... used in big steel mill for delivering liquid steel specially from blast furnace —MAXDRILL Tap hole Drill Bit (1)Diameter:38mm-70mm.( ... 2) shape, carbide 3-blade type , steel cross bit , carbide cross bit ,button bit andetc(3 ... . MAXDRILL is offering tap hole drilling tools for blast furnace, including tap hole drill rods and tap hole drill bits, according to ...