Abstract: Apparatus including a nozzle or refractory pipe lance for the secondary refinement of a bath of molten metal by the injection of a gas under pressure, having one or more low porosity-high density refractory plugs which contain apertures of constant diameter, at least those about the perimeter of the plugs having an arcuate shape. For the manufacture of a pipe lance, the lower porosity-high density refractory plugs are attached to a central tube. The low porosity-high density of the refractory plugs provides a corrosion resistance to any change in the diameter of the gas nozzles and thereby produces a controlled high velocity radial burst gas stream. Generating the radial burst of small bubbles and maintaining the gas velocity of a high constant rate reduces erosion of the refractory material around the tope of the apparatus and extends the lifetime of the pipe lance or nozzle.

Abstract: A high temperature refractory brick wall is repaired by removing and replacing damaged brick while the wall is maintained at a temperature below normal operating temperature but sufficiently high to avoid damage from contraction resulting from cooling. New brick having a coefficient of thermal expansion compatible with the heated wall are used to avoid cracking of the wall due to expansion during heat-up. Workers wearing protective clothing, preferably incorporating a circulating fluid cooling system, remove the damaged brick and install new brick in their place in walls having surface temperatures of about 500.degree. F. or higher and internal temperatures substantially above 500.degree. F., preferably at least about 1500.degree. F.