Submarine pipeline laying vessel

Abstract

This invention relates to a method and to an apparatus for use in laying a submarine pipeline from a pipe-laying vessel. According to one aspect of the present invention, there is provided a reel pipe-laying method for continuously laying a pipeline of up to 24-inch diameter without a stinger by (1) aligning a pipe portion as it is being paid out from the reel, (2) straightening the aligned pipe portion, (3) tensioning the pipe, (4) discharging the straightened pipe under tension into the body of water, and (5) changing for different water depths and pipe conditions the lift off angle of the pipe relative to the horizontal by pivoting a diverter about a horizontal pivot, the diverter supporting at least the straightener and the tensioner and extending from the horizontal pivot mounted near the aft end of the vessel, upwardly toward the reel.

What is claimed is: 
     
       1. A vessel for continuously laying a pipeline on the bed underlying a body of water, comprising: a pipe supply reel mounted for rotation on said vessel about .[.its horizontal.]. .Iadd.a predetermined .Iaddend.axis;   drive means for rotating said reel .[.thereby unwinding a pipe section.].;   a diverter structure having one end coupled to one end of said vessel and having the other end extending upwardly in the direction of said reel and at an acute angle relative to the deck of said vessel; and pipe-conditioning means mounted on said diverter structure for conditioning said pipe section and discharging the conditioned pipe section into said body of water.   
     
     
       2. The vessel of claim 1 and further including: pivot means mounted near said one end of said vessel for pivotably mounting said one end of said diverter structure, and extensible means mounted on said vessel and being operably coupled to said diverter structure for pivoting said diverter structure about said pivot means, whereby said pipe is discharged directly from said one end of said vessel into said body of water.   
     
     
       3. The vessel of claim 2 and further including: force-producing means positioned between said reel and said diverter structure for maintaining the unwound pipe section in a fixed vertical plane prior to and during the pipe conditioning.   
     
     
       4. The vessel of claim 3 wherein, said reel comprises a hollow hub and a pair of vertically-disposed side flanges secured to the opposite ends of said hub; and   drive means angularly disposed under at least one of said flanges for rotating said reel.   
     
     
       5. A vessel for continuously laying a pipeline on the seabed underlying a body of water, comprising: a pipe supply reel mounted for rotation on said vessel about its horizontal axis;   drive means for rotating the reel;   level winding means for level winding a pipe section as it is being pulled from the reel;   aligning means for aligning the pipe into a desired single vertical center plane;   straightening means for straightening the aligned pipe section;   diverter means;   said aligning means and said straightening means being mounted on said diverter means, and said diverter means being pivotably mounted on said vessel for changing the lift-off angle of the pipe relative to the horizontal, whereby said aligning and straightening means are positioned on and over the deck of said vessel; and   means for discharging the straightened pipe under tension into said body of water at a desired lift-off angle.   
     
     
       6. The vessel of claim 5 wherein said aligning means are mounted on said diverter means between said straightening means and said reel. 
     
     
       7. The vessel of claim 6 and further including level-winding means mounted near the reel to guide the pipe laterally across the reel as the pipe is wound on and unwound from the reel. 
     
     
       8. The vessel of claim 7 and further including adjustable, horizontal-force-producing means positioned near the aligning means for maintaining the pipe in said vertical center plane prior to and during the straightening of the pipe by said straightening means. .Iadd. 9. A vessel for laying a pipeline on the bed underlying a body of water, comprising: a reel for carrying a continuous length of pipe spooled thereon mounted on said vessel for rotation about a predetermined rotational axis;   a diverter structure having one end portion mounted to said vessel and its other end portion extending upwardly at an acute angle relative to the deck of the vessel;   pipe conditioning means mounted on said diverter structure for conditioning pipe after it is unspooled from said reel and for discharging the conditioned pipe into said body of water; and   drive means for adjusting said diverter structure about its pivot axis to thereby selectively control the angle of discharge of said conditioned pipe into said body of water. .Iaddend..Iadd. 10. A vessel according to claim 9, wherein said pipe conditioning means comprises straightening means for bending the unspooled pipe to a bending radius whose value is selected to substantially straighten the pipe prior to its being discharged into the body of water. .Iaddend..Iadd. 11. A vessel according to claim 10, further including:   level winding means for guiding the pipe laterally across the reel as the pipe is unwound from the reel to said pipe conditioning means. .Iaddend. .Iadd. 12. A vessel according to claim 11, wherein said level winding means is movable in a plane substantially normal to the rotational axis of the reel as pipe is unwound from the reel. .Iaddend..Iadd. 13. A vessel according to claim 9, wherein said diverter structure is pivotably mounted adjacent one end portion of said vessel; and said drive means comprises extensible means mounted on said vessel and operably coupled to said diverter structure for pivoting said diverter structure about said pivot means to a desired elevation as determined by the depth of the body of water and the diameter and size of the pipe. .Iaddend..Iadd. 14. A vessel according to claim 13, wherein:   said reel comprises a hollow hub and a pair of vertically-disposed side flanges secured to the opposite ends of said hub; and   further drive means are provided to cooperate with at least one of said flanges for rotating said reel. .Iaddend..Iadd. 15. A vessel according to claim 9, wherein said pipe conditioning means comprises:   aligning means for aligning the pipe in a desired substantially vertical plane; and   straightening means for straightening the aligned pipe section. .Iaddend..Iadd. 16. A vessel according to claim 15, wherein said diverter structure is pivotably mounted adjacent one end portion of said vessel; and said drive means comprises extensible means mounted on said vessel and operably coupled to said diverter structure for pivoting said diverter structure about said pivot means to a desired elevation as determined by the depth of the body of water and the diameter and size of the pipe. .Iaddend..Iadd. 17. A vessel according to claim 16, wherein said aligning means are mounted on said diverter means between said straightening means and said reel. .Iaddend..Iadd. 18. A vessel according to claim 17, further including:   level-winding means for guiding the pipe laterally across the reel as the pipe is wound on and unwound from the reel through said pipe conditioning means. .Iaddend..Iadd. 19. A vessel for laying a pipeline on the bed underlying a body of water, comprising:   a reel for carrying a continuous length of pipe spooled thereon mounted on said vessel for rotating about a predetermined rotational axis;   a diverter structure pivotably mounted to said vessel;   pipe conditioning means mounted on said diverter structure for conditioning pipe after it is unspooled from said reel and for discharging the conditioned pipe into said body of water, said pipe conditioning means including aligning means for aligning the unspooled pipe in desired plane, and straightening means for plastically bending the unspooled pipe to a bending radius whose value is selected to substantially straighten the pipe prior to its being discharged into the body of water;   level-winding means for guiding the pipe laterally across the reel as the pipe is unwound from the reel; and   drive means for pivoting said diverter structure about its pivot axis to thereby selectively control the angle of discharge of said conditioned pipe into said body of water. .Iaddend..Iadd. 20. A vessel according to claim 19, wherein said level-winding means is movable in a plane substantially normal to the rotational axis of the reel as pipe is unwound from the reel. .Iaddend..Iadd. 21. A vessel according to claim 19, wherein said diverter structure is pivotably mounted adjacent one end portion of said vessel; and said drive means comprises extensible means mounted on said vessel and operably coupled to said diverter structure for pivoting said diverter structure about said pivot means to a desired elevation as determined by the depth of the body of water and the diameter and size of the pipe. .Iaddend..Iadd. 22. A vessel according to claim 19, wherein said aligning means are mounted on said diverter means between said straightening means and said reel. .Iaddend. .Iadd. 23. A vessel for laying a pipeline on the bed underlying a body of water, comprising:   a reel for carrying a continuous length of pipe spooled thereon mounted on said vessel for rotation about a predetermined rotational axis;   a diverter structure pivotably mounted to said vessel;   pipe conditioning means mounted on said diverter structure for conditioning pipe after it is unspooled from said reel and for discharging the conditioned pipe into said body of water, said pipe conditioning means including aligning means for aligning the unspooled pipe in a desired plane, and straightening means for plastically bending the unspooled pipe to a bending radius whose value is selected to substantially straighten the pipe prior to its being discharged into the body of water; and   drive means for pivoting said diverter structure about its pivot axis to thereby selectively control the angle of discharge of said conditioned pipe into said body of water. .Iaddend..Iadd. 24. A vessel according to claim 23, wherein said diverter structure is pivotably mounted adjacent one end portion of said vessel; and said drive means comprises extensible means mounted on said vessel and operably coupled to said diverter structure for pivoting said diverter structure about said pivot means to a desired elevation as determined by the depth of the body of water and the diameter and size of the pipe. .Iaddend..Iadd. 25. A vessel according to claim 23, wherein said aligning means are mounted on said diverter means between said straightening means and said reel. .Iaddend.