A method for assembling two tubes (1, 2) made from thermoplastic materials, that involves welding by heating two applied rotational contact surfaces of two parts of two tubes (1, 2), respectively, arranged end to end or overlapping coaxially (XX′). The method involves induction heating of at least one conductive welding element (4), arranged at the interface (3) between the two contact surfaces, by generating a magnetic field at said conductive welding element or elements, such that the melting of the thermoplastic materials constituting said contact surfaces produces a continuous and sealed weld at said interface on at least one closed loop along the entire perimeter of said interface.