Hydraulic and earth engineering – Subterranean or submarine pipe or cable laying – retrieving,... – Submerging – raising – or manipulating line of pipe or cable...
Reexamination Certificate
2002-10-31
2004-05-11
Lagman, Frederick L. (Department: 3673)
Hydraulic and earth engineering
Subterranean or submarine pipe or cable laying, retrieving,...
Submerging, raising, or manipulating line of pipe or cable...
C405S170000, C405S168300, C405S168100, C405S168400, C405S166000
Reexamination Certificate
active
06733208
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable
REFERENCE TO A “MICROFICHE APPENDIX”
Not applicable
BACKGROUND
1. Field
The present invention relates to the placement of pipelines and pipeline manifolds in a marine environment. More particularly, the present invention relates to an improved method and apparatus for laying a pipeline in a marine environment, wherein a specially configured pipeline laying ship provides a hull with a deck area and having a pair of reels independently rotatable during use, and wherein a pipeline fabricating “firing line” fabricates a pipeline that is then wound upon a selected one of the reels. The pipeline “firing line” can be moved in order to align with either of the reels that is selected. Additionally, the pipeline can be payed out from either of the selected reels after it has been fabricated. A tower is provided for directing the pipeline from a reel through bend control and straightening stations and then to the seabed. The tower can be positioned at the vessel stern, or amidships for launching the pipeline through a vertical hull opening or “moon pool”.
2. General Background
For many years, pipelines have been fabricated at sea and lowered to the seabed at a desired location. For example, early patents to Tesson include U.S. Pat. Nos. 3,237,438 and 3,337,469 that are directed to a pipeline laying barge and method of operation. In the Tesson patents, the joints of pipe are welded on deck and then spooled or wound upon a reel. At a desired location, the pipeline is then placed on the seabed by unwinding the pipe from the reel and straightening it before it is lowered to the seabed. A tilting tower has also been used to lower a pipeline to the seabed as the pipeline is being unwound from a reel. An example of such a titling tower and reel pipeline laying arrangement can be seen in the Uyeda U.S. Pat. No. 4,345,855 as an example. A similar arrangement is seen in the Springett U.S. Pat. No. 4,340,322. The Uyeda U.S. Pat. No. 4,345,855 and the Springett U.S. Pat. No. 4,430,322 are hereby incorporated herein by reference. Another method of laying a pipeline is through the use of a stinger. A stinger is simply an elongated boom structure that extends from usually one end of a hull or barge. The stinger supports the pipeline as it is being lowered to the seabed. Examples of the use of stingers can be seen us U.S. Pat. Nos. RE28,922, RE29,591 and 5,533,834.
Reel type pipeline laying systems are typically employed in deep water situations. While it is known to weld the pipeline joints on the deck of a vessel and wind them upon a reel (for example, see the above discussed Tesson patents), it is also known to weld the pipeline on shore and then wind it upon the reel before the ship leaves port.
General Discussion
The present invention provides an improved pipeline laying vessel and its method of operation. The method employs a preferably dynamically positioned barge or self-propelled dynamically positioned reel ship that has two independently rotatable reels or drums. The ship has a deck area that enables pipe joints to be welded together to form a pipeline. Joints of pipe are placed in a storage area on the deck of a vessel in suitable pipe racks. Welding stations near this storage area are arranged to receive multiple joints of pipe that have been internally cleaned and prepared for welding. Part of this preparation can include, for example, end bevels that are applied to the pipeline and to individual pipe joints.
As pipeline fabrication proceeds, pipe joints are moved from the rack storage areas to the pipeline fabrication area, also referred to herein as the “firing line.”
This fabrication area or “firing line” can comprise essentially a set of rollers supporting the pipeline along the center line of the fabrication area. Welding equipment (manual or automatic) can be provided together with known weld preparation tools.
The incoming pipe joints are aligned with the pipeline being fabricated. The welded area between the pipe joints and the joints previously welded together can be adjusted as required. The pipe joints are progressively welded together to form a pipeline at multiple welding stations. The welds are tested and field joints are then coated at another work station located in the pipeline fabrication area.
When one or more joints of pipe have been welded together end-to-end on the firing line, a selected reel or drum is readied for storage of the assembled pipeline on provided reels or drums. In keeping with the present invention, two (2) reels or drums are provided. A selected length (eg. about forty feet or 12 m) of pipeline is advanced at any time and wound upon the reel by plastic bending. The pipeline moves ahead in the pipeline fabrication area by the same distance (eg. 40 feet increments or 12 m increments) through a back tensioning device.
The pipeline welding progresses until the selected drum or reel is filled with the pipeline that is being welded on the deck of the vessel. Each reel or drum can be between 30 and 70 feet (9 and 21 m) in diameter, have a width of between about 10-20 feet (3-6 m), and store, eg. 30,000-50,000 feet (9-15 km) of six inch (15.24 cm) pipe.
In order to arrange properly the pipeline on the selected reel drum during spooling, the firing line travels from one side of the ship to the other side in a coordinated back and forth direction to spool each wrap of the pipeline next to the previous wrap on the reel.
The firing line can also be configured to travel or be moved from one side of the ship to the other side if it is to align with the second drum, so that the pipeline fabricated on the ship deck can be spooled on either one of the reels. In other words, the pipeline “firing line” moves laterally as it is being spooled upon a first reel. However, the entire firing line can travel transversely on the ship's deck a larger distance in order to align with the second reel when the second reel is to be filled with pipeline.
When the ship undertakes pipe laying on the sea bottom, the pipeline that is stored on a selected reel leaves the drum in a direction tracking toward the top of the tilting tower. The titling tower can tilt in a position that varies, such as for example, between about 65 and 95 degrees from the deck plane. At the top of the tower, the pipeline bends through a bend controller downwardly toward the seabed. The tilting tower can also be provided with a device for straightening the pipeline, a tensioning device and a clamping device that can hold the pipeline and support the weight of the pipeline that extends downwardly toward the seabed.
It should be understood that the general concept of paying a wound pipeline from a reel to a tilting tower that has a bend controller, straightener, tensioner, and clamp mechanism is old and known in the art such as is shown in the above discussed Springett U.S. Pat. No. 4,340,322 and Uyeda U.S. Pat. No. 4,345,855 patents, each incorporated herein by reference.
With the improved arrangement of the present invention, the tower can move transversely in a port to starboard direction and in a starboard to port direction for two reasons. The tower can move transversely in order to coordinate with the reel rotation. This arrangement enables spooling the welded pipeline upon the reel or removing pipeline from the reel in an orderly fashion. Secondly, the firing line and tilting tower can be moved transversely in order to align with either the first or the second drum as selected by the vessel operators. This larger transverse movement occurs when winding of the pipeline on the first reel is complete, and the winding of the pipeline on the second reel begins.
When leaving the bend controller, the pipeline passes through a straightening device that imposes a reversed plastic bending on the pipeline in order to straighten it. The straightened pipeline then passes through a tensioner aligned with the tower. The combined tension imposed on the pipeline by the tensioner and the drum back tension compensates for the suspended weight o
Doody Stephen R.
Garvey, Jr. Charles C.
Garvey, Smith, Nehrbass & Doody, L.L.C.
Lagman Frederick L.
Torch Offshore, Inc.
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