A furnace vessel is supported by way of a pair of trunnion pins rotatably mounted in bearings on pedestal structures. To allow vibrations set up in the vessel in the direction parallel to the common axis of the trunnion pins to be absorbed, the pedestal structures are pivotably mounted on fixed supports so as to be pivotable about a pair of parallel axes spaced from and normal to the common axis of the trunnion pins, and at least one of the structures has damping means associated therewith by which movement of the structure and hence of the vessel can be absorbed.