BOF taphole(A BOF taphole is replaced when the inner diameter of the existing taphole sleeve becomes excessively large and tap time becomes short. 当氧气顶吹转炉的出钢口袖砖内径变得过大、出钢时间变短时，其出钢口就应更换。)
wall thickness at taphole(Hearth diameter refers to the diameter of the circle determined by the inside face of the refractory lining of the hearth, excluding any increase in the wall thickness at the tapholes. 炉缸直径指的是炉缸耐火衬内面圆的直径，铁口处炉墙厚度的增加部分不含其内。)
