The present disclosure relates to a tube structure comprising an inner tube of metal and an outer tube of metal, wherein the inner tube extends in the outer tube, and wherein either the inner tube and the outer tube are mechanically tight fitted over the entire length of the inner tube, at least one space in a radial direction of the tube structure in the form of a groove extends at least in an outer surface of the inner tube or in an inner surface of the outer tube, and the at least one space extends in a longitudinal direction of the inner tube and over an entire longitudinal extension of the inner tube, or a spacer tube is located between the inner tube and the outer tube, the inner tube, the outer tube and the spacer tube are mechanically tight fitted over the entire length of the spacer tube, the spacer tube comprises at least one space in the form a slit extending in a radial direction of the tube structure from an outer surface of the inner tube to an inner surface of the outer tube, the at least one space extends in a longitudinal direction of the spacer tube and over an entire longitudinal extension of the spacer tube, and wherein the at least one space is at least partially filled with a thermal interface material providing a thermal contact between the outer tube and the inner tube.

The present disclosure relates to a tube structure comprising an inner tube of metal and an outer tube of metal, wherein the inner tube extends in the outer tube, and wherein either the inner tube and the outer tube are mechanically tight fitted over the entire length of the inner tube, at least one space in a radial direction of the tube structure in the form of a groove extends at least in an outer surface of the inner tube or in an inner surface of the outer tube, and the at least one space extends in a longitudinal direction of the inner tube and over an entire longitudinal extension of the inner tube, or a spacer tube is located between the inner tube and the outer tube, the inner tube, the outer tube and the spacer tube are mechanically tight fitted over the entire length of the spacer tube, the spacer tube comprises at least one space in the form a slit extending in a radial direction of the tube structure from an outer surface of the inner tube to an inner surface of the outer tube, the at least one space extends in a longitudinal direction of the spacer tube and over an entire longitudinal extension of the spacer tube, and wherein the at least one space is at least partially filled with a thermal interface material providing a thermal contact between the outer tube and the inner tube.

A method for manufacturing an electric resistance welded steel pipe having an identifiable seam portion. The method includes electric resistance welding a steel pipe, cutting an inner surface bead and an outer surface bead of the steel pipe in such a manner so as to cut: (i) a whole the outer surface bead and a part of the inner surface bead to leave an uncut portion in the inner surface bead, or (ii) a whole of the inner surface bead and a part of the outer surface bead to leave an uncut portion in the outer surface bead, coating the steel pipe with zinc phosphate, and cold drawing the steel pipe using a plug and a die to make the seam portion of the steel pipe identifiable.

A method for manufacturing an electric resistance welded steel pipe having an identifiable seam portion. The method includes electric resistance welding a steel pipe, cutting an inner surface bead and an outer surface bead of the steel pipe in such a manner so as to cut: (i) a whole the outer surface bead and a part of the inner surface bead to leave an uncut portion in the inner surface bead, or (ii) a whole of the inner surface bead and a part of the outer surface bead to leave an uncut portion in the outer surface bead, coating the steel pipe with zinc phosphate, and cold drawing the steel pipe using a plug and a die to make the seam portion of the steel pipe identifiable.

The present disclosure relates to a tube structure comprising an inner tube of metal and an outer tube of metal, wherein the inner tube extends in the outer tube, and wherein either the inner tube and the outer tube are mechanically tight fitted over the entire length of the inner tube, at least one space in a radial direction of the tube structure in the form of a groove extends at least in an outer surface of the inner tube or in an inner surface of the outer tube, and the at least one space extends in a longitudinal direction of the inner tube and over an entire longitudinal extension of the inner tube, or a spacer tube is located between the inner tube and the outer tube, the inner tube, the outer tube and the spacer tube are mechanically tight fitted over the entire length of the spacer tube, the spacer tube comprises at least one space in the form a slit extending in a radial direction of the tube structure from an outer surface of the inner tube to an inner surface of the outer tube, the at least one space extends in a longitudinal direction of the spacer tube and over an entire longitudinal extension of the spacer tube, and wherein the at least one space is at least partially filled with a thermal interface material providing a thermal contact between the outer tube and the inner tube.

The present disclosure relates to a tube structure comprising an inner tube of metal and an outer tube of metal, wherein the inner tube extends in the outer tube, and wherein either the inner tube and the outer tube are mechanically tight fitted over the entire length of the inner tube, at least one space in a radial direction of the tube structure in the form of a groove extends at least in an outer surface of the inner tube or in an inner surface of the outer tube, and the at least one space extends in a longitudinal direction of the inner tube and over an entire longitudinal extension of the inner tube, or a spacer tube is located between the inner tube and the outer tube, the inner tube, the outer tube and the spacer tube are mechanically tight fitted over the entire length of the spacer tube, the spacer tube comprises at least one space in the form a slit extending in a radial direction of the tube structure from an outer surface of the inner tube to an inner surface of the outer tube, the at least one space extends in a longitudinal direction of the spacer tube and over an entire longitudinal extension of the spacer tube, and wherein the at least one space is at least partially filled with a thermal interface material providing a thermal contact between the outer tube and the inner tube.

The invention relates to a process for producing a multilayer pipe (1) from a tubular element having a metallurgical bond comprising at least one outer pipe (10) of metallic material and one inner pipe (20) of metallic material arranged within the outer pipe, the inner surface of the outer pipe (10) being mechanically bonded to the outer surface of the inner pipe (20) at least in parts of their interface, in which, in a production line, the tubular element is simultaneously heated and drawn, wherein each portion of the tubular element is submitted to heating by induction and then to hot-drawing, wherein the tubular element is drawn with a mandrel located therein. Through this process, the existing mechanical connection between the pipes is trans-formed in a metallurgical connection. The invention also relates to a multilayer pipe (1) produced for this process, wherein the outer pipe (10) is made of a carbon manganese steel alloy and the inner pipe (2) is made of a corrosion-resistant alloy.

The invention relates to a process for producing a multilayer pipe (1) from a tubular element having a metallurgical bond comprising at least one outer pipe (10) of metallic material and one inner pipe (20) of metallic material arranged within the outer pipe, the inner surface of the outer pipe (10) being mechanically bonded to the outer surface of the inner pipe (20) at least in parts of their interface, in which, in a production line, the tubular element is simultaneously heated and drawn, wherein each portion of the tubular element is submitted to heating by induction and then to hot-drawing, wherein the tubular element is drawn with a mandrel located therein. Through this process, the existing mechanical connection between the pipes is trans-formed in a metallurgical connection. The invention also relates to a multilayer pipe (1) produced for this process, wherein the outer pipe (10) is made of a carbon manganese steel alloy and the inner pipe (2) is made of a corrosion-resistant alloy.

A matrix for shaping a valve preform has a circular through opening and a reduced conical section. The reduced conical section tapers from an outer diameter to a reduced cone inner diameter, the outer diameter being greater than or equal to the initial outer diameter of the valve preform, and the matrix inner diameter being smaller than the initial outer diameter.

A friction assisted tube fabrication method is disclosed. The friction assisted tube fabrication includes a set of methods such as a friction assisted tube forming, a friction assisted tube extrusion, and a friction assisted tube straining method. A metal object, for example, a deformable tube is simply deformed into the tube using a mandrel. The metal object with an initial diameter is forced across the slope of the mandrel with an angle. The mandrel is configured to rotate while forcing the metal object to deform into the tube with the desired radius. While rotating the mandrel, a friction is generated due to contact between the tube and the mandrel, thereby generating thermal energy to heat a deformation area of the tube for simply and easily softening and forming into the desired shape with accuracy diameter, and dimensions using a nominal pressing force without additional equipment and power.