An apparatus for mounting a gas washing sink in a centered manner within an opening through a perforated brick in a wall of a metallurgical vessel and for removing the sink from the perforated brick includes a support assembly to be fixedly mounted on the exterior of the wall of the metallurgical vessel adjacent the opening in the perforated brick. A fastening assembly supports the sink and is mounted with respect to the support assembly for movement relative thereto between an operating position, whereat the sink is pressed into the opening throgh the perforated brick in a centered manner, and a maintenance position, whereat the sink is withdrawn from the opening through the perforated brick. Structure moves the fastening assembly relative to the support assembly to the operating position. A withdrawal apparatus moves the fastening assembly relative to the support assembly from the operating position to the maintenance position.