Abstract: Disclosed is a spiral hose which includes a hard spiral member made from polyethylene and a thin soft spiral member made from polyethylene tarpaulin, and which can be used not only as a general hose but also as a gas duct or a watering hose. The spiral hose is wound in a spiral shape to have flexibility. The spiral hose comprises: a hard member made from polyethylene, which is wound in a spiral shape with a uniform spiral gap formed between turns of the hard member, and a soft member having a shape of a band and being formed of polyethylene tarpaulin, the soft member being disposed along the spiral gap while lateral edges of the soft member are fixed to portions of the hard member, which are disposed oppositely on both sides of the spiral gap.

Abstract: A flexible hose adapted construction for conveying fluids under pressure. The construction includes a core tube having a circumferential inner core tube surface and an opposing circumferential outer core tube surface. A first reinforcement layer surrounds the outer core tube surface, and is formed of one or more filaments of a first fiber. A second fiber reinforcement layer surrounds the first reinforcement layer, and is formed of one or more filaments of a second fiber. The first and second reinforcement layers are bonded together by means of a bonding agent such as an adhesive, resin, plasticizer, tackifier, or solvent, the application of which is controlled to wet only a portion of the filaments of the reinforcement layers.

Abstract: The present invention relates to a multilayer hose, especially for conveying fuel, comprising an outer layer and a conductive, fluorine-containing, elastomeric inner layer, said inner layer comprising a fluorine-containing elastomer mixed with graphite.

Abstract: A flexible fuel hose having improved fuel vapor barrier properties wherein the fuel hose comprises a first fluoropolymer layer forming a first barrier tubular structure and a second fluoropolymer layer forming a second tubular structure around the first barrier tubular structure; and a method for the manufacture of such hose are described.

Abstract: The present invention is directed to a flexible hose for transporting hydrogen and oxygen gases for use in a fuel cell vehicle. The hose has a low permeation rate and will not contaminate the fuel cell system due to interactions between the hose and the transported gases. The hose has a multi-layer inner tube, a reinforcing layer, and a cover layer wherein the multi-layer inner tube is characterized by the innermost layer being formed from a liquid crystal polymer. A second low permeability layer may be present radially outward of the liquid crystal polymer.

Abstract: The present invention relates to a method for repairing and reinforcing an underground pipe. The method of the present invention comprises the steps of inserting an inner mold made of flexible material through the interior of a reinforcing element including a fiber preform surrounded by impermeable inner and outer tubes made of the flexible material and combining the inner mold with the reinforcing element; positioning a combined element, which includes the reinforcing element and the inner mold, into the underground pipe to be repaired and reinforced; injecting and expanding the inner mold with and by high temperature fluid, and brining the reinforcing element into close contact with an inner wall of the underground pipe; injecting the reinforcing element with thermosetting resin; and removing the inner mold after the thermosetting resin has been cured.

Abstract: A substantially formaldehyde-free duct liner is manufactured from at least one fiber component that may be mineral or organic fibers blended with at least one non-liquid substantially formaldehyde-free binder. The fiber component may comprise virgin textile glass fibers, virgin rotary glass fibers, organic fibers, or natural fibers. The non-liquid substantially formaldehyde-free binder may be plastic-containing bonding fibers, a powder binder, or a mixture thereof.

Abstract: The present invention is directed to a method for manufacturing a curved hose. The method is comprised of the steps of (a) forming a hose assembly, the hose assembly comprising: (i) an innermost layer of a halogenated polyolefin rubber; (ii) a polyester reinforcement overlaying the innermost layer, the reinforcement having disposed on its surface an RFL adhesive comprising a chlorosulfonated polyethylene rubber; and (iii) an elastomeric cover overlaying the braided reinforcement; (b) cutting the hose assembly into hose lengths; (c) shaping the hose lengths into predetermined curved hose shapes; and (d) curing the curved hose shapes.

Abstract: A hose comprising an inner tube of a synthetic resin, a non-reinforcing, abrasion-resistant layer of monofilament strands overlying the inner tube and, a cover layer overlying the inner tube and encapsulating the abrasion-resistant layer, and, optionally, a reinforcing layer between the inner tube and the abrasion-resistant layer of monofilament strands. The monofilament strands can be arranged in a regular pattern, for example, in a loosely-woven net of the monofilament strands and can have a diameter greater or less than the spacing between the monofilament strands, with the spacing between the monofilament strands ranging from 50-200% of the diameter of the monofilament strands.

Abstract: A flexible hose for use as a refrigerant passageway in a vehicular refrigerating cycle has an inner hose and an outer hose. The outer hose covers the inner hose with a space formed in a given distance. The outer hose and the inner hose are formed of resin having flexibility.

Abstract: Multi-layer tubular polymeric composite for articles such as tubing and hoses. The composite may be formed of an innermost and an outermost layer, and at least one interlayer between the innermost and the outermost layer. The innermost and the outermost layer each may be bonded directly to one of the interlayers, and may be formed of a thermoplastic polymeric material which may be a polyamide. Each of the interlayers may be formed of a thermoplastic polymeric material which may be a polyester or copolyester, or a polyurethane.

Abstract: A composite pipe includes a polytetrafluoroethylene (PTFE) inner layer and a covering layer of fiber-reinforced plastics material which are joined to one another by force-locking and form-locking through an intermediate layer. The intermediate layer is formed of a PFA layer and a layer of glass or carbon fibers, in order to improve adhesive and shear strength between the PTFE inner layer and the covering layer. The PFA layer is adjacent the PTFE inner layer and the layer of glass or carbon fibers is adjacent the covering layer of fiber-reinforced plastics material.

Abstract: A corrugated resin tube which comprises, in at least one part of an axial direction of the tube, a corrugated portion having an undulated cross section along the axial direction, characterized in that the corrugated portion comprises at least one fiber-reinforced layer made of a thermoplastic resin or a thermoplastic elastomer, which contains inorganic fibers, and at least one resinous layer made of a thermoplastic resin or a thermoplastic elastomer, which contains no inorganic fibers or contains inorganic fibers in an amount less than the amount in the fiber-reinforced layer, wherein these layers are laminated and the outermost layer is the resinous layer. The content of the inorganic fibers in the fiber-reinforced layer is preferably from 5 to 20 wt %, and the thickness of the fiber-reinforced layer is from 30 to 70% of the whole thickness.

Abstract: A hose suitable for use in refrigerant systems. The hose has a barrier layer formed of at least two layers of thermoplastic resin. At least one of the layers is a vinyl resin. The resins are selected so that the hose has a permeation rate of virtually zero.

Abstract: A heat pipe has a pipe container and a fiber wick structure. The fiber wick structure is arranged on an inner wall of the pipe container, and the fiber wick structure has at least two kinds of fibers with different melting points. Furthermore, when the fiber wick structure is manufactured in a sintering process, the higher melting point of fiber provides a support force for the fiber wick structure coupled to the inner wall of the pipe container, and the lower melting point of fiber is melted in the sintering temperature of the pipe container to adhere to the higher melting point of fiber on the inner wall of the pipe container.

Abstract: A flexible hose construction adapted for conveying fluids under pressures and capable of withstanding relatively high external pressures without collapsing. The tubular construction includes a first reinforcement layer, an inner jacket surrounding the first reinforcement layer, a second reinforcement layer surrounding the inner jacket, and outer jacket covering the second reinforcement layer.

Abstract: According to the present invention, there is provided a hose assembly with an inner fluoropolymer layer having a smooth inner surface and an outer polyamide layer having an undulated surface.

Abstract: The combination of a flexible pipe, e.g. plastic, and a reinforcing member mounted around the pipe to strengthen the pipe and to enhance its ability to resist deformation under load. In one embodiment the reinforcing member includes a flexible perforated plastic netting containing an aggregation of lightweight elements such as expanded polystyrene beads capable of wrapping around the pipe, preferably in helical fashion along the length of the pipe. In another embodiment, a number of members are mounted on the pipe in longitudinally extending fashion.

Abstract: This invention provides stretch-resistant liners for lining pipes, pipes lined with stretch-resistant liners, and methods for lining pipes with stretch-resistant liners. The liners are made from a layer of stretch-resistant woven material, which may be a scrim, sandwiched between two layers of non-woven resin-impregnated material to form a laminate structure which is rolled into a tube to provide a liner having concentric sleeves.

Abstract: A compounded alloy of nylon 6 and nylon 12 serves as a layer of a hose suited to use in airbrake materials. The alloy is resistant to degradation by zinc chloride and moisture and thus may be used as a peripheral layer of the hose in place of a conventional protective layer comprising a pure polyamide, such as nylon 11 or 12. Alternatively, the alloy may be used as a tie layer for rendering a peripheral layer comprising nylon 12 compatible with a layer of nylon 6, allowing the less expensive nylon 6 material to comprise the bulk of the hose thickness. The alloy includes a compatibilizer, such as a maleic anhydride grafted polyethylene in sufficient amount to render the alloy compatible with adjacent layers, thus avoiding the need for an intermediate layer of an adhesive. One or more of plasticizers and impact modifiers are preferably also present in the alloy to provide improved strength and flexural characteristics.

Abstract: A reinforced liner for cured in place pipe rehabilitation of an existing pipeline having a plurality of high-strength low-elongation fiber bundles disposed circumferentially around the tubular liner at both inner and outer surfaces of a resin absorbent layer of the liner is provided. The bundles of reinforcing fibers are continuous lengths of high modulus fibers laid circumferentially with the ability to stretch to accommodate variations in host pipe diameter. The fibers on the inner surface are secured to a porous scrim to form an inner tubular reinforcing layer. A resin absorbent layer is formed into a tube about the inner layer. An outer layer of bundles of reinforcing fiber are formed into a tube about the absorbent layer. An outer impermeable tubular layer is wrapped around the inner layers. The reinforcing layer may include longitudinal reinforcing fiber in either or both reinforcing layers to increase the longitudinal strength of the liner.

Abstract: A hose suitable for use in refrigerant systems. The hose has a barrier layer formed of at least two layers of thermoplastic resin. At least one of the layers is a vinyl resin. The resins are selected so that the hose has a permeation rate of virtually zero.

Abstract: An object of the present invention is to provide ultra-low permeation hoses which have at the interior thereof a refrigerant barrier layer that consists in large part of a metal layer and is capable of conforming to hose deformation, which have an excellent resistance to refrigerant permeation (i.e., barrier properties to refrigerants), particularly an excellent CO2 permeation resistance and an excellent heat resistance when CO2 is used as the refrigerant. The object can be accomplished by an ultra-low permeation hose having at least a refrigerant barrier layer and a rubber layer and/or a resin layer; wherein the refrigerant barrier layer is a laminated film comprising a resin layer and, on the outside thereof, a metal layer, which the resin layer and the metal layer are bonded together by a polyamide-epoxy reactive adhesive.

Abstract: An ultralow expansion brake rubber hose comprising an inner rubber tube, a first reinforcing layer, a second reinforcing layer and an outer rubber layer, wherein a thermosetting resin which penetrates the reinforcing fibers constituting the first reinforcing layer and which is cured at vulcanizing temperatures is cured by vulcanization to turn the first reinforcing layer into a solid cured layer. By turning the first reinforcing layer into the solid cured layer, the mutual slippage between the reinforcing fibers of the first reinforcing layer can be prevented, and a brake rubber hose having low expansion and excellent durability can be obtained.

Abstract: A spoolable composite tube capable of being spooled onto a reel for storage and for use in oil field applications. The spoolable tube exhibits unique anistropic characteristics that provide improved burst and collapse pressures, increased tensile strength, compression strength, and load carrying capacity, while still remaining sufficiently bendable to be spooled onto a reel in an open bore configuration. The spoolable composite tube can include an inner liner, an interface layer, fiber composite layers, a pressure barrier layer, and an outer protective layer. The fiber composite layers can have a unique triaxial braid structure.

Abstract: A cryogenic fluid system having a flexible conduit for conducting cryogenic materials and a method for fabricating such a flexible conduit is herein disclosed. The flexible conduit of the cryogenic fluid system generally includes a first tube and a second tube disposed about the first tube. The first and second tubes can be made from the same or different materials (including composites) as long as the material which makes up at least one of the first and second tubes is silicone rubber-impregnated glass cloth. The flexible conduit also generally includes a fluorocarbon polymer liner disposed against a first inner wall of the first tube, so that the first tube is positioned between the second tube and the fluorocarbon polymer liner. Some variations of the flexible conduit have an annulus between the first and second tubes which optionally is occupied, at least in part, by insulation.

Abstract: As the first object, the present invention intends to provide high-pressure composite pipes which show remarkable pressure resistance and optimum applicability in various uses and which can be economically manufactured in a light weight. As the second object, the present invention intends to provide a joining method which is capable of firmly joining the high-pressure composite pipes in a simple operation, firmly joining the high-pressure composite pipes by reinforcing the joint strength at the butt-fused area, and making a joint area adjustable to strain of the high-pressure composite pipes. To achieve these objects, a high-pressure composite pipe of the present invention comprises a pipe-shaped inner layer made of a synthetic resin, a reinforcing layer made of a stretched polyolefin resin sheet and wound on an external circumferential surface of the inner layer, and an outer layer made of a synthetic resin and disposed on an external circumferential surface of the reinforcing layer.

Abstract: A high pressure rubber hose has a plurality of reinforced layers. Each reinforced layer is buried by way of an intermediate rubber layer between an inner rubber layer and an outer rubber layer, in which an organic fiber reinforced layer braided from organic fiber cords into two spiral layers or one braided layer is disposed to the inner rubber layer on the outer circumference thereof. A steel wire reinforced layer braided from steel wires into two spiral layers is disposed to the organic fiber reinforced layer at the outer circumference thereof. The braiding angle of the organic fiber reinforced layer is less than braiding angle of the steel wire reinforced layer and the braiding tension of the organic fiber reinforced layer is higher than the braiding tension of the steel wire reinforced layer.

Abstract: The present invention relates to a multi layer agricultural hose configured to have two layers or three layers, wherein joining surfaces of the hose has an increased adhesive strength required to prevent the joining surfaces from being separated due to a high water pressure, and a manufacturing device therefore. The agricultural hose is formed by laminating layers of tarpaulin obtained by a process where a fabric having polyethylene (HDPE+EVA) as a main component is firstly coated with resin at its external surface and then two fabrics are overlapped and attached by adhesion; and said layers are attached to one another by adhesion, with a joining surface of each of the layers being overlapped in a predetermined length.

Abstract: A laminated nylon air brake tubing is formed from outer and inner layers of nylon 11 or nylon 12 with inner layers of nylon 6. The nylon 6 and nylon 11 or 12 layers are adhered together by a tie layer. The tie layer is preferably a nylon 6-12 or an anhydride modified polyolefin. The air brake tubing has improved high temperature strength and low temperature impact resistance characteristics.

Abstract: A composite hose includes a conductive fiber media extending contiguously from one end of the hose to the other. The conductive fiber media is covered by silver plating, and in one described embodiment comprises a silver-plated nylon fiber. The nylon fiber provides a flexible medium not readily prone to breakage, while the silver plating provides relatively low electrical resistance, due to its relatively high electrical conductivity, for avoiding potentially lethal effects of static electricity. In one described embodiment, the hose includes an inner layer of an insulation material, such as rubber. An electrically conductive fiber strand is applied over the inner layer in a spiral pattern, and an outer cover material is an extruded over the inner layer of the hose and the fiber strand. In another embodiment, the hose includes a textile braided yam layer positioned directly above the strand over the inner layer, immediately beneath the outer cover.

Abstract: Inversion liners are provided which in a first embodiment include first and second flexible fabric layers separated by one or more glass fiber containing layers and joined in tubular form. The second flexible fabric layer further is bonded to a third flexible fabric layer comprising a substantially fluid impermeable layer. An invertible glass-faced liner is also provided by this invention which includes a glass facing on one side and a substantially fluid impermeable layer on the other. The substantially fluid impermeable layer is joined to a flexible fabric layer which is preferably heat bonded to a thin veil joined to a second glass containing layer of this liner embodiment. The inversion liners of this invention can be built-up in multiple layers or blocks to meet end-use design demands while still providing flexural moduli in excess of 500 ksi, preferably about 700-800 ksi.

Abstract: Inversion liners are provided which in a first embodiment include first and second flexible fabric layers joined to first and second glass fiber containing layers and joined in tubular form, whereby the first and second flexible fabric layers face one another. The second glass fiber containing layer further is bonded to a thin, third flexible fabric layer. A substantially fluid impermeable layer is applied to the opposite side of the thin, third flexible fabric layer.

Abstract: A flexible hose having air-permeability is formed by either: sandwiching an air-permeable tape between tape end edge portions, as leading and trailing in a hose longitudinal direction, of a soft resin tape that is helically wound integrally with the air-permeable tape; or by helically winding only an air-permeable tape. The flexible hose can be properly used as a cleaner hose of a discharge circulation type by using it as an outer tube of a double tube structure. By providing lubricating properties to an inner circumference of the outer tube or an outer circumference of the inner tube, it is possible to prevent wear which might otherwise be caused by rubbing contact between the inner tube and outer tube.

Abstract: A heat-resistant multi-layer hose is described. The hose includes inner and outer elastomeric layers, and an intermediate reinforcing layer. The inner and outer layers each include a substantial fraction of ethylene-octene copolymer, and may include one or more compatible polymers such as EPDM, chlorosulfonated polyethylene, and chlorinated polyethylene. The use of relatively large amounts of ethylene-octene copolymer results in improved high heat resistance.

Abstract: This invention provides stretch-resistant liners for lining pipes, pipes lined with stretch-resistant liners, and methods for lining pipes with stretch-resistant liners. The liners are made from a layer of stretch-resistant woven material, which may be a scrim, sandwiched between two layers of non-woven resin-impregnated material to form a laminate structure which is rolled into a tube to provide a liner having concentric sleeves.

Abstract: A low permeable hose having at least a refrigerant barrier layer and a rubber layer is provided. The barrier layer is a laminate film having a structure such that resin layers sandwich a metal layer therebetween and having an elongation at breakage of 10% or more. The outermost layer of the resin layer may be an adhesive layer composed of a phenol resin based composition. The hose can be produced by heating the refrigerant barrier layer and the rubber layer to a temperature no lower than the melting point of a resin that constitutes the resin layers to melt the resin and vulcanizing said rubber layer, or, laminating an adhesive layer composed of a phenol resin based composition and the rubber layer, thereby splicing the refrigerant barrier layer and the rubber layer.

Abstract: The present invention generally includes a composite fuel rail with integral damping provided by flat sections, molded into the rail conduit, that flex in response to a pressure pulsation and a co-injected composite laminate structure wherein the compounds of the laminates can be selectively varied to provide impact resistance, chemical resistance and a vapor permeation barrier, as needed.

Abstract: A reinforced flexible tubular pipe including an inner liner (3) that forms a barrier against outflow of medium that flows through the pipe, the inner liner (3) being encased by at least one reinforcing layer having a space in which a number of profiles are configured that are coiled around the inner liner such that the profiles are completely or partially surrounded by a lumen (10) that allows transport of fluids in the longitudinal direction of the pipe. Outside the reinforcing layer an outer coating (9) is provided to form a barrier against inflow of fluids or gases from the surroundings of the pipe to the reinforcing layer. At least one flow path (11) is provided to convey fluid or gas away from the lumen (10). This flow path (11) is provided with an inlet opening that debouches in the lumen (10) and an outlet opening (13) that ends in the inner liner of the tubular pipe.

Abstract: A flexible duct construction and method of manufacture is provided in which the duct is formed from a continuously wound elongate member comprising a core of insulating material, a reinforcing wire element and a casing comprising a strip of substrate material extending around the core and the reinforcing element. In the preferred method of manufacture, adhesive is applied to one side of the strip of substrate, the casing has a tail part extending from a generally circular part which encapsulates the core and the reinforcing element, and the elongate encapsulated insulating member is wound helically so that the circular part of one winding overlies and adheres to the tail part of the previous winding.

Abstract: As the first object, the present invention intends to provide high-pressure composite pipes which show remarkable pressure resistance and optimum applicability in various uses and which can be economically manufactured in a light weight. To achieve this object, a high-pressure composite pipe of the present invention comprises a pipe-shaped inner layer made of a synthetic resin, a reinforcing layer made of a stretched polyolefin resin sheet and wound on an external circumferential surface of the inner layer, and an outer layer made of a synthetic resin and disposed on an external circumferential surface of the reinforcing layer. The winding direction of the reinforcing layer is oriented at a predetermined angle relative to the axis of the pipe. Between the inner layer and the reinforcing layer and between the outer layer and the reinforcing layer, adhesion layers having affinity to these layers are interposed.

Abstract: A method of manufacturing a hose includes the step of extruding a tube assembly comprising (i) a first inner non-foamed layer, (ii) a first outer non-foamed layer positioned around the first inner non-foamed layer, and (iii) a first foamed layer interposed between the first inner non-foamed layer and the first outer non-foamed layer. The method further includes the step of positioning a textile reinforcement on the tube assembly. Additionally, the method includes the step of extruding a cover assembly over the textile reinforcement, the cover assembly comprising (i) a second inner non-foamed layer, (ii) a second outer non-foamed layer positioned around the second inner non-foamed layer, and (iii) a second foamed layer interposed between the second inner non-foamed layer and the second outer non-foamed layer.

Abstract: A hose (10) comprising a tubular body (12) of flexible material arranged between an inner and an outer helically wound wire (22, 24). The hose (10) further comprises an axial strengthening means (20) adapted to reduce deformation of the tubular body (12) when the tubular body (12) is subjected to axial tension, the axial strengthening means (20) being adapted to exert a radially inward force on at least part of the tubular body (12) when axial strengthening means (20) is subjected to axial tension.

Abstract: A pipeline for the transport of refrigerated media, including at least two metal pipes, positioned concentrically and at a distance to one another, an insulating layer made of layers of insulating material and reflecting material alternately positioned over one another being provided in the ring gap between the metal pipes and the ring gap being evacuated and a spacer in the form of a helix being wound onto the inner pipe. The spacer (3) is a metal wire (3a), onto which bodies (3b) made of a mechanically resistive insulating material, which are provided with a hole, are threaded at specific intervals.

Abstract: A fiber reinforced plastic article is disclosed which include a liner, at least one single material fiber layer wound on the liner, and at least one composite fiber layer wound on the single material fiber layer. The at least one single material fiber layer and the at least one hybrid fiber layer are impregnated with resin.

Abstract: A hose includes a tube assembly surrounded by a textile reinforcement that is surrounded by a cover assembly. The tube assembly includes an inner non-foamed layer that is surrounded by a foamed layer that is surrounded by an outer non-foamed layer. The textile reinforcement surrounds the outer non-foamed layer of the tube assembly and preferably consists of a first spiral threading and a second mesh threading. The cover assembly includes an inner non-foamed layer that is surrounded by a foamed layer that is surrounded by an outer non-foamed layer. The adjacent relationship of the outer non-foamed layer of the tube assembly and the inner non-foamed layer of the cover assembly provide a substantial increase in adhesion between the two assemblies. Further, this configuration reduces the tendency for water seepage between the layer or plies that can cause bubbles and separation.

Abstract: A straight opposing member insertion section located at the end of a hose tube and has a ring-shaped groove for inserting a sealing ring. The opposing member insertion section has a ring-shaped tongue piece and/or a ring-shaped ring supporting section. Tongue-piece has a sloped surface and an overhang positioned over the ring-shaped groove. Ring supporting section is an indentation on the ring-shaped groove that protrudes away from the end of the hose tube. A sealing ring is tightly inserted into the ring-shaped groove. A ring-shaped engagement projection on the end of the tube-shaped opposing member is pushed into the opposing member insertion section until the engagement projection abuts the sealing ring. Sealing ring and the section of the tube wall with the ring-shaped groove can be constructed to handle seal deterioration. The resulting fuel hose connection structure has superior fuel sealing properties, fuel impermeability and can be contructed simplely and inexpensively.

Abstract: A spoolable composite tube capable of being spooled onto a reel for storage and for use in oil field applications. The spoolable tube exhibits unique anistropic characteristics that provide improved burst and collapse pressures, increased tensile strength, compression strength, and load carrying capacity, while still remaining sufficiently bendable to be spooled onto a reel in an open bore configuration. The spoolable composite tube can include an inner liner, an interface layer, fiber composite layers, a pressure barrier layer, and an outer protective layer. The fiber composite layers can have a unique triaxial braid structure.

Abstract: An improved coiled air brake tubing is formed from a nylon polyurethane laminate. The laminate includes an innermost nylon layer surrounded with a thick intermediate polyurethane layer in turn covered with an outermost thin nylon layer. The polyurethane layer is fiber reinforced. The product is extruded and coiled around a heated mandril causing it to assume a coiled set. This exhibits improved low temperature properties and is less expensive than a nylon product.

Abstract: A composite pipe includes a polytetrafluoroethylene (PTFE) inner layer and a covering layer of fiber-reinforced plastics material which are joined to one another by force-locking and form-locking through an intermediate layer. The intermediate layer is formed of a PFA layer and a layer of glass or carbon fibers, in order to improve adhesive and shear strength between the PTFE inner layer and the covering layer. The PFA layer is adjacent the PTFE inner layer and the layer of glass or carbon fibers is adjacent the covering layer of fiber-reinforced plastics material.