Field joint transfer system

Abstract

A field joint transfer system for transferring a hot field joint along a curved path between a tensioner and a stinger during deployment of a pipeline from a pipelay vessel. The system comprises a plurality of adjustable pipe support units defining a curved path between the tensioner and the stinger, wherein one or more of the pipe support units can be moved out of engagement with the pipeline to allow the hot fieldjoint to pass the respective pipe support unit without contact, while maintaining support for the pipeline along the curved path. A mobile pipe support may be provided on an overhead gantry to follow the pipe as it passes along the curved path.

Claims

1. A method of deploying a pipeline from a vessel, the vessel comprising at least one tensioner for controlling the tension of the pipeline between the vessel and the seabed, a stinger over which the pipeline is deployed and a series of adjustable pipe support units defining a curved path between the tensioner and the stinger wherein the adjustable pipe support units are located at fixed distances along the curved path, the method comprising: applying a hot field-joint coating to a weld region of the pipeline; traversing the curved path with the hot field-joint; moving one or more of the adjustable pipe support units out of the curved path to allow the hot field-joint to pass the respective pipe support unit without contact, and wherein a mobile pipe support is provided and is moved with the pipeline, thus maintaining support for the pipeline along the curved path.

2. The method according to claim 1, wherein the mobile pipe support comprises an overhead gantry extending above the curved path and the method comprises supporting the pipe from the gantry adjacent to the hot field joint.

3. The method according to claim 2, wherein the mobile pipe support is adjustable in height to follow the curved path and the method comprises controlling the height automatically in response to a position of the pipe or a force on the mobile pipe support due to the pipe.

4. The method according to claim 1, wherein one or more of the pipe support units are movable along the curved path.

5. The method of claim 1, wherein the field joint coating is applied between the tensioner and a first of the pipe support units and quenching of the coating takes place at least partially after the first of the pipe support units.

6. The method of claim 1, comprising automatically moving the pipe support units out of engagement with the pipe and moving them back into engagement once the hot field joint has passed.

7. A field joint transfer system for transferring a hot field joint along a curved path between a tensioner and a stinger during deployment of a pipeline from a pipelay vessel, the system comprising a plurality of adjustable pipe support units defining a curved path between the tensioner and the stinger, wherein one or more of the pipe support units can be moved out of engagement with the pipeline to allow the hot field-joint to pass the respective pipe support unit without contact, further comprising a mobile pipe support arranged to move with the pipeline while maintaining support for the pipeline along the curved path.

8. The system according to claim 7, further comprising an overhead gantry extending above the curved path and the mobile pipe support traverses along the gantry to support the pipeline.

9. The system according to claim 8, wherein the mobile pipe support comprises a hoist and is adjustable in height to support the pipeline along the curved path.

10. The system according to claim 8, wherein the mobile pipe support is mounted on a bridge carried by the gantry and can move laterally across the bridge with respect to the gantry and the pipeline.

11. The system according to claim 8, wherein the mobile pipe support comprises a sling in which the pipeline rests.

12. The system according to claim 8, comprising two mobile pipe supports arranged to traverse on the gantry and being engageable with the pipeline on either side of the hot field-joint.

13. The system according to claim 7, comprising at least three pipe support units and wherein the curved path has a length of at least 18 meters.

14. The system according to claim 7, wherein the mobile pipe support is adjustable in height to follow the curved path and the system further comprises a controller adapted to control the height automatically in response to a position of the pipe or a force on the mobile pipe support due to the pipe.

15. A pipelay vessel comprising a stinger for deployment of a pipeline from the vessel a tensioner located onboard the vessel for controlling tension in the pipeline and a field joint coating station located between the tensioner and the stinger for applying a field joint coating to a field joint on the pipeline, whereby the pipeline follows a curved path from the tensioner to the stinger during deployment of the pipeline from the vessel, the vessel further comprising a field joint transfer system comprising a plurality of adjustable pipe support units arranged along the curved path between the tensioner and the stinger, wherein one or more of the adjustable pipe support units can be moved out of engagement with the pipeline to allow a field-joint to pass the respective pipe support unit without contact with the field joint coating, further comprising a mobile pipe support arranged to move with the pipeline in a direction of deployment in order to maintain support for the pipeline along the curved path.

16. The vessel according to claim 15, further comprising an overhead gantry extending above the curved path and the mobile pipe support is arranged to traverse along the gantry and comprises a hoist, adjustable in height to support the pipeline along the curved path.

17. The vessel according to claim 15, wherein the mobile pipe support is adjustable in height to follow the curved path and the field joint transfer system further comprises a controller adapted to control the height automatically in response to a position of the pipe or a force on the mobile pipe support due to the pipe.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The features and advantages of the invention will be appreciated upon reference to the following drawings of a number of exemplary embodiments, in which:

(2) FIG. 1 shows a side elevation of part of a vessel operating in S-lay configuration;

(3) FIG. 2 shows a stern starboard side elevation of the vessel during application of the hot field-joint;

(4) FIGS. 3 to 6 show stern starboard side elevations of the vessel of FIG. 2 during deployment of the pipeline;

(5) FIG. 7 shows a stern view of a mobile pipe support.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(6) FIG. 1 shows a side elevation of part of a vessel 4 operating in S-lay configuration to deploy a pipeline 6 over a stinger 5. On board the vessel 4, the pipeline 6 is assembled in a main firing line 1 from single joints by butt welding the joints together as is generally conventional and will not be further described here. The pipeline 6 is lowered through tensioners 2 and over pipe support units 3 and stinger 5 to the seabed 7. The tension applied by the tensioners 2 determines the curvature of the lower section (sagbend) 9 of the pipeline 6, while the angle of the stinger 5 determines the curvature of the upper section (overbend) 8.

(7) FIG. 2 shows a stern starboard side elevation of the vessel 4 in greater detail illustrating the tensioners 2, the pipe support units 3 and the stinger 5. In the illustrated embodiment, three pipe support units 3 are shown although it will be understood that this number may vary according to the length of the curved path that the pipeline 6 must span between the last tensioner 2 and the stinger 5. Between the last tensioner 2 and the first pipe support unit 3 there is located a field-joint coating station 14. A second field joint coating station 14 is located between the first and second pipe support units 3. A butt weld 16 after passing through the last tensioner 2 enters the field joint coating station and a field-joint coating 17 is applied to restore the anticorrosion protective layers and any other layers required by the pipeline 6. Also shown in FIG. 2 is an overhead gantry 13 on which traverses a pair of mobile pipe supports 12 including slings 15, which engage beneath the pipeline 6 close to the field joint coating 17.

(8) Operation of the invention will now be described with reference to FIGS. 3 to 6, which show stern starboard side elevations of the vessel of FIG. 2 during various stages of deployment of the pipeline.

(9) According to FIG. 3, the pipeline 6 has advanced by about half of a pipe joint length (around 6 m) to a point where the still hot field joint coating 17 has approached the pipe support unit 3. In fact, the pipeline 6 has moved rearwards while the vessel 4 has advanced. During this movement, the mobile pipe supports 12 have moved along the gantry 13 supporting partially the weight of the pipeline. Overall operation of the system is controlled by suitable software that monitors the pipelay operation. This software receives real-time input information on pipeline motion including the pipeline laying speed and status of the pipe support units 3 with respect to the position of the hot field-joint coating 17. Additional information received in real-time is the pipeline curvature of the upper section 8. The system software adjusts in real-time the reaction applied from the pipe support units 3 located below the pipeline 6 and the force applied by the mobile pipe supports 12 in order to ensure the same reaction on the pipeline 6 over the curved path.

(10) In FIG. 4, the first two pipe support units 3 have been moved downwards under the control of the system software, out of contact with the pipeline 6. The weight of the pipeline 6 at this location is now supported by the slings 15 of the mobile pipe supports 12. The still hot and not fully cured field-joint coatings 17 can pass through the pipe support units 3 without the field-joint coating 17 becoming damaged.

(11) In FIG. 5, the pipeline 6 has advanced to a position where the field-joint coatings 17 have passed through the pipe support units 3 and the pipe support units 3 have again been raised to take the weight of the pipeline 6. Simultaneously, the system software has reduced the force applied by the mobile pipe supports 12 through the slings 15.

(12) FIG. 6 shows a similar view to FIG. 5, in which the slings 15 have been released whereby the mobile pipe supports 12 may be returned to their starting position. This may take place either manually or automatically.

(13) FIG. 7 shows a stern view of a mobile pipe support 12 showing its support from the gantry 13, which comprises a pair of rails aligned with the fore and aft direction of the vessel 4 and with the pipeline 6. It will be understood that alternative systems using a single rail could also be envisaged. A bridge 20 is mounted on the gantry 13 and is moveable along the gantry rails. The mobile pipe support 12 is mounted to traverse laterally on the bridge 20 such that it can accommodate lateral movement of the pipeline 6. The sling 15 is suspended from mobile pipe support 12, which is embodied as a winch such that the sling 15 can be shortened and lengthened as required during movement of the pipeline 6. Also shown in FIG. 7 is a quick-release system 18 which allows automatic opening of the sling 15 and release of the pipeline 6 once the field-joint coating 17 has passed the pipe support units 3 to the position of FIG. 6.

(14) Thus, the invention has been described by reference to certain embodiments discussed above. It will be recognized that these embodiments are susceptible to various modifications and alternative forms well known to those of skill in the art. In particular, although a gantry system for supporting the pipeline has been shown it will be understood that other systems achieving the same result may also be used. Many modifications in addition to those described above may be made to the structures and techniques described herein without departing from the spirit and scope of the invention. Accordingly, although specific embodiments have been described, these are examples only and are not limiting upon the scope of the invention.