A cracked gas cooling heat exchanger includes a tube connection between an uncooled tube (1) and a cooled tube (2), having a cooled inner tube (3) enclosed by a jacket tube (4), with a tube intermediate space (5) for flowing cooling medium. A gas inlet header (11) has a GI tube inner part (12) and a GI tube outer part (13) and a cooling space (14) with an insulating layer (15). The GI tube outer part connects via a water chamber (6) to the jacket tube. The GI tube inner part faces the inner tube and is connected on a face (8) of the water chamber. A weld backing ring (16), between an end face (9) of the cooling space and a bottom face (8) of the water chamber, is in the insulating layer of the cooling space, arranged in a turn-out/groove (17) in the insulating layer.

Laser cutting on a plated steel sheet is executed by cutting the plated steel sheet by irradiating the plated steel sheet covered with a plate metal with laser light at a wavelength in a 1 micrometer band; and emitting assist gas onto a cut surface of the plated steel sheet, the cut surface being formed in the step of cutting, to make the plate metal fused by irradiation of the laser light flow to the cut surface so as to cover the cut surface with the plate metal.

Laser cutting on a plated steel sheet is executed by cutting the plated steel sheet by irradiating the plated steel sheet covered with a plate metal with laser light at a wavelength in a 1 micrometer band; and emitting assist gas onto a cut surface of the plated steel sheet, the cut surface being formed in the step of cutting, to make the plate metal fused by irradiation of the laser light flow to the cut surface so as to cover the cut surface with the plate metal.

A device for positioning at least two joining parts during a welding process includes a support element. The support element has a surface on which for the joining parts are positioned, a recess under the joining parts when a joining region of the joining parts are on the surface, and a fluid connection for supplying a fluid to the recess. When fluid in the recess is pressurized, during a welding process to connect the joining parts a weld melt is supported by the positive pressure.

A device for positioning at least two joining parts during a welding process includes a support element. The support element has a surface on which for the joining parts are positioned, a recess under the joining parts when a joining region of the joining parts are on the surface, and a fluid connection for supplying a fluid to the recess. When fluid in the recess is pressurized, during a welding process to connect the joining parts a weld melt is supported by the positive pressure.

A gas cutting method for cutting a steel material and a steel material producing method including arranging one steel material and another steel material in proximity, setting a preheating region on the one steel material in such a way that a preheating flame applied thereto does not reach the other steel material, preheating the one steel material by applying the preheating flame to the preheating region, and gas-cutting the one steel material by moving a cutting oxygen from the preheating region across a boundary between the one steel material and the other steel material until the cutting oxygen enters the other steel material. The preheating region may be set in such a way that an outer edge of the preheating flame is at least 2 mm away from the other steel material.

A gas cutting method for cutting a steel material and a steel material producing method including arranging one steel material and another steel material in proximity, setting a preheating region on the one steel material in such a way that a preheating flame applied thereto does not reach the other steel material, preheating the one steel material by applying the preheating flame to the preheating region, and gas-cutting the one steel material by moving a cutting oxygen from the preheating region across a boundary between the one steel material and the other steel material until the cutting oxygen enters the other steel material. The preheating region may be set in such a way that an outer edge of the preheating flame is at least 2 mm away from the other steel material.

Wire arc additive manufacturing-spinning combined machining device and method are provided. The machining device includes a spinning mechanism and a fused deposition modeling mechanism. The spinning mechanism includes a machine tool and a spinning head. The spinning head is installed on the machine tool by a main shaft, and the main shaft is configured to drive the spinning head to rotate to achieve the movement in three vertical directions. The spinning head includes a spinning base and balls. Each of the balls is installed in a corresponding one of arc grooves at a bottom of the spinning base. The fused deposition modeling mechanism includes a moving track, a robot and a heat source generator. The arc moving track is arranged around the machine tool in a surrounding mode. The robot is movably installed on the moving track. The heat source generator is installed at a tail end of the robot.

A welding support block supports, from the rear surface of a joint to be welded, a weld pool created during a welding process. The welding support block comprises a block of metal and an outer layer of ceramic material providing a supporting surface. The ceramic material layer has a thickness between 0.25 mm and 1.5 mm. The metal material immediately beneath the ceramic material layer is made of steel. An internal line-up clamp for holding pipes in end-to-end alignment ready for welding may include multiple such welding support blocks. The use of such welding support blocks is particularly useful when laying a sour service carrying pipeline (high H.sub.2S content).

A welding support block supports, from the rear surface of a joint to be welded, a weld pool created during a welding process. The welding support block comprises a block of metal and an outer layer of ceramic material providing a supporting surface. The ceramic material layer has a thickness between 0.25 mm and 1.5 mm. The metal material immediately beneath the ceramic material layer is made of steel. An internal line-up clamp for holding pipes in end-to-end alignment ready for welding may include multiple such welding support blocks. The use of such welding support blocks is particularly useful when laying a sour service carrying pipeline (high H.sub.2S content).