PURPOSE: To eliminate temperature differences in a fluid plastic and achieve a regularity of a pipe wall thickness by distributing a molten plastic arriving from an extruder in a distribution head to supply to two independent annular pipes which are to be joined at a bright of an extrusion tool.

CONSTITUTION: By feeding a distribution head (A) comprising a feed duct 1 connected to an outlet of an extruder with a molten plastic by means of the extruder, the duct, which is subdivided into two divergent ducts 2, 3, permits the plastic to flow in the molten state in two superimposed annular conduits 4 and 5 converging toward each other up to the point of meeting that is located in the device preferably essentially at the level of the extrusion tool. Two streams of the plastic in the meeting point, preferably between a mandrel 6 and a die 7 of the extruding tool are jointed and completely integrated. The device is maintained at the temperature suitable for the transmission of the plastic used. In addition to the regularity of the pipe thickness, the pipe is also perfectly homogeneous.