Abstract: An impervious refractory plug clad in a metal canister, adapted for insertable registration in an opening in a refractory block of a ladle, is provided with an array of narrow peripheral passages formed in the plug's lateral surface to distribute a flow of inert gas into molten metal within the ladle. The passages are defined by slots preformed in the plug's peripheral surface and the inner surface of the tightly fitted canister. An elongated metallic strip is preferably located in each passage to induce solidification of any molten metal which tends to flow against the output ends of the passages.