Separable trenching apparatus
First Claim
1. Apparatus for entrenching an elongated pipeline and the like on the bottom of a body of water comprisinga burying sled base, includingfirst and second pontoon skids having generally parallel longitudinal axes, said pontoon skids being connected by a cross support means to straddle said pipeline,a trench cutting assembly adapted to be connected to said sled base for cutting a trench beneath said pipeline, when said pipeline lies on said water bottom, andremote connecting and disconnecting means operative in a first state for remotely connecting said cutting assembly in an operational relationship to said sled base for entrenching said pipeline and in a second state for remotely disconnecting and separating said cutting assembly from said sled base,whereby said sled base may be left on the bottom of said body of water and said cutting assembly may be raised aboard a floating vessel.
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Abstract
A method and apparatus for entrenching an elongated pipeline and the like uses a trenching apparatus having a trench cutting assembly which is detachably connected to a sled base. A floating vessel has means to control positioning of the trenching apparatus, including means to raise and lower, and to connect and disconnect, the trench cutting assembly and the sled base. Several methods and apparatus are disclosed for raising and lowering the trench cutting assembly while leaving the sled base positioned on the bottom of the body of water, straddling the elongated pipeline. In each embodiment, the cutting means may be lifted on board the vessel for maintenance and/or repair, leaving the sled base in position relative to the pipeline. Means are provided for abandoning the sled base at the entrenching site and returning later to lower the trench cutting assembly into its operational relationship with the sled base.
20 Citations
39 Claims
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1. Apparatus for entrenching an elongated pipeline and the like on the bottom of a body of water comprising
a burying sled base, including first and second pontoon skids having generally parallel longitudinal axes, said pontoon skids being connected by a cross support means to straddle said pipeline, a trench cutting assembly adapted to be connected to said sled base for cutting a trench beneath said pipeline, when said pipeline lies on said water bottom, and remote connecting and disconnecting means operative in a first state for remotely connecting said cutting assembly in an operational relationship to said sled base for entrenching said pipeline and in a second state for remotely disconnecting and separating said cutting assembly from said sled base, whereby said sled base may be left on the bottom of said body of water and said cutting assembly may be raised aboard a floating vessel.
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11. Apparatus for entrenching an elongated pipeline and the like on the bottom of a body of water comprising
a burying sled base, said sled base having first and second pontoon skids, said skids having generally parallel longitudinal axes, said skids being connected by a cross support means to straddle said pipeline, a trench cutting assembly for cutting a trench beneath said pipeline while the pipeline lies on the bottom of said body of water, an umbilical between a floating vessel and said cutting assembly, said cutting assembly including a plurality of horizontally directed thrusters attached thereto and responsive to a horizontal control signal from said vessel for adjusting the horizontal position of the cutting assembly in said body of water, said cutting assembly including a buoyancy means for at least partially neutralizing the weight of said cutting assembly, means for providing information to the vessel indicating the position of the cutting assembly relative to the sled base, said information means including a sonar transmitter and receiver and a television camera transmitter and receiver, a vertical positioning means for changing the position of the cutting assembly in a vertical direction, the vertical positioning means including a support means connected between the cutting assembly and a winch assembly on board said vessel for effecting controlled lowering of the cutting assembly to the bottom of said body of water in a first state, and for effecting controlled raising of said cutting assembly from the bottom of said body of water in a second state, a mechanical guide means for guiding said cutting assembly into said operational relationship with said sled base, a plurality of remotely controlled interlocking member pairs for securing the cutting assembly to the sled base in an operational relationship and for releasing the cutting assembly from the sled base when the cutting assembly is to be removed from the operational relationship with the sled base, each member pair including first and second cooperating members, said first member on the sled base and said second member on the cutting assembly, and means on said cutting assembly and controlled from the vessel to rotate said second cooperating member through an angle of substantially 90° - .
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22. Apparatus for entrenching an elongated pipeline and the like on the bottom of a body of water comprising
a burying sled base, the sled base having first and second pontoon skids, the skids having generally parallel longitudinal axes, the skids being connected by a cross-support means to straddle the pipeline, a trench cutting assembly for cutting a trench beneath the pipeline while the pipeline is on the bottom of said body of water, an electrical umbilical between the cutting assembly and a vessel, the cutting assembly including a plurality of horizontally directed thrusters attached thereto and responsive to a horizontal control signal from the vessel for adjusting the horizontal position of the cutting assembly in said body of water, the cutting assembly further including a buoyancy means secured to and forming a part of the cutting assembly, the buoyancy means having a state wherein the net buoyancy of the cutting assembly is fixed and urges the cutting assembly upwards, means for providing information to the vessel indicating the position of the cutting assembly relative to the sled base, the means including a television camera transmitting and receiving means, the transmitting means being carried by the cutting assembly and the receiving means being carried by said vessel, a vertical positioning means responsive to a control signal from the vessel for changing the position of the cutting assembly in a vertical plane, the vertical means including a plurality of guidelines and a plurality of driven rotating members carried by the cutting assembly, each guideline extending from a different one of said driven rotating members to the sled base, the guideline at one end, being secured to the sled base, and at the other end, to the driven rotating member, remotely controlled drive means for rotating each said rotating member in response to an output signal from the vessel, a plurality of remotely controlled interlocking member pairs for securing the cutting assembly to the sled base in an operational relationship and releasing the cutting assembly from the sled base when the operational relationship is to be no longer maintained, each member pair including first and second cooperating members, said first member on the sled base and said second member on the cutting assembly, and means remotely controlled from the vessel to rotate the second cooperating member through an angle of substantially 90° - .
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33. Apparatus for entrenching an elongated pipeline and the like on the bottom of a body of water comprising
a burying sled base, said sled base having first and second pontoon skids, said skids having generally parallel longitudinal axes, said skids being connected to a cross-support means to straddle said pipeline, a trench cutting assembly for cutting a trench beneath said pipeline while the pipeline lies on the bottom of a body of water, said cutting assembly having a buoyancy assembly and a cutting means, an electrical umbilical between the cutting assembly and a vessel, said cutting assembly including a plurality of horizontally directed thrusters attached to the cutting assembly and responsive to a horizontal control signal from said vessel for adjusting the horizontal position of the cutting assembly in the body of water, at least two guidelines, said buoyancy assembly including a buoyancy means having a fixed buoyancy to provide said cutting assembly with a net positive buoyancy, at least two driven rotating members, each guideline extending from a different one of said driven rotating members to said sled base, each said guideline at one end being secured to said sled base and at the other end to said driven rotating members, means responsive to a remotely generated rotation control signal from said vessel for operating said rotating members, first latch means responsive to a latch control signal from said vessel, for securing said cutting means to the buoyancy assembly in a second operational relationship and for releasing said cutting means from said buoyancy assembly when the cutting means is to be removed from said second operational relationship, means for providing information to the vessel indicating the position of the cutting assembly relative to the sled base, said means including a television camera transmitting and receiving means, a plurality of remotely controlled interlocking member pairs for securing the cutting assembly to the sled base in the operational relationship and releasing the cutting assembly from the sled base when the cutting assembly is to be removed from the operational relationship with the sled base, each member pair including first and second cooperating portions, one portion on the sled base and one portion on the cutting assembly, and means responsive to a signal from said vessel to rotate one said cooperating portion through an angle of substantially 90° - .
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34. A method for entrenching an elongated pipeline and the like on the bottom of a body of water comprising the steps of
placing a burying sled having a burying sled base and a trench cutting assembly at the bottom of said body of water in an operational relationship to said pipeline wherein said sled straddles said pipeline and said cutting assembly is connected to said sled base, pulling said sled base and trench cutting assembly along said pipeline to entrench said pipeline, remotely unlatching said trench cutting assembly from said sled base, remotely raising and removing said trench cutting assembly from its operational relationship with said sled base, leaving said sled base on the bottom of said body of water, remotely lowering the trench cutting assembly to an operational relationship with said sled base and said pipeline, and remotely securing said cutting trench assembly to said sled base in said operational relationship.
Specification