Not applicable.
The present invention relates to the field of burying underwater pipelines, and more specifically to a method and device for promoting self-burial and/or stabilization of underwater pipelines.
A smooth and circular conduit often has a tendency toward self-burial, but the effect often is insufficient, so that the conduit is easily exposed again and/or the time for self-burying is very long, with the inherent danger of damage by anchors, fishing gears or the like. In view regulations of several governments that require that a conduit be buried so much within one year that there is at least a covering layer of a height of 20 cm above it, various methods of burying conduits have been proposed.
Prior methods of burial have included the making of trenches by dredging, by cutting with rotary cutters or by strong water jets and to position the pipeline or conduit therein. Such prior methods have been realized in such a way that the conduit has lowered to the bottom underwater during the preparation of such a trench. After positioning of the conduit in the trench, the trench may be filled up above the conduit with the material which first has been removed for making the trench so as to obtain sufficient earth material above the conduit, so that it is not again exposed by the stirring action of the water flows along the bottom. These traditional methods of burying conduits suffered from numerous problems, including, but not limited to, adverse environmental impact and cost.
A method of self-burial of a conduit in a seabed using protruding parts such as fins was disclosed in U.S. Pat. No. 4,648,745, entitled “Method and Device for Burying a Conduit in the Bottom of a Waterbed,” which is incorporated by reference herein in its entirety. That patent disclosed a method in which protrusions such as fins are provided on or in the vicinity of the conduit, which cause disturbances in the flow of water near the conduit to erode the bottom of the waterbed in such a way that the conduit will be buried.
It has appeared that by application of the invention horizontal water flows near the conduit generate flow disturbances and/or turbulences, swirling up, dragging with it and removing the bottom material to the side of and in many cases also below the conduit, so that the conduit sinks into the bottom by its own weight, which process proceeds until the conduit is sufficiently buried, after which the depression, which is thereby formed in the proximity of the conduit, silts up so that so much earth will cover the conduit that it remains buried safely.
The method of that patent was realized in such a way that the protruding parts were provided at a horizontal distance from the conduit and extending substantially parallel thereto, provided on or in the bottom, and this possibility could be combined with the application of one or more protruding parts on the conduit itself. That design was believed to be particularly advantageous when the horizontal flows along the bottom in the water are in one direction only instead of switching to and fro by tide currents.
The patent further noted that tilting of the conduit may occur in certain environments, and if the conduit may easily tilt to a more considerable extent, it was possible to provide a number of protruding parts, distributed over a greater part of or over the entire periphery of the conduit so that always the parts protruding in a direction to be effective for the erosion generate sufficient disturbance in the water flow for burying erosion. For example, in order to guide a downwardly directed swirl generated at the luff side and directed downwardly along the wall of the conduit, an embodiment was disclosed wherein the conduit had a radial longitudinal fin in an inclined position in the upper part e.g. at an angle of about 45.degree. to the horizontal direction. An even better guiding of said swirl was obtained by curving such a fin concavely downwardly. If the water flow was alternating as by the tide, there would normally be two such fins on the conduit.
Several advances in the use of protrusions or fins to promote self-burial of pipelines are disclosed in European Patent Specification No. EP 0466219 B1, entitled “Pipeline with Ground Anchors,” which is incorporated by reference herein in its entirety. That European patent disclosed a “seat” and “spoiler” structure in which the spoilers would be mounted to a seat that would “grab” across part of the outer surface of a pipe. The seat and spoiler would then be kept in place on the pipe by metal straps.
In practice, the spoilers or fins typically are aligned approximately over dead center, slightly spaced along the length of a section of pipe 110 such as is shown in
A further advance was disclosed in European Patent Specification No. EP 0717223 B1, entitled “Assembly of pipelines intended to lie on a seabed and saddle for securing a second pipeline to a first pipeline,” which is incorporated by reference herein in its entirety. That patent disclosed a structure of the seat for protrusions from a pipeline in the form of a saddle for accommodating a second pipe.
The present invention provides a new and different method and apparatus for stabilizing and burying a conduit in a pipeline. The method for promoting self-burial and stabilization of a conduit in the bottom of a water bed comprises the steps of providing a first protruding part approximately over dead center along a first portion of the conduit with the first protruding part being securely connected to said conduit; providing a second protruding part approximately 10° to 30° from over dead center on a second portion of the conduit different than the first portion with the second protruding part being securely connected to said conduit. The method may further comprise the step of providing a third protruding part on the conduit approximately 10° to 30° from over dead center in an opposite circumferential direction from the second protruding part on a third portion of the conduit different than the first and second portions with the third protruding part being securely connected to the conduit. The method likewise may comprise further protruding parts in alternating radial locations along the conduit.
The apparatus may comprise a seat and fin structure secured to a pipeline such as via metal straps. The spoiler seat further may provide for piggy-backing of a second pipeline or cable.
The invention of the present application will now be described in more detail with reference to preferred embodiments of the architecture and method, given only by way of example, and with reference to the accompanying drawings, in which:
The present invention presents a new alignment of submarine pipeline spoilers that provides numerous advantages in terms of self-burial, re-burial, reduced vortex-induced vibration, upheaval buckling prevention, and environmental protection in certain marine environments.
As shown in
A second spoiler 500 is secured to the pipeline 400 at a longitudal position on the pipe spaced from spoiler 500 and at a radial position +α° from on top of dead center, where 10°≦α≦30°, and, in a preferred embodiment, α is approximately equal to 20°.
The longitudinal spacing between spoilers 600 and 500 may vary but is approximately four inches in a preferred embodiment. The spacing between spoilers is included to permit water flow between the spoilers. This water flow promotes self-burial of the pipeline. Alternatively, the spoilers could be placed adjacent to one another and opening could be incorporated into the fins to permit the water flow that promotes self-burial.
A third spoiler 700 is secured to the pipeline 400 at a longitudal position on the pipe spaced from spoiler 500 and at a radial position −β° from on top of dead center, where 10°≦β≦30°, and, in a preferred embodiment, P is approximately equal to 20°. The longitudinal spacing between spoilers 700 and 500 may vary but is approximately four inches in a preferred embodiment.
This pattern of radially alternating the placement of spoilers on a pipe may be repeated along a length of pipe. Further, the radial placement of spoilers 500 and 700 may be reversed.
The spoilers may be secured to the pipeline by any of a variety of means. In one embodiment, the spoilers are secured to the pipeline using a conventional seat and fin arrangement as shown in
Further, the spoiler seat may be a piggy-back style seat such as is shown in
A conventional fin that may be used in the present invention is shown in
In a second embodiment, the present invention is incorporated by way of a new seat template as shown in
In a third embodiment, a piggy-back seat structure such as is shown in
While the foregoing invention has been described in terms of its preferred embodiments, it should be understood that various modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims. It is intended that all such modifications fall within the scope of the appended claims.
This is a continuation of U.S. patent application Ser. No. 10/797,319 filed on Mar. 10,2004, now abandoned.
Number | Name | Date | Kind |
---|---|---|---|
2674857 | Fortes | Apr 1954 | A |
3454051 | Goepfert et al. | Jul 1969 | A |
4648745 | Hulsbergen | Mar 1987 | A |
4722367 | Swink et al. | Feb 1988 | A |
6347911 | Blair et al. | Feb 2002 | B1 |
6561734 | Allen et al. | May 2003 | B1 |
6695540 | Taquino | Feb 2004 | B1 |
6896447 | Taquino | May 2005 | B1 |
Number | Date | Country |
---|---|---|
0466219 | Jan 1992 | EP |
0717223 | Jun 1996 | EP |
2335248 | Sep 1999 | GB |
07318275 | Dec 1995 | JP |
Number | Date | Country | |
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20050232706 A1 | Oct 2005 | US |
Number | Date | Country | |
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Parent | 10797319 | Mar 2004 | US |
Child | 11155239 | US |