BLAST FURNACE TUYERE AND METHOD FOR MAKING WELDED SEAM OF TUEYRE Russian patent published in 1997 - IPC

FIELD: metallurgy, namely repairing and manufacture of blast furnace tuyeres. SUBSTANCE: blast furnace tuyere includes mutually connected by welded joints mouth portion, flange, outer and inner housings. Welded seam joining outer housing of tuyere with its mouth portion includes on its outer face protective layer whose thickness is equal to 0.6-1.2 of thickness of wall of outer housing and whose width is equal to 1.5-3.0 of width of welded seam covering. Method for making protective layer includes steps of preparing surface, heating it up to 200-300 C, plasma fusing at electric current equal to (31-42)δ(A)(A), where δ - thickness of outer housing, mm. At process of plasma fusion tuyere is rotated by 65% of its diameter. Electric current is smoothly decreased in end period of plasma fusion by 10-20% of its initial value. Heating and fusion are performed at time period no more than two hours. EFFECT: enhanced reliability of welded seam. 3 cl, 1 dwg