Buoyant self-propelled underwater trenching apparatus

Claim 2

An underwater trenching apparatus for burying a pipeline or the like beneath the bottom of a body of water comprising: a frame for positioning over the pipeline to be buried, jet means supported by said frame, comprising a plurality of vertically arranged nozzles for digging a trench in said bottom for burying said pipeline, eductor means supported by said frame for drawing up portions of said bottom cut by said jet means and discharging these portions away from said apparatus, a first set of rollers secured to said apparatus and contacting said pipeline to direct said apparatus along said pipeline, drive means to drive at least one of said first rollers for movement of said apparatus along said pipeline, resilient means positioned between said first rollers and said apparatus to permit movement of said first rollers toward and away from the axis of said pipeline while following variations in circumference in said pipeline, and including guide roller means mounted on said frame and extending in front of said jet means in contact with said pipeline to detect direction changes in said pipeline, guide roller mounting means secured at one end to said frame and having guide rollers mounted thereon at the other end for applying a torque to said frame angularly disposed to the direction of motion of said apparatus to correct the alignment of said apparatus in accordance with the direction of the pipeline whereby upon said guide roller means sensing a preselected magnitude of change in pipeline direction relative to the axis of said apparatus, a torque is applied to said apparatus to align the apparatus with said pipeline.

Claim 3

The apparatus of claim 1 including mounting said guide rollers mounting means forwardly of the mounting of said first rollers whereby a torque is applied to said frame in accordance to the direction of the pipeline.

Claim 4

The apparatus of claim 1 including guide roller resilient means mounted between said guide rollers and said guide roller mounting means to permit said guide rollers to remain in contact with the pipeline while following variation in pipeline circumference.

Claim 5

The apparatus of claim 3 including abutment means operatively connected to said guide roller resilient means and positioned to bottom out upon the pipeline changing direction.

Claim 6

The apparatus of claim 1 including said guide rollers being mounted, mounting means forwardly of the mounting of said first rollers whereby a torque is applied to said frame in accordance to the direction of the pipeline, guide roller resilient means mounted between said guide rollers and said guide roller mounting means to permit said guide rollers to remain in contact with the pipeline while following variation in pipeline circumference, abutment means operatively connected to said guide roller resilient means and positioned to bottom out upon the pipeline changing direction.

Claim 7

The apparatus of claim 1 including elongated rollers positioned above and below said pipeline and mounted for rotation within said apparatus, said bottom roller being secured to said apparatus by a shear pin whereby a compressive force of sufficient magnitude between the pipeline and said bottom roller acts to shear said pin and release said apparatus from said pipeline.

Claim 8

The apparatus of claim 5 including drive means to drive at least one of said first rollers for movement of said apparatus along said pipeline, first rollers being rotatably mounted on an arm pivotally secured to said frame and said resilient means being positioned in contact with said arm and said frame to operatively control the position of said arm and maintain the first rollers in contact with said pipeline.

Claim 9

The apparatus of claim 7 including detection means operably connected to said drive means to detect obstacles in the path of said apparatus.

Claim 10

The apparatus of claim 1 including guide roller resilient means mounted between said guide rollers and said guide roller mounting means to permit said guide rollers to remain in contact with the pipeline while following variation in pipeline circumference, abutment means operatively connected to said guide roller resilient means and positioned to bottom out upon the pipeline changing direction, first rollers being rotatably mounted on an arm pivotally secured to said frame and said resilient means being positioned in contact with said arm and said frame to operatively control the position of said arm and maintain the first rollers in contact with said pipeline, said eductor means including at least one substantially vertical tube, water supply inlet at the top of said tube, said inlet communicating with a venturi means at approximately a right angle to the longitudinal axis of said tube, a tube outlet extending outwardly from said tube and communicating with said venturi, a tube inlet extending below said frame whereby portions of the bottom are sucked up the tube and discharged out the outlet, said eductor tube inlet facing forwardly and inwardly and the axis of the outlet lies in substantially the same vertical plane as the axis of the eductor tube inlet.

Claim 11

The apparatus of claim 9 including said nozzles being longitudinally arranged in vertical rows along and being held stationary to the axis of a vertical cutting tube and projecting therefrom in the direction of motion of said apparatus, said rows being radially positioned at an angle of 20°-50° from each other.

Claim 12

The apparatus of claim 1, including a ballast tank support on said frame, a ballast tank mounted on each side of said tank support and said pipeline, each said tank including a plurality of compartments partitioned fore to aft, each compartment having a water inlet and outlet at the bottom and an air inlet connected to an air supply for admitting air into said compartment, means controlling the amount of water in each compartment by admitting or releasing air from said compartment thereby affecting the pitch, roll and buoyancy of the apparatus.

Claim 13

The apparatus of claim 9 including said nozzles positioned upon one of said cutting tubes being pointed in an angular direction relative to the pipeline to offset the torque effect of a complementary nozzle positioned upon the other of said cutting tubes.

Claim 14

The apparatus of claim 10 including guide roller means mounted on said frame at a location rearwardly of said nozzles and extending into contact with said pipeline forwardly of said nozzles.

Claim 15

The apparatus of claim 1 including said nozzles being longitudinally arranged in vertical rows along a vertical cutting tube and projecting therefrom in the direction of motion of said apparatus, said rows being radially positioned at an angle of 20°-50° from each other.

Claim 16

The apparatus of claim 14 including said nozzles positioned upon one of said cutting tubes being pointed in an angular direction relative to the pipeline to offset the torque effect of a complementary nozzle positioned upon the other of said cutting tubes.

Claim 17

The apparatus of claim 1 including guide roller means mounted on said frame at a location rearwardly of said nozzles and extending into contact with said pipeline forwardly of said nozzles.

Claim 18

The apparatus of claim 1, including yoke means included in said guide roller mounting means for selected movement toward and away from said frame, said guide roller means including an arm extending from said frame forwardly of said jet means in mounting said roller means.

Claim 19

The apparatus of claim 17, including abutment means mounted between said frame and said rollers to transmit a torque to said frame from rearward movement of said rollers and resilient means positioned between said roller and said abutment means.

Claim 20

The apparatus of claim 18, including stop-limit means limiting the movement of said rollers upon contact with said abutment means.

Claim 21

The apparatus of claim 1, including guide roller means including an arm extending forwardly from said frame, a yoke means carried by said arm, said guide rollers mounted within said yoke for contact with said pipeline to sense changes in direction of said pipeline relative to said apparatus, resilient means positioned between said arm and said yoke, stop-limit means positioned between said rollers and said arm and abutment means to cooperate with said stop-limit means, whereby upon selected movement of said guide rollers following changes in direction of said pipeline, said rollers force said yoke to permit contact with said abutment means and said stop-limit means to torque the apparatus through said arm to a selected alignment with said pipeline.

Claim 22

The apparatus of claim 1, including said guide roller mounting means being positioned below selected jet nozzles whereby said jet nozzles are able to clear a path in front of said guide rollers.

Claim 23

The apparatus of claim 1, including centering rollers secured for rotation on the frame and positioned to contact the pipeline, said centering rollers being elongated in the direction of the axis of rotation.

Claim 24

The apparatus of claim 1, guide rollers having guide roller mounting means being positioned below selected jet nozzles whereby said jet nozzles are able to clear a path in front of said guide rollers.

Claim 25

The apparatus of claim 1, including air nozzle means carried on said frame and cooperating with said jet means to discharge air to provide a flotation effect to bottom cuttings dislodged by said jet means.

Claim 26

The apparatus of claim 1, including said guide roller mounting means being positioned below selected jet nozzles whereby said jet nozzles are able to clear a path in front of said guide rollers, and air nozzle means carried on said frame and cooperating with said jet means to discharge air to provide a flotation effect to bottom cuttings dislodged by said jet means.

Claim 27

The apparatus of claim 1, including said jet nozzles being positioned on opposite sides of said pipeline and wherein substantially each nozzle is positioned to point in a particular direction relative to the center line of the pipeline in a direction to substantially offset the torque produced by a complementary nozzle on the opposite side of the center line of said pipeline.

Claim 28

The apparatus of claim 1, including said guide roller mounting means being positioned below selected jet nozzles whereby said jet nozzles are able to clear a path in front of said guide rollers, air nozzle means carried on said frame and cooperating with said jet means to discharge air to provide a flotation effect to bottom cuttings dislodged by said jet means, said jet nozzles being positioned on opposite sides of said pipeline and wherein substantially each nozzle is positioned to point in a particular direction relative to the center line of the pipeline in a direction to substantially offset the torque produced by a complementary nozzle on the opposite side of the center line of said pipeline.

Claim 29

The apparatus of claim 26 including said nozzles being longitudinally arranged in vertical rows along and being held stationary to the axis of a vertical cutting tube and projecting therefrom in the direction of motion of said apparatus, and said rows being radially positioned at an angle of 20°-50° from each other.

Claim 30

The apparatus of claim 1, including independent buoyancy means supported upon said frame on each side of said pipeline, each said buoyancy means having a plurality of separate individual compartments, opening means in each compartment to provide communication with the water, and means selectively operable upon the water level of each compartment to control the buoyant effect of each compartment including a gaseous inlet means and a gaseous outlet means for each compartment whereby the fore-to-aft and port-to-starboard attitude of the apparatus is controllable.

Claim 31

The apparatus of claim 29 including said gaseous inlet being positioned towards to bottom of said compartment and said gaseous outlet being positioned towards the top of said compartment.

Claim 32

The apparatus of claim 29, including said jet nozzles being positioned on opposite sides of said pipeline and wherein substantially each nozzle is positioned to point in a particular direction relative to the center line of the pipeline in a direction to substantially offset the torque produced by a complementary nozzle on the opposite side of the center line of said pipeline.

Claim 33

An underwater trenching apparatus for burying a pipeline or the like beneath the bottom of a body of water comprising: a frame for positioning over the pipeline to be buried: jet means supported by said frame, comprising a plurality of vertically arranged nozzles for digging a trench in said bottom for burying said pipeline, eductor means supported by said frame for drawing up portions of said bottom cut by said jet means and discharging these portions away from said apparatus, a first set of rollers secured to said apparatus and contacting said pipeline to direct said apparatus along said pipeline, drive means to drive at least one roller of said first set rollers for movement of said apparatus along said pipeline, resilient means positioned between said first rollers and said apparatus to permit movement of said first rollers toward and away from the axis of said pipeline while following variations in circumference in said pipeline, including at least one water hose connected to said apparatus and at least one air hose connected to said apparatus, said hoses being held together to form a bundle, said air hose being of diameter sufficient to buoy a portion of said bundle.

Claim 34

An underwater trenching apparatus for burying a pipeline or the like beneath the bottom of a body of water comprising: a frame for positioning over the pipeline to be buried: jet means supported by said frame, comprising a plurality of vertically arranged nozzles for digging a trench in said bottom for burying said pipeline, eductor means supported by said frame for drawing up portions of said bottom cut by said jet means and discharging these portions away from said apparatus, a first set of rollers secured to said apparatus and contacting said pipeline to direct said apparatus along said pipeline, drive means to drive at least one roller of said first set rollers for movement of said apparatus along said pipeline, resilient means positioned between said first rollers and said apparatus to permit movement of said first rollers toward and away from the axis of said pipeline while following variations in circumference in said pipeline, including at least one water hose connected to said apparatus and at least one air hose connected to said apparatus, said hoses being held together to form a bundle, said air hose being of diameter sufficient to buoy a portion of said bundle.

Claim 35

An underwater trenching apparatus for burying a pipeline or the like beneath the bottom of a body of water comprising: a frame for positioning over the pipeline to be buried, jet means supported by said frame, comprising a plurality of vertically arranged nozzles for digging a trench in said bottom for burying said pipeline, eductor means supported by said frame for drawing up portions of said bottom cut by said jet means and discharging these portions away from said apparatus, a first set of rollers secured to said apparatus and contacting said pipeline to direct said apparatus along said pipeline, drive means to drive at least one roller of said first set of rollers for movement of said apparatus along said pipeline, resilient means positioned between said first rollers and said apparatus to permit movement of said first rollers towards and away from the axis of said pipeline while following variations in circumference in said pipeline, and including said nozzles being held longitudinally arranged in vertical rows along and being held stationary relative to the axis of a vertical cutting tube and projecting therefrom in the direction of motion of said apparatus, said nozzles positioned upon one of said cutting tubes being pointed in an angular direction relative to the pipeline to offset the torque effect of a complementary nozzle positioned upon the other of said cutting tubes.

Claim 36

An underwater trenching apparatus for burying a pipeline or the like beneath the bottom of a body of water comprising: a frame for positioning over the pipeline to be buried, jet means supported by said frame, comprising a plurality of vertically arranged nozzles for digging a trench in said bottom for burying said pipeline, eductor means supported by said frame for drawing up portions of said bottom cut by said jet means and discharging these portions away from said apparatus, a first set of rollers secured to said apparatus and contacting said pipeline to direct said apparatus along said pipeline, drive means to drive at least one roller of said first set of rollers for movement of said apparatus along said pipeline, resilient means positioned between said first rollers and said apparatus to permit movement of said first rollers towards and away from the axis of said pipeline while following variations in circumference in said pipeline, and including said nozzles being held longitudinally arranged in vertical rows along and being held stationary relative to the axis of a vertical cutting tube and projecting therefrom in the direction of motion of said apparatus, said nozzles positioned upon one of said cutting tubes being pointed in an angular direction relative to the pipeline to offset the torque effect of a complementary nozzle positioned upon the other of said cutting tubes.

Claim 37

An underwater trenching apparatus for burying a pipeline or the like beneath the bottom of a body of water comprising: a frame for positioning over the pipeline to be buried, jet means supported by said frame, comprising a plurality of vertically arranged nozzles for digging a trench in said bottom for burying said pipeline, a set of rollers secured to said apparatus and contacting said pipeline to direct said apparatus along said pipeline, drive means to drive at least one of said first rollers for movement of said apparatus along said pipeline, resilient means positioned between at least one of said rollers and said frame to permit movement of said roller toward and away from the axis of said pipeline while following variation in the circumference of said pipeline and including at least one waterhose connected to said apparatus, and at least one air hose connected to said apparatus, said hoses being held together to form a bundle, said air hose being of diameter sufficient to buoy a portion of said bundle.

Claim 38

An underwater trenching apparatus for burying a pipeline or the like beneath the bottom of a body of water comprising: a frame for positioning over the pipeline to be buried, jet means supported by said frame, comprising a plurality of vertically arranged nozzles for digging a trench in said bottom for burying said pipeline, a set of rollers secured to said apparatus and contacting said pipeline to direct said apparatus along said pipeline, drive means to drive at least one of said first rollers for movement of said apparatus along said pipeline, resilient means positioned between at least one of said rollers and said frame to permit movement of said roller toward and away from the axis of said pipeline while following variation in the circumference of said pipeline and including at least one waterhose connected to said apparatus, and at least one air hose connected to said apparatus, said hoses being held together to form a bundle, said air hose being of diameter sufficient to buoy a portion of said bundle.

Claim 39

The apparatus of claim 34, including independent buoyancy means supported upon said frame on each side of said pipeline, each said buoyancy means having a plurality of separate individual compartments, opening means in each compartment to provide communication with the water, and means selectively operably upon the water level of each compartment to control the buoyant effect of each compartment including a gaseous inlet means and a gaseous outlet means for each compartment whereby the fore-to-aft and port-to-starboard attitude of the apparatus is controllable.

Claim 40

The apparatus of claim 34, including said jet nozzles being positioned on opposite sides of said pipeline and wherein substantially each nozzle is positioned to point in a particular direction relative to the center line of the pipeline in a direction to substantially offset the torque produced by a complementary nozzle on the opposite side of the center line of said pipeline.

Claim 41

The apparatus of claim 34, including guide rollers and guide roller mounting means being positioned below selected nozzles of said jet means whereby said nozzles are able to clear a path in front of said guide rollers.

Claim 42

The apparatus of claim 34, including air nozzle means carried on said frame and cooperating with said jet means to discharge air to provide a flotation effect to bottom cuttings dislodged by said jet means.

Claim 43

An underwater trenching apparatus for burying a pipeline or the like beneath the bottom of a body of water comprising: a frame for positioning over the pipeline to be buried, jet means supported by said frame, comprising a plurality of vertically arranged nozzles for digging a trench in said bottom for burying said pipeline, eductor means supported by said frame for drawing up portions of said bottom cut by said jet means and discharging these portions away from said apparatus, a first set of rollers secured to said apparatus and contacting said pipeline to direct said apparatus along said pipeline, drive means to drive at least one roller of said first set of rollers for movement of said apparatus along said pipeline, resilient means positioned between said first rollers and said apparatus to permit movement of said first rollers towards and away from the axis of said pipeline while following variations in circumference in said pipeline, said jet nozzles being positioned on opposite sides of said pipeline and wherein substantially each nozzle is positioned at an angle relative to the center line of the pipeline in a direction to substantially offset the torque produced by a complementary nozzle on the opposite side of the center line of said pipeline.

Claim 44

An underwater trenching apparatus for burying a pipeline or the like beneath the bottom of a body of water comprising: a frame for positioning over the pipeline to be buried, jet means supported by said frame, comprising a plurality of vertically arranged nozzles for digging a trench in said bottom for burying said pipeline, eductor means supported by said frame for drawing up portions of said bottom cut by said jet means and discharging these portions away from said apparatus, a first set of rollers secured to said apparatus and contacting said pipeline to direct said apparatus along said pipeline, drive means to drive at least one roller of said first set of rollers for movement of said apparatus along said pipeline, resilient means positioned between said first rollers and said apparatus to permit movement of said first rollers towards and away from the axis of said pipeline while following variations in circumference in said pipeline, said jet nozzles being positioned on opposite sides of said pipeline and wherein substantially each nozzle is positioned at an angle relative to the center line of the pipeline in a direction to substantially offset the torque produced by a complementary nozzle on the opposite side of the center line of said pipeline.

Claim 45

The apparatus of claim 39, including said rows being radially positioned at an angle of 20°-50° from each other.

Claim 46

The apparatus of claim 39, including said nozzles being longitudinally arranged in vertical rows along and being held stationary to the axis of a vertical cutting tube and projecting therefrom in the direction of motion of said apparatus, and said rows being radially positioned at an angle of 20°-50° from each other.

Claim 47

An underwater trenching apparatus for burying a pipeline or the like beneath the bottom of a body of water comprising: a frame for positioning over the pipeline to be buried, jet means supported by said frame, comprising a plurality of vertically arranged nozzles for digging a trench in said bottom for burying said pipeline, eductor means supported by said frame for drawing up portions of said bottom cut by said jet means and discharging these portions away from said apparatus, a first set of rollers secured to said apparatus and contacting said pipeline to direct said apparatus along said pipeline, drive means to drive at least one roller of said first set of rollers for movement of said apparatus along said pipeline, resilient means positioned between said first rollers and said apparatus to permit movement of said first rollers towards and away from the axis of said pipeline while following variations in circumference in said pipeline, and including said nozzles being longitudinally arranged in vertical rows along and being held stationary relative to the axis of a vertical cutting tube and projecting therefrom in the direction of motion of said apparatus, including said guide roller mounting means being positioned below selected jet nozzles whereby said jet nozzles are able to clear a path in front of said guide rollers, air nozzle means carried on said frame and cooperating with said jet means to discharge air to provide a flotation effect to bottom cuttings dislodged by said jet means, said jet nozzles being positioned on opposite sides of said pipeline and wherein substantially each nozzle is positioned to point in a particular direction to substantially offset the torque produced by a complementary nozzle on the opposite side of the center line of said pipeline.

Claim 48

An underwater trenching apparatus for burying a pipeline or the like beneath the bottom of a body of water comprising: a frame for positioning over the pipeline to be buried, jet means supported by said frame, comprising a plurality of vertically arranged nozzles for digging a trench in said bottom for burying said pipeline, eductor means supported by said frame for drawing up portions of said bottom cut by said jet means and discharging these portions away from said apparatus, a first set of rollers secured to said apparatus and contacting said pipeline to direct said apparatus along said pipeline, drive means to drive at least one roller of said first set of rollers for movement of said apparatus along said pipeline, resilient means positioned between said first rollers and said apparatus to permit movement of said first rollers towards and away from the axis of said pipeline while following variations in circumference in said pipeline, and including said nozzles being longitudinally arranged in vertical rows along and being held stationary relative to the axis of a vertical cutting tube and projecting therefrom in the direction of motion of said apparatus, including said guide roller mounting means being positioned below selected jet nozzles whereby said jet nozzles are able to clear a path in front of said guide rollers, air nozzle means carried on said frame and cooperating with said jet means to discharge air to provide a flotation effect to bottom cuttings dislodged by said jet means, said jet nozzles being positioned on opposite sides of said pipeline and wherein substantially each nozzle is positioned to point in a particular direction to substantially offset the torque produced by a complementary nozzle on the opposite side of the center line of said pipeline.

Claim 49

An underwater trenching apparatus for burying a pipeline or the like beneath the bottom of a body of water comprising: a frame for positioning over the pipeline to be buried, jet means supported by said frame, comprising a plurality of vertically arranged nozzles for digging a trench in said bottom for burying said pipeline, eductor means supported by said frame for drawing up portions of said bottom cut by said jet means and discharging these portions away from said apparatus, a first set of rollers secured to said apparatus and contacting said pipeline to direct said apparatus along said pipeline, drive means to drive at least one roller of said first set of rollers for movement of said apparatus along said pipeline, resilient means positioned between said first rollers and said apparatus to permit movement of said first rollers towards and away from the axis of said pipeline while following variations in circumference in said pipeline, and including said nozzles being longitudinally arranged in vertical rows along and being held stationary relative to the axis of a vertical cutting tube and projecting therefrom in the direction of motion of said apparatus, including independent buoyancy means supported upon said frame on each side of said pipeline, each said buoyancy means having a plurality of separate individual compartments, opening means in each compartment to provide communications with the water, and means selectively operable upon the water level of each compartment to control the buoyant effect of each compartment including a gaseous inlet means and a gaseous outlet means for each compartment whereby the fore-to-aft and port-to-starboard attitude of the apparatus is controllable.

Claim 50

An underwater trenching apparatus for burying a pipeline or the like beneath the bottom of a body of water comprising: a frame for positioning over the pipeline to be buried, jet means supported by said frame, comprising a plurality of vertically arranged nozzles for digging a trench in said bottom for burying said pipeline, eductor means supported by said frame for drawing up portions of said bottom cut by said jet means and discharging these portions away from said apparatus, a first set of rollers secured to said apparatus and contacting said pipeline to direct said apparatus along said pipeline, drive means to drive at least one roller of said first set of rollers for movement of said apparatus along said pipeline, resilient means positioned between said first rollers and said apparatus to permit movement of said first rollers towards and away from the axis of said pipeline while following variations in circumference in said pipeline, and including said nozzles being longitudinally arranged in vertical rows along and being held stationary relative to the axis of a vertical cutting tube and projecting therefrom in the direction of motion of said apparatus, including independent buoyancy means supported upon said frame on each side of said pipeline, each said buoyancy means having a plurality of separate individual compartments, opening means in each compartment to provide communications with the water, and means selectively operable upon the water level of each compartment to control the buoyant effect of each compartment including a gaseous inlet means and a gaseous outlet means for each compartment whereby the fore-to-aft and port-to-starboard attitude of the apparatus is controllable.

Claim 51

An underwater trenching apparatus for burying a pipeline or the like beneath the bottom of a body of water comprising: a frame for positioning over the pipeline to be buried, jet means supported by said frame, comprising a plurality of vertically arranged nozzles for digging a trench in said bottom for burying said pipeline, eductor means supported by said frame for drawing up portions of said bottom cut by said jet means and discharging these portions away from said apparatus, a first set of rollers secured to said apparatus and contacting said pipeline to direct said apparatus along said pipeline, drive means to drive at least one roller of said first set of rollers for movement of said apparatus along said pipeline, resilient means positioned between said first rollers and said apparatus to permit movement of said first rollers towards and away from the axis of said pipeline while following variations in circumference in said pipeline, and including said nozzles being longitudinally arranged in vertical rows along and being held stationary relative to the axis of a vertical cutting tube and projecting therefrom in the direction of motion of said apparatus, including said jet nozzles being positioned on opposite sides of said pipeline and wherein substantially each nozzle is positioned to point at at angle relative to the center line of the pipeline in a direction to substantially offset the torque produced by a complementary nozzle on the opposite side of the center line of said pipeline.

Claim 52

An underwater trenching apparatus for burying a pipeline or the like beneath the bottom of a body of water comprising: a frame for positioning over the pipeline to be buried, jet means supported by said frame, comprising a plurality of vertically arranged nozzles for digging a trench in said bottom for burying said pipeline, eductor means supported by said frame for drawing up portions of said bottom cut by said jet means and discharging these portions away from said apparatus, a first set of rollers secured to said apparatus and contacting said pipeline to direct said apparatus along said pipeline, drive means to drive at least one roller of said first set of rollers for movement of said apparatus along said pipeline, resilient means positioned between said first rollers and said apparatus to permit movement of said first rollers towards and away from the axis of said pipeline while following variations in circumference in said pipeline, and including said nozzles being longitudinally arranged in vertical rows along and being held stationary relative to the axis of a vertical cutting tube and projecting therefrom in the direction of motion of said apparatus, including said jet nozzles being positioned on opposite sides of said pipeline and wherein substantially each nozzle is positioned to point at at angle relative to the center line of the pipeline in a direction to substantially offset the torque produced by a complementary nozzle on the opposite side of the center line of said pipeline.