Refractory plate formed with expansion joints

In a refractory plate assembly, particularly for use as a movable refractory plate in a sliding closure unit for regulating the discharge of molten metal from a metallurgical vessel, said unit being of the type including a refractory plate having therethrough at least one discharge opening and a sheath tightly fitted around the periphery of said plate, the improvement of means for reducing the formation in said plate of cracks resulting from thermal stress during use of said assembly, said means comprising:

• said plate being formed of plural separate plate portions separated along respective confronting planar surfaces extending outwardly from said discharge opening, each said planar surface extending from said discharge opening to said periphery;
• said planar surfaces being separated by compressible refractory packing material, thereby forming expansion joints, said refractory packing material being compressible at all operating temperatures of said refractory plate assembly;
• said sheath compressing said packing material and maintaining said expansion joints sealed during expansion of said plate portions during operation of said refractory plate assembly;
• and whereby said expansion joints are formed at positions where thermal stress cracks would normally occur if said plate were of unitary construction.