[en] Basis of the R and D program of the Project Nuclear Process heat (PNP) was defined according to the significant operating conditions for the prototype plant for nuclear process heat. Thermal insulation is of major significance in the PNP Project. The ideal solution is the internal insulation loaded by the gas flow which does not require an additional liner. hence the methods applied in conventional technology cannot be transferred directly to nuclear technology. The results obtained from this research can be applied directly to the steam reformer and can be used for hot gas valves and hot gas ducts. Manufacturing process, tests of materials and components and obtained results are described