A method for welding tubular elements comprising respective zones to be welded that face each other, wherein the method comprises the steps of: • defining outlines of sections of said tubular elements by means of the steps of: ∘ arranging a scanner comprising a scanning surface and a scanner "sheet" configured to have the tubular element rested thereon; ∘ defining a scanning resolution for said scanner; ∘ arranging on the scanner a tubular element to be worked, wherein said tubular element comprises at least one outline of a section; ∘ scanning said at least one outline in a framing position so as to obtain an image of said outline and define edges of said image; ∘ refining said edges so as to define a refined image, the edges being deformed so as to conform as closely as possible to the actual outline; ∘ scale mapping said outline starting from said refined image as a function of said resolution, thereby defining coordinates of the position of said outline; ∘ wherein said scale mapping step defines reference points (PRi) of said outline for grooves and containing compartments; • arranging at least two tubular elements with the respective zones to be welded that face each other; • making a groove in each zone to be welded, of the tubular elements, said groove being made by means of a removal procedure on the perimeter of the outline of the section of each tubular element, wherein removal is carried out as a function of said scale mapping; • heating said zones to be welded; • coupling the zones to be welded one to the other by pressing the tubular elements one against the other so as to keep the zones in contact with each other, said step for coupling the zones to be welded defining a sub-step of fusing the zones one to the other so as to define a welding bead. • defining outlines of sections of said tubular elements by means of the steps of: ∘ arranging a scanner comprising a scanning surface and a scanner "sheet" configured to have the tubular element rested thereon; ∘ defining a scanning resolution for said scanner; ∘ arranging on the scanner a tubular element to be worked, wherein said tubular element comprises at least one outline of a section; ∘ scanning said at least one outline in a framing position so as to obtain an image of said outline and define edges of said image; ∘ refining said edges so as to define a refined image, the edges being deformed so as to conform as closely as possible to the actual outline; ∘ scale mapping said outline starting from said refined image as a function of said resolution, thereby defining coordinates of the position of said outline; ∘ wherein said scale mapping step defines reference points (PRi) of said outline for grooves and containing compartments; ∘ arranging a scanner comprising a scanning surface and a scanner "sheet" configured to have the tubular element rested thereon; ∘ defining a scanning resolution for said scanner; ∘ arranging on the scanner a tubular element to be worked, wherein said tubular element comprises at least one outline of a section; ∘ scanning said at least one outline in a framing position so as to obtain an image of said outline and define edges of said image; ∘ refining said edges so as to define a refined image, the edges being deformed so as to conform as closely as possible to the actual outline; ∘ scale mapping said outline starting from said refined image as a function of said resolution, thereby defining coordinates of the position of said outline; ∘ wherein said scale mapping step defines reference points (PRi) of said outline for grooves and containing compartments; • arranging at least two tubular elements with the respective zones to be welded that face each other; • making a groove in each zone to be welded, of the tubular elements, said groove being made by means of a removal procedure on the perimeter of the outline of the section of each tubular element, wherein removal is carried out as a function of said scale mapping; • heating said zones to be welded; • coupling the zones to be welded one to the other by pressing the tubular elements one against the other so as to keep the zones in contact with each other, said step for coupling the zones to be welded defining a sub-step of fusing the zones one to the other so as to define a welding bead.