An expansion seal assembly for sealingly connecting first and second conduits which experience relative thermal expansion and contraction due to the flow of hot material through the conduits. The conduits each comprise a plurality of hollow tubes integral therewith, a portion of the second conduit telescopically overlapping a portion of the first conduit in a spaced relationship to permit the relative axial and lateral movements of the conduits. A fluid circulatory system is provided for passing a heat transfer fluid through the tubes to remove heat from the material passing within the conduits. First and second corrugated plates extend outwardly from the first and second conduits, respectively and are sealed with a composite fabric belt dimensioned to permit the relative movements. Alternatively, a first plate extends outwardly from the second conduit and the second plate is rigidly secured to and extends between the first conduit and the first plate having corrugations to permit the relative movements. Finally, thermal insulation is disposed between the plates exterior to the conduits to inhibit heat flow.