Finned tubing manufacture

Claim 1

THE METHOD OF MAKING A FINNED METAL HEAT EXCHANGER TUBE WHICH INCLUDES THE STEPS OF INITIALLY FORMING GROOVE MEANS IN THE OUTER SURFACE OF A METAL TUBE WITH SAID GROOVE MEANS EXTENDING INWARDLY OF THE TUBE METAL FROM SAID TUBE OUTER SURFACE AND OPENING OUTWARDLY AT SAID TUBE OUTER SURFACE AND WITH CERTAIN PORTIONS OF THE TUBE METAL OUTWARDLY OVERLYING PARTS OF SAID GROOVE MEANS, SAID TUBE HAVING SUFFICIENT RADIAL STRENGTH FOR WITHSTANDING SUBSEQUENT RADIAL PRESSURE FORMING OPERATIONS; THEN AT LEAST PARTIALLY TELESCOPICALLY ENCASING THE TUBE WITH A METAL SHEATH WITH SAID SHEATH ABUTTING THE TUBE OUTER SURFACE AND HAVING HELICALLY EXTENDING FINS FORMED THEREON AND EXTENDING RADIALLY THEREFROM; LOCATING SHEATH FIN MEANS FREE FROM OVERLYING THE TUBE GROOVE MEANS WITH SAID SHEATH SPANNING THE GROOVE MEANS BETWEEN THE FIN MEANS ALONG THE TUBE OUTER SURFACE; AND THEN RADIAL PRESSURE FORMING, DISPLACING AND EMBEDDING THE SHEATH METAL BETWEEN THE FIN MEANS IN THE ZONE OF THE GROOVE MEANS INWARDLY INTO THE GROOVE MEANS WITH PARTS OF THE SHEATH METAL AT LEAST PARTIALLY INWARDLY UNDERLYING SAID TUBE METAL CERTAIN PORTIONS SO THAT THE SHEATH METAL PARTS ARE INTERENGAGED WITH SAID TUBE METAL CERTAIN PORTIONS WITHIN THE GROOVE MEANS, THEREBY PROVIDING AN INTERLOCKING METAL-TO-METAL HEAT TRANSFER BOND BETWEEN THE TUBE AND SHEATH METALS RESISTING SEPARATION DESPITE SUBJECTION TO SEVERE TEMPERATURE GRADIENTS.

Claim 2

THE METHOD OF MAKING A FINNED METAL HEAT EXCHANGER TUBE WHICH INCLUDES THE STEPS OF INITIALLY FORMING GROOVE MEANS IN THE OUTER SURFACE OF A METAL TUBE WITH SAID GROOVE MEANS EXTENDING INWARDLY OF THE TUBE METAL FROM SAID TUBE OUTER SURFACE AND OPENING OUTWARDLY AT SAID TUBE OUTER SURFACE AND WITH CERTAIN PORTIONS OF THE TUBE METAL OUTWARDLY OVERLYING PARTS OF SAID GROOVE MEANS, SAID TUBE HAVING SUFFICIENT RADIAL STRENGTH FOR WITHSTANDING SUBSEQUENT RADIAL PRESSURE FORMING OPERATIONS; THEN AT LEAST PARTIALLY TELESCOPICALLY ENCASING THE TUBE WITH A METAL SHEATH WITH SAID SHEATH ABUTTING THE TUBE OUTER SURFACE AND HAVING HELICALLY EXTENDING FINS FORMED THEREON AND EXTENDING RADIALLY THEREFROM; LOCATING SHEATH FIN MEANS FREE FROM OVERLYING THE TUBE GROOVE MEANS WITH SAID SHEATH SPANNING THE GROOVE MEANS BETWEEN THE FIN MEANS ALONG THE TUBE OUTER SURFACE; AND THEN RADIAL PRESSURE FORMING, DISPLACING AND EMBEDDING THE SHEATH METAL BETWEEN THE FIN MEANS IN THE ZONE OF THE GROOVE MEANS INWARDLY INTO THE GROOVE MEANS WITH PARTS OF THE SHEATH METAL AT LEAST PARTIALLY INWARDLY UNDERLYING SAID TUBE METAL CERTAIN PORTIONS SO THAT THE SHEATH METAL PARTS ARE INTERENGAGED WITH SAID TUBE METAL CERTAIN PORTIONS WITHIN THE GROOVE MEANS, THEREBY PROVIDING AN INTERLOCKING METAL-TO-METAL HEAT TRANSFER BOND BETWEEN THE TUBE AND SHEATH METALS RESISTING SEPARATION DESPITE SUBJECTION TO SEVERE TEMPERATURE GRADIENTS.