Device for producing pipes made of thermoplastic with annular transverse profilings with a cross section in the form of undulation peaks and undulation troughs, - with half-moulds (6, 6a), -- which complete one another pairwise along a straight mould section to form a closed mould, which is moveable in a motion direction, with a central longitudinal axis, -- which are transportable in the circuit counter to the movement direction of the mould to an upstream end of the mould section and -- which have an annular internal profiling, which is loadable with a partial vacuum, with a smallest internal diameter D39 to produce the transverse profiling, and - with an extrusion tool (3, 3'), -- which has a nozzle support body (33, 33') with an external diameter D33 or D33' with at least one channel (17, 17') for plastic melt, -- which has a nozzle (19, 19') with a diameter D19, which is connected by means of a channel end portion widening toward the nozzle (19, 19') to the channel (17, 17'), -- which has an inner nozzle ring (29, 29') and an outer nozzle ring (30, 30'), which between them limit the channel end portion and which are fastened to the nozzle support body (33, 33'), characterized in that the external diameter D33 or D33' of the nozzle support body (33, 33') is smaller than the diameter D19 of the nozzle (19, 19'), in that the nozzle support body (33, 33') - in relation to the movement direction - upstream of the outer nozzle ring, is covered with exchangeably attached hollow half-shells (36, 36a, 36'), which form a cylindrical external face with a diameter D37 and in that a narrow annular gap with a gap width a is formed between the cylindrical external face and the internal profiling with the smallest internal diameter D39. - with half-moulds (6, 6a), -- which complete one another pairwise along a straight mould section to form a closed mould, which is moveable in a motion direction, with a central longitudinal axis, -- which are transportable in the circuit counter to the movement direction of the mould to an upstream end of the mould section and -- which have an annular internal profiling, which is loadable with a partial vacuum, with a smallest internal diameter D39 to produce the transverse profiling, and -- which complete one another pairwise along a straight mould section to form a closed mould, which is moveable in a motion direction, with a central longitudinal axis, -- which are transportable in the circuit counter to the movement direction of the mould to an upstream end of the mould section and -- which have an annular internal profiling, which is loadable with a partial vacuum, with a smallest internal diameter D39 to produce the transverse profiling, - with an extrusion tool (3, 3'), -- which has a nozzle support body (33, 33') with an external diameter D33 or D33' with at least one channel (17, 17') for plastic melt, -- which has a nozzle (19, 19') with a diameter D19, which is connected by means of a channel end portion widening toward the nozzle (19, 19') to the channel (17, 17'), -- which has an inner nozzle ring (29, 29') and an outer nozzle ring (30, 30'), which between them limit the channel end portion and which are fastened to the nozzle support body (33, 33'), characterized in that the external diameter D33 or D33' of the nozzle support body (33, 33') is smaller than the diameter D19 of the nozzle (19, 19'), in that the nozzle support body (33, 33') - in relation to the movement direction - upstream of the outer nozzle ring, is covered with exchangeably attached hollow half-shells (36, 36a, 36'), which form a cylindrical external face with a diameter D37 and in that a narrow annular gap with a gap width a is formed between the cylindrical external face and the internal profiling with the smallest internal diameter D39. -- which has a nozzle support body (33, 33') with an external diameter D33 or D33' with at least one channel (17, 17') for plastic melt, -- which has a nozzle (19, 19') with a diameter D19, which is connected by means of a channel end portion widening toward the nozzle (19, 19') to the channel (17, 17'), -- which has an inner nozzle ring (29, 29') and an outer nozzle ring (30, 30'), which between them limit the channel end portion and which are fastened to the nozzle support body (33, 33'),