Abstract: A slag blower wall box has a first seal incorporated therein engagable with a slag blower or lance tube extending therethrough and a second seal fixed to the wall box and engagable with the slag blower and with a flange on the wall box. The second seal which is split diametrically is held together by a spring and is held against the outer flange of the wall box by a thrust ring. The second seal floats or is movable radially of the wall box so as to provide a seal with the wall box flange and at the same time to provide a seal around the periphery of the tubular slag blower.