FIELD: furnaces. SUBSTANCE: heat insulating casing consists of square modules arranged in series without space and secured to the wall. The modules consists of cloths made of fiber mats assembled together and packed under the action of preliminary pressure in the direction parallel to the tool. The fiber mat modules that abuts against each other are assembled together to form a flexible joint over the sides free from the preliminary loading with the use of at least one threadlike, temperature resistant joining means that passes from the outer surface of heat insulating casing to the wall. The module for heat insulating casing has cloths made of fiber material that are preliminary loaded and assembled to form a stack. At least two cloths are interconnected by threads. EFFECT: improved heat insulation. 4 cl, 13 dwg
