Abstract: A porous plug assembly for use in a vessel containing molten metal, such as a melting furnace or a holding furnace, for introducing fluxing or other gases into the molten metal. The porous plug assembly includes a frustoconical porous refractory core member that is enclosed around its side and bottom by a non-porous refractory lining. Positioned about the outer surface of the non-porous refractory lining is a metallic outer liner, preferably made from inconel, which includes a ceramic anti-corrosion coating. A gas distribution pipe, which also can be made from inconel, extends upwardly through the bottom of the metallic outer liner, through the non-porous refractory lining, and into the interior of the core member for introducing a fluxing gas therein. Surrounding the intermediate, non-porous refractory lining and the metallic outer liner is a refractory nest block. The fluxing gas passes through the porous core member and exits at the top thereof to enter the molten metal melt.