Hot top refractory and/or exothermic unit

Claim 1

A HOT TOP STRUCTURE COMPRISING A HOT TOP CASING HAVING A CENTRAL OPENING THERETHROUGH, A REFRACTORY LINING IN SAID CASING, A PANEL INSERT UNIT FOR PROVIDING A PROTECTIVE HEAT AND MECHANICAL DAMAGE BARRIER BETWEEN A MASS OF METAL IN THE HOT TOP AND THE REFRACTORY LINING IN THE HOT TOP CASING, SAID PANEL INSERT UNIT INCLUDING A PLURALITY OF HEAT-COLLAPSIBLE REFRACTORY INSERT PANELS HAVING FRONT SIDES DEFINING ADJACENT WALL PORTIONS OF THE OPENING THROUGH SAID CASING AND BACK SIDES DISPOSED SO AS TO FACE SAID REFRACTORY LINING, SAID INSERT PANELS BEING OF A REFRACTORY MATERIAL BONDED BY A HEAT-DESTRUCTIBLE BINDER AND RETARDING HEAT TRANSMISSION TO THE INSULATING REFRACTORY LINING OF THE CASING, FLEXIBLE MATERIAL HINGEDLY INTERCONNECTING SAID INSERT PANELS FOR RELATIVE MOVEMENT FROM RELATIVE POSITIONS WHEREIN THE PANELS ARE DISPOSED IN SIDEBY-SIDE RELATIONSHIP WITH ADJACENT EDGE SURFACES OF THE PANELS FACING EACH OTHER TO ANGULARLY RELATED POSITIONS WHEREIN THE PANELS ARE DISPOSED WITH THE ADJACENT EDGE SURFACES THEREOF IN AREA CONTACT AND FORMING THE INSERT UNIT.