Patent ID: 6913730

Claim:
Refractory mono-block stopper of substantially cylindrical configuration comprising an upper end, a lower end and an inner surface defining an axial bore extending from the upper end towards the lower end, an attachment provided in the axial bore at a distance from the upper end, the stopper being divided into a) a first portion extending from the upper end towards the lower end, the first portion having a length longer than the distance and having a first cross-section; b) a second portion extending from the first portion towards the lower end, the second portion comprising a second cross-section, where an average of the second cross-section is smaller than the first section; and c) a third portion extending from the second portion and comprising a stopper nose ending at the lower end of the stopper, the third portion having a third cross-section adjacent to the second portion that is larger than the second cross-section adjacent to the third portion.