METHOD OF PRECISION PIPE MANUFACTURE Russian patent published in 1996 - IPC

FIELD: pipes production by welding, thick wall pipes production in particular. SUBSTANCE: method provides for manufacture of welded straight seam pipe blank of diameter: D2md

/D_pr(2-t_md/t_pr)≅ D_w≅ t_md/t_pr•D2md/D_pr, with Dw, Dmd, Dpr - diameter correspondingly of welded pipe blank, pipe blank diameter after mandrelless deformation and pipe blank diameter after precision pipe; t md and t pr wall thickness correspondingly of pipe blank after mandrelless deformation and after precision pipe. Processing of produced pipe blank before walls difference operation: P_wtd≅ P_pr(D_md/D_pr), with Pwtd and Ppr - pipe walls thickness difference correspondingly before mandrelless deformation and precision pipe, before realization of mandrelless deformation with increasing thickness of pipe blank wall and cold drawing on mandrel. Method allows to produce welded pipes with wall thickness up to 6 - 7 mm and walls thickness difference of less than 0.2 mm. EFFECT: improved process of welded pipes production. 1 tbl