Abstract: A lining for a furnace chamber which is at least approximately round in cross-section is divided into at least two layers in a radial direction and into at least two portions in an axial direction. A gas seal is disposed between the lining portions, the gas seal being in the form of a foil as of metal and being divided in a radial direction into at least two portions releasably connected together in such a manner as to permit the inner portion to be removed in an axial direction. The gas seal can therefore be composed of individual seal portions, in a radial direction, and can be fitted separately.