow way 19a therein. In preferred form, the member 19 is merely a section of pipe having an opening in a side thereof adjacent to the lower end of the member so that flow way 19a forms a part of a suction line arranged to carry away cuttings removed from a trench being excavated by operation of cutting members 13.

The two cutting heads are supported upon a support 21. by means providing tilting movement of the cutting heads from substantially vertical positions to inclined positions with lower ends of the cutting heads substantially converging beneath a pipe 22 to be buried. This means is illustrated in FIG. 3 as arms 23 of the cutting heads pivoted at 24 upon support 21.

A means is provided for moving the cutting heads from substantially vertical to inclined converging positions with the lower ends of the cutting heads below the pipe to be buried, and is best illustrated in FIGS. 4 and 8 as a pair of fluid actuated cylinders 26 and 27 having pistons therein and connected to move extensions 28 and 29 of the cutting heads in arcuate movement in a plane substantially perpendicular to the longitudinal axis of the pipe.

FIG. 8 shows a preferred detailed arrangement of these cylinders. The cylinders 26 and 27 contain pistons 30 and 31 to which piston rods 32 and 33 are connected. The piston rods have pivoted connections 34 and 35 to the extensions 28 and 29 of the cutting heads. A line 36 having connections to each of outer ends of cylinders 26 and 27 and a line 37 having connections to the inner ends of the two pistons are provided for supplying fluid 'under pressure to the pistons 30 and 31. The lines 36 and 37 lead to the carrier and a source of fluid under pressure located thereon so that the tilting mechanism is controllable from the carrier.

FIG. 7 shows in detail an alternative type of means for tilting the cutter heads. In this modification, a screw jack designated generally as 38 is provided and comprises a screw having threads inclined in opposite directions on its opposite ends. The threads engage blocks 39 and 40 having matching internal threads in openings therein so that rotation of the screw will move blocks 39 and 40 closer together when the screw is rotated in one direction, and will move them apart when rotation in an opposite direction occurs. Links 41, pivoted at opposite ends to blocks 39 or 40 and to blocks 42 and 43, respectively, cause the blocks 42 and 43 to move outward 'as blocks 39 and 40 approach each other, thus transmitting thrust through members 44 and 45 to extensions 28 and 29 and tilting the cutting heads. A reversible motor 138, operable by switch 238, preferably located on the carrier, is connected to drive the screw jack.

A motor 46 is operatively connected to drive the cutting heads. This connection is illustrated in FIG. 4 as a drive shaft 47 rotated by the motor and containing a universal joint 47a, connected to drive a differential gear 48 and a pair of axles 49 and 50, each containing a universal joint 52. The axles carry pinions (not shown) receiving noncircular outer ends of the axles for sliding movement therethrough and connected to drive endless chains 12 in a manner conventional in ditching machines. A roller 53 is mounted on the lower part of support 21 so that it carries a part of the load of the apparatus when the digging assembly is placed upon an underwater pipe.

Rollers 53a and 53b also may be provided to prevent lateral contact of the endless chains with pipe 22.

Each of the central members 19 of the cutting heads preferably is constructed as a hollow cylinder so that this member serves not only as a support but as an end of a suction line for removing cuttings cut out by members 13 from an excavation. When so constructed, the interior of member 19 has a connection at 55 to a suction line 56 connected to a pump 57 on the carrier so that all cuttings cut out by the cutting heads are conveyed through line 56 to the opposite end of carrier 1 where they are discharged. Discharge of cuttings in this manner aids in filling the ditch which has been cut by movement of the cutting heads through the earth at the bottom of the body of water, so that a pipe laid therein is more quickly buried than if the ditch were left open to be filled in by wave action.

A pair of guard members preferably is provided to prevent the cutting heads from engaging and damaging any pipes that may have been laid previously in position across the path of the line to be buried. The guard preferably is merely a pipe 62 supported by supports 54 having a large number of jet openings 63 and connected by lines 64 and 65 to a source of Water under pressure (not shown) located on the carrier. As the guard advances through the soil, hydraulic jet action enables it to cut its way through clay, sand or shell but when it encounters a pipe, the guard arrests forward motion of the cutting heads.

A means for moving the carrier and attached digging assembly along paths corresponding to the course of an underwater pipe is provided. This means may include propellers 66 arranged to drive the carrier, if desired. When the bottom being excavated is of variable type, it is often preferred to provide a pair of kedge anchors 67 connected by a line 68 wound upon winch 69 to move the carrier. It is further preferred that all controls, such as control lines 70 and 71 to the variable speed motor 46 and to the pump in suction line 56, respectively, be located in a small area on the carrier where they are convenient to a single operator, as in actual use of this device it has been found that an operator can sense the progress of digging by sight, sound and feel of the equipment as it operates, so that greatest efiiciency is attained when all controls are located where a single operator can handle them.

Operation of the device described above is very simple. When a pipeline such as a petroleum pipeline crossing a harbor or other body of water is to be buried, the carrier 1 is moved to a location above the line of pipe previously laid upon the bottom of the body of water. A pair of studs 58 vertically movable through sockets 59 and carried adjacent to the after end of the carrier are lowered so that the studs 58 are on opposite sides of the line. The studs 58 are connected near the bottom by a bar 60 which preferably carries a pair of short studs 61 which are adjustably spaced apart according to the size of the pipe to be buried so that these short studs loosely engage the outer side of the pipe. Alternative positions of studs 61 for pipe of various sizes are shown in broken lines.

The digging assembly is then lowered upon the line so that the cutting heads are on opposite sides of the line. The cutting heads are then tilted and their lower ends are brought in to substantially converging position beneath the line as motor 46 begins to run, driving endless chains 12 carrying the cutting members 13. Soil undercut by the cutting heads sags downward by gravity to contact the moving cutting members 13 and is torn up or comminuted so that it is easily removed through the flow ways 19a and suction line 56.

A depression in the bottom of the body of water is quickly excavated by the cutting heads so that roller 53 comes in contact with the top of line 22. Roller 53 not only bears a part of the weight of the digging assembly but prevents the cutting heads from penetrating to a greater depth than that intended since roller 53 is located at a selected position to control this depth. Continuous cyclic rotation of the endless chains then excavates soil from beneath the pipe 22 and, as the carrier and attached digging assembly is drawn along the pipe by movement of the carrier in a path corresponding to that of the underwater pipe, a ditch is dug out from beneath the pipe and the pipe sinks into the ditch as it is formed.

The boom arrangement described above is the preferred arrangement when the depth, or wave motion, of the water is not too great for satisfactory operation with a boom. The boom operation, however, is ordinarily limited to moderate depths and to relatively quiescent water and if a pipe is to be buried in open ocean waters where waves normally run high and the depth is great, the bridle arrangement shown in FIG. 9 is preferred. In this modification, the lines 8 and 8a are connected to a support 21a which carries the digging assembly in the manner described above. In this arrangement, however, the motor 46a is of hydraulic or waterproof electric type operable from the carrier and is mounted directly upon support 21a so that it is submerged along with the digging assembly. A means for supplying power to the motor is illustrated as a hydraulic line 61 leading to a source of fluid under pressure in the carrier. It will be seen that in this arrangement, there is no rigid connection between the digging assembly and the carrier although the cables 8 and 8a connect the carrier and digging assembly so that movement of the carrier along the path of the underwater line draws the digging assembly along the line to be buried. When drawn along the pipe in this manner, the digging assembly will not rock upon the pipe in response to rocking motion imparted to the carrier by waves at the surface of the water. The motor 46a is operated and controlled from the carrier through a flexible line 61.

In offshore operations such as in the Gulf of Mexico where, on relatively quiet days, Waves of four to six feet in height are often encountered, the provision of the flexible connection in this apparatus has been found to be very effective in maintaining proper position of the digging assembly as it moves along the underwater pipe.

From the foregoing, it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus and structure.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claim.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in :the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

The invention having been described, what is claimed 1s:

In apparatus for digging trenches in underwater locations including a floating carrier, a boom pivotally connected at one end to said carrier and a digging assembly attached to the other end of said boom, said digging assembly comprising a pair of laterally spaced cutting heads having peripheral endless chains carrying cutting members, a support horizontally positioned between the upper portions of said cutting heads, means pivotally connecting the cutting heads to the support providing tilting movement of the cutting heads from substantially vertical mutually parallel positions to inclined position with lower parts of the cutting heads converging to a position substantially below an underwater pipe, means operatively connected to the cutting heads for tilting the cutting heads to and from said vertical and inclined posit'ions, means on said support and positioned therebelow and adapted to ride along the pipe, 2. motor connected to drive the endless chains, said boom being vertically movable through an arc suflicient for raising and lowering the digging assembly between a position above the surface of a body of water and an effective digging position adjacent said pipe; means for moving the carrier and digging assembly connected thereto along the path of the underwater pipe; suction means associated with said digging assembly for removing soil loosened by said cutting heads.

References Cited by the Examiner UNITED STATES PATENTS Huelsdonk 3769 X Von Voorhis 3783 Joy 37--86 Salnikov 6172.4 Hauber 6172.4 X Symmank 61-726 X Skakel et a1. 3769 X CHARLES E. OCONNELL, Primary Examiner.

EARL J. WITMER, JACOB L. NACKENOFF,

Examiners.

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