Within examples, a method of manufacturing a double-walled titanium conduit is described. Example methods include stitch welding multiple concentric sheets to form a stitch layer, providing the stitch layer between an inner wall and an outer wall of the double-walled titanium conduit, circumferentially seam welding the inner wall and the outer wall to the stitch layer to create a welded assembly, die forming the welded assembly at temperature and pressure to form inner structures between the multiple concentric sheets according to stitch welding lines and to enable a diffusion bond process among the inner wall, the stitch layer, and the outer wall, and removing the double-walled titanium conduit from the die.

Within examples, a method of manufacturing a double-walled titanium conduit is described. Example methods include stitch welding multiple concentric sheets to form a stitch layer, providing the stitch layer between an inner wall and an outer wall of the double-walled titanium conduit, circumferentially seam welding the inner wall and the outer wall to the stitch layer to create a welded assembly, die forming the welded assembly at temperature and pressure to form inner structures between the multiple concentric sheets according to stitch welding lines and to enable a diffusion bond process among the inner wall, the stitch layer, and the outer wall, and removing the double-walled titanium conduit from the die.

A double tube includes an inner tube having a corrugated petal shape in a wave form in an outer tube. The double tube is manufactured by a method including: inserting the inner tube into the outer tube and coaxially disposing the inner tube and the outer tube; inserting a plurality of petal forming bars into a space between the outer tube and the inner tube and arranging the petal forming bars along a circumferential direction at predetermined intervals; disposing an assembly of the outer tube, the inner tube, and the petal forming bars in a mold of a hydroforming machine; supplying a fluid in the inner tube while applying a pressure to the inner tube in an axial direction to expand the inner tube; and separating the petal forming bars from the space between the outer tube and the inner tube.

A double tube includes an inner tube having a corrugated petal shape in a wave form in an outer tube. The double tube is manufactured by a method including: inserting the inner tube into the outer tube and coaxially disposing the inner tube and the outer tube; inserting a plurality of petal forming bars into a space between the outer tube and the inner tube and arranging the petal forming bars along a circumferential direction at predetermined intervals; disposing an assembly of the outer tube, the inner tube, and the petal forming bars in a mold of a hydroforming machine; supplying a fluid in the inner tube while applying a pressure to the inner tube in an axial direction to expand the inner tube; and separating the petal forming bars from the space between the outer tube and the inner tube.

A double tube includes an inner tube having a corrugated petal shape in a wave form in an outer tube. The double tube is manufactured by a method including: inserting the inner tube into the outer tube and coaxially disposing the inner tube and the outer tube; inserting a plurality of petal forming bars into a space between the outer tube and the inner tube and arranging the petal forming bars along a circumferential direction at predetermined intervals; disposing an assembly of the outer tube, the inner tube, and the petal forming bars in a mold of a hydroforming machine; supplying a fluid in the inner tube while applying a pressure to the inner tube in an axial direction to expand the inner tube; and separating the petal forming bars from the space between the outer tube and the inner tube.

A tailor-layered tube, includes an inner tube, an outer tube having a greater diameter than the inner tube and disposed outside the inner tube, and at least one intermediate tube disposed between the inner tube and the outer tube and having a length different from the inner tube and the outer tube to be locally disposed between the inner tube and the outer tube. The inner tube, the intermediate tube, and the outer tube are hydroformed in a state of being laminated so that the inner tube, the intermediate tube, and the outer tube are sequentially brought into close contact with each other in a region where the intermediate tube is disposed and the inner tube is brought into direct contact with the outer tube in a region where the intermediate tube does not exist, and accordingly regions having locally different thicknesses are successively arranged.

An apparatus and method for manufacturing a pipe assembly having an inner pipe and an outer jacket may include a support member, a pair of lance assemblies and a pair of caps. The support member supports the outer jacket of the pipe assembly and is drivable between a first position and a second position. The pair of lance assemblies are configured to be inserted into opposing ends of the inner pipe such that the pair of lance assemblies engage an inner wall of the inner pipe. One of the outer jacket and the inner pipes moves relative to the other of the outer jacket and the inner pipe to center the inner pipe within the outer jacket when the support member is driven from the first position to the second position. Insulation is inserted through at least one cap into a space between the inner pipe and outer jacket.

An apparatus and method for manufacturing a pipe assembly having an inner pipe and an outer jacket may include a support member, a pair of lance assemblies and a pair of caps. The support member supports the outer jacket of the pipe assembly and is drivable between a first position and a second position. The pair of lance assemblies are configured to be inserted into opposing ends of the inner pipe such that the pair of lance assemblies engage an inner wall of the inner pipe. One of the outer jacket and the inner pipes moves relative to the other of the outer jacket and the inner pipe to center the inner pipe within the outer jacket when the support member is driven from the first position to the second position. Insulation is inserted through at least one cap into a space between the inner pipe and outer jacket.

A tailor-layered tube, includes an inner tube, an outer tube having a greater diameter than the inner tube and disposed outside the inner tube, and at least one intermediate tube disposed between the inner tube and the outer tube and having a length different from the inner tube and the outer tube to be locally disposed between the inner tube and the outer tube. The inner tube, the intermediate tube, and the outer tube are hydroformed in a state of being laminated so that the inner tube, the intermediate tube, and the outer tube are sequentially brought into close contact with each other in a region where the intermediate tube is disposed and the inner tube is brought into direct contact with the outer tube in a region where the intermediate tube does not exist, and accordingly regions having locally different thicknesses are successively arranged.

A pipe joint device configured to interconnect two pipes to be inserted therein through openings of both opened ends thereof including a joint main body and a joint assembly disposed in the joint main body is provided. The joint main body includes a small-diameter part formed at a central part and large-diameter parts formed at both sides of the small-diameter part. Each of the large-diameter parts has a first horizontal part, a diameter-reduced part of which a diameter gradually decreases from the first horizontal part toward the opening, and a second horizontal part extending horizontally from the diameter-reduced part toward the opening. A portion of each of the second horizontal parts is configured as a curled part inclined toward an outer-diameter direction and the opening of the pipe joint device and then again inclined toward an inner-diameter direction and the opening and having a mountain-shaped section as a whole.