Metal fabrication

Claim 1

IN A METHOD OF MAKING SEAMLESS FINNED TUBING THE STEPS COMPRISING FORMING A BLANK BY SUPERIMPOSING INTO SUBSTANTIAL CONTIGUITY A PAIR OF COMPONENT METAL SHEETS, INTERPOSING A THIN LAYER OF STOP-WELD MATERIAL INTERFACIALLY SEPARABLE EXCEPT AT LATERALLY SPACED PORTIONS, JOINING SAID SHEETS AT SAID LATERAL SPACED PORTIONS, APPLYING SPACED POINTS OF FORGING PRESSURE CONCURRENTLY TO EACH OF THE OPPOSITE FACES OF SAID BLANK WITH THE POINTS OF SAID PRESSURE APLLIED ON ONE OF SAID FACES BEING DISPOSED IN OFFSET RELATIONSHIP TO THE POINTS OF PRESSURE APPLIED TO THE OTHER OF SAID FACES, SAID APPLICATION OF PRESSURE BEING SUFFICIENT TO FORGE ON ECACH OF SAID FACES INTERMEDIATE EACH OF SAID POINTS EXTERNALLY EXTENDING PROJECTIONS WITH SAID PRESSURE INDUCING SUFFICIENT INTERNAL FLOW OF METAL IN SAID BLANK TO DEFORM THE INTERFACE OF SAID SHEETS TO FORM OFFSET INTERNAL PROJECTIONS ON THE ADJACENT FACES OF SAID SHEETS IN INTERMESHED RELATIONSHIP WITH EACH OTHER WITH THE INTERNAL PROJECTION ON ONE OF SAID SHEETS BEING IN OFFSET RELATIONSHIP WITH THE EXTERNAL PROJECTION ON SAID ONE SHEET AND SAID EXTERNAL PROJECTIONS ON ONE OF SAID FACES BEING IN OFFSET RELATIONSHIP WITH THE EXTERNAL PROJECTIONS ON THE OTHER OF SAID FACES, SAID SUPERIMPOSITION BEING MAINTAINED BY JOINDER OF SAID SHEETS AT SAID LATERAL SPACED PORTIONS.