METHOD FOR PRODUCING IN TUBE ROLLING PLANTS WITH PILGER MILLS SEAMLESS HOT-DEFORMED LARGE- AND MEAN-DIAMETER TUBES FOR STEAM BOILERS, STEAM CONDUITS AND MANIFOLDS OF PLANTS WITH HIGH AND SUPER-CRITICAL PARAMETERS OF STEAM FROM ELECTROSLAG REFINING INGOTS OR CONTINUOUSLY CAST BILLETS Russian patent published in 2008 - IPC B21B19/04 

FIELD: production of seamless hot-deformed mean- and large-diameter tubes for steam boilers, steam conduits and manifolds of plants with high super-critical parameters of steam from electroslag refining ingots or continuous cast billets, possibly in tube rolling plants with pilger mills including also helical rolling mills.

SUBSTANCE: method comprises steps of melting ingots by electroslag refining and billets in continuous casting plants from steel of given kinds; further turning and drilling in them central opening; heating ingots and billets till yielding temperature depending upon kind of steel; piercing ingots or billets in skew rolling mill at deforming metal with diameter fit in range 8 - 16%; rolling in pilger mills with elongation values depending upon diameter and wall thickness; piercing ingots of electroslag refining and continuously cast billets in skew rolling mill with diameter fit depending upon steel kind and total elongation value at conversion electroslag refining ingot - tube or continuously cast billet - tube. Values of diameter fit of said ingots and billets in skew rolling mills are determined with use of given expressions Δ_iesr = K_i esr/μ_iΣ and Δ_i ccb =K_i ccb/μ_iΣ where Δ_i esr - diameter fit values at piercing in skew rolling mills electroslag refining ingots of i- kind of steel, %; Δ_i ccb - diameter fit values at piercing in skew rolling mills continuous cast billets of i-kind of steel, %; μ_iΣ = μ_psμ_tr where μ_iΣ - total elongation factor at rolling tubes of j-size; μ_ps - elongation factor at piercing sleeves for rolling tubes of j-size; μ_tr - elongation factor at rolling tubes of j-size in pilger mill; K_i esr -coefficient taking into account Diameter fit value at piercing sleeve of electroslag refining ingots of i-kind steel,%; K_i ccb - coefficient taking into account diameter fit value at piercing sleeves of continuous cast billets of i-kind steel,%. At rolling tubes of electroslag refining ingots of two given kinds of steel coefficient K esr is set equal to 40 while at rolling ingots of other given kinds of steel said coefficient is set to be equal to 0.9Kesr, 0.8Kesr, 0.7 Kesr and 0.6 Kesr respectively. At rolling tubes of continuously cast billets of said two kinds of steel coefficient Kccb is equal to 35 and at rolling tubes of other given kinds of steel it is equal respectively to 0.9Kccb, 0.85Kccb, 0.8Kccb, 0.75Kccb.

EFFECT: lowered metal consumption factor due to reduced number of tubes rejected by sliver, decreased cost of boiler tubes.

3 cl, 2 tbl