A LAYING TOWER AND METHOD FOR LAYING PIPELINES ON A BED OF A BODY OF WATER

Abstract

A laying tower for laying pipelines on the bed of a body of water has a supporting structure extending along a longitudinal axis and provided with guides parallel to the longitudinal axis; a first clamp, which is mounted on the supporting structure and configured for selectively clamping and releasing the pipeline in a given point along the longitudinal axis; and a second clamp, which is selectively movable along a path, which extends along a first section above the first clamp; and a second section below the first clamp and, partly, below the supporting structure and configured for selectively clamping and releasing the pipeline along the path.

Claims

1-38. (canceled)

39: A laying tower configured to lay a pipeline on a bed of a body of water, the laying tower comprising: a supporting structure extending along a longitudinal axis and comprising a plurality of guides parallel to the longitudinal axis; a first U-shaped clamp mounted on the supporting structure and selectively arrangeable in a first position along the longitudinal axis and in a second position remote from the longitudinal axis, the first U-shaped clamp configured to selectively clamp and release the pipeline at a designated point along the longitudinal axis, the first U-shaped clamp comprising a U-shaped structure, a first jaw, and a first actuator supported by the U-shaped structure and configured to actuate the first jaw from a closed position to an open position; and a second clamp movable along a path that extends along a first section extending above the first U-shaped clamp and a second section below the first U-shaped clamp and partly below the supporting structure, the second clamp configured to selectively clamp and release the pipeline along the path.

40: The laying tower of claim 39, further comprising a cable actuating device configured to control a position of the second clamp along at least one of the supporting structure and the pipeline.

41: The laying tower of claim 40, wherein the cable actuating device comprises two winches mounted to the supporting structure and two cables connected to the second clump.

42: The laying tower of claim 39, further comprising a first arm hingedly connected to the supporting structure and configured to support the first U-shaped clamp and tilt the first U-shaped clamp from the first position to the second position.

43: The laying tower of claim 39, further comprising a trolley comprising a frame and two cursors arranged on opposite sides of the frame and configured to engage the guides.

44: The laying tower of claim 43, wherein the second clamp is configured to be hung on the trolley and hingedly connectable to the trolley.

45: The laying tower of claim 39, wherein the second clamp comprises an annular structure, a second jaw and a second actuator supported by the annular structure and configured to actuate the second jaw from an open position to a closed position.

46: The laying tower of claim 39, wherein the second clamp comprises a plurality of rollers configured to guide the second clamp along the pipeline.

47: The laying tower of claim 39, further comprising a supply and control system comprising a supply cable connectable to the second clamp.

48: The laying tower of claim 39, further comprising a transfer clamp arranged above the first clamp and mounted to the supporting structure by a movable arm configured to arrange the transfer clamp in a rest position remote from the longitudinal axis, an operative position along the longitudinal axis and an operative position offset from the longitudinal axis, the transfer clamp configured to selectively clamp, release and support a multiple joint.

49: The laying tower of claim 48, wherein the movable arm is hingedly connected to the supporting structure and comprises a telescopic arm.

50: The laying tower of claim 39, further comprising a plurality of manipulator arms mounted to the supporting structure above the first U-shaped clamp and selectively clamped to a multiple joint to transfer the multiple joint from an offset position with respect to the longitudinal axis to a position coincident with the longitudinal axis.

51: The laying tower of claim 39, further comprising a plurality of guiding devices configured to slidably axially couple to a multiple joint.

52: The laying tower of claim 39, further comprising an aligning device movable along the longitudinal axis and configured to house an upper free end of a multiple joint, wherein the aligning device is moveably mountable on the supporting structure to keep the multiple joint aligned with the longitudinal axis.

53: The laying tower of claim 39, further comprising a load device comprising an arm, an actuator to arrange the arm from a lowered position to a raised position substantially parallel to the longitudinal axis, and a plurality of gripping devices distributed along the arm and configured to selectively grip a multiple joint at a plurality of points.

54: The laying tower of claim 39, wherein the supporting structure comprises a main frame hingedly connectable to a laying vessel about an axis, and a lower frame, the guides extending along the main frame and the lower frame.

55: The laying tower of claim 39, wherein the supporting structure comprises a main frame hingedly connectable to a laying vessel about an axis, and an upper frame hingedly connected to the main frame and movable from an operative position that defines a prolongation of the main frame to a rest position wherein the upper frame is arranged side by side to the main frame.

56: A laying vessel for laying a pipeline on a bed of a body of water, the laying vessel comprising: a deck; and a laying tower moveably hinged about an axis, the laying tower extending above and below the axis and comprising: a supporting structure extending along a longitudinal axis and comprising a plurality of guides parallel to the longitudinal axis, a first U-shaped clamp mounted on the supporting structure and selectively arrangeable in a first position along the longitudinal axis and in a second position remote from the longitudinal axis, the first U-shaped clamp configured to selectively clamp and release the pipeline at a designated point along the longitudinal axis, the first U-shaped clamp comprising a U-shaped structure, a first jaw, and a first actuator supported by the U-shaped structure and configured to actuate the first jaw from an open position to a closed position, and a second clamp movable along a path that extends along a first section extending above the first U-shaped clamp and a second section below the first U-shaped clamp and partly below the supporting structure, the second clamp configured to selectively clamp and release the pipeline along the path.

57: The laying vessel of claim 56, further comprising an assembling station moveably mounted along the deck and selectively arranged in an operative position about the longitudinal axis and above the first clamp to join a multiple joint to the pipeline and in a remote position with respect to the operative position.

58: The laying vessel of claim 56, further comprising a platform movable from a rest position to an operative position parallel to the longitudinal axis and configured to arrange a multiple joint coupleable to a part of the pipeline a designated distance from the supporting structure.

59: A laying method for laying a pipeline on a bed of a body of water, the method comprising: keeping a free end of the pipeline in a designated position with a first U-shaped clamp arranged in a supporting structure of a laying tower; joining a multiple joint to the free end of the pipeline in the laying tower above the first U-shaped clamp; clamping the pipeline with a second clamp, wherein the second clamp is movable along a designated path which extends along a first section above the first U-shaped clamp and along a second section below the first U-shaped clamp and partly below the supporting structure, wherein when the multiple joint has a length corresponding to a length of the first section, the second clamp is above the first U-shaped clamp and when the multiple joint has a length corresponding to a length of the second section, the second clamp is below the first U-shaped clamp; releasing the first U-shaped clamp from the pipeline; arranging the first U-shaped clamp from a first position along the path to a second position remote from the path; and laying the pipeline by a stroke of the second clamp along a portion of the path.

60: The laying method of claim 59, wherein the first section is shorter than the second section.

61: The laying method of claim 59, further comprising guiding the second clamp along the supporting structure and along the pipeline.

62: The laying method of claim 59, further comprising releasing the second clamp from the supporting structure, and guiding the second clamp by the pipeline in the body of water along at least a part of the second section.

63: The laying method of claim 59, further comprising moving the second clamp along the path by a cable actuating device.

64: The laying method of claim 63, wherein the cable actuating device comprises two winches and two cables connected to the second clamp.

65: The laying method of claim 59, further comprising guiding the second clamp along the pipeline by a plurality of rollers rotatably mounted on the second clamp.

66: The laying method of claim 59, further comprising supplying the second clamp by a supply cable.

67: The laying method of claim 59, further comprising supporting a multiple joint transfer clamp arranged above the first U-shaped clamp and mounted to the supporting structure by a movable arm configured to arrange the multiple joint transfer clamp in a rest position remote from the longitudinal axis, an operative position along the longitudinal axis, and an operative position offset from the longitudinal axis, wherein the multiple joint transfer clamp is configured to selectively clamp, release and support the multiple joint.

68: The laying method of claim 59, further comprising transferring the multiple joint from a position offset from the longitudinal axis to a position coincident with the longitudinal axis by a plurality of manipulator arms mounted to the supporting structure above the first U-shaped clamp, wherein the manipulator arms are selectively coupleable to the multiple joint.

69: The laying method of claim 59, further comprising guiding the multiple joint along the first section of the path by a plurality of guiding devices supported by the supporting structure and configured to axially slidably couple to the multiple joint.

70: The laying method of claim 59, further comprising housing an upper end of the multiple joint by an aligning device, and aligning the multiple joint with the longitudinal axis by the aligning device.

71: The laying method of claim 70, further comprising varying a position of the aligning device along the longitudinal axis to adjust the position of the aligning device to the length of the multiple joint.

72: The laying method of claim 59, further comprising supplying the multiple joint to the supporting structure by a load device comprising an arm, an actuator configured to arrange the arm from a lowered position to a raised position substantially parallel to the longitudinal axis, and a plurality of gripping devices distributed along the arm and configured to selectively grip the multiple joint at a plurality of points.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0057] Further features and advantages of the present invention will become clear from the following description of a non-limiting embodiment thereof, with reference to the figures of the attached drawings, wherein:

[0058] FIG. 1 is a side elevational view, with parts removed for clarity, of a laying vessel comprising a laying tower made according to the present invention;

[0059] FIG. 2 is a schematic view, with parts removed for clarity, relating to a unitary joint, a quadruple joint, a joint with a special piece, and a hexajoint, manipulable by the laying vessel in FIG. 1;

[0060] FIG. 3 is a front elevational view, on an enlarged scale and with parts removed for clarity, of a laying tower of the laying vessel in FIG. 1 made according to the present invention;

[0061] FIG. 4 is a sectional view, with parts removed for clarity, of the laying tower in FIG. 3 according to the section lines IV-IV;

[0062] FIGS. 5 and 6 are side elevational views, with parts removed for clarity and on an enlarged scale, of a detail in FIG. 4 in two different configurations;

[0063] FIG. 7 is a perspective view, with parts removed for clarity, of a detail of the laying tower in FIG. 3;

[0064] FIG. 8 is a sectional view, with parts removed for clarity, of the detail in FIG. 7;

[0065] FIGS. 9 and 10 are perspective views, on an enlarged scale and with parts removed for clarity, of the laying vessel in FIG. 1;

[0066] FIG. 11 is a perspective view, with parts removed for clarity, of a detail of the laying tower in FIG. 3; and

[0067] FIG. 12 is a schematic view, with parts removed for clarity, of the laying tower that is the subject of the present invention.

PREFERRED EMBODIMENT OF THE INVENTION

[0068] A laying vessel 1 for laying a pipeline 2 on the bed 3 of a body of water 4 is globally represented, with reference to FIG. 1. The term “pipeline” is understood to mean both a complete pipeline and a pipeline in the process of being manufactured.

[0069] With reference to FIG. 2, the term “unitary joint” J is understood to mean a piece of tube having a unitary length, generally 12 meters, which is joined in a prefabrication station (not shown) to one or more unitary joints J to form “multiple joints” (QJ quadruple joint; HJ sextuple joint or hexajoint; and QJS quadruple joints comprising special pieces).

[0070] With reference to FIG. 1, the laying vessel 1 comprises a deck 5; and a laying tower 6, which is hinged to the laying vessel 1 close to the deck 5 about an axis A1 and extends above and below the first axis A1 and partly in the body of water 4. The laying tower 6 extends along a longitudinal axis A transverse to the axis A1 and it is selectively movable between a lowered position substantially parallel to the deck 5 and a raised position substantially perpendicular to the deck 5.

[0071] By way of example, in the present description of a preferred embodiment of the invention, reference will be made to a laying vessel 1 and to a laying tower 6 sized to lay a pipeline 2 to which quadruple joints QJ (FIG. 2) are progressively joined in successive steps, but which is also capable of operating with hexajoints HJ (FIG. 2). Furthermore, the definition of “multiple joint” comprises both the quadruple joints QJ (FIG. 2), and hexajoints HJ (FIG. 2). In the present description, besides defining the extension axis of the laying tower 6, the longitudinal axis A identifies the axis along which the pipeline 2 and/or the multiple joint extend, when the pipeline 2 and/or the multiple joint are in the laying tower 6. Basically, the position of the pipeline 2 or of the multiple joint inside the laying tower 6 can be identified by the longitudinal axis A.

[0072] The laying vessel 1 comprises an assembling station 7 mounted in a movable manner on the deck 5 for selectively being arranged in an operative position about the longitudinal axis A and a remote position with respect to the operative position; a platform 8 movable between a horizontal rest position and an operative position parallel to the longitudinal axis A for the loading of quadruple joints comprising special pieces QJS (FIG. 2), i.e. elements of a considerable size; and a prefabrication station, not shown in the attached Figures, wherein the unitary joints J (FIG. 2) are assembled to form the multiple joints.

[0073] With reference to FIGS. 3 and 4, the laying tower 6 comprises a supporting structure 9, which extends along the longitudinal axis A and comprises guides 10 parallel to the longitudinal axis A; a trolley 11 engageable in the guides 10 and selectively movable along a path P; a clamp 12, which is mounted on the supporting structure 9 and configured for selectively clamping and releasing the pipeline 2 (FIG. 1) in a given point along the longitudinal axis A; and a clamp 13, which is mounted on the trolley 11 and configured for selectively clamping and releasing the pipeline 2 (FIG. 1), both along a section T1 (FIG. 10) of path P extending above the clamp 12, and along a section of path T2 (FIG. 10), which extends below the clamp 12 and, partly, below the supporting structure 9.

[0074] The supporting structure 9 comprises a main frame 14 hinged to the laying vessel 1 about the axis A1; and a lower frame 15. The main frame 14 comprises two longitudinal beams 16 substantially parallel to the longitudinal axis A; and transverse beams 17. The longitudinal beams 16 and the transverse beams 17 are made with box-like profiles, of a metal material. The lower frame 15 is mounted at the lower end of the main frame 14 and defined by a reticular structure, which is generally called a “stinger” in the sector of pipeline laying.

[0075] The laying tower 6 comprises an upper frame 18, which, in this case, is a reticular structure, hinged to the main frame 14 and selectively movable between an operative position, wherein it defines the prolongation of the main frame 14, and a rest position, not shown in the attached Figures and wherein it is arranged side by side to the main frame 14.

[0076] The clamp 12 is mounted to the supporting structure 9 so as to be selectively arranged in a first position along the longitudinal axis A (FIG. 5) and in a second position remote from the longitudinal axis A (FIG. 6).

[0077] With reference to FIGS. 5 and 6, the laying tower 6 comprises an arm 19, which is hinged to the supporting structure 9, configured for supporting the clamp 12 and tilting the clamp 12 between the first (FIG. 5) and the second position (FIG. 6) by means of an actuation not shown in the attached Figures.

[0078] The clamp 12 comprises a U-shaped plan structure 20; a plurality of jaws (not shown in the attached Figures) and a plurality of actuators 21 supported by the U-shaped structure 20 and configured to actuate the jaws (not shown) between an open position and a closed position.

[0079] With reference to FIG. 7, the trolley 11 comprises a frame 22; and two cursors 23 integral with the frame 22, which are arranged on opposite sides of the frame 22, configured to engage the guides 10 (FIGS. 3 and 4). The frame 22 further has a central opening for housing the pipeline 2 or a multiple joint with clearance.

[0080] With reference to FIG. 6, the clamp 13 is hung to the trolley 11 and hinged to the trolley 11 so as to be able to oscillate freely with respect to the trolley 11 about an axis and comprises an annular structure 24; a plurality of jaws 25; and a plurality of actuators 26 supported by the annular structure 24 and configured to actuate the respective jaws 25 between a closed position and an open position. The clamp 13 further comprises rollers 27, configured for guiding the clamp 13 along the pipeline 2. The rollers 27 are mounted to the annular structure 24 and at the opposite ends of the clamp 13 with the function of favouring the sliding of the clamp 13 along the pipeline 2 or the multiple joint without damaging the pipeline 2 and the multiple joint.

[0081] With reference to FIGS. 3 and 4, the laying tower 6 comprises a cable actuating device 28 configured to control the position of the trolley 11 and the clamp 13 along the supporting structure 9 and along the pipeline 1 below the supporting structure 9. In other words, the trolley 11 is guided by the supporting structure 9 along the main frame 14 and along the lower frame 15 by the guides 10 and can come out of the guides 10 in the body of water 4. When the trolley 11 is not coupled to the guides 10 of the supporting structure 9, the trolley 11 and the clamp 13 are integrally coupled to the pipeline 2 or they are guided by the pipeline 2 inside the body of water 4.

[0082] To allow the trolley 11 to temporarily abandon the supporting structure 9 and be coupled again to the supporting structure 9, each guide 10 substantially has a recess, the lower ends of which are open and, in particular, flared.

[0083] In this case, the cable actuating device 28 comprises two winches 29 mounted to the supporting structure 9; two cables 30 connected to the trolley 11 and two return pulleys 31 mounted to the supporting structure 9 above the respective winches 29.

[0084] With reference to FIG. 5, the laying tower 6 comprises a supply and control system, which comprises two umbilical cables 32 parallel to the cables 30 and connected to the trolley 11 and to the clamp 13. The umbilical cables 32 contain hydraulic pipes, electric cables and signal cables (not shown in the attached Figures, for actuating and respectively controlling the clamp 13.

[0085] With reference to FIGS. 9 and 10, the laying tower 6 comprises a supply and guiding system for supplying and guiding the multiple joints in a given position in the laying tower 6. A joint QJ is illustrated in FIG. 9, while a joint HJ is illustrated in FIG. 10. Basically, the multiple joints from the deck 5 of the laying vessel 1 must be arranged between the two longitudinal beams 17 in alignment and in contact with the pipeline 2 in order to be able to join the multiple joint to the pipeline 2 held by the clamp 12 (not visible in FIG. 9). The supply and guiding system comprises a load device 33, which comprises an arm 34 hinged about the axis A1; an actuating mechanism 35 for selectively arranging the arm 34 between a lowered position substantially parallel and close to the deck 5 of the laying vessel 1 (FIG. 9) and a raised position substantially parallel to the longitudinal axis A of the laying tower 6 (FIG. 6); and a plurality of gripping devices 36 distributed along the arm 34 for selectively gripping a multiple joint in a plurality of points and releasing the multiple joint. The arm 34 extends for almost the entire length of the laying tower 6 and has the function of arranging a multiple joint close to the longitudinal axis A. The supply and guiding system comprises devices associated with the laying tower 6 for transferring the multiple joint from the arm 34 to the laying tower 6 in alignment with the pipeline 2 and the longitudinal axis A.

[0086] In this particular case and with reference to FIGS. 3 and 4, the laying tower 6 comprises a transfer clamp 37, which is arranged above the clamp 12, it is configured for selectively clamping, releasing and supporting a multiple joint in proximity of the lower end of the same, and it is mounted to the supporting structure 9 by means of a movable arm 38 configured for arranging the transfer clamp 37 between a rest position remote from the longitudinal axis A; an operative position along the longitudinal axis A; and a second operative position offset with respect to said longitudinal axis A.

[0087] With reference to FIG. 11, the movable arm 38 is hinged to the supporting structure 9 and it is telescopic. The transfer clamp 37 is configured to support the weight of the entire multiple joint.

[0088] With reference to FIGS. 3 and 4, the supply and guiding system comprises a plurality of manipulator arms 39, which are mounted to the supporting structure 9 above the transfer clamp 37, they can be selectively coupled to a multiple joint for transferring the multiple joint from a position offset with respect to the longitudinal axis A and a position coincident with the longitudinal axis A. Basically, between a multiple joint held by the load device 33 (FIG. 7), when the arm 34 is parallel to the longitudinal axis A.

[0089] The supply and guiding system comprises a plurality of guiding elements 40, which are mounted in a retractable manner on the supporting structure 9 and configured for axially coupling in a sliding manner to a multiple joint.

[0090] The supply and guiding system comprises an aligning device 41 movable along the longitudinal axis A, and configured for housing the upper free end of a multiple joint. The aligning device 41 is mounted in a sliding manner parallel to the longitudinal axis A on the upper frame 18 to support the upper end of the multiple joint having a length equal to six times the length of the unitary joint. The aligning device 41 is designed to operate only with the hexajoints HJ since the alignment of the quadruple joints QJ can be carried out by the clamp 13.

[0091] In use, a sequence of laying steps is described, wherein the laying tower 6 passes from a configuration for laying a pipeline 2 to which quadruple joints QJ are progressively joined (FIG. 2), to a configuration, wherein the pipeline 2 is joined, in successive steps, to hexajoints HJ (FIG. 2). For the laying of quadruple joints QJ, the clamp 13 performs travels along the section T1 of the path P above the clamp 12 where such travels are substantially equal to the length of a quadruple joint QJ.

[0092] With reference to FIG. 10, the clamp 13 is shown with a continuous line at the upper end of the section T1 of the path P and sketched at the lower end of the section T1 of the path P, directly above the clamp 12. When a quadruple joint QJ is supplied to the supporting structure and aligned with the pipeline 2, the clamp 13 is lowered and inserted about the quadruple joint QJ at the upper end of the quadruple joint QJ. The clamp 13 grips the quadruple joint QJ in a given position depending on the laying travel it has to complete and on the position the clamp 13 must be in after completing the laying travel. The assembling station (not shown in FIG. 8) joins the quadruple joint QJ to the free end of the pipeline 2 held in position by the clamp 12.

[0093] After completing the joining of the quadruple joint QJ to the pipeline 2, the clamp 12 is released and tilted in the configuration shown with sketched lines so as to allow the passage of the clamp 13, at the clamp 12. The travel downwards or laying travel of the clamp 13 is equal to the length of the quadruple joint QJ and the clamp 13 is stopped below the clamp 12, which is arranged in position again (with a complete line) ready to grip the pipeline 2.

[0094] The new position of the clamp 13 along the section T2 of the path P was determined by the choice of the point in which the clamp 13 gripped the quadruple joint QJ in the section T1 of the path P.

[0095] When the clamp 13 is arranged along the section T2 of path P, the laying tower 9 is ready to receive the hexajoints HJ. A hexajoint HJ is loaded into the supporting structure 9 in the same way as the quadruple joints QJ are loaded. The only difference lies in the fact that the hexajoint HJ is aligned by means of the aligning device 41 instead of with the clamp 13.

[0096] Once the hexajoint HJ has been joined to the pipeline 2, the clamp 12 releases the pipeline 2, and the clamp 13 performs a laying travel equal to the length of the hexajoint HJ along the section T2. The laying travel of the clamp 13 along the section T2 is completed, partly, along the supporting structure 9 and, partly, freely in the body of water below the supporting structure 9. When the clamp 13 is not guided by the supporting structure 9, the clamp 13 is guided by the pipeline 2, which starts to bend slightly (the extent of the curvature depends on the depth of the sea-bed). Then, the clamp 13 is brought back by the cable actuating device 28 into the position directly below the clamp 12.

[0097] As in the previous description, the clamp 13 can be brought back to the section T1 of the path P. In particular, on completion of the laying travel, the clamp 13 grips the pipeline 2 in proximity of the clamp 12 and below the clamp 12, which is tilted to allow the passage of the clamp 13. When the clamp 13 is arranged along the section T1, the clamp 12 is positioned in the operative position and grips the pipeline 2 so that the pipeline 2 has the free end thereof at the assembling station 7. The clamp 13 releases the pipeline 2 and is then taken to the upper end of the section T1 of the path P, to allow the loading of a quadruple joint QJ or a quadruple joint comprising a special piece.

[0098] Clearly, the present invention includes further variations, not explicitly described, without thereby departing from the protective scope of the following claims.