WO2000031169A1 - Composite materials for use in buoyancy applications - Google Patents

Composite materials for use in buoyancy applications Download PDF

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Publication number
WO2000031169A1
WO2000031169A1 PCT/GB1999/003926 GB9903926W WO0031169A1 WO 2000031169 A1 WO2000031169 A1 WO 2000031169A1 GB 9903926 W GB9903926 W GB 9903926W WO 0031169 A1 WO0031169 A1 WO 0031169A1
Authority
WO
WIPO (PCT)
Prior art keywords
fibres
buoyancy
matrix
buoyancy means
acetylated
Prior art date
Application number
PCT/GB1999/003926
Other languages
French (fr)
Inventor
Brian Chandler
Original Assignee
Adtech Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GBGB9825768.6A external-priority patent/GB9825768D0/en
Priority claimed from GBGB9827188.5A external-priority patent/GB9827188D0/en
Application filed by Adtech Limited filed Critical Adtech Limited
Priority to AU12855/00A priority Critical patent/AU1285500A/en
Publication of WO2000031169A1 publication Critical patent/WO2000031169A1/en

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/0085—Use of fibrous compounding ingredients
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
    • E21B17/01—Risers
    • E21B17/012—Risers with buoyancy elements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L11/00—Hoses, i.e. flexible pipes
    • F16L11/04—Hoses, i.e. flexible pipes made of rubber or flexible plastics
    • F16L11/12—Hoses, i.e. flexible pipes made of rubber or flexible plastics with arrangements for particular purposes, e.g. specially profiled, with protecting layer, heated, electrically conducting
    • F16L11/133—Hoses, i.e. flexible pipes made of rubber or flexible plastics with arrangements for particular purposes, e.g. specially profiled, with protecting layer, heated, electrically conducting buoyant

Definitions

  • This invention relates to composite materials, and especially those materials which are particularly useful in buoyancy applications, and especially those which have a high modulus and a low density/S.G.
  • a buoyancy application comprises a situation where a degree of displacement has to be added to an article member or structure so as in effect to reduce its effective weight when on or in a liquid, in particular water.
  • Particular buoyancy applications include subsurface support systems in offshore, gas and marine industries.
  • a particular buoyancy application comprises the support of rigid riser pipes in off shore oil installations (the term riser pipe as used herein is intended to cover the installation and insulation of seabed collector pipe systems, known to those skilled in the art) .
  • riser pipe for transporting oil from under the sea bed to the sea surface typically may be of steel, and may be in a number of sections so that the riser can extend over substantial distances.
  • the longer the riser the greater the weight of same, and the heavier the riser, the greater the power/buoyancy which is needed for example to neutralise the strain on the umbilical strings, which can be several thousand meters long, extending between the sea bed and the surface installation.
  • a further particular buoyancy application comprises the subsurface support horizontal or essentially horizontal pipelines or groups of pipelines used for transporting gas or oil along the seabed to the riser pipelines
  • a yet further particular buoyancy application comprises the support of flexible riser pipes in offshore oil and gas installations. Because of this difficulty, it has been established that pipes or pipe lengths are provided with buoyancy cladding in order to decrease the effective weight of the pipe or pipe lengths when in use in the water. This cladding additionally provides a degree of insulation, which can be important in some applications, for example the transport of oil, as the insulation prevents the oil from becoming too cold and viscous, impeding flow through the pipe.
  • the cladding which has been adopted heretofore comprises mainly a composition of syntactic foam to which is added hollow or essentially hollow bodies, typically spherical bodies, which are strengthened with fibre reinforced plastic coats .
  • the spheres are typically fabricated from a thermoplastic or from glass, or from polystyrene foam.
  • the reinforcing fibre for the synthetic resin coat is typically glass but may be wollastonite, or less typically because of cost considerations, carbon.
  • the resin may typically be polyester or epoxy resin in basic or modified forms, and the composite is made by coating the spheres with a matrix of fibres and synthetic resin.
  • the resin may typically be polyester or epoxy resin in basic or modified forms.
  • Glass fibre is typically used because in a composite it provides the required modulus to resist crushing pressure and in a composite it can be agoraphobic and will stand up to wet degradation, but it does have the disadvantage that it is relatively heavy (being approximately twice the specific gravity of natural fibre) and this reduces the degree of buoyancy which can be achieved by the coated hollow or essentially hollow spheres . Additionally, glass fibre is a poor thermal insulator which is a disadvantage where insulation is required.
  • the cladding has to withstand fairly substantial hydrostatic pressures, especially where it is applied to the pipelines and/or a collector pipe system in deep water installations. It should also be noted that the lower profile achievable reduces the strain on the pipes caused by underwater currents.
  • fibre reinforced plastic coating of the buoyancy spheres is to prevent collapse or implosion of these spheres in the cladding when subjected to hydrostatic pressure.
  • more coats provided greater strength to the buoyancy spheres but at the same time increasing the true density and reducing the buoyancy capability of the spheres. Accordingly larger and therefore more cumbersome cladding modules are required to provide the necessary degree of buoyancy.
  • the present invention aims to provide an alternative form of composite which does not suffer from the disadvantages indicated.
  • a buoyancy material comprising or including acetylated natural fibres, a synthetic resin to form a resin fibre matrix, and a buoyancy means.
  • the invention also provides a method of making the material.
  • the material preferably comprises or includes natural fibres which have been acetylated and mixed with a synthetic resin to form a resin fibre matrix, and that matrix is used to coat a buoyancy means, such as polystyrene beads or tubes or hollow shapes such as spheres.
  • a buoyancy means such as polystyrene beads or tubes or hollow shapes such as spheres.
  • Acetylated fibres are ones which have been subjected to acetylation treatment such as that set forth in our European patent application numbers 0910602, 0909618 and 0915121 and, and the acetylation process has the effect as is known of rendering the natural fibres substantially hydrophobic, whereas in their natural unacetylated state they are hydrophilic and therefore will swell and degrade when they become wet. This makes their use in a composite unsuitable for this application.
  • the acetylation treatment therefore renders the fibres suitable for applications such as buoyancy applications of the nature described above, but it is appreciated that perhaps the composite according to the invention may well have other applications where the advantage of high modulus and low density together with low degradation are desirable and of which we are not aware.
  • the acetylated fibres are cut, milled or ground in order to reduce their size, and then the reduced acetylated fibres are mixed with the resin which may typically be an epoxy or a polyester resin.
  • the resulting matrix is mixed with the buoyancy means, for example polystyrene beads so that the matrix coats the beads .
  • the coating process may be carried out in two or more stages to achieve a specific crushing or buckling strength.
  • the beads are either embedded in the matrix, or the matrix and beads form a material which is flowable, but in each case the material is capable of being shaped to form a buoyancy article or a buoyancy cover or attachment for an article.
  • the resulting composite is then moulded to the shape of for example the article whose buoyancy is to be increased, and where such article is a riser pipe or sealed collector , the composite may be moulded into the shape of cylindrical half shells for application to the riser pipe.
  • the fibres are acetylated before being milled, the invention also extends to the case where the acetylation takes place after milling.
  • Any suitable form of natural fibre can be used, but we have obtained good results using coir fibres, which are much lighter and have better thermal insulation properties than glass fibres, and the resulting composite is much lighter than the known composite used for buoyancy applications of the type described.
  • fibre suitable for use in the invention comprise but are not limited to jute, hemp, flax, and combinations of these fibres with synthetic fibres may be used if desired.
  • the acetylated fibre When the acetylated fibre is milled, it is preferably reduced to a size to between 5000 and 300 micron to be suitable for the coating compound which relates to the size of object to be coated.
  • the mixing of the ingredients of the composition may be done in a conventional mixer, and in any desired sequence.
  • buoyancy composite material in offshore pipes or pipelines or collector pipes
  • the material may be used in other buoyancy applications, including tow pipe transporting, enhancing the buoyancy of submersibles, the provision of buoyancy units for use in mid water arches of main riser systems, and so on.
  • the density of the composition is an important consideration and required total up-thrust or lift must be calculated.
  • the density normally has to be kept as low as technically possible, and the use of the acetylated fibres assists in this direction, providing the high modulus/low density required of the coating compound.
  • acetylated fibres in the coating composition provides the high modulus necessary to resist the crushing and buckling forces the materials are exposed to at great depths now being exploited in the industry.
  • the use of acetylated fibres helps to resist water ingress into the composition, which is an advantage, because the greater the water ingress, the greater the loss in buoyancy.

Abstract

The invention provides a buoyancy material comprising or including acetylated natural fibres, a synthetic resin to form a resin fibre matrix, and a buoyancy means. For the manufacture of the material, the resin and fibres are mixed to form a matrix and then the matrix is mixed, in sequence using batches of the matrix, with buoyancy material, specifically in the form of polystyrene beads or hollow shapes such as spheres or tubes, which become coated with the matrix. They are either embedded in the matrix, or the matrix and beads form a material which is flowable, but in each case the material is capable of being shaped to form an article or a cover for an article.

Description

COMPOSITE MATERIALS FOR USE IN BUOYANCY APPLICATIONS
This invention relates to composite materials, and especially those materials which are particularly useful in buoyancy applications, and especially those which have a high modulus and a low density/S.G.
A buoyancy application comprises a situation where a degree of displacement has to be added to an article member or structure so as in effect to reduce its effective weight when on or in a liquid, in particular water. Particular buoyancy applications include subsurface support systems in offshore, gas and marine industries.
A particular buoyancy application comprises the support of rigid riser pipes in off shore oil installations (the term riser pipe as used herein is intended to cover the installation and insulation of seabed collector pipe systems, known to those skilled in the art) . These riser pipes for transporting oil from under the sea bed to the sea surface typically may be of steel, and may be in a number of sections so that the riser can extend over substantial distances. Obviously, the longer the riser, the greater the weight of same, and the heavier the riser, the greater the power/buoyancy which is needed for example to neutralise the strain on the umbilical strings, which can be several thousand meters long, extending between the sea bed and the surface installation.
A further particular buoyancy application comprises the subsurface support horizontal or essentially horizontal pipelines or groups of pipelines used for transporting gas or oil along the seabed to the riser pipelines
A yet further particular buoyancy application comprises the support of flexible riser pipes in offshore oil and gas installations. Because of this difficulty, it has been established that pipes or pipe lengths are provided with buoyancy cladding in order to decrease the effective weight of the pipe or pipe lengths when in use in the water. This cladding additionally provides a degree of insulation, which can be important in some applications, for example the transport of oil, as the insulation prevents the oil from becoming too cold and viscous, impeding flow through the pipe.
The cladding which has been adopted heretofore comprises mainly a composition of syntactic foam to which is added hollow or essentially hollow bodies, typically spherical bodies, which are strengthened with fibre reinforced plastic coats . The spheres are typically fabricated from a thermoplastic or from glass, or from polystyrene foam. The reinforcing fibre for the synthetic resin coat is typically glass but may be wollastonite, or less typically because of cost considerations, carbon. The resin may typically be polyester or epoxy resin in basic or modified forms, and the composite is made by coating the spheres with a matrix of fibres and synthetic resin. The resin may typically be polyester or epoxy resin in basic or modified forms.
Glass fibre is typically used because in a composite it provides the required modulus to resist crushing pressure and in a composite it can be agoraphobic and will stand up to wet degradation, but it does have the disadvantage that it is relatively heavy (being approximately twice the specific gravity of natural fibre) and this reduces the degree of buoyancy which can be achieved by the coated hollow or essentially hollow spheres . Additionally, glass fibre is a poor thermal insulator which is a disadvantage where insulation is required.
It should be borne in mind that the cladding has to withstand fairly substantial hydrostatic pressures, especially where it is applied to the pipelines and/or a collector pipe system in deep water installations. It should also be noted that the lower profile achievable reduces the strain on the pipes caused by underwater currents.
The purpose of fibre reinforced plastic coating of the buoyancy spheres is to prevent collapse or implosion of these spheres in the cladding when subjected to hydrostatic pressure. Typically, more coats provided greater strength to the buoyancy spheres but at the same time increasing the true density and reducing the buoyancy capability of the spheres. Accordingly larger and therefore more cumbersome cladding modules are required to provide the necessary degree of buoyancy.
The present invention aims to provide an alternative form of composite which does not suffer from the disadvantages indicated.
In accordance with the invention, in general terms there is provided a buoyancy material comprising or including acetylated natural fibres, a synthetic resin to form a resin fibre matrix, and a buoyancy means.
The invention also provides a method of making the material.
The material preferably comprises or includes natural fibres which have been acetylated and mixed with a synthetic resin to form a resin fibre matrix, and that matrix is used to coat a buoyancy means, such as polystyrene beads or tubes or hollow shapes such as spheres.
Acetylated fibres are ones which have been subjected to acetylation treatment such as that set forth in our European patent application numbers 0910602, 0909618 and 0915121 and, and the acetylation process has the effect as is known of rendering the natural fibres substantially hydrophobic, whereas in their natural unacetylated state they are hydrophilic and therefore will swell and degrade when they become wet. This makes their use in a composite unsuitable for this application.
The acetylation treatment therefore renders the fibres suitable for applications such as buoyancy applications of the nature described above, but it is appreciated that perhaps the composite according to the invention may well have other applications where the advantage of high modulus and low density together with low degradation are desirable and of which we are not aware.
Preferably, in this application, the acetylated fibres are cut, milled or ground in order to reduce their size, and then the reduced acetylated fibres are mixed with the resin which may typically be an epoxy or a polyester resin. The resulting matrix is mixed with the buoyancy means, for example polystyrene beads so that the matrix coats the beads . The coating process may be carried out in two or more stages to achieve a specific crushing or buckling strength.
The beads are either embedded in the matrix, or the matrix and beads form a material which is flowable, but in each case the material is capable of being shaped to form a buoyancy article or a buoyancy cover or attachment for an article.
The resulting composite is then moulded to the shape of for example the article whose buoyancy is to be increased, and where such article is a riser pipe or sealed collector , the composite may be moulded into the shape of cylindrical half shells for application to the riser pipe. Although the fibres are acetylated before being milled, the invention also extends to the case where the acetylation takes place after milling.
Any suitable form of natural fibre can be used, but we have obtained good results using coir fibres, which are much lighter and have better thermal insulation properties than glass fibres, and the resulting composite is much lighter than the known composite used for buoyancy applications of the type described.
Other forms of fibre suitable for use in the invention comprise but are not limited to jute, hemp, flax, and combinations of these fibres with synthetic fibres may be used if desired.
When the acetylated fibre is milled, it is preferably reduced to a size to between 5000 and 300 micron to be suitable for the coating compound which relates to the size of object to be coated.
The mixing of the ingredients of the composition may be done in a conventional mixer, and in any desired sequence.
Although the examples given relate to the use of the buoyancy composite material in offshore pipes or pipelines or collector pipes, the material may be used in other buoyancy applications, including tow pipe transporting, enhancing the buoyancy of submersibles, the provision of buoyancy units for use in mid water arches of main riser systems, and so on.
It is felt that in all probability there will be other fields of application not yet identified.
In buoyancy applications, the density of the composition is an important consideration and required total up-thrust or lift must be calculated. The density normally has to be kept as low as technically possible, and the use of the acetylated fibres assists in this direction, providing the high modulus/low density required of the coating compound.
Buoyancy can be lost due to compression, but the use of the acetylated fibres in the coating composition provides the high modulus necessary to resist the crushing and buckling forces the materials are exposed to at great depths now being exploited in the industry. The use of acetylated fibres helps to resist water ingress into the composition, which is an advantage, because the greater the water ingress, the greater the loss in buoyancy.
It is also to be mentioned that coatings may be applied to

Claims

1. A buoyancy material comprising or including acetylated natural fibres, a synthetic resin to form a resin fibre matrix, and a buoyancy means.
2. A material according to claim 1 wherein the buoyancy means is in the form of discrete particulate form and the particles are coated with a matrix comprising the resin and the fibres.
3. The material according to claim 2, wherein the matrix and buoyancy means are mixed to provide that the matrix coats the buoyancy means.
4. The material according to claim 1 ,2 or 3, wherein the buoyancy means comprises substantially hollow spheres or tubes.
5. The material according to claim 1 ,2 or 3, wherein the buoyancy means comprises polystyrene beads.
6. The material according to any of claims 1 to 5, wherein the fibres have a length in the range 300 to 5000 micron.
7. A method of producing a buoyancy material comprising mixing acetylated natural fibres, a synthetic resin and a buoyancy means.
8. The method according to claim 7, wherein the fibres are first mixed with the resin to form a matrix, and then the matrix is mixed with the buoyancy means.
9. The method according to claim 8 wherein two or more batches of the matrix are mixed with the buoyancy means in sequence.
10. The method according to claim 7, 8 or 9, wherein the buoyancy means is substantially hollow spheres or tubes.
1 1. The method according to claim 7, 8 or 9, wherein the buoyancy means is polystyrene beads.
12. The method according to any of claims 7 to 1 1 , wherein the fibres are milled after being acetylated.
13. The method according to any of claims 7 to 11 , wherein the fibres are acetylated after being milled.
14. The method according to any of claims 7 to 13 wherein the fibres have a length in the range 300 to 5000 micron.
15. The method according to any of claims 7 to 14, wherein the resulting material is mouldable.
16. The method according to claim 15, wherein the material is moulded to the shape of for the article which is to have a predetermined buoyancy, or whose buoyancy is to be increased.
17. The method according to claim 16, wherein such article is a riser pipe, and the composite is moulded into the shape of cylindrical half shells for application to the riser pipe.
18. The method according to any of claims 7 to 17, wherein the fibres are acetylated before being milled.
19. The method according to any of claims 7 to 17, wherein the fibres are milled before being acetylated.
20. The method according to any of claims 6 to 14, wherein the fibres are taken singly or in combination from coir fibres, jute, hemp, or flax which are much lighter than glass fibres.
PCT/GB1999/003926 1998-11-26 1999-11-26 Composite materials for use in buoyancy applications WO2000031169A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU12855/00A AU1285500A (en) 1998-11-26 1999-11-26 Composite materials for use in buoyancy applications

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GBGB9825768.6A GB9825768D0 (en) 1998-11-26 1998-11-26 Composite materials,especially for use in buoyancy applications
GB9825768.6 1998-11-26
GB9827188.5 1998-12-11
GBGB9827188.5A GB9827188D0 (en) 1998-12-11 1998-12-11 Composite materials,especially for use in buoyancy applications

Publications (1)

Publication Number Publication Date
WO2000031169A1 true WO2000031169A1 (en) 2000-06-02

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Application Number Title Priority Date Filing Date
PCT/GB1999/003926 WO2000031169A1 (en) 1998-11-26 1999-11-26 Composite materials for use in buoyancy applications

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AU (1) AU1285500A (en)
WO (1) WO2000031169A1 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003025331A1 (en) * 2001-09-15 2003-03-27 Crp Group Ltd. Buoyancy element and module
US6758710B2 (en) 2002-07-02 2004-07-06 Crp Balmoral Inc. Method of reinforcement of marine buoyancy modules
CN103665768A (en) * 2013-11-26 2014-03-26 上海复合材料科技有限公司 Method for preparing high-strength solid buoyancy material
CN108329511A (en) * 2018-01-10 2018-07-27 中国船舶重工集团公司第七二五研究所 A kind of preparation method of solid buoyancy material nucleocapsid grade bead

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1168778A (en) * 1965-10-21 1969-10-29 Sumitomo Bakelite Co Structural Foamed Products and Method for Production Thereof.
US4706711A (en) * 1984-09-12 1987-11-17 Taurus Gumiipari Vallalat Elastic technical hose with a foam insert
JPH06198610A (en) * 1993-01-08 1994-07-19 Yamaha Corp Preparation of wooden fibrous material

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1168778A (en) * 1965-10-21 1969-10-29 Sumitomo Bakelite Co Structural Foamed Products and Method for Production Thereof.
US4706711A (en) * 1984-09-12 1987-11-17 Taurus Gumiipari Vallalat Elastic technical hose with a foam insert
JPH06198610A (en) * 1993-01-08 1994-07-19 Yamaha Corp Preparation of wooden fibrous material

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Section Ch Week 199433, Derwent World Patents Index; Class A81, AN 1994-268993, XP002132541 *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003025331A1 (en) * 2001-09-15 2003-03-27 Crp Group Ltd. Buoyancy element and module
GB2393152A (en) * 2001-09-15 2004-03-24 Crp Group Ltd Buoyancy element and module
GB2393152B (en) * 2001-09-15 2004-08-04 Crp Group Ltd Buoyancy element and module
US7214114B2 (en) 2001-09-15 2007-05-08 Trelleborg Crp Ltd. Buoyancy element and module
US6758710B2 (en) 2002-07-02 2004-07-06 Crp Balmoral Inc. Method of reinforcement of marine buoyancy modules
CN103665768A (en) * 2013-11-26 2014-03-26 上海复合材料科技有限公司 Method for preparing high-strength solid buoyancy material
CN103665768B (en) * 2013-11-26 2016-08-17 上海复合材料科技有限公司 The preparation method of High-strength solid buoyancy material
CN108329511A (en) * 2018-01-10 2018-07-27 中国船舶重工集团公司第七二五研究所 A kind of preparation method of solid buoyancy material nucleocapsid grade bead

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