CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority from the provisional application designated Ser. No. 60/949,103 filed Jul. 11, 2007 and entitled “Streamlined Annular Buoy for Marine Pipelines”. This application is hereby incorporated by reference.
BACKGROUND OF THE INVENTION The present invention relates to marine buoys, and in particular to a streamlined annular buoy for marine pipelines.
Annular buoys have been in use for decades in the interest of reducing the wear and tear of the ocean bottom on the pipeline. They have been less than optimally successful due to high drag and slippage along the pipe. This causes undesired bending in the pipe as the pipe dips and rises with uneven buoyancy. There is a need for an improved annular buoy for marine pipelines.
SUMMARY OF THE INVENTION According to an aspect of the invention, a streamlined annular buoy for marine pipelines, comprising a first annular buoy half comprising syntactic foam, where the first buoy half includes a substantially planar exterior first mating surface that includes an axial first channel formed therein and a first domed exterior surface radial to the axial first channel. The buoy also includes a second annular buoy half comprising syntactic foam, where the second buoy half includes a substantially planar exterior second mating surface that includes an axial second channel formed therein and a second domed exterior surface radial to the axial second channel. A fastener secures the first and second annular buoy halves together around a flow-line that passes through a flow-line channel formed by the axial first and second channels, such that the exterior first and second mating surfaces are face-to-face.
These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of preferred embodiments thereof, as illustrated in the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective illustration of a first pipe secured to a second pipe by a clamp surrounded by a streamlined annular buoy in the open position;
FIG. 2 is a perspective illustration of the clamp having first and second Kevlar straps secured about hemispherical halves of the clamp;
FIG. 3 illustrates an exploded pictorial illustration of the first and second buoy halves displaced from the closed clamp, and first and second metal bolts that secure the first and second halves of the streamlined annular buoy;
FIG. 5 illustrates the first and second buoy halves mounted in an assembly frame along with the first and second halves of the clamp and the first pipe;
FIG. 6 illustrates a partial cut-a-way side view of the first and second halves 16, 18 of streamlined annular buoy surrounding the clamp 14 and the first and second lengths of pipe 10, 12;
FIG. 7 illustrates a coaxial cut away view of the streamlined annular buoy arranged around the clamp and a portion of the length of pipe;
FIG. 8 is a pictorial illustration of a J-lay;
FIG. 9 is a pictorial illustration of an S-lay; and
FIG. 10 includes a cross-sectional illustration of a streamlined annular buoy and a cross sectional illustration of a conventional blunt annular buoy 102 mounted to the flow line for comparison purposes.
DESCRIPTION OF THE INVENTION FIG. 1 is a perspective illustration of a first pipe 10 secured to a second pipe 12 by a clamp 14. The first and second pipes 10, 12 typically have an inner diameter of 4-6 inches and a wall thickness typically of about 0.25 to 0.5 inches. Multiple lengths of pipe are often referred to as a “flow line” because oil or gas, or in most cases a combination of the two passes through the pipe. The clamp 14 may be configured and arranged in a clam shell arrangement having first and second halves 13, 15 that are secured together by one or more Kevlar straps 17. FIG. 2 is a perspective illustration of the clamp 14 having first and second Kevlar straps secured about the hemispherical halves of the clamp.
Referring again to FIG. 1, once the first and second pipes 10, 12 have been secured by the clamp 14, first and second annular buoy halves 16, 18 respectively are secured around the clamp 14 and portions of each of the first and second pipes 10, 12. The first and second buoy halves 16, 18 may be arranged in a clam shell arrangement such that when closed and bolted together the buoy halves are securely positioned around the clamp 14 and portions of the first and second lengths of pipe. For ease and manufacturability of the annular buoys around the pipeline, an interior surface 19 of the first buoy half 16 may include a storage region 20 for storage of parts such as various rods and bolts that are used to secure the first and second buoy halves 16, 18. The first planar surface 19 may include a first stub 22 and a second stub 24 that cooperate with respect to first and second openings 26, 28 in the second buoy half 18 to more securely join the first and second buoy halves 16, 18. Similarly, the first planar surface 19 may also include first and second openings 30, 32 that meet with corresponding stub portions 34, 36 on a second planar surface 38 of the second buoy half 18. Each of the first and second halves 16,18 may also include lift points that allow the first and second halves to be positioned on a assembly frame 40 for easier assembly of the first and second lengths of pipe 10, 12, the clamp 14 and the first and second buoy halves 16, 18.
FIG. 3 illustrates an exploded pictorial illustration of the first and second buoy halves 16,18 displaced from the closed clamp 14 and first and second metal bolts 42, 44 that secure the first and second halves 16, 18 of the annular buoy. In the interest of ease of illustration, the first and second pipe 10, 12 have not been shown in FIG. 3.
FIG. 4 illustrates the first and second buoy halves 16, 18 mounted in the assembly frame 40 along with the first and second halves of the clamp 14 and the first pipe 10. The assembly frame 40 illustrated in FIG. 4 is in the open position. FIG. 5 illustrates the assembly frame 40 populated with the first and second halves 16,18 of the annular buoy and the first and second halves of the clamp 14 and the pipe 10 in a closed position such that the first and second halves of the annular buoy are operatively arranged around the clamp and the first and second pipes.
FIG. 6 illustrates a partial cut away side view of the first and second halves 16, 18 of the buoy surrounding the clamp 14 and the first and second lengths of pipe 10, 12. As shown in FIG. 6, the clamp 14 is secured together with the Kevlar strap 17 and a plurality of metal rods and bolts 50, and the first and second halves 16, 18 of the annular buoy are secured together with a plurality of rods and bolts 52.
FIG. 7 illustrates a coaxial cut away view of the buoy arranged around the clamp 14 and a portion of the length of pipe. As shown in FIGS. 6 and 7, the annular buoy may have a length of about 2,790 millimeters, an outside diameter of about 2,000 millimeters and pipe diameter of approximately 580 millimeters. In one embodiment, the annular buoy has a weight of about 2,071 kg and a buoyancy of approximately 3,270 kg. The assembly tool 40 may be located on a lay barge and used by the crew of the lay barge to assemble the clamp 14 around the first and second lengths of pipe 10, 12 and then the first and second halves 16, 18 of the annular buoy around the clamp 14.
FIG. 8 is a pictorial illustration of a lay barge 80. The illustration of FIG. 8 includes a plurality of buoys 82-85 arranged along a flow line 86 at various depths. By placing these buoys 82-85 along the flow line at selected intervals, the flow line pipeline will be suspended beneath the water at a prescribed depth. The pictorial illustration of FIG. 8 is often referred as the j-lay. Similarly, FIG. 9 is a pictorial illustration of a technique referred as a s-lay. As shown in FIG. 9 the plurality of annular buoys 82-85 are arranged at specific intervals along the pipeline to suspend the pipeline at a prescribed depth. Depending upon the required buoyancy, the typical buoy size is approximately 36 inches in diameter and 54 inches long. The first and second halves 16, 18 of the buoy comprise syntactic foam whose density is proportional to the desired operational depth of the buoy and the buoy size and weight. The density and buoy size are selected based upon the desired operational depth of the particular buoy along the length of pipe.
Significantly, as illustrated in FIGS. 1, 3, 6 and 7, the buoy of the present invention is a streamlined buoy in contrast to the conventional blunt buoy of the prior art. FIG. 10 is a cross-sectional illustration of a streamlined annular buoy 100 according to an aspect of the present invention mounted to a flow line. FIG. 10 also illustrates a conventional blunt annular buoy 102 mounted to the flow line for companion purposes. The streamline buoy 100 is hydro dynamically streamlined in comparison to the prior art blunt buoy 102. Specifically, rather than employing elongated side walls perpendicular to the longitudinal axis as in the prior art blunt buoy 102, the hydro dynamically streamlined buoy 100 includes relatively shorter side walls that are perpendicular to the longitudinal axis, and elongated rounded edges running from and interconnecting the perpendicular sidewalls with the longitudinal side walls. The streamlined buoy 100 includes straight longitudinally perpendicular exterior sidewalls 104 and convex longitudinal exterior sidewalls 106.
The ends of the streamlined buoy 100 are shaped at the ends for reduced drag. This optimizes the buoyancy along the pipeline and reduces the danger of slippage. Specifically, the streamlined buoy reduces the drag force and thus slippage of the buoy along the pipeline. That is, The streamlined buoy remains in its prescribed location along the pipeline during deployment, and exhibits less force on the pipeline while deployed under the surface of the water.
Although the present invention has been shown and described with respect to several preferred embodiments thereof, various changes, omissions and additions to the form and detail thereof, may be made therein, without departing from the spirit and scope of the invention.
