Metallic pipe lined with glass subject to substantially no compressive stress and process for the manufacture thereof

Claim 1

A GLASS LINED METALLIC PIPE OF THE CHARACTER DESCRIBED COMPRISING A METALLIC PIPE, A GLASS PIPE POSITIONED INTERIORLY OF SAID METALLIC PIPE IN COAXIAL RELATIONSHIP THEREWITH AND AN INORGANIC HEAT RESISTANT BUFFER LAYER INTERPOSED BETWEEN THE INNER AND OUTER SURFACES OF THE METALLIC AND GLASS PIPES, RESPECTIVELY, THE METALLIC PIPE, BUFFER LAYER, AND GLASS PIPE BEING FUSED TO EACH OTHER AT SAID SURFACES WHEREBY A RELATIVELY LOW COMPRESSIVE STRESS IS IMPARTED TO THE GLASS PIPE BY THE METAL PIPE, THE BUFFER LAYER HAVING A LOWER FUSING POINT THAN THAT OF THE METALLIC AND GLASS PIPES AND INCLUDING AN OXIDE SELECTED FROM THE GROUP CONSISTING OF BORON OXIDE AND LEAD OXIDE.