Multiple layer thermal insulation device

A thermal insulating device adapted to be affixed to a surface of a furnace or like structure and having a hot face and a cold face, said cold face being adjacent to said surface and said hot face being exposed to the highest service temperature in the furnace or like structure when said insulating device is in use, said insulating device comprising:

• (a) a first insulation layer comprised of a first serpentine folded fibrous insulating blanket defining a first plurality of inner and outer folds, said first inner folds being nearest said cold face and said first outer folds being nearest said hot faces;
• (b) attachment means secured to said first insulation layer and adapted to affix said device to said surface of said furnace or like structure, said first insulation layer thereby providing the cold face of said device;
• (c) a second insulation layer comprised of a second serpentine folded fibrous insulating blanket defining a second plurality of inner and outer folds, said second inner folds being nearest the cold face and said second outer folds being nearest said hot face, some of the inner folds of said second insulation layer abutting the outer folds of said first insulation layer, said second insulation layer thereby providing the hot face of said device;
• and
• (d) at least one of the inner folds of said second serpentine folded fibrous insulating blanket extending from said second insulation layer into said first insulation layer and being disposed within one of the inner folds of said first serpentine folded thermal insulating blanket to a depth sufficient to retain said first insulation layer and said second insulation layer in abutting relationship without the need for additional mechanical connections therebetween.