Tubular structures, systems, and methods are generally directed to support structures having structural properties similar to thick-walled structures while being formed using materials having thickness amendable to rolling and welding and, thus, useful for rapid and cost-effective fabrication.

Herein a tubular element (2) is disclosed. The tubular element comprises a first tubular portion (4) comprising a first metal or alloy and a second tubular portion (6) comprising a second metal or alloy. At least a portion of an interface (9) between the first and second tubular portions (4, 6) extends within a fixed diameter range along a longitudinal direction (L) of the tubular element. The second tubular portion (6) comprises a first end portion (8) arranged around the first tubular portion (4). The second tubular portion (6) comprises a sealing surface (10) extending circumferentially around the second tubular portion (6) at the first end portion (8).

A heat exchange tube, a heat exchanger, and a manufacturing method for the heat exchange tube are provided. The heat exchange tube includes a tube wall and an outer fin, the tube wall is folded into a tube body, the tube body is provided with an inner fin therein, and the inner fin divides an inner chamber of the tube body into a plurality of flow channels. The outer fin is arranged outside the tube body. The outer fin is folded from a same plate with at least one of the tube wall and the inner fin.

A coaxial heat exchanger is provided. Embodiments of the present disclosure relate to a coaxial heat exchanger for use in water source heat pumps or other applications involving fluid to fluid heat transfer. Embodiments of the present disclosure allow for the use of pre-existing engineered tubing with a textured or riffled interior surface and a folded fin intermediate member. Some methods of the present disclosure involve annealing and hydrostatically expanding the engineered tubing to increase contact and thermal transfer between the inner tube and the intermediate member. Additional systems, devices, and methods are also disclosed.

A process for manufacturing a high nitrogen stainless steel pipe material includes keeping an outside surface and/or an inside surface of an austenite stainless steel pipe material in contact with a substance that becomes a nitrogen (N) source, heating the steel pipe together with the nitrogen source substance at a temperature of 800° C. to 1100° C. in a range of temperatures not higher than the critical temperature for crystal grain enlargement of the steel pipe material to cause nitrogen to be absorbed into the surface of the pipe and diffused into the steel solid phase, and applying to the heat-treated pipe material annealing treatment in the range of temperatures in vacuum, inert gas including argon gas or an atmosphere of a gas with a reducing substance including H.sub.2 gas added thereto, to result in a decrease of nitrogen concentration gradient.

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 long tubular pipe comprising an outer tube, an inner fluid-transporting tube mounted in the outer tube, and a separating member designed to transmit bending efforts between said outer tube and said inner tube when said outer tube is bent, the separating member comprising means for the longitudinal passage of fluid between the inner tube and the outer tube, the separating member comprising a first edge and a second edge together defining an assembly slot, the first edge and the second edge respectively comprising a first connecting element and a second connecting element designed to cooperate mechanically on the outer periphery of the inner tube.

The present disclosure relates to a bimetallic tube comprising a first metallic tube having an inner diameter and an outer diameter, and a second metallic tube having an inner diameter and an outer diameter, wherein the first metallic tube is arranged within and force-fitted to the second metallic tube and wherein the first metallic tube comprises a zirconium (Zr) based alloy and wherein the second metallic tube comprises an austenitic stainless steel. The present disclosure also relates to a method for manufacturing a bimetallic tube comprising the steps of providing a first metallic tube having an inner diameter and an outer diameter, providing a second metallic tube having an inner diameter and an outer diameter, wherein the outer diameter of the first metallic tube is smaller than the inner diameter of the second tube, insetting the first metallic tube into the second metallic tube, cold-drawing the first and second metallic tubes together, such that the first and second metallic tubes are force-fitted together.

A method of manufacturing a two-layer metal wire, in particular in a gold-based alloy and of silver, which comprises a succession of steps which consist in coupling an outer metal tube (2) to an inner metal tube (4) interposing a first binding thickness (3) in low-melting metal material, welding the inner surface (12) of the outer metal tube (2) to the outer surface (13) of the first binding thickness (3) and the inner surface (13″) of the same first binding thickness (3) to the outer surface (141) of the inner metal tube (4), to firmly associate the outer tube (2) with the inner tube (4) together, so as to form a tubular element (7, 107) which has at least three metal layers, and then draw, by final drawing, the tubular element (7, 107) to obtain a compound metal wire (9) from at least three metal layers. The object of the present invention is also a semi-finished tubular element (7, 107), having at least three metal layers, which comprises an outer metal tube (2), an Inner metal tube (4) and a first binding thickness (3) interposed between the outer metal tube (2) and the inner metal tube (4).

A method to make a tubular element to transfer abrasive materials such as concrete, inert materials or suchlike, where the tubular element includes an external tubular component made of steel and an internal tubular component, coaxial to the external tubular component, where the internal tubular component is made of chromium carbide, or other similar material resistant to wear.