Strongback Traveling Clamp
A modified strongback for laying pipeline offshore that utilizes a movable clamp. One end of the strongback is modified to include a travel mechanism. A pipe clamp is mounted on the travel mechanism to allow movement of the clamp as necessary to accommodate different pipe joint lengths. A mechanism for locking the clamp in the desired position is provided on the strongback.
The invention is related to offshore pipe laying equipment and more particularly to equipment for handling long lengths of pipe.
Near vertical laying of pipeline offshore utilizes specialized equipment for handling lengths of pipe (pipe joints). U.S. Pat. Nos. 5,421,675 and 5,464,307 are directed to equipment for near vertical laying of pipeline offshore and provide descriptions of the handling steps required for pipeline lay operations. Near vertical laying of pipeline requires equipment capable of picking up a pipe joint from the horizontal position and moving it into a near vertical position for adding it to the pipeline being installed. This equipment positions the pipe joint in alignment with the pipeline so that the pipe joint can be welded to the pipeline. Existing arrangements utilize a strongback, typically a triangular frame with clamps for gripping the pipe joint and moving it into a tower for welding to the pipeline. Depending on the vessel arrangement, the strongback or tower may be used to hold the pipe joint in position during the welding step.
To align the pipe joint coaxially with the pipe line for welding, the clamps in the strongback or tower have been adjustable in the radial direction.
In the past, four forty foot pipe sections welded together at a fabrication facility on shore has been the standard length of one pipe joint. The clamps in the strongback have been in fixed positions that are spaced specifically to handle this length pipe joint. The required number of pipe joints for a pipeline job was fabricated on shore, loaded on a barge, and transferred to the pipe lay vessel as required during the laying operation to add the pipe joints to the pipeline.
Recent changes in pipeline requirements have led to varied pipe joint lengths. The result is that the prior standard clamp spacing in the strongback is no longer able to clamp one end of the pipe joint and provide the required support over the full length of the pipe joint.
The near vertical tower in some pipe laying arrangements uses a gripper around the pipe that moves in the axial direction of the pipe for paying out the pipeline after a pipe joint has been welded to the pipeline or for purposes of aligning pipe joints for welding. However the applicants are not aware of any strongback modifications that address the need for accommodating different pipe joint lengths that allow the use of a single strongback on a vessel no matter what the current variation in pipe joint length may be. It should be kept in mind that a single pipe joint of steel pipe may weigh several tons, depending upon the diameter and wall thickness of the steel pipe. Thus, the strongback and associated equipment for handling the pipe is large, heavy, expensive and should be capable of multiple duties to provide the most cost efficient pipe laying vessels and equipment.
SUMMARY OF INVENTIONThe present invention is drawn to a modified strongback that utilizes a movable clamp. One end of the strongback is modified to include a travel mechanism. A pipe clamp is mounted on the travel mechanism. Means for locking the clamp in a desired position is provided on the strongback.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming part of this disclosure. For a better understanding of the present invention, and the operating advantages attained by its use, reference is made to the accompanying drawings and descriptive matter, forming a part of this disclosure, in which a preferred embodiment of the invention is illustrated.
In the accompanying drawings, forming a part of this specification, and in which reference numerals shown in the drawings designate like or corresponding parts throughout the same:
The invention is generally indicated in
The strongback 12 is generally triangular in cross section, which is typical in the industry to provide the required strength and means for mounting clamps 18. Clamps 18 are fixed in their position relative to the length of the strongback 12. Clamps 16 and 18 are extendible along the longitudinal axis of the clamps (radially relative to the strongback 12) for gripping pipe 20 (
As best seen in
Instead of being triangular as in a standard strongback, the modified section 14 is rectangular. The gear arrangement 26 is mounted on the top rail 24 of the modified section 14. The top of the movable clamp 16 is movably engaged with the gear arrangement 26 such that the movable clamp 16 moves on the gear arrangement 26 along the longitudinal axis of the modified section 14 as the gear arrangement 26 is turned.
As best seen in the sectional view of
In operation, the movable clamp 16 is unlocked and moved on the gear arrangement 26 by turning the gear arrangement 26 until the clamp 16 is in the desired position. The brake unit 28 is used to lock the upper portion of the clamp 16 to the gear arrangement and a pin is inserted through the apertures 34 in the lower rails 32 of the modified section 14 and the clamp 16 to lock the lower portion of the clamp 16 in position at the lower rails 32. The movable clamp 16 and fixed clamps 18 are then used to grip a pipe section as illustrated in
The invention provides several advantages over the prior art fixed clamp arrangement.
The traveling clamp allows a wider range of pipe lengths to be handled on the near vertical pipe lay vessel without loss of operational efficiency. This is accomplished through selective positioning of the clamp along the longitudinal axis of the pipe joint.
The traveling clamp engage/disengage arrangement is designed to minimize the time required for clamp engagement.
The traveling clamp engagement lock-off arrangement is designed for fail safe operation (i.e., does not require hydraulic or air power for maintaining engagement during pipe lay operations).
A rack and pinion gear arrangement is used for moving/repositioning the traveling clamp along the clamp rails.
Overall cycle time efficiency is maintained by keep time required for disengaging/moving/repositioning of the traveling clamp to a minimum. Controls for repositioning and engagement of the traveling clamp are operated remotely.
The traveling clamp allows handling of pipe joints of an increased range of lengths without any loss of operational efficiency. By allowing an increased range of pipe lengths, the cost of supplying the pipe lengths is reduced, thereby lowering the overall cost of the project.
While specific embodiments and/or details of the invention have been shown and described above to illustrate the application of the principles of the invention, it is understood that this invention may be embodied as more fully described in the claims, or as otherwise known by those skilled in the art (including any and all equivalents), without departing from such principles.
Claims
1. In an improved strongback used for gripping and moving pipe and having a plurality of pipe clamps in fixed positions spaced along the length of the strongback, the improvement comprising:
- a. a modified section on the strongback; and
- b. a pipe clamp mounted on said modified section so as to be movable along the longitudinal axis of said modified section.
2. The improved strongback of claim 1, wherein said movable pipe clamp is mounted on a gear arrangement mounted on said modified section.
3. The improved strongback of claim 1, further comprising means for securing said movable clamp in a desired position along the length of said modified section.
4. The improved strongback of claim 3, wherein said means for securing said movable clamp comprises a brake unit.
5. The improved strongback of claim 3, wherein said means for securing said movable clamp comprises a pin received through apertures in said movable clamp and said modified section.
6. In an improved strongback used for gripping and moving pipe and having a plurality of pipe clamps in fixed positions spaced along the length of the strongback, the improvement comprising:
- a. a modified section on the strongback;
- b. a gear arrangement mounted on said modified section;
- c. a clamp mounted on said gear arrangement so as to be selectively movable on said gear arrangement along the longitudinal axis of said modified section; and
- d. means for securing said movable clamp in a desired position along the length of said modified section.
7. The improved strongback of claim 6, wherein said means for securing said movable clamp comprises a brake unit.
8. The improved strongback of claim 6, wherein said means for securing said movable clamp comprises a pin received through apertures in said movable clamp and said modified section.
9. In an improved strongback used for gripping and moving pipe and having a plurality of pipe clamps in fixed positions spaced along the length of the strongback, the improvement comprising:
- a. a modified section on the strongback;
- b. a gear arrangement mounted on said modified section;
- c. a clamp mounted on said gear arrangement so as to be selectively movable on said gear arrangement along the length of said modified section; and
- d. means for securing said movable clamp in a desired position along the length of said modified section, comprising a brake unit and a pin received through apertures in said movable clamp and said modified section.
Type: Application
Filed: Jun 8, 2007
Publication Date: Dec 11, 2008
Inventors: Brian Michael Katterhenry (Houston, TX), Ravi Kumar Kannan (Morgan City, LA), William Joseph Wilson (LaPlace, LA), Kevin Patrick Zaeringer (Metairie, LA), McArthur Bassett (Morgan City, LA), Mark Thomas Alexander, JR. (Youngsville, LA), Roy Stephen Heitkamp (Covington, LA)
Application Number: 11/760,008
International Classification: E21B 19/16 (20060101);