Industrial oven wall construction

Claim 1

IN AN INDUSTRIAL OVEN WALL, THE COMBINATION COMPRISING AN INNER WALL, AN OUTER WALL SPACED FROM THE INNER WALL, AN INSULATING MATERIAL INTERPOSED BETWEEN THE INNER AND OUTER WALL, EACH SAID WALL COMPRISING PREFABRICATED PANELS OF SHEET METAL INCLUDING A CENTRAL PORTION HAVING LONGITUDINAL SIDE EDGES, A LONGITUDINALLY EXTENDING FLANGE BENT FROM AND EXTENDING ALONG ONE SIDE EDGE OF THE CENTRAL PORTION, AND A REVERSELY BENT PORTION BENT FROM AND EXTENDING ALONG THE OTHER SIDE EDGE OF THE CENTRAL PORTION INTO WHICH THE FLANGE OF THE ADJACENT PANEL EXTENDS TO DEFINE A JOINT, THE INTERENGAGING JOINTS OF THE INNER WALL HAVING A CONTINUOUS UNINTERRUPTED LONGITUDINAL CRIMP INTERMEDIATE THE BEND AND THE FREE LONGITUDINAL EDGE OF THE JOINT WHICH IS FORMED BY CONTINUOUSLY LONGITUDINALLY CRIMPING IN PLACE AFTER THE OUTER WALL IS ASSEMBLED TO COLD WORK THE INTERENGAGING FLANGE AND REVERSELY BENT PORTIONS AND THEREBY PROVIDE A VAPOR IMPERVIOUS SEAL AT THE JOINTS OF THE INNER WALL, SAID JOINTS OF THE OUTER WALL BEING UNCRIMPED TO PERMIT VAPOR TO PASS THERETHROUGH.