Abstract: A method for assembling at least two parts includes using transparent welding using an energy input beam which travels a trajectory in a closed loop. The trajectory of the energy input beam and/or at least one parameter of the energy input beam is configured so that the weld bead has mechanical and/or geometrical characteristics that are substantially constant over all its length. A method for assembling a primary structure of an aircraft pylon which uses this assembly method to link the panels of the primary structure to one another, a primary structure of an aircraft pylon thus obtained, as well as an aircraft comprising at least one such primary structure is also described.

Abstract: A method for assembling at least two parts includes using transparent welding using an energy input beam which travels a trajectory in a closed loop. The trajectory of the energy input beam and/or at least one parameter of the energy input beam is configured so that the weld bead has mechanical and/or geometrical characteristics that are substantially constant over all its length. A method for assembling a primary structure of an aircraft pylon which uses this assembly method to link the panels of the primary structure to one another, a primary structure of an aircraft pylon thus obtained, as well as an aircraft comprising at least one such primary structure is also described.

Abstract: A weld protecting device by gas diffusion including several elements mounted one after the other and hinged to each other, and including a front element, intermediate elements mounted one after the other and behind the front element. A back element is mounted behind the last intermediate element, each element including a housing open downwards and towards each other adjacent element, forming a gas diffusion chamber, wherein two adjacent elements are hinged to each other and they are free to pivot relative to each other, regardless of the operating conditions of the protecting device. A facility for welding two opposite edges of two pieces, a weld protecting device, and a system for guiding the protecting device are disclosed.