Hot isostatic pressure furnace with enhanced insulation properties

In a cylindrical, elongated furnace for the treatment of materials at high temperatures and in a gaseous atmosphere under high pressure, said furnace comprising a cylindrical pressure chamber which includes a high-pressure cylinder in which is located a furnace space;

• end closures projecting into the opposite ends of the high-pressure cylinder;
• force-absorbing members for absorbing axial forces exerted on the end closures;
• and an insulating mantle positioned between the high-pressure cylinder and the internally-located furnace space, said insulating mantle including an innermost concentric tube nearest said furnace space, at least one outermore concentric tube enclosing said innermost concentric tube, an insulating material located between said innermost concentric tube and the nearest said outermore concentric tube, an insulating lid and an insulating bottom, the improvement wherein the said innermost concentric tube includes a number of clamping rings on the inner side thereof facing said furnace space and wherein at least one layer of felt-like insulating material is positioned against said inner side of said innermost concentric tube by said clamping rings.