METHOD OF MANUFACTURING PIPES WITH SPIRAL RIBS OUT OF CHEMICALLY ACTIVE METALS AND ALLOYS Russian patent published in 2016 - IPC B21C37/20 

FIELD: heating.

SUBSTANCE: method includes spinning of a pipe with external longitudinal ribs during its longitudinal movement upon the pipe local heating, inert gas supply on the internal and on the external surfaces of the pipe with its cooling. The inert gas supply is started prior to local heating switching on, on the external surface of the pipe the inert gas is supplied in the pipe local heating zone and on the pipe section leaving this zone, the pipe local heating is performed to a specified temperature, wherein the pipe is cooled to the temperature not exceeding the temperature of formation of an oxide layer dissoluble by acid etching.

EFFECT: manufacturing of pipes with a permanent pitch and required surface quality without the use of alkali etching processes.

4 cl, 2 dwg, 2 ex