A radiant tube assembly (12) has at least one tubular structure (14, 16, 22, or 24), and a heat source (30), with a thermal protective layer (18) is on at least one side, interior or exterior (17 or 15), thereof. An outer tubular structure (16) may be present. A protective layer (18) may be disposed on the outer tubular structure's (16) interior and/or exterior sides (17 and/or 15). A shield (26), having two sides (25 and 27) and a thermal protective layer (18) may be disposed along an exterior or interior side (27 or 25).