Disclosed is an apparatus for conditioning molten glass. The apparatus includes a connecting tube assembly having a conduit for conveying the molten glass, the conduit (108) including at least two flanges (112, 114) and a sealing member (118) disposed between the at least two flanges (112, 114) around an outer peripheral region of the flanges, thereby forming an enclosed volume between an outer wall (110) of the conduit, the at least two flanges (112, 114) and the sealing member (118). An atmosphere within the volume may be controlled such that a predetermined partial pressure of hydrogen or a predetermined partial pressure of oxygen may be maintained within the volume. A current may be established between the at least two flanges to heat the conduit.