Process for the production of steel pipes strongly alloyed

A method for manufacturing a highly alloyed pipe, comprising: forming by hot working, a pipe with a high-alloy material, which has unacomposicion chemistry is expressed as a percentage of mass, C : 0.03% or less, Si: 1.0% or less, Mn: 0.5 to 0.75%, P: 0.03% or less, S: 0.03% or less, Ni: more than 22% and no more than 40%, Cr: from 20 to 30%, Mo: not less than 0.1% and less than 4.0%, Cu: from un0 , 1 to 4.0%; Al: 0.001 to 0.30%, N: from 0.06 to 0.30%, and O: 0.010% age or younger, optionally containing one or more kinds of Ca: 0.01% or less , Mg: 0.01% or less, rare earth yelementos: 0.2% or less, and the balance being Fe and impurities, and satisfying the formula (1) to the arithmetic product of the contents of N for the content of O; and then effecting worked friopara shape pipe high alloy, wherein the final cold working process is carried out under conditions such that the ratio of RDEN work area reduction, satisfies the formula (2): N x O <= 0.001 ... (1) 15 <= Rd (%) <= 370 x (C + N) ... (2) where N, O and C are the contents (percent by mass) of the respective elements, and Rd is the working ratiode (in%) in the reduction of area.