Subsea pig launchers

Patent metadata

Field	Value
Publication number	US-11137103-B2
Application number	US-201916966593-A
Country	US
Kind code	B2
Filing date	Feb 5, 2019
Priority date	Feb 6, 2018
Publication date	Oct 5, 2021
Grant date	Oct 5, 2021

Abstract

A multiple pig launcher includes a tubular structure along which a series of pipeline pigs may be advanced in stepwise fashion to be launched into a pipeline in succession. A launching station holds a first pig at a downstream end of the series in readiness for launch. A pig stopper mechanism is operable selectively to hold a second pig at a holding station upstream of the launching station when launching the first pig and to release the second pig from the holding station to be advanced into the launching station after the first pig has been launched. The pig stopper mechanism comprises at least one radially movable gripper element that can apply radially inward gripping force to a pig held at the holding station.

First claim

The invention claimed is:

1. A multiple pig launcher comprising a tubular structure along which a series of pipeline pigs may be advanced stepwise in a downstream direction to be launched into a pipeline in succession, the launcher comprising:
a launching station arranged to hold a first pig at a downstream end of the series in readiness for launch;
a holding station upstream of the launching station in the tubular structure; and
a pig stopper mechanism that is operable selectively to hold a second pig at the holding station when launching the first pig and to release the second pig from the holding station to be advanced into the launching station after the first pig has been launched;
wherein the pig stopper mechanism comprises at least one radially movable gripper element that is arranged to apply radially-inward gripping force to a pig held at the holding station and wherein the at least one gripper element is moveable radially inwardly by a camming action applied to it by an associated longitudinally moveable cam formation.

2. The pig launcher of claim 1 , wherein the pig stopper mechanism is operable to reduce the internal diameter of the tubular structure at the holding station.

3. The pig launcher of claim 1 , wherein the pig stopper mechanism comprises an angularly spaced array of gripper elements that surround the holding station.

4. The pig launcher of claim 1 , wherein the at least one gripper element is fixed longitudinally with respect to the holding station.

5. The pig launcher of claim 1 and having a plurality of gripper elements spaced longitudinally with respect to each other along the holding station.

6. The pig launcher of claim 1 , wherein the at least one gripper element is movable radially outwardly by resilience upon being released by the cam formation.

7. The pig launcher of claim 1 and having an angularly spaced array of the cam formations disposed around the tubular structure at the holding station.

8. The pig launcher of claim 1 , wherein the at least one cam formation is supported for said longitudinal movement by a longitudinally movable actuator.

9. The pig launcher of claim 8 , wherein the actuator is annular and surrounds the holding station.

10. The pig launcher of claim 8 , wherein the actuator comprises a piston that is movable longitudinally along the tubular structure.

11. The pig launcher of claim 10 , wherein the cam formations are supported by a sleeve that is fixed to the piston and that extends longitudinally beyond the piston.

12. The pig launcher of claim 1 and having a plurality of cam formations spaced longitudinally with respect to each other along the holding station.

13. The pig launcher of claim 1 , wherein the at least one gripper element comprises a free end facing in the downstream direction, movable radially relative to an opposed radially fixed root end.

14. The pig launcher of claim 13 , wherein the at least one gripper element comprises a finger supported by a pipe that extends along the holding station.

15. The pig launcher of claim 14 , wherein the at least one finger is integral with the pipe and is defined by cut-outs that penetrate a wall of the pipe.

16. The pig launcher of claim 1 , wherein the launching station is arranged to hold the first pig by frictional engagement.

17. The pig launcher of claim 16 , wherein the launching station comprises a tube that tapers internally in the downstream direction.

18. The pig launcher of claim 1 , further comprising a pusher arranged to apply force in the downstream direction to a pig at an upstream end of the series to advance the at least one remaining pig in the downstream direction after the first pig has been launched.

19. The pig launcher of claim 18 , wherein the pusher comprises a deadweight that is movable under its weight along the tubular structure.

20. The pig launcher of claim 18 , wherein the pusher comprises a piston or a fluid injection system.

21. The pig launcher of claim 1 , further comprising a pig magazine upstream of, and communicating with, the holding station.

22. The pig launcher of claim 1 , when containing at least one pig.

23. The pig launcher of claim 22 , wherein the launching station comprises a tube whose internal diameter is less than an external diameter of the at least one pig in the launcher.

24. The pig launcher of claim 22 , wherein the pusher comprises a deadweight that is movable under its weight along the tubular structure and the deadweight bears down upon an upstream end of the at least one pig in the launcher.

25. The pig launcher of claim 22 , wherein the pig stopper mechanism is arranged simultaneously to engage at least two successive sealing discs along the length of the at least one pig in the launcher.

26. A method of launching a series of pipeline pigs into a pipeline in succession, the method comprising:
holding a first pig at a downstream end of the series at a launch position in readiness for launch wherein the first pig is held by a frictional engagement that is overcome, on launch, by kicker fluid pressure;
generating a radially-inward gripping force by moving an actuator longitudinally with respect to a second pig of the series immediately upstream of the first pig; and
by selective application and release of said radially-inward gripping force, holding the second pig when launching the first pig and then releasing the second pig to be advanced into the launch position after the first pig has been launched.

27. The method of claim 26 , comprising advancing the second pig, when released, by applying pusher force behind the second pig.

28. The method of claim 26 , comprising applying said gripping force to the second pig in response to a command to launch the first pig.

29. The method of claim 26 , comprising applying said gripping force to the second pig from at least two mutually opposed radial directions.

30. The method of claim 26 , comprising applying said gripping force to the second pig at two or more locations spaced along the pig.

31. The method of claim 26 , comprising advancing the second pig, when released, through the actuator.

Assignees

• Subsea 7 Norway As

Inventors

• Meling Torstein
• Stangeland Oivind
• Bird William Tobias

Classifications

• B08B9/0551

  Control mechanisms therefor · CPC title

• F16L55/46 Primary

  Launching or retrieval of pigs or moles · CPC title