Patent ID: 7537723

Claim:
A thermal lance apparatus for unplugging a molten metal containing vessel's discharge port, said apparatus comprising: an elongated tubular housing having a hollow interior chamber and a top open end; a conduit communicating with the interior chamber of the housing for introducing pressurized oxygen into the housing, an axially displaceable tube disposed within the housing, and an axially displaceable thermal lance disposed within the tube and adapted to be projected upwardly when pressurized oxygen is introduced into the housing, the axially displaceable lance comprising: a low carbon steel sheath having an internal bore and a length dimension; a thin cylindrical rod that is roll-formed from low carbon steel sheet, the rod being sized for conforming fit in the bore of the sheath and having a length dimension that is longer than the length of the sheath; the rod being inserted into the bore of the sheath and allowed to move axially within the sheath under propulsion of the pressurized oxygen to allow the rod to be burned at a rate independent of the burn rate of the sheath.