WO1999066246A1 - A reinforced, flexible conduit and a method of manufacturing same - Google Patents

A reinforced, flexible conduit and a method of manufacturing same Download PDF

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Publication number
WO1999066246A1
WO1999066246A1 PCT/DK1999/000329 DK9900329W WO9966246A1 WO 1999066246 A1 WO1999066246 A1 WO 1999066246A1 DK 9900329 W DK9900329 W DK 9900329W WO 9966246 A1 WO9966246 A1 WO 9966246A1
Authority
WO
WIPO (PCT)
Prior art keywords
tensile strength
strength imparting
reinforced
imparting elements
elongated tensile
Prior art date
Application number
PCT/DK1999/000329
Other languages
French (fr)
Inventor
Jan Christian Rytter
Jens Vinge Nygaard
Original Assignee
Nkt Cables A/S
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
Application filed by Nkt Cables A/S filed Critical Nkt Cables A/S
Priority to AU43595/99A priority Critical patent/AU4359599A/en
Publication of WO1999066246A1 publication Critical patent/WO1999066246A1/en

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Classifications

    • 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
    • F16L11/08—Hoses, i.e. flexible pipes made of rubber or flexible plastics with reinforcements embedded in the wall

Definitions

  • the present invention relates to a reinforced, flexible pipeline and a method of manufacturing such a pipeline comprising an inner lining forming a barrier against flow of the medium flowing through the pipeline out to the armouring layers arranged around the inner lining, said in ⁇ ner lining being surrounded by a compression reinforce- ment which comprises a plurality of profiles wound heli ⁇ cally around the inner lining, a tension reinforcement being arranged externally on the compression reinforcement and comprising a plurality of elongated tensile strength imparting elements which twist substantially along the longitudinal direction of the pipeline so as to allow bending of the pipeline without this creating con ⁇ siderable bending resistance.
  • Such pipelines are frequently used for conveying liquids and gases at various depths of water, and they are particularly used in situations where very great or varying water pressures prevail.
  • Examples of fields of use thus include riser pipes which extend from the sea bed up to an installation near the surface of the sea, and between two or more installations which are positioned on the sea bed at a great depth.
  • the pipelines are frequently constructed such that an outer pipeline layer is arranged around the reinforce- ment, consisting of a material which serves to prevent migration of liquids from the surroundings of the pipe into the compression reinforcement as well as the tension reinforcement, as this may cause collapse of the inner lining or corrosion of the reinforcement. If the pipe is constructed with an inner carcass, the purpose of this is primarily to protect against such a collapse.
  • GB 2002084 A discloses a flexible pipeline which has a combined tension and compression relief, externally on which an outer jacket surrounded by metal strips is ar- ranged.
  • An inner lining and a carcass are provided inwardly of the combined tension and compression relief, but no sepa ⁇ rate compression reinforcement.
  • the object of the present invention is to provide a pipeline which, to a higher degree than the known ones, prevents liquids from flowing from the surroundings and into particularly the above-mentioned ar- mouring layers.
  • the matrix of the solid material may thus form a barrier against the above-mentioned migration of liquids into the layers of the pipeline which are present between the tension reinforcement and the inner lining.
  • This barrier is thereby protected by means of the embedded elongated tensile strength imparting elements against being destroyed by e.g. laying and drift of the pipeline, as the elongated tensile strength imparting elements counteract a through-going perforation of the barrier.
  • the structure of the elongated tensile strength imparting elements does not serve to absorb compression loads, as an independent compression reinforcement is present inwardly of the tensile strength imparting elements according to the invention.
  • a particularly flexible pipeline is achieved if at least one or more of the elongated tensile strength imparting elements forming part of the tension reinforcement are formed by a material having a modulus of elasticity which is higher than the modulus of elasticity of the different solid material forming the matrix which embeds these.
  • the tensile strength imparting elements may be bound chemically or mechanically to the surrounding matrix, but, alternatively, they may be freely embedded in the matrix.
  • the flexibility of the pipeline is increased additionally if at least some of the elongated tensile strength i - parting elements are twisted around the longitudinal axis of the pipeline.
  • the elongated flexible elements are twisted around the longitudinal axis of the pipeline at an angle relative to the longitudinal axis of the pipe which is smaller than the corresponding angle at which the profiles forming the compression reinforcement are wound helically around the longitudinal axis of the pipeline .
  • the material different from the tensile strength imparting elements is formed by a plastics material, such as e.g. an elastomer.
  • the matrix may hereby be formed in a simple extrusion process.
  • the elongated tensile strength imparting elements may be made of many different materials which each have advantageous properties. Thus, there is a free choice between inter alia metal profiles or profiles which are formed by a composite of metal and ceramics. Alternatively, the elongated tensile strength imparting elements may be formed by a plurality of fibres which are embedded in a plastics material, or by a bundle of fibres which are held together completely or partly to form a pultruded material or a rope.
  • the elongated tensile strength imparting elements form at least two substantially concentric layers around the longitudinal axis of the pipeline.
  • very good properties may be achieved with respect to balancing of torsional forces in the pipe, if the elongated tensile strength imparting elements in each of the substantially concentric layers are twisted around the pipeline at different angles relative to the longitudinal axis of the pipeline, or they twist in an opposite direction around the longitudinal axis of the pipeline so that the elongated tensile strength imparting elements in a first one of the substantially concentric layers intersect the corresponding elongated tensile strength imparting elements in a second one of the substantially concentric layers.
  • the individual layers of the tensile strength imparting elements forming the tension reinforcement may be twisted around the pipeline at different angles, thereby balanc ⁇ ing possible torsional forces that are created in the in- dividual layers by a longitudinal pull in the pipeline.
  • the elongated tensile strength imparting elements in a first one of the substantially concentric layers are embedded in such a manner in the surrounding matrix that they do not touch the corresponding elongated tensile strength imparting elements in a second one of the substantially concentric layers.
  • the material used for the elongated tensile strength imparting elements may be materials such as carbon fibre, aramid fibre, UHMPE fibre or the like, which have a very high modulus of elasticity and strength in the tensile direction, but a very poor impact resistance.
  • the pipeline may advantageously be provided with a carcass consisting of one or more helically wound profiles nested or hooked to- gether, thereby providing an additional safeguard against collapse of the inner lining if the pressure on the inner side of the lining drops below the pressure on the outer side of it.
  • the reinforced, flexible pipeline may be constructed such that the profiles forming the compression reinforcement in the pipeline are surrounded completely or partly by a free volume which allows flow of liquids or liquid gases along the pipe.
  • the elongated tensile strength imparting elements m a first one of the substantially concentric layers are constructed such that they have a substantially plane face which faces toward the corresponding elongated tensile strength imparting elements m an adjacent second layer. This counteracts high tension concentrations m the matrix, and the durability of the matrix is therefore ensured to a maximum degree so that the advantageous properties of the pipeline are main ⁇ tained for a long time.
  • This effect may e.g. be improved if the elongated tensile strength imparting elements are formed with a substan- tially quadrangular cross-section and with corners which have a radius of curvature which is greater than 7% of the smallest dimension of the quadrangular cross-section. Curvature avoids notch effects m the matrix material near the corners of the quadrangular cross-section of the tensile strength imparting elements, so that the durability of the matrix is increased additionally.
  • the present invention also relates to a method of manufacturing a reinforced, flexible pipeline comprising an inner lining for forming a barrier against a medium flowing m the pipe, said inner lining being surrounded by a compression reinforcement which comprises a plurality of profiles wound around the inner lining, a tension reinforcement being arranged externally on the compression reinforcement and comprising a plurality of elongated tensile strength imparting elements which extend substantially along the longitudinal direction of the pipe.
  • the invention provides an extremely simple way of producing such a pipeline, by means of which a rela- tively low weight of the produced pipe may be obtained, while allowing the use of composite materials m the structure of the pipe.
  • This method may be simplified additionally if the elongated tensile strength imparting elements are held at a predetermined mutual distance until they are embedded m the extruded matrix.
  • Fig. 1 is a basic view illustrating the structure of a segment of a pipe according to the invention.
  • Fig. 2 is a corresponding sectional view illustrating an example of the structure of a known pipe.
  • Fig. 2 thus shows a segment of a flexible pipeline of a generally known type which is frequently used as a riser pipe between installations on the sea bed and an installation which is present at the surface of the sea.
  • This may e.g. be m connection with oil or gas recovery or transport.
  • the pipeline may also be used as a transport pipeline between two installations both of which are present on the sea bed or relatively deep below the surface of the sea.
  • the pipe may be used between two installations at the surface of the sea, such as two ships.
  • the pipeline may be affected by very great pressures from the surroundings in particular, which makes very great demands on the structure of the pipe which must be capable of withstanding these pressures.
  • this layered structure consists of an inner layer in the form of a carcass 1, which is formed by one or more metal strips 2 which are wound helically so as to form an inner pipe, said metal strip 2, during the winding, being formed with flaps which engage each other so as to lock the individual turns in the helically wound strip 2 to each other in such a manner that the carcass 1 can still bend after the winding.
  • a lining 3 of a suitable plastics material is then provided externally on the carcass 1 in a generally known extrusion process, said lining forming a suitable barrier ensuring that the medium flowing in the pipeline does not penetrate into the intermediate layers of the pipeline.
  • One or more metal profiles 5, 6, which form turns having a very small pitch relative to the longitudinal direction of the pipeline, are then wound helically externally on the lining 3 in a conventional manner. From a conventional point of view, these turns thus offer a great resistance to bursting of the lining 3 and the carcass 1 because of a high pressure on the inner side of the pipeline, the reinforcement formed by these profiles being frequently called a compression reinforcement 4.
  • the profiles 5, 6, which constitute the compression reinforcement 4 are formed by C-, T- or other pro- files, the profiles 5, 6 being so oriented in the pipe- line that two layers of turns wound around the lining 3 in the same direction engage each other.
  • a further reinforcement is ar- ranged externally on the compression reinforcement 4, said further reinforcement consisting of one or more layers of profiles 7, 8 which are frequently helically wound with a considerably greater pitch than the profiles 5, 6 which form the above-mentioned compression rein- forcement 4, so that they can effectively absorb the great tensile forces which are created in the pipeline in use.
  • This outer reinforcement is therefore frequently called the tension reinforcement.
  • the individual layers of profiles 7, 8 in the tension reinforcement may expediently be wound in mutually different directions around the longitudinal axis of the pipeline, as shown in fig. 2, whereby they moreover create an effective balancing of torsional moments in the pipe dur- ing tensile impacts on it.
  • the above-mentioned layers of profiles may have interposed between them relatively thin layers of a material which inter alia serve to prevent tearing be- tween adjacent profiles when the pipes are bent, but may also have other use-specific purposes.
  • the known pipelines have an outer jacket 9 which may be constructed very differently, but which at least comprises a layer preferably of plastics, whose purpose is inter alia to serve as a barrier against flow of fluids inwards between the profiles 5, 6, 7, 8 from the surroundings.
  • an outer jacket 9 which may be constructed very differently, but which at least comprises a layer preferably of plastics, whose purpose is inter alia to serve as a barrier against flow of fluids inwards between the profiles 5, 6, 7, 8 from the surroundings.
  • there are known pipelines having other structures than the one shown m fig. 2.
  • the inner carcass 1 is omitted so that the lining 3 forms the innermost layer of the pipeline.
  • the carcass is frequently used in connection with pipelines which are affected by great outer pressures, as a possible increase in the pressure between the outer jacket 9 and the lining 3 because of a possible leakage on the pipeline to the external environment may cause collapse of the lining 3, which is counteracted by the carcass 1.
  • fig. 1 shows a pipeline according to the present in ⁇ vention which contains all the layers shown in fig. 2, except the outer jacket 9 and the tension reinforcement consisting of the profiles 7, 8 according to fig. 1.
  • the structure thus corresponds in principle to the corresponding parts of the pipeline shown in fig. 2.
  • the tension reinforcement consisting of the profiles 7, 8 and the outer jacket 9 shown in fig. 2
  • a hydrostatic- ally tight tension reinforcement 10 comprising a plurality of profiles 15, 16, which are embedded in a matrix 17 of a material having a modulus of elasticity which is smaller than the modulus of elasticity of the profiles 15, 16.
  • the tension reinforcement 10 hereby forms an outer jacket which both constitutes a barrier against ingress of fluids from the surroundings to the underlying layers of the pipe, but which moreover gives the pipeline the necessary resistance to tensile forces during laying and particularly use of the pipeline.
  • the tension reinforcement 10 according to the invention is thus an integrated unit which forms a substantially hydrostatically tight pipe around the vital inner layers of the pipeline, and since this hydrostatically tight pipe contains reinforced profiles 15, 16, it is clear that the risk of the hydrostatically tight pipe be ⁇ ing perforated m use is extremely low, as the profiles 15, 16 prevent this.
  • the profiles 15, 16 m the tension reinforcement 10 are wound around the longitudinal axis of the pipeline with a very high pitch, and since they are wound m mutually opposite directions around the longitudinal axis of the pipeline, great bal- ancmg of torsional forces, which may occur m the pipeline m particular in use, is achieved.
  • the skilled person will be able to devise a number of other embodiments of pipelines which basically involve the same advantages and basic principles as the one shown in fig. 1.
  • more layers may be arranged in the pipes depending on the specific use. These additional layers may both be arranged below the above-mentioned tension reinforcement 10 and externally on it.
  • many different materials may be used both for the pro- files forming part of the pipeline, and for the plastics layers which are incorporated.
  • the stated matrix may be arranged such that it is chemically or mechanically anchored to the tension re- inforcement, but it may also be loose in it.
  • the carcass and the profiles 18, 19, which form the compression reinforcement 14, are made of a metal, such as steel, stainless steel, titanium or aluminium.
  • a metal such as steel, stainless steel, titanium or aluminium.
  • the tension reinforcement 10 this is advantageously formed by profiles 15, 16 which are made of steel or a titanium alloy, or a material consisting of fibres of glass, carbon, aramid or another material containing the desired properties which is embedded in a matrix of a polymeric material, and the matrix material 17 surrounding the profiles 15, 16 may advantageously be formed by a thermoplastic elastomer or a vulcanizable polymeric material.
  • the profiles 15, 16 forming part of the tension reinforcement 10 may advantageously be formed with at least one plane side which is wider than 20% of the maximum cross-sectional width of the profile 15, 16, and more expediently the profiles 15, 16 may be formed as quadrangu- lar profiles having at least two parallel sides, with the corners formed with a radius of curvature which is greater than 7% of the smallest cross-sectional width of the quadrangular cross-section.

Abstract

A reinforced, flexible pipeline and a method of manufacturing same, said pipeline comprising an inner lining which forms a barrier against flow of the medium flowing through the pipe out to the armouring layers arranged around the inner lining, said inner lining being surrounded by a compression reinforcement which comprises a plurality of profiles wound helically around the inner lining, and a tension reinforcement arranged externally on the compression reinforcement and comprising a plurality of elongated tensile strength imparting elements which extend substantially along the longitudinal direction of the pipe, said elongated tensile strength imparting elements being embedded in a matrix consisting of a solid material different from the elongated tensile strength imparting elements.

Description

A reinforced, flexible conduit and a method of manufacturing same
The present invention relates to a reinforced, flexible pipeline and a method of manufacturing such a pipeline comprising an inner lining forming a barrier against flow of the medium flowing through the pipeline out to the armouring layers arranged around the inner lining, said in¬ ner lining being surrounded by a compression reinforce- ment which comprises a plurality of profiles wound heli¬ cally around the inner lining, a tension reinforcement being arranged externally on the compression reinforcement and comprising a plurality of elongated tensile strength imparting elements which twist substantially along the longitudinal direction of the pipeline so as to allow bending of the pipeline without this creating con¬ siderable bending resistance.
Such pipelines are frequently used for conveying liquids and gases at various depths of water, and they are particularly used in situations where very great or varying water pressures prevail. Examples of fields of use thus include riser pipes which extend from the sea bed up to an installation near the surface of the sea, and between two or more installations which are positioned on the sea bed at a great depth.
The pipelines are frequently constructed such that an outer pipeline layer is arranged around the reinforce- ment, consisting of a material which serves to prevent migration of liquids from the surroundings of the pipe into the compression reinforcement as well as the tension reinforcement, as this may cause collapse of the inner lining or corrosion of the reinforcement. If the pipe is constructed with an inner carcass, the purpose of this is primarily to protect against such a collapse. GB 2002084 A discloses a flexible pipeline which has a combined tension and compression relief, externally on which an outer jacket surrounded by metal strips is ar- ranged.
An inner lining and a carcass are provided inwardly of the combined tension and compression relief, but no sepa¬ rate compression reinforcement.
Accordingly, the object of the present invention is to provide a pipeline which, to a higher degree than the known ones, prevents liquids from flowing from the surroundings and into particularly the above-mentioned ar- mouring layers.
This is achieved according to the present invention by providing a pipeline as mentioned in the opening paragraph, said pipeline being unique in that the elongated tensile strength imparting elements are embedded in a matrix consisting of a solid material different from the elongated tensile strength imparting elements.
The matrix of the solid material may thus form a barrier against the above-mentioned migration of liquids into the layers of the pipeline which are present between the tension reinforcement and the inner lining. This barrier is thereby protected by means of the embedded elongated tensile strength imparting elements against being destroyed by e.g. laying and drift of the pipeline, as the elongated tensile strength imparting elements counteract a through-going perforation of the barrier.
It should moreover be noted that the tensile strength im- parting elements are protected by the embedded matrix against mechanical point loads, and that the outer jacket, which is now not present as an independent jacket, is integrated with and reinforced by the armouring wires.
On the other hand, the structure of the elongated tensile strength imparting elements does not serve to absorb compression loads, as an independent compression reinforcement is present inwardly of the tensile strength imparting elements according to the invention.
A particularly flexible pipeline is achieved if at least one or more of the elongated tensile strength imparting elements forming part of the tension reinforcement are formed by a material having a modulus of elasticity which is higher than the modulus of elasticity of the different solid material forming the matrix which embeds these.
The tensile strength imparting elements may be bound chemically or mechanically to the surrounding matrix, but, alternatively, they may be freely embedded in the matrix.
The flexibility of the pipeline is increased additionally if at least some of the elongated tensile strength i - parting elements are twisted around the longitudinal axis of the pipeline.
In a preferred embodiment, the elongated flexible elements are twisted around the longitudinal axis of the pipeline at an angle relative to the longitudinal axis of the pipe which is smaller than the corresponding angle at which the profiles forming the compression reinforcement are wound helically around the longitudinal axis of the pipeline . It is particularly advantageous if the material different from the tensile strength imparting elements is formed by a plastics material, such as e.g. an elastomer. The matrix may hereby be formed in a simple extrusion process.
The elongated tensile strength imparting elements may be made of many different materials which each have advantageous properties. Thus, there is a free choice between inter alia metal profiles or profiles which are formed by a composite of metal and ceramics. Alternatively, the elongated tensile strength imparting elements may be formed by a plurality of fibres which are embedded in a plastics material, or by a bundle of fibres which are held together completely or partly to form a pultruded material or a rope.
It is moreover possible to obtain a great protection against penetration of the outer barrier of the pipe, if the elongated tensile strength imparting elements form at least two substantially concentric layers around the longitudinal axis of the pipeline.
In addition, very good properties may be achieved with respect to balancing of torsional forces in the pipe, if the elongated tensile strength imparting elements in each of the substantially concentric layers are twisted around the pipeline at different angles relative to the longitudinal axis of the pipeline, or they twist in an opposite direction around the longitudinal axis of the pipeline so that the elongated tensile strength imparting elements in a first one of the substantially concentric layers intersect the corresponding elongated tensile strength imparting elements in a second one of the substantially concentric layers. The individual layers of the tensile strength imparting elements forming the tension reinforcement may be twisted around the pipeline at different angles, thereby balanc¬ ing possible torsional forces that are created in the in- dividual layers by a longitudinal pull in the pipeline.
In this connection it is particularly advantageous if the elongated tensile strength imparting elements in a first one of the substantially concentric layers are embedded in such a manner in the surrounding matrix that they do not touch the corresponding elongated tensile strength imparting elements in a second one of the substantially concentric layers. This ensures that the elongated ten¬ sile strength imparting elements do not destroy each other upon loading of the pipe, so that the material used for the elongated tensile strength imparting elements may be materials such as carbon fibre, aramid fibre, UHMPE fibre or the like, which have a very high modulus of elasticity and strength in the tensile direction, but a very poor impact resistance.
Further, internally on the inner lining, the pipeline may advantageously be provided with a carcass consisting of one or more helically wound profiles nested or hooked to- gether, thereby providing an additional safeguard against collapse of the inner lining if the pressure on the inner side of the lining drops below the pressure on the outer side of it.
In addition, the reinforced, flexible pipeline may be constructed such that the profiles forming the compression reinforcement in the pipeline are surrounded completely or partly by a free volume which allows flow of liquids or liquid gases along the pipe. In a particularly advantageous embodiment of the reinforced, flexible pipeline, the elongated tensile strength imparting elements m a first one of the substantially concentric layers are constructed such that they have a substantially plane face which faces toward the corresponding elongated tensile strength imparting elements m an adjacent second layer. This counteracts high tension concentrations m the matrix, and the durability of the matrix is therefore ensured to a maximum degree so that the advantageous properties of the pipeline are main¬ tained for a long time.
This effect may e.g. be improved if the elongated tensile strength imparting elements are formed with a substan- tially quadrangular cross-section and with corners which have a radius of curvature which is greater than 7% of the smallest dimension of the quadrangular cross-section. Curvature avoids notch effects m the matrix material near the corners of the quadrangular cross-section of the tensile strength imparting elements, so that the durability of the matrix is increased additionally.
As mentioned above, the present invention also relates to a method of manufacturing a reinforced, flexible pipeline comprising an inner lining for forming a barrier against a medium flowing m the pipe, said inner lining being surrounded by a compression reinforcement which comprises a plurality of profiles wound around the inner lining, a tension reinforcement being arranged externally on the compression reinforcement and comprising a plurality of elongated tensile strength imparting elements which extend substantially along the longitudinal direction of the pipe. The invention provides an extremely simple way of producing such a pipeline, by means of which a rela- tively low weight of the produced pipe may be obtained, while allowing the use of composite materials m the structure of the pipe. This is achieved m that the inner lining and the associated compression reinforcement, together with the elongated tensile strength imparting elements, are advanced through an extruder which extrudes a matrix surrounding each of the elongated tensile strength imparting elements so as to form a pipe around the compression reinforcement, said pipe consisting of the elongated tensile strength imparting elements which are embedded in the extruded matrix. Application of these layers may take place m one or more stages.
This method may be simplified additionally if the elongated tensile strength imparting elements are held at a predetermined mutual distance until they are embedded m the extruded matrix.
The invention will be described more fully below with reference to the drawing, m which:
Fig. 1 is a basic view illustrating the structure of a segment of a pipe according to the invention.
Fig. 2 is a corresponding sectional view illustrating an example of the structure of a known pipe.
Fig. 2 thus shows a segment of a flexible pipeline of a generally known type which is frequently used as a riser pipe between installations on the sea bed and an installation which is present at the surface of the sea. This may e.g. be m connection with oil or gas recovery or transport. The pipeline may also be used as a transport pipeline between two installations both of which are present on the sea bed or relatively deep below the surface of the sea. As a third possibility, the pipe may be used between two installations at the surface of the sea, such as two ships. In at least some of the above-mentioned fields of use it is clear that the pipeline may be affected by very great pressures from the surroundings in particular, which makes very great demands on the structure of the pipe which must be capable of withstanding these pressures. This makes it expedient to have a layered pipe structure in which the individual layers have different functions. As shown in fig. 2, this layered structure consists of an inner layer in the form of a carcass 1, which is formed by one or more metal strips 2 which are wound helically so as to form an inner pipe, said metal strip 2, during the winding, being formed with flaps which engage each other so as to lock the individual turns in the helically wound strip 2 to each other in such a manner that the carcass 1 can still bend after the winding.
A lining 3 of a suitable plastics material is then provided externally on the carcass 1 in a generally known extrusion process, said lining forming a suitable barrier ensuring that the medium flowing in the pipeline does not penetrate into the intermediate layers of the pipeline.
One or more metal profiles 5, 6, which form turns having a very small pitch relative to the longitudinal direction of the pipeline, are then wound helically externally on the lining 3 in a conventional manner. From a conventional point of view, these turns thus offer a great resistance to bursting of the lining 3 and the carcass 1 because of a high pressure on the inner side of the pipeline, the reinforcement formed by these profiles being frequently called a compression reinforcement 4. As will be seen, the profiles 5, 6, which constitute the compression reinforcement 4, are formed by C-, T- or other pro- files, the profiles 5, 6 being so oriented in the pipe- line that two layers of turns wound around the lining 3 in the same direction engage each other.
In the known pipelines, a further reinforcement is ar- ranged externally on the compression reinforcement 4, said further reinforcement consisting of one or more layers of profiles 7, 8 which are frequently helically wound with a considerably greater pitch than the profiles 5, 6 which form the above-mentioned compression rein- forcement 4, so that they can effectively absorb the great tensile forces which are created in the pipeline in use. This outer reinforcement is therefore frequently called the tension reinforcement.
The individual layers of profiles 7, 8 in the tension reinforcement may expediently be wound in mutually different directions around the longitudinal axis of the pipeline, as shown in fig. 2, whereby they moreover create an effective balancing of torsional moments in the pipe dur- ing tensile impacts on it.
Furthermore, the above-mentioned layers of profiles may have interposed between them relatively thin layers of a material which inter alia serve to prevent tearing be- tween adjacent profiles when the pipes are bent, but may also have other use-specific purposes.
Externally on the tension reinforcement, which comprises the above-mentioned helically wound profiles 7, 8, the known pipelines have an outer jacket 9 which may be constructed very differently, but which at least comprises a layer preferably of plastics, whose purpose is inter alia to serve as a barrier against flow of fluids inwards between the profiles 5, 6, 7, 8 from the surroundings. Clearly, there are known pipelines having other structures than the one shown m fig. 2. Thus, e.g., there are pipelines in which the inner carcass 1 is omitted so that the lining 3 forms the innermost layer of the pipeline. However, the carcass is frequently used in connection with pipelines which are affected by great outer pressures, as a possible increase in the pressure between the outer jacket 9 and the lining 3 because of a possible leakage on the pipeline to the external environment may cause collapse of the lining 3, which is counteracted by the carcass 1.
Now, fig. 1 shows a pipeline according to the present in¬ vention which contains all the layers shown in fig. 2, except the outer jacket 9 and the tension reinforcement consisting of the profiles 7, 8 according to fig. 1.
As regards the carcass 11, the lining 13 and the compres¬ sion reinforcement 14, the structure thus corresponds in principle to the corresponding parts of the pipeline shown in fig. 2.
According to the invention, however, the tension reinforcement consisting of the profiles 7, 8 and the outer jacket 9 shown in fig. 2, is replaced by a hydrostatic- ally tight tension reinforcement 10 comprising a plurality of profiles 15, 16, which are embedded in a matrix 17 of a material having a modulus of elasticity which is smaller than the modulus of elasticity of the profiles 15, 16. The tension reinforcement 10 hereby forms an outer jacket which both constitutes a barrier against ingress of fluids from the surroundings to the underlying layers of the pipe, but which moreover gives the pipeline the necessary resistance to tensile forces during laying and particularly use of the pipeline. Since the tension reinforcement 10 according to the invention is thus an integrated unit which forms a substantially hydrostatically tight pipe around the vital inner layers of the pipeline, and since this hydrostatically tight pipe contains reinforced profiles 15, 16, it is clear that the risk of the hydrostatically tight pipe be¬ ing perforated m use is extremely low, as the profiles 15, 16 prevent this.
This makes it possible completely to omit or at least to dimension particularly the carcass 1 smaller than is com¬ mon m the known pipelines, without this involving an in¬ creased risk of collapse of the pipeline by unintended influx of fluids from the surroundings of the pipe and the consequently increased pressure on the outer sides of the carcass 1 and of the lining 3.
Since, additionally, the shown structure involves an em¬ bodiment m which the profiles 15, 16 do not touch each other directly, it is clear that this allows more liberty m the selection of materials for forming the profiles 15, 16. Thus, it is possible to select materials which have a lower impact resistance than e.g. various steel and aluminium materials, but which have a considerably higher specific strength m the tensile direction, without this having a significant importance for the risk of mechanical damage on the profiles particularly m the areas m which they intersect each other.
As will be seen m the figure, the profiles 15, 16 m the tension reinforcement 10 are wound around the longitudinal axis of the pipeline with a very high pitch, and since they are wound m mutually opposite directions around the longitudinal axis of the pipeline, great bal- ancmg of torsional forces, which may occur m the pipeline m particular in use, is achieved. Clearly, the skilled person will be able to devise a number of other embodiments of pipelines which basically involve the same advantages and basic principles as the one shown in fig. 1. Thus, more layers may be arranged in the pipes depending on the specific use. These additional layers may both be arranged below the above-mentioned tension reinforcement 10 and externally on it. Further, many different materials may be used both for the pro- files forming part of the pipeline, and for the plastics layers which are incorporated.
Clearly, the stated matrix may be arranged such that it is chemically or mechanically anchored to the tension re- inforcement, but it may also be loose in it.
In the preferred embodiments of the invention, the carcass and the profiles 18, 19, which form the compression reinforcement 14, are made of a metal, such as steel, stainless steel, titanium or aluminium. As regards the tension reinforcement 10, this is advantageously formed by profiles 15, 16 which are made of steel or a titanium alloy, or a material consisting of fibres of glass, carbon, aramid or another material containing the desired properties which is embedded in a matrix of a polymeric material, and the matrix material 17 surrounding the profiles 15, 16 may advantageously be formed by a thermoplastic elastomer or a vulcanizable polymeric material.
The profiles 15, 16 forming part of the tension reinforcement 10 may advantageously be formed with at least one plane side which is wider than 20% of the maximum cross-sectional width of the profile 15, 16, and more expediently the profiles 15, 16 may be formed as quadrangu- lar profiles having at least two parallel sides, with the corners formed with a radius of curvature which is greater than 7% of the smallest cross-sectional width of the quadrangular cross-section. As a result, the risk that the matrix 17 surrounding the profiles 15, 16 is destroyed by bending of the pipeline is minimized, since a relatively large uniformly thick face of the matrix material is obtained between the closest areas on two profiles which intersect each other, so that no great tension concentrations are created in the material, and there is no risk of notch effects in the matrix material because of the rounded corners.

Claims

P a t e n t C l a i m s
1. A reinforced, flexible pipeline comprising an inner lining which forms a barrier against flow of the medium flowing through the pipe out to the armouring layers ar¬ ranged around the inner lining, said inner lining being surrounded by a compression reinforcement which comprises a plurality of profiles wound helically around the inner lining, a tension reinforcement being arranged externally on the compression reinforcement and comprising a plural¬ ity of elongated tensile strength imparting elements which extend substantially along the longitudinal direction of the pipe, c h a r a c t e r i z e d in that the elongated tensile strength imparting elements are embed¬ ded in a matrix consisting of a solid material different from the elongated tensile strength imparting elements.
2. A reinforced, flexible pipeline according to claim 1, c h a r a c t e r i z e d in that at least one or more of the elongated tensile strength imparting elements forming part of the tension reinforcement are formed by a material having a modulus of elasticity which is higher than the modulus of elasticity of the surrounding solid material forming the matrix which embeds these.
3. A reinforced, flexible pipeline according to claim 1 or 2, c h a r a c t e r i z e d in that at least some of the elongated tensile strength imparting elements are twisted around the longitudinal axis of the pipeline.
4. A reinforced, flexible pipeline according to claim 3, c h a r a c t e r i z e d in that the elongated flexible elements which are twisted around the longitudinal axis of the pipeline, are twisted at an angle relative to the longitudinal axis of the pipe which is smaller than the corresponding angle at which the profiles forming the compression reinforcement are wound helically around the longitudinal axis of the pipeline.
5. A reinforced, flexible pipeline according to one of the preceding claims, c h a r a c t e r i z e d in that the material different from the tensile strength impart¬ ing elements is formed by a thermoplast, a rubber or a thermoplastic elastomer and mixtures in which these are contained.
6. A reinforced, flexible pipeline according to one of the preceding claims, c h a r a c t e r i z e d in that at least some of the elongated tensile strength imparting elements are formed by metal profiles, or by profiles which are formed by a composite of metal and ceramics.
7. A reinforced, flexible pipeline according to one of the preceding claims, c h a r a c t e r i z e d in that at least some of the elongated tensile strength imparting elements are formed by a plurality of fibres which are embedded in a plastics material.
8. A reinforced, flexible pipeline according to one of the preceding claims, c h a r a c t e r i z e d in that at least some of the elongated tensile strength imparting elements are each formed by a bundle of fibres which are held together completely or partly to form a pultruded material or a rope.
9. A reinforced, flexible pipeline according to one of the preceding claims, c h a r a c t e r i z e d in that the elongated tensile strength imparting elements form at least two substantially concentric layers around the lon- gitudinal axis of the pipeline.
10. A reinforced, flexible pipeline according to claim 9, c h a r a c t e r i z e d in that the elongated tensile strength imparting elements in each of the substan¬ tially concentric layers are twisted around the pipeline at different angles relative to the longitudinal axis of the pipeline, or in that they twist in an opposite direction around the longitudinal axis of the pipeline, so that the elongated tensile strength imparting elements in a first one of the substantially concentric layers inter- sect the corresponding elongated tensile strength imparting elements in a second one of the substantially concen¬ tric layers.
11. A reinforced, flexible pipeline according to claim 9 or 10, c h a r a c t e r i z e d in that the elongated tensile strength imparting elements in a first one of the substantially concentric layers are embedded in such a manner in the surrounding matrix that they do not touch the corresponding elongated tensile strength imparting elements in a second one of the substantially concentric layers .
12. A reinforced, flexible pipeline according to one of the preceding claims, c h a r a c t e r i z e d in that internally on the inner lining the pipeline is provided with a carcass consisting of one or more helically wound and nested or interconnected profiles.
13. A reinforced, flexible pipeline according to one of the preceding claims, c h a r a c t e r i z e d in that the profiles forming the compression reinforcement in the pipeline are surrounded completely or partly by a free volume which allows flow of liquids or liquid gases in the longitudinal direction of the pipe.
14. A reinforced, flexible pipeline according to one of claims 9 to 11, c h a r a c t e r i z e d in that the elongated tensile strength imparting elements in a first one of the substantially concentric layers are formed such that they have a substantially plane face which faces toward the corresponding elongated tensile strength imparting elements in an adjacent second layer.
15. A reinforced, flexible pipeline according to claim 14, c h a r a c t e r i z e d in that the elongated ten¬ sile strength imparting elements are formed with a sub¬ stantially quadrangular cross-section and with corners having a radius of curvature which is greater than 7% of the smallest dimension of the quadrangular cross-section.
16. A method of manufacturing a reinforced, flexible pipeline comprising an inner lining for forming a barrier against a medium flowing in the pipe, said inner lining being surrounded by a compression reinforcement which comprises a plurality of profiles wound around the inner lining, a tension reinforcement being arranged externally on the compression reinforcement and comprising a plurality of elongated tensile strength imparting elements which extend substantially along the longitudinal direc- tion of the pipe, c h a r a c t e r i z e d in that the inner lining and the associated compression reinforcement, together with the elongated tensile strength imparting elements, are advanced through an extruder which extrudes a matrix surrounding each of the elongated ten- sile strength imparting elements so as to form a pipe around the compression reinforcement, said pipe consisting of the elongated tensile strength imparting elements which are embedded in the extruded matrix.
17. A method according to claim 16, c h a r a c t e r i z e d in that it is performed in two or more stages.
18. A method according to claim 16 or 17, c h a r a c t e r i z e d in that the elongated tensile strength imparting elements are held at a predetermined mutual dis- tance until they are embedded in the extruded matrix.
PCT/DK1999/000329 1998-06-16 1999-06-16 A reinforced, flexible conduit and a method of manufacturing same WO1999066246A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
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Application Number Priority Date Filing Date Title
DKPA199800798 1998-06-16
DK79898 1998-06-16

Publications (1)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002090812A1 (en) * 2001-05-03 2002-11-14 Pipelife Nederland B.V. Reinforced pipe for a pressurised medium
FR2828924A1 (en) 2001-08-27 2003-02-28 Coflexip FLEXIBLE PIPE FOR THE TRANSPORT OF A FLUID
FR2834039A1 (en) 2001-12-21 2003-06-27 Inst Francais Du Petrole Flexible pipe with high resistance to axial compression e.g. for transporting petroleum products, has reinforcing layer of spiral-wound filaments
FR2852658A1 (en) 2003-03-21 2004-09-24 Coflexip Flexible tubular pipe for transport of fluids in offshore petroleum exploitation contains space to allow for gas drainage between layers of pipe wall
WO2005103545A1 (en) * 2004-04-26 2005-11-03 Nv Bekaert Sa A tube reinforced with a polymer and steel cord strip

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US3334663A (en) * 1964-04-06 1967-08-08 John D Drinko Method and articles for splicing plastic pipe
US3477474A (en) * 1967-03-22 1969-11-11 American Chain & Cable Co Wire reinforced conduit
US3506040A (en) * 1968-11-14 1970-04-14 United States Steel Corp Armored hose
DE2105120A1 (en) * 1971-02-04 1972-08-10 Battelle Institut E V Metal wire reinforced plastic tubing - with multi layer embedded sheath/braiding

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3334663A (en) * 1964-04-06 1967-08-08 John D Drinko Method and articles for splicing plastic pipe
US3477474A (en) * 1967-03-22 1969-11-11 American Chain & Cable Co Wire reinforced conduit
US3506040A (en) * 1968-11-14 1970-04-14 United States Steel Corp Armored hose
DE2105120A1 (en) * 1971-02-04 1972-08-10 Battelle Institut E V Metal wire reinforced plastic tubing - with multi layer embedded sheath/braiding

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002090812A1 (en) * 2001-05-03 2002-11-14 Pipelife Nederland B.V. Reinforced pipe for a pressurised medium
NL1017986C2 (en) * 2001-05-03 2002-12-03 Pipelife Nederland Bv Reinforced pipe for overpressure.
FR2828924A1 (en) 2001-08-27 2003-02-28 Coflexip FLEXIBLE PIPE FOR THE TRANSPORT OF A FLUID
WO2003019064A1 (en) 2001-08-27 2003-03-06 Technip France Flexible pipe for transporting a fluid
US6926039B2 (en) 2001-08-27 2005-08-09 Technip France Flexible pipe for transporting a fluid
FR2834039A1 (en) 2001-12-21 2003-06-27 Inst Francais Du Petrole Flexible pipe with high resistance to axial compression e.g. for transporting petroleum products, has reinforcing layer of spiral-wound filaments
WO2003056224A1 (en) 2001-12-21 2003-07-10 Institut Francais Du Petrole Flexible pipe with high axial compression strength and method for making same
FR2852658A1 (en) 2003-03-21 2004-09-24 Coflexip Flexible tubular pipe for transport of fluids in offshore petroleum exploitation contains space to allow for gas drainage between layers of pipe wall
WO2004085900A1 (en) 2003-03-21 2004-10-07 Technip France Flexible tubular fluid-transfer conduit
US7124780B2 (en) 2003-03-21 2006-10-24 Technip France Flexible tubular fluid-transfer conduit
WO2005103545A1 (en) * 2004-04-26 2005-11-03 Nv Bekaert Sa A tube reinforced with a polymer and steel cord strip

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