Abstract: A composite hose is provided with a corrugated metal tube as a barrier layer against permeation of conveyed fluid, and an elastic filler layer which is filled in valley gaps between corrugation hills on an outer peripheral side of the corrugated metal tube. The elastic filler layer is filled completely in the valley gaps to tops of the corrugation hills. A radial thickness of the elastic filler layer measured radially outwardly from a radial position of the tops of the corrugation hills is designed 0.3 mm or less.

Abstract: A continuous drain hose for an electrical appliance having a water outlet is disclosed. The drain hose comprises a first cylindrical end portion being connectable to the water outlet, a second end portion being connectable to a drain pipe and comprising a bellows that is able to form a permanent bend when a temporary bending force is applied thereto, and a flexible corrugated portion connected between the first cylindrical end portion and the second end portion. The bellows is also permanently expandable or retractable when a temporary pulling or pressing force is applied thereto. The drain hose further comprises an elastic connection member, which is integrally molded to the first cylindrical end portion and is sealably connectable to the water outlet. The first cylindrical end portion comprises at least one annular ring externally formed thereon so as to prevent the molded elastic connection member from being disengaged from the first cylindrical end portion.

Abstract: A composite hose is provided with a corrugated metal tube of an inner layer and rubber filler which is filled in valley gaps between corrugation hills on an outer peripheral side of the corrugated metal tube. A tubular hard resin layer is further provided as cover layer on an outer side of the corrugated metal tube in order to enclose the rubber filler within the valley gaps to prevent the rubber filler from escaping radially outwardly.

Abstract: A corrugated pipe 2 has a plurality of corrugation structures 10, 12 positioned adjacent one another. The corrugation structures 10, 12 comprise an inner cylindrical wall 22, two annular wall portions 28, 32 that extend outwardly from the inner cylindrical wall 22, and a bowed annular wall portion 40 that is connected to the outer ends 36, 38 of the two annular wall portions 28, 32. The corrugation structure 10, 12 includes a centroid 48, 49 and at least a portion of the inner surface 50 of the bowed wall portion 40 has a radius R1 centered on the centroid 48, 49 and at least a portion of the outer surface 52 of the bowed wall portion 40 has a radius R2 centered on the centroid 48, 49. The cavity 56 defined by the corrugation structure 10, 12 has an inner surface with an inner radius R1, R3 that is equal to or greater than one half the thickness T1 of the inner cylindrical wall 22.

Abstract: A drill string member is formed by providing a former and a cylindrical member to be shaped in relationship with the former. Seals are provided between opposing ends of a thick wall cylinder and the cylindrical member, a pressure is applied in the annulus between the cylindrical member and the thick wall cylinder sufficient to deform the cylindrical member against the former. The drill string member thus formed has a constant wall thickness and a non-circular former provides a non-circular drill string member.

Abstract: The invention relates to a winding tube for winding up bands, films, sheets of metal or similar made of a spiral shaped wound metal strip whose adjacent strip windings overlap at least partially. The metal strip has a corrugated or ribbed profile in the cross-section thereof, whose external corrugated heads (1) are disposed on the outer wall of the winding tube after winding and are wider than the internal corrugated heads (2) disposed on the inner wall of the winding tube after winding.

Abstract: A vibration absorbing hose has a corrugated portion extending substantially entire part of the hose and end portions of straight cylindrical shape. The vibration absorbing hose has multi-layered construction of tubular inner rubber layer, pressure resistant reinforcement layer circumscribing an outer side of the inner rubber layer and outer rubber layer as outermost cover layer. The pressure resistant reinforcement layer is formed, for example, by braiding reinforcing yarns, so as to have corrugations along the corrugated portion of the inner rubber layer.

Abstract: A composite strip 10 windable to form a helical pipe is disclosed. The composite strip 10 comprises: an elongate plastic strip 11 having a base portion 12 and at least one lengthwise extending rib portion 20 upstanding from the base portion 12; and an elongate reinforcing strip 30 extending lengthwise and supported laterally by the rib portion 20, the reinforcing strip 30 having a height to thickness ratio of at least three to one and orientated substantially perpendicular to the base portion 12. When wound into a helical pipe, the reinforcing strip 30 reinforces the pipe against radial crushing loads. A bead 40 seals the reinforcing strip 30 from the environment. Desirably the composite strip 10 further comprises: a planar lamina 50 extending lengthwise and bonded to the base portion 12, the lamina 50 having a higher Young's modulus and strength than those of the plastic strip 11. The lamina 50 greatly improves the pressure rating of a pipe wound from the strip 10.

Abstract: A vibration absorbing hose including a corrugated portion has multi-layered construction of tubular inner rubber layer, pressure resistant reinforcement layer formed on an outer side of the inner rubber layer by providing reinforcing yarns. A radial depth B of the pressure resistant reinforcement layer at a position of each of corrugation valleys of the rubber layer has such relationship with respect to a corrugation valley depth A of the rubber layer as 0< or =B< or =0.7×A, and an opening angle ? of each of the corrugation valleys of the rubber layer satisfies ?< or =100°.

Abstract: A flexible conduit includes a metal hose provided with a helical groove having a plurality of turns; a plastic jacket surrounding the metal hose and conforming to the helical groove thereof; a plastic inner hose received in the metal hose and having a projecting length portion extending beyond an end of the metal hose. The conduit further includes a plastic coupling part which surrounds the metal hose. The coupling part includes a cylindrical collar surrounding the projecting length portion and having a material-to-material bond therewith; and an overlapping portion adjoining the cylindrical collar and extending away therefrom. The overlapping portion surrounds the jacket and extends into the helical groove. The overlapping portion and the plastic jacket have a material-to-material bond with one another.

Abstract: An annulated tubular sheath which is split down a longitudinal section thereof. According to the invention, a longitudinal strip of the sleeve is made of a flexible material and is disposed in an angular position of 5-180 degrees in relation to the longitudinal section or is disposed in the region of the sheath in which the longitudinal section is made. Preferably, the flexible material is a thermoplastic elastomer. The invention also relates to a method for producing a sleeve by extruding a plastic material, a longitudinal strip made of a flexible material obtained by co-extruding an elastomer material. A device for carrying out said method comprises an extrusion head provided with an insert for placing the co-extrusion in a stop position on a die in order to block the flow of the extruded plastic material and to enable the flow of elastomer material.

Abstract: A vibration absorbing hose including a corrugated portion has multi-layered construction of tubular inner rubber layer, pressure resistant reinforcement layer circumscribing an outer side of the inner rubber layer and outer rubber layer as outermost cover layer. The pressure resistant reinforcement layer is formed, for example, by providing reinforcing yarns, so as to have corrugations along the corrugated portion of the inner rubber layer. The inner rubber layer contains scaly filler in an amount of 50 phr to 200 phr so as to be oriented in a stretching direction of the inner rubber layer. The scaly filler has an aspect ratio of 2 to 90.

Abstract: A plastics material tube that is particularly resistant to fire, such that its wall is formed by a corrugated tube of flammable plastics material, by a smooth tube lining the outside of the corrugated tube and made of a plastics material that limits flame propagation, and by a fireproofing composition received between the two tubes.

Abstract: An elongate flexible plastic tubing includes a helical support bead, and defines a central passage opening on opposite ends of the tubing. The tubing may also include one or more lumens extending helically in the support bead from end to end of the tubing. Also, the tubing may include one or more electrical conductors also extending helically from end to end of the tubing. Additionally, one or plural fiber optic conductors may extend helically from end to end of the tubing. The lumen(s), electrical conductors, and fiber optic conductors, are available for utilization to, for example: conduct electricity, carry out electrical resistance heating of fluid flow in the central passage, carry electrical signals, carry fluid, transmit fluidic signals, or to convey light, and/or optical signals, along a length of the tubing.

Abstract: The present invention is directed towards an improved flexible hose (10). The hose (10) is comprised of at least a flexible material (28) and a reinforcing rod (12) positioned externally of the flexible material (28). Terminal ends (16, 18) define both the flexible material (28) and the reinforcing rod (12). At least one terminal end (16) of the reinforcing rod (12) is located short of the terminal ends (18) of the flexible material (28), so that the non-reinforced end of the flexible material (28) forms a soft cuff (20) adapted to be received by a hose fitting. Also disclosed is an improved method of manufacturing the flexible hose (10).

Abstract: A static hydro-dynamic mixer undulating interior conduit provides a static mixing apparatus which utilizes a spiral, coiled or curved conduit to cause dynamic mixing of its flowing contents while they are pumped through it. The application includes a method of use in separating oil sands. The mixing is caused by the resistance to flow through the undulated conduit and the resistance increases with pitch and conduit diameter.

Abstract: A damped sleeve having a damping layer attached to a backing layer is disclosed. The damping layer is formed from a non-woven energy absorbing felt and is attached to the backing layer by lines of attachment which define pockets between the layers. The layers are positioned coaxially around an axis and define a central space for receiving elongated items to be protected from vibration. Resilient filamentary support members are arranged between the damping and backing layers to support the layers radially in spaced relation relative to the axis. The support members may be helically wrapped around the axis, circumferentially positioned or arranged in a zig-zag pattern transversely to the axis. A slit in the layers provides access to the central space.

Abstract: A small-diameter part in the vicinity of a center of a bellows portion in an axial direction has a smaller diameter. A tip end of the small-diameter part contacts at a point A with an outer peripheral face of an interlock pipe. The interlock pipe vibrates with using the point A and points B in both ends as fulcrums. The addition of the point A reduces distance between the fulcrums. In accordance with this reduction, deflection amount of the interlock pipe is reduced and vibration amplitude of the interlock pipe is decreased. Therefore, the interlock pipe does not contact with the bellows portion so that troubles such as noises can be prevented from occurring.

Abstract: A corrugated pipe (2) has a plurality of corrugation structures (10, 12) positioned adjacent one another. The corrugation structures (10, 12) comprise an inner cylindrical wall (22), two annular wall portions (28, 32) that extend outwardly from the inner cylindrical wall (22), and a bowed annular wall portion (40) that is connected to the outer ends (36, 38) of the two annular wall portions (28, 32). The corrugation structure (10, 12) includes a centroid (48, 49) and at least a portion of the inner surface (50) of the bowed wall portion (40) has a radius R1 centered on the centroid (48, 49) and at least a portion of the outer surface (52) of the bowed wall portion (40) has a radius and at least R2 centered on the centroid (48, 49). The cavity (56) defined by the corrugation structure (10, 12) has an inner surface with an inner radius R2 centered on the centroid (48, 49).

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 and a method for manufacturing the same includes a hose tube having a smooth exterior surface. The hose tube exterior surface has a fabric and cover laminated or wrapped thereon. The lead end of a single wire is helically wound about the hose tube on top of the cover. The wire in turn is at least partially encased by a rubber ridge preferably having a height greater than the thickness of the hose tube wall. The rubber ridge tapers in the direction of valleys formed between the ridges, and the resulting hose structure has improved flexibility by enabling the hose to flex at every valley, yet sufficient strength for heavy duty applications.

Abstract: A tubing assembly including conductive corrugated tubing including convolutions of peaks and valleys and a conductive polymer jacket disposed in said valleys along a length of said corrugated tubing.

Abstract: The present invention relates to a medium-carrying hose, preferably for pressure medium and for use in, for instance, an engine unit, the wall of the hose comprising at least one wall portion (5). The wall portion (5) is connected with at least one expansion portion (4) to form a continuous hose casing, so that the circumference of the hose is variable between a minimum value, when the expansion portion (4) is unexpanded, and a maximum value, when the expansion portion (4) is maximally expanded. The expansion portion (4) extends in the transverse and the longitudinal direction of the hose, the wall portions (5) being displaced relative to each other both in the transverse and in the longitudinal direction of the hose as the circumference increases and the expansion portion (4) expands. The invention also relates to a method for manufacturing such a hose.

Abstract: A damped sleeve adapted to receive and protect elongated substrates is disclosed. The sleeve has a flexible, resilient support layer corrugated for added radial stiffness and bending flexibility. The support layer surrounds and defines an interior space for receiving the substrates. A longitudinal slit defined by facing edges in the support layer provides access to the interior space. A damping layer of non-woven felt covers the outer surface of the support layer and is attached to it along the edges defining the slit. Hook-and-loop fasteners are used to close the slit. All of the components are made from the same material so they can be attached to each other by fusing via ultrasonic welding.

Abstract: A leak-free flexible conduit and method of making the same is described. By attaching a flexible outer hose to a flexible inner hose without directly clamping the outer hose to the inner hose, the life of the inner hose is increased. Furthermore, the outer flexible hose creates a heat-resistant, airtight seal that prevents exhaust leaks from the inner flexible hose from escaping, substantially reduces the heat lost to the atmosphere, decreases the amount of vibration, reduces noise, and protects the inner flexible hose from corrosive elements and contaminants, thereby also extending the life of the inner flexible hose.

Abstract: A corrugated pipe (2) has a plurality of corrugation structures (10, 12) positioned adjacent one another. The corrugation structures (10, 12) comprise an inner cylindrical wall (22), two annular wall portions (28, 32) that extend outwardly from the inner cylindrical wall (22), and a bowed annular wall portion (40) that is connected to the outer ends (36, 38) of the two annular wall portions (28, 32). The corrugation structure (10, 12) includes a centroid (48, 49) and at least a portion of the inner surface (50) of the bowed wall portion (40) has a radius R1 centered on the centroid (48, 49) and at least a portion of the outer surface (52) of the bowed wall portion (40) has a radius and at least R2 centered on the centroid (48, 49). The cavity (56) defined by the corrugation structure (10, 12) has an inner surface with an inner radius R2 centered on the centroid (48, 49).

Abstract: A fluid line connector assembly has a length of flexible tubing with a generally cylindrical tubing end. An end fitting is secured to the tubing end with a brazing material between the end fitting and the tubing end.

Abstract: A flexible hose comprising (A) a soft hose main body formed of polyvinyl chloride resin; and (B) a helical rigid reinforcing means embedded in the soft hose main body formed of polyvinyl chloride resin wherein the specific gravity of the helical rigid reinforcing means is less than the specific gravity of the hose main body and the overall specific gravity of the flexible hose is less than 1.0 g/cm3.

Abstract: A flexible hose which has a hose body made of soft synthetic resin, a reinforcement made of hard synthetic resin wound spirally and joined to the hose body by fusion, and a conductor arranged inside the reinforcement in its longitudinal direction. The conductor does not adhere to the reinforcement and is movable. The hose body is formed by: extruding a tube made of soft resin from a head of an extruder; pressing and flattening the tube to form a strip; and winding the strip spirally with the adjacent side edges joined together.

Abstract: A resinous hose formed by the process for producing a resinous hose, wherein the hose comprises cylindrical portions extending rectilinearly and a bent bellows portion wherein the bellows portion includes a bellows wall having continuous crests and valleys, and a non-bellows wall located on the side diametrically opposite to the bellows wall. The outside diameter of the valleys of the bellows wall is smaller than an outside diameter of the cylindrical portions, and an outside diameter of the non-bellows wall is larger than the outside diameter of the cylindrical portions.

Abstract: A flexible tube for a vacuum system includes a tube body and a cover. The tube body is made of hard material. The tube body has projected parts and depressed parts. The cover is provided over an outer surface of the tube body. The cover is made of elastic material. The cover may be in contact with the projected parts of the tube body and extend over the depressed parts of the tube body so that a vacant space is formed between the tube body and the cover.

Abstract: A corrugated pipe is provided having a pipe structure of an inner wall having an interior surface and an exterior surface, and an outer wall having corrugations, each of the corrugations having an interior surface and an exterior surface, each corrugation having a crown. The pipe structure has a trough between each corrugation, and each trough has a center-point, with the distance between the center-points of adjacent troughs defining the pitch of the pipe. The pipe structure has at each crown a first distance extending in a straight line from the crown exterior surface to the interior surface of the inner wall, with the distance defining the pitch being a second distance, with the ratio of the first distance to the second distance being less than 0.8:1.0.

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: A flexible hose and a method for manufacturing the same includes a hose tube having a smooth exterior surface. The hose tube exterior surface has a fabric and cover laminated or wrapped thereon. The lead end of a single wire is helically wound about the hose tube on top of the cover. The wire in turn is at least partially encased by a rubber ridge preferably having a height greater than the thickness of the hose tube wall. The rubber ridge tapers in the direction of valleys formed between the ridges, and the resulting hose structure has improved flexibility by enabling the hose to flex at every valley, yet sufficient strength for heavy duty applications.

Abstract: A flexible tube for a vacuum system includes a tube body and a cover. The tube body is made of hard material. The tube body has projected parts and depressed parts. The cover is provided over an outer surface of the tube body. The cover is made of elastic material. The cover is in contact with around the projected parts of the tube body and formed over the depressed parts of the tube body so that a vacant space is formed between the tube body and the cover.

Abstract: The present invention provides a tubular member construction capable of preventing the end portion of a flexible pipe formed of a band member from coming loose without costing. The flexible pipe is formed by winding a metallic tubular member in a spiral shape in an overlapped manner, and a plurality of wavy corrugations are formed on the peripheral wall surface of the flexible pipe continuously in the axial direction. In order to prevent a band member located in an end portion of the flexible pipe from coming loose, collapsed portions are formed on corrugations located in the end portions of the tubular member.

Abstract: An improved flexible hose for carrying fluids is disclosed. The hose has a first end and a second end, and is typically in a retracted position when no tensile force placed on an end of the hose and in an extended condition when a tensile force of a pulling nature is placed on an end of the hose. The hose has a thermoplastic cover on its outer surface. The thermoplastic cover has an interior surface and an exterior surface. On the interior surface there is a helical member adhered thereto this helical member being comprised of a material capable of carrying a current of electricity. The hose of the present invention stretches at least 100 percent over its at rest position when a pulling force is placed on one end of the hose.

Abstract: A linearly self-actuated hose for use in transporting fluids (liquids, gases, solid particles, and combinations of these three). Hose (30b) has a biasing spring (36) extends along the full length, and can comprise single or multiple springs and/or multiple diameter spring coils. Spring (36) is covered with hose cover material (32) on the outside and hose cover material (34) on the inside to form a sealed hose and are bowed inward or outward radially between the individual spring coils depending on the intended use of hose (30b) to give the cover materials room to move out of the way when the hose retracts and the coils of spring (36) are forced close together. Hose (30b) is designed with a source end (26) and a output end (68). A pressure control mechanism is used on output end (68) to control the extending and retracting of hose (30b). The Linearly Retractable Hose is operated by changing internal pressure within the hose relative to the ambient pressure on the exterior of the hose.

Abstract: A leak-free flexible conduit and method of making the same is described. By attaching a flexible outer hose to a flexible inner hose without directly clamping the outer hose to the inner hose, the life of the inner hose is increased. Furthermore, the outer flexible hose creates a heat-resistant, airtight seal that prevents exhaust leaks from the inner flexible hose from escaping, substantially reduces the heat lost to the atmosphere, decreases the amount of vibration, reduces noise, and protects the inner flexible hose from corrosive elements and contaminants, thereby also extending the life of the inner flexible hose.

Abstract: A corrugated pipe is provided having a pipe structure of an inner wall having an interior surface and an exterior surface, and an outer wall having corrugations, each of the corrugations having an interior surface and an exterior surface, each corrugation having a crown. The pipe structure has a trough between each corrugation, and each trough has a center-point, with the distance between the center-points of adjacent troughs defining the pitch of the pipe. The pipe structure has at each crown a first distance extending in a straight line from the crown exterior surface to the interior surface of the inner wall, with the distance defining the pitch being a second distance, with the ratio of the first distance to the second distance being less than 0.8:1.0.

Abstract: Flexible metal tube having a box element and flexible pipe comprising such a metal tube.

Abstract: A flexible hose comprising

Abstract: A length-controlled flexible hose includes a body formed by spiral-winding a continuous metal band with interlocked leading and trailing edges. A length control adhesive strip is applied to the flexible hose along a surface thereof and minimizes length changes of the flexible hose whereby a design or engineered length can be maintained. A method of manufacturing a length-control flexible hose includes the steps of spiral-winding a continuous metal band, interlocking leading and trailing edges thereof and applying a length control adhesive strip to a surface thereof.

Abstract: A flexible metal conduit is disclosed that comprises a thin metal ribbon arranged in a helix about a longitudinal axis. Convolutions of the helix are disposed adjacent each other with the ribbon defining helical, sinuously corrugated inwardly and outwardly facing conduit surfaces forming radially inner and radially outer apices that are spaced substantially evenly apart and extend parallel to the convolution edges. A first ribbon edge region is defined by a partial corrugation and a flange extending radially from the partial corrugation. A second ribbon edge region is defined by a second partial corrugation and a second flange extending radially from the second partial corrugation. The first and second partial corrugations abut to form a helical seam running along the convolution junctures. The first and second edge flanges abut at the corrugation seam and are interlocked to secure the convolutions together.

Abstract: A convoluted hose is disclosed, being particularly suitable for use in a motor vehicle engine. The hose has a series of annular corrugations, which improve the flexibility of the hose. Each corrugation varies gradually in height around the hose, from a minimum height to a maximum height. In one embodiment, the minimum height is separated from the maximum height by at least 120°, preferably 180°, and the minimum height may be zero. In another embodiment, the corrugations are of elliptical cross section, each corrugation having two maximum height parts and two minimum height parts, the minimum height being 10% or more of the maximum height. The arrangement of minimum height parts of the corrugations allows limitation of axial expansion of the hose.

Abstract: An apparatus for providing a variable pitch thread includes a hollow cylindrical element configured to provide a plurality of parallel, radially projecting ridges extending circumferentially around the cylindrical element and spaced apart with a given step as measured parallel to a central axis of the cylindrical element. The cylindrical element also featuring a slit extending substantially parallel to the central axis along the length of the cylinder. An actuation mechanism is configured to selectively generate controlled relative displacement between the opposing edges on opposing sides of the slit so as to vary a helical angle of the projecting ridges relative to the central axis. The actuation mechanism is preferably configured to relatively displace the opposing edges such that the plurality of projecting ridges together form alternatively a helical pattern and a pattern of substantially closed rings.

Abstract: A spiral bellows structure having a longitudinal axis includes at least one peak portion extending spirally around and along the longitudinal axis and at least one valley portion extending in parallel with the peak portion to thereby define a flow passage. The spiral bellows structure has a reduced flow resistance because of its tendency to suppress turbulence and eddies while allowing to keep the original characteristics, such as flexibility, of a straight bellows structure substantially unchanged.

Abstract: The present invention relates to a polytetrafluoroethylene (PTFE) tube, and more particularly to a PTFE tube for a flexible hose. In particular the invention relates to a PTFE tube having a smooth bore for use in the production of a lined hose assembly farther comprising hose braids, external hose protection and end fittings. The PTFE tube comprises external roots and peaks, which tube is obtainable from a non-convoluted tube having an original wall thickness W0 and an internal diameter ID by a process in which a region of the tube is thinned to provide external convolutions with a root wall thickness W1 characterised in that the convoluted PFTE tube has an improved resistance, of greater than 7.6%, to permeation by comparison with the non-convoluted tube, the comparison being made between tubes of (i) equal nominal bore ID; and (ii) equal weight of PTFE per unit length.

Abstract: A flexible hose (1) with a corrugated wall (2), comprising an internal surface (3) with projections (4, 5) and recesses (6, 7), said hose (1) being obtained by moulding a plastic material, wherein each internal projection (4, 5) comprises a substantially flat and smooth top face (8, 9). Each top face (8, 9) has a first width (W1) and each internal recess has a second width (W2). The ratio between first width and second width (W1/W2) is preferably larger than or equal to 2.2. The hose may comprise a hollow longitudinal protuberance or score.

Abstract: Disclosed is a process for obtaining a flexible conduit comprising a tube and a helical structure. The process comprises extruding a crosslinkable plastic material in a malleable or formable state, so as to form a profiled strip having, as one piece, a web with two mutually complementary marginal edges, and at least one rib projecting on one side from the web; winding the profiled strip about an axis in a helix with touching turns so that the complementary marginal edges of the profiled strip, belonging respectively to two different turns, form between them, directly, a sealed joint; varying and controlling a winding pitch of the profiled strip, in order to modulate and control a quantity of available and formable plastic material of the tube along the length of the conduit; and crosslinking the wound profiled strip.