Abstract: A heat insulation system may protect surfaces along which a hot gas stream is conducted. The insulation may be several plies of slightly compressed ceramic fiber mats, separated by intermediate plates. Cover plates are attached to the hot side. The cover plates are mounted by holding bolts on the support structure carrying the insulation. The support structure may be the liner of a nuclear reactor pressure vessel. Thickness and size of the cover plates are optimized with regard to the stresses occurring at the edges of the holes provided for the holding bolts to ensure dimensional stability of the fiber mats and the functional capability of the metallic mounting system during a long period of time. Several sealing sleeves may be arranged on each holding bolt. In a first solution, some intermediate plates exhibit lug-shaped points stamped out of the plates on both sides in vertical areas of the heat insulation system. The lug-shaped points which transfer the forces of the fiber mats to the intermediate plates.