PURPOSE: To eliminate risk of molten breakthrough due to cracking of a inner pipe by determining the closing stroke of an outer pipe such that the lower end thereof is mounted on an annular plane extending around the inner pipe without causing any leakage.
CONSTITUTION: Opening 5 of an inner pipe 2 is aligned with the opening 7 of an outer pipe 3 at open position. Molten flow from a vessel is changed by turning or moving the outer pipe 3. When emergency shutoff is required in order to prevent molten breakthrough, the outer pipe 3 is moved quickly in the direction of longitudinal axis until the edge 8 thereof abuts against an annular plane 10. The outer pipe 3 does not abut against the upper edge of the inner pipe 2. Since the edge 8 of the outer pipe is mounted on the annular plane, a hermetically sealed region is formed additionally. The outer pipe 3 covers the opening 5 of the inner pipe 2 and surrounds the entire length thereof projecting into a vessel. This structure prevents flow-out of molten even if the inner pipe 2 is damaged or cracked.
ERUNSUTO RIYUURUZEN
ANDOREEASU SHIYUURERU
