GB2269877A

GB2269877A - Hydrobouy-bouyancy system

Info

Publication number: GB2269877A
Application number: GB9217061A
Authority: GB
Inventors: Terence Jeffrey Corbishley
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-08-12
Filing date: 1992-08-12
Publication date: 1994-02-23
Anticipated expiration: 2012-08-12
Also published as: GB9217061D0; GB2269877B; ZA935868B

Abstract

The invention provides buoyancy for underwater structures, objects and equipment which is required to reduce permanently the submerged weight on an in situ structure, or to provide temporary buoyancy to aid its installation or recovery. A method of making structural object 2 buoyant is achieved by attaching to the structural objects 2 by mechanical means, either prior to or following its installation in liquid, an enclosure 1 or plurality of enclosures each containing ceramic microspheres 3 where the void space within the enclosure 1 is filled with a gas or a liquid. The gas may be air and the liquid may be water. The enclosure may be formed by a compartment which is an integral part of the object. The enclosure may surround the object. The space between a pipeline and an elongate jacket may be filled with the microspheres. <IMAGE>

Description

HYDROBUOY - BOUYANCY SYSTEM This invention relates to the provision of "buoyancy" for underwater structures, objectes and equipment, hereinafter referred to as a "structure".

The provision of buoyancy being required to reduce permanently the submerged weight of an in-situ structure, or to provide temporary buoyancy to aid its installation or recovery.

Buoyancy of a structure is presently achieved by the introduction of a medium, having a specific gravity less than water, typically air or other gas.

Other suitable medium include open or closed cell foams. The gas and the foams compress with increasing applied pressure (water depth) or correspondingly expand with decreasing applied pressure. Buoyancy may also be provided by more consolidated materials, again of specific gravity less than water, such as polyurethane which have been blown or foamed with a gas to also form a closed cell structure. Polyurethane foams and alike are usually encapsulated in a thin skin of more dense material following application of the buoyant material.

The "structure" is made buoyant by introduction of buoyant material into enclosures forming an integral part of the structure, or seperate enclosures installed within, surrounding, encircling, surrounding, enveloping or attached adjacent to the structure.

The principle of the invention is to provide buoyancy by utilising, as an alternative to the gas and other mediums descibed above, ceramic microspheres which have a particle specific gravity of approximately 0.7 and a bulk specific gravity of 0.4 when tightly packed with air contained in the void space between the microspheres. When the microspheres are entrained in an enclosure effectively impermeable to the surrounding water and containing only microspheres and gas (air)), the microspheres prevent the compression and subsequent collapse of the enclosure when the enclosure is subjected to increasing externally applied pressure.

Where the microspheres are housed within the enclosure but the void space between the microspheres is also water, the buoyancy provided remains constant, irrespective of increases or decreases of externally applied pressure (water depth).

For a structure or structures to be installed in water or those already located in water, I provide as follows: From a first aspect of the invention a method of making buoyant a structure by attaching to that structure an enclosure or plurality of enclosures, which are entirely or partly filled with ceramic microspheres. The void space around and between the microspheres being a gas or a liquid, typically air or water respectively.

For a second aspect of the invention a method of making buoyant a structure by filling an enclosure or plurality of enclosures, being an integral part of that structure, with microspheres all as aforesaid.

For a third aspect of the invention a method of making buoyant a structure, by incorporating or installing within a compartment or compartments, being an integral part of that structure, an enclosure or a plurality of enclosures being filled with microspheres all as aforesaid.

For a fifth aspect of the invention a method of making buoyant a structure, by surrounding the structure with an enclosure or plurality of enclosures each filled with microspheres all as aforesaid.

For a sixth aspect of the invention method of making buoyant a structure by enveloping the structure with an enclosure filled with microspheres all as aforesaid.

For a seventh aspect of the invention a method of making buoyant a single pipeline or group of pipelines by locating them within an elongate jacket filled with microspheres all as aforesaid.

For an eighth aspect of the invention a method of making buoyant a pipeline or group of pipelines each comprising a plurality of pipes that are joined end-to-end, in which each pipe is located within a surrounding elongate jacket, each jacket terminating short of each end of the respective pipe and each end of each jacket being secured to an end cap which circumferentially surrounds and is secured to the respective pipes. Alternatively, the jacket may comprise a plurality of jacket sections, typically of length equal to the pipe joint of which the pipeline or group of pipelines is formed. The sections of jacket may be abutted and adjoined to each other and secured at their ends to the end caps or bulkheads which surround and are in turn secured to the pipeline or group of pipelines.

For a ninth aspect of the invention buoyant objects by utilising jackets and microspheres all as aforesaid.

In order that the invention may be better understood specific embodiments thereof will now be described in more detail, by way of example only, with reference to the accompanying drawings: Figure 1 A general illustration of a typical externally attached buoyant enclosure.

Figure 2 A general illustration of a typical buoyant compartment being an integral part of a structure.

Figure 3 A general illustration of a buoyant enclosure housed within an integral part of a structure.

Figure 4 A general arrangement of a buoyant enclosure surrounding a structure.

Figure 5 A general arrangement of a buoyant enclosure envloping a structure.

Figure 6 A general illustration of the introduction of microspheres in to a submerged enclosure or compartment of a structure.

Figure 7 A general illustration of a pipeline made buoyant by locating within an elongate jacket filled with microspheres.

Referring to Figure 1, this shows a separate enclosure 1, attached to a structure 2, the enclosure being made of an elastomeric material (typically rubber or rubber and fabric assembly) or a more rigid material (typically steel), containing ceramic microspheres 3, the void space within the enclosure but surrounding and between the microspheres being gas or liquid, typically air or water. The enclosure may be attached to the structure prior to its installation in the water or attached and filled with microspheres whilst it is located in the water.

Figure 2 shows an buoyant enclosure formed by a compartment being an integral part of the structure 4, the enclosure being filled with microspheres 5 as described in the preceding paragraph.

Figure 3 shows a buoyant enclosure 6 as shown in and as discussed above for Figure 1 which is located within a compartment being an integral part of the structure 7.

Figure 4 shows a buoyant enclosure 8 as shown in and as discussed above for Figure 1, which surrounds the structure 9.

Figure 5 shows a buoyant enclosure 10 as shown in and as discussed above for Figure 1, which envelopes the structure 11.

Figure 6 shows the microspheres 12 being introduced to an enclosure 13, together with either a gas (typically air) or liquid (typically water) utilised as a transmission medium. In the case of air as the transmission medium the air may be allowed to escape from a vent valve or plurality of vent valves 14, suitably located in the enclosure, which allow the expulsion of the air but not the microspheres. In the case of water as the transmission medium the water may be allowed to escape from a orifice 15 at the base (shown) or other suitable location.

Figure 7A shows two pipes, 16, 17 of an underwater pipeline, the pipes being joined end to end 18. Each pipe is located within a surrounding elongate jacket 19, 20 respectively, the jackets terminating short of each end of the respective pipe. Alternatively, jacket 19 may be abutted and adjoined to jacket 20 following the joining of pipe 16 and 17 all as illustrated in Figure 7B. The jackets are of similar construction and only that associated with pipe 17 will be described in detail.

Thus the jacket 20 with optional cover 22 may be of flexible or rigid material, extending between end caps 21 circumferentially surrounding the pipe 17. If desired, the end caps may be secured to the pipe by suitable adhesive. The end caps may also be bonded to the jacket, either by adhesive or by co-curing the jacket and the end caps to form an integral assembly. The space or cavity between the pipe 17 and the jacket 20 contains tightly packed microspheres 20A.

A wide range of materials are suitable for the construction shown in Figures 7. The jacket may be fabricated of suitable elastomeric material such as polyethylene, polyurethane, polyvinylchloride, polyolefines, glass reinforced resins, SBR and EPDM.

The cover if required will also be preferably fabricated of a suitable elastomeric material such as SBR or EPDM. The jacket and cover should be effectively impermeable to the liquid with which the jacket may be filled and the surrounding water. The construction and thickness of the jacket and cover should be as to avoid tearing, and may incorporate one or more layers of reinforcing material or a wound wire or textile cord. Reinforcing ribs or slats may be incorporated to stiffen the cover. It is desirable, however, that the cover has a low modulus in order that the jacket is elastic. Alternatively the jacket may be fabricated of more rigid material, typically steel.

If desired pipe 2 may be coated with thermal insulation material and/or anti-corrosion material which is also terminated short of each end of each respective pipe to facilitate joining 18.

The end caps 7 are also of suitable rubber or plastic material such as polyethylene, polyurethane, polyvinylchloride, polyolefines, glass reinforced resins, SBR and EPDN.

The dimensions and materials from which the jacket, cover end-caps and bulkheads is to be fabricated, will be selected to suit the anticipated pipe temperature and other design requirements.

The materials from which the enclosures shown in Figures 1 to 6 will be similar to those described for the pipeline application shown in Figure 7 and as described all as aforesaid.

The microspheres will have a bulk specific gravity less than that of water when tightly packed.

Microspheres having a specific gravity of typically 0.7, with a corresponding bulk density typically 0.4, with a packing factor of typically 65% particle size of the microspheres range from 5-300 microns, but a particle size distribution can be selected for utilisation in the invention.

Claims

CLAIMS:

1. A method is claimed of making a structure or object buoyant by attaching to the structure or object by mechanical means not shown, either prior to or following its installation in liquid (generally seawater), an enclosure or plurality of enclosures each containing ceramic microspheres where the void space within the enclosure(S) is filled with a gas (typically air) or a liquid (typically water).

2. A method is claimed in 1. where the enclosure is formed by a compartment within or forming an integral part of the structure or object.

3. A method is claimed in 1. where the enclosure is introduced or installed within a compartment within or forming an integral part of the structure or object.

4. A method is claimed in 1. where the enclosure surrounds the structure or object.

5. A method is claimed in 1. where the enclosure envelopes the structure or object.

6. A method is claimed in 1. 2. 3. 4. and 5. where each enclosure is formed of a plurality of enclosures to form the main enclosure.

7. A method is claimed in 1. 2. 3. 4. 5. and 6.

where the microspheres are introduced to the enclosure or enclosure as a mixture of gas and microspheres or liquid and microspheres, the gas being typically air and the liquid typically water.

Whilst the enclosure or structure is submerged in water.

8. A method is claimed in 7. where gas (typically air) used as a transmission medium to introduce the microspheres, is allowed to escape from the enclosure via suitably located vents, but which prevent the escape of the microspheres.

9. A method is claimed in 7. where the liquid (typically water) used as a transmission medium to introduce the microspheres, is allowed to escape from the enclosure via suitably located orifice.

10. A method of making buoyant an underwater pipeline or group of pipelines by locating them within a surround elongate jacket formed of elastic material being tightly packed with microspheres or other suitable material.

11. A method according to claim 10. in which the jacket is of more rigid material and construction, typically steel.

12. A method according to claims 10. and 11. in which the jacket is an elongate jacket extending from adjacent one end to adjacent the other end of the pipeline or pipeline assemblies where the pipelines comprise a plurality of pipes joined end to end, in which each pipe is located within a surrounding elongate jacket terminating short of each end of the respective pipe and each end of each jacket being secured to an end-cap which circumferentially surrounds the respective pipe, each jacket being tightly packed with microspheres. The gap between the adjacent jackets being filled with other material or a cover also filled with mirospheres.

13. A method according to claims 10. to 12. in which said jacket comprises a plurality of elongate jackets which are abutted and adjoined to each other and secured to bulkheads.

14. A method according to claims 10. to 13. in which the said jacket comprises a plurality of elongate steel jackets which are joined to each other at their ends by welding.

15. A structure or object made buoyant by attaching to the structure or object by mechanical means not shown, either prior to or following its installation in liquid, (generally seawater), an enclosure or plurality of enclosures each containing ceramic microspheres where the void space within the enclosure(S) is filled with a gas (typically air) or a liquid (typically water).

16. A structure or object as claimed in 15. where the enclosure is formed by a compartment within or forming an integral part of the structure or object.

17. A structure or object as claimed in 15. where the enclosure is introduced or installed within a compartment within or forming an integral part of the structure or object.

18. A structure or object as claimed in 15. where the enclosure surrounds the structure or object.

19. A structure or object as claimed in 15. where the enclosure envelopes the structure or object.

20. A structure or object as claimed in 15. 16. 17.

18. and 19. where each enclosure is formed of a plurality of enclosures to form the main enclosure.

21. A structure or object as claimed in 15. 16. 17.

18. and 19. where the microspheres are introduced to the enclosure or enclosure as a mixture of gas and microspheres or liquid and microspheres, the gas being typically air and the liquid typically water.

22. A structure or object as claimed in 21. where gas (typically air) used as a transmission medium to introduce the microspheres, is allowed to escape from the enclosure via suitably located vents, but which prevent the escape of the microspheres.

23. A structure or object as claimed in 21. where the liquid (typically water) used as a transmission medium to introduce the microspheres, is allowed to escape from the enclosure via suitably located orifice.

24. An underwater pipeline or group of pipelines made buoyant by locating them within a surround elongate jacket formed of elastic material being tightly packed with ceramic microspheres or other suitable material.

25. An underwater pipeline as claimed in 24. in which the jacket is of more rigid material and construction, typically steel.

26. An underwater pipeline as claimed in 24. and 25. in which the jacket is an elongate jacket extending from adjacent one end to adjacent the other end of the pipeline or pipeline assemblies where the pipelines comprise a plurality of pipes joined end to end, in which each pipe is located within a surrounding elongate jacket terminating short of each end of the respective pipe and each end of each jacket being secured to an end-cap which circumferentially surrounds the respective pipe, each jacket being tightly packed with microspheres. The gap between adjacent jackets being filled with other material or a cover also filled with microspheres.

27. A method according to claims 24. to 26. in which said jacket comprises a plurality of elongate jackets which are abutted and adjoined to each other and secured at there ends to the end-caps or bulkheads.

28. A method according to claims 24. to 27. in which the said jacket comprises a plurality of elongate steel jackets which are joined to each other at their ends by welding.