Abstract: The invention relates to furnaces equipped with an insulating inner lining formed from fibers. The object of the invention is to reduce the thermal discontinuities at the level of the orifice tube of the burner. For this purpose, the orifice tube consists of blankets of fibers arranged radially round the burner and compressed to a greater extent in the inner part facing the axis of the burner than in the outer part. The density in the inner part preferably reaches 300 to 400 kg/m.sup.3.

Abstract: A ceramic fiber modular assembly for lining walls of furnaces is disclosed. The modular assembly comprises stacked strips of ceramic fibers and a refractory steel anchoring system. The anchoring system comprises two platelike lateral member which protrude parallel to the ceramic fiber strips with teeth projecting from both sides by the lateral members. One of the lateral member is rigidly fixed to a platelike central member and the other admits of translation relative thereto. An aperture in the central member permits securement to the wall of the furnace. During manufacture the modular assembly is partially wrapped in packaging material tied with straps, applying compression to the fibers. The packaging material is removed prior to installation of the modular assembly. When installed tight fitting contiguous modular assemblies exert compression on the fibers.