Pipelay vessel

Abstract

A pipelay vessel has a stinger extending along and outboard of one side of the vessel. A diverter is arranged to lead pipe onto the stinger input end through a predominantly horizontal diversion angle from a pipeline source having a substantially horizontal orientation. The vessel is selectively operable in any one of three modes, namely: (1) shallow S-lay, in which the pipe is launched over a stern-mounted stinger with a launch angle which has a predominantly horizontal component; (2) steep S-lay, in which the pipe is launched over the side-mounted stinger with a launch angle which has a predominantly vertical component; and (3) J-lay, in which the pipe is welded at and launched from a tower. The axis of the J-lay apparatus is aligned with the departure axis of the side-mounted stinger.

1 . A pipelay vessel having a stinger extending along and outboard of one side of the vessel, the stinger having an input end and a launch end, the launch end being operable at a desired angle to the horizontal, and a diverter arranged to lead pipe onto the stinger input end through a predominantly horizontal diversion angle from a pipeline source having a substantially horizontal orientation. 
     
     
         2 . A pipelay vessel according to  claim 1 , in which the diversion angle has both horizontal and vertical components with the vertical diversion being the minor component. 
     
     
         3 . A pipelay vessel according to  claim 1 , further including a straightening and tensioning apparatus located on a section of a pipeline path, between the diverter and the input end of the stinger. 
     
     
         4 . A pipelay vessel according to  claim 3 , in which the straightening and tensioning apparatus comprises at least one straightener and at least one tensioner, sequentially arranged alongside said section of the pipeline path. 
     
     
         5 . A pipelay vessel according to  claim 3 , in which the straightening and tensioning apparatus extends along a curved path located substantially above deck level such that the pipeline path has a downward component on entry to the stinger. 
     
     
         6 . A pipelay vessel according to  claim 1 , in which the input end of the stinger is disposed adjacent the stern of the vessel, the launch end of the stinger is disposed forward of the input end, and the diverter comprises at least one ramp extending around either a stern or a bow of the vessel. 
     
     
         7 . A pipelay vessel according to  claim 6 , in which the ramp is supported outboard of the hull. 
     
     
         8 . A pipelay vessel according to  claim 6 , in which the launch end of the stinger is adapted to be positioned, in use, in a vertical orientation within a length of the vessel. 
     
     
         9 . A pipelay vessel according to  claim 1 , including a J-lay apparatus positioned outboard of said one side of the vessel to have a J-lay axis collinear with the launch axis of the stinger. 
     
     
         10 . A pipelay vessel according to  claim 1 , in which said pipeline source having a substantially horizontal pipe orientation comprises a pipe firing line extending parallel to and adjacent a side of the vessel opposite to a side on which the stinger is disposed. 
     
     
         11 . A pipelay vessel according to  claim 1 , further including a shallow angle stinger extending from the stern of the vessel and generally aligned with said firing line. 
     
     
         12 . A pipelay vessel according to  claim 1 , further including a vertical-axis pipe reel located adjacent a pipeline path extending between the pipeline source and the stinger. 
     
     
         13 . A pipelay vessel according to  claim 12 , in which the diverter comprises a first ramp for diverting pipe from the pipeline source to the stinger, a second ramp for diverting pipe from the pipeline source to the reel. 
     
     
         14 . A pipelay vessel according to  claim 1 , including one or more cranes at least one of which is positioned adjacent to a side of the vessel opposite to a side on which the stinger is disposed. 
     
     
         15 . A pipelay vessel according to  claim 1 , in which the stinger is formed by articulated sections, and the vessel includes a stinger support and handling mechanism operable to move the stinger between a fully deployed position with a vertical departure axis and a retracted position above the vessel's waterline. 
     
     
         16 . A pipelay vessel according to  claim 15 , in which there are two articulation points for the stinger, the stinger having a first curved section articulated at about deck level and a second curved section articulated to the distal end of the first section somewhere below the water line when deployed. 
     
     
         17 . A pipelay vessel according to  claim 15 , in which the stinger support and handling mechanism comprises a flexible suspension member connected between the hull and an intermediate point on the second section and a flexible handling member connected between the hull and a point adjacent the distal end of the second section. 
     
     
         18 . A pipelay vessel according to  claim 1 , in which the launch end of the stinger is flared transversely of the launch path by between 4° and 10° to permit limited relative motion between the pipe axis and the vessel. 
     
     
         19 . A pipelay vessel having:
 a firing line having an axis on which pipe sections are welded together to form a continuous pipeline;   shallow water launching support aligned with the firing line;   deep water launching support contained within the length of the vessel; and   a diverter arranged to selectively lead said pipeline from the firing line to the deep water launching support.   
     
     
         20 . A pipelay vessel according to  claim 19 , in which the shallow water launching support comprises a shallow water stinger extending from a stem of the vessel for supporting pipeline as it bends to a departure angle. 
     
     
         21 . A pipelay vessel according to  claim 19 , in which the deep water launching support comprises a deep water stinger disposed along and outboard of one side of the vessel for supporting pipeline as it bends to a departure angle. 
     
     
         22 . A pipelay vessel according to  claim 19 , further comprising a J-lay apparatus comprising a tower which in use is disposed generally vertically, the tower being provided with pipe tensioning apparatus and one or more welding stations, wherein the J-lay apparatus has a launch axis aligned with the in-use position of a launch end of the deep water stinger. 
     
     
         23 . A pipelay vessel according to  claim 19 , further including a vertical axis pipe reel, wherein the diverter is selectively operable to lead pipe from the firing line to the storage reel. 
     
     
         24 . A pipelay vessel which is selectively operable in any one of three modes, namely (1) shallow S-lay, in which the pipe is launched over a stinger with a launch angle which has a predominantly horizontal component; (2) steep S-lay, in which the pipe is launched over a stinger with a launch angle which has a predominantly vertical component; and (3) J-lay, in which the pipe is welded at and launched from a tower which has a generally vertical orientation. 
     
     
         25 . A pipelay vessel according to  claim 24 , including a single firing line for forming pipe for both shallow S-lay and steep S-lay modes. 
     
     
         26 . A pipelay vessel according to  claim 25 , further including a vertical axis pipe reel arranged to selectively supply pipe to the steep S-lay stinger and/or to receive pipe from the firing line.