Composite electrode with non-consumable upper section

Claim 1

A composite electrode for electric arc furnaces, comprising: an elongated metallic portion having a top end and a bottom end, the portion including an outer wall of substantially uniform section along its length, the outer wall having an outside surface and an inside surface, an inner wall spaced inwardly from the outer wall to define a passage of annular section, conduit means longitudinally within said metallic portion and communicating with the bottom of said passage to allow cooling liquid to move within said portion along a path which brings cooling liquid into intimate contact with substantially all of the inside surface of said outer wall, an elongated consumable portion having a top end and a bottom end, and connector means for joining the top end of the consumable portion to the bottom end of the metallic portion, the said connector means including a metallic double-male threaded nipple, and a female recess in the bottom end of said elongated metallic portion, said female recess opening through to the interior of the metallic portion, the threaded nipple being hollow with one end open and the other end closed, and being threaded into said female recess with the open end upward so that the interior of the nipple communicates with the interior of the metallic portion; and in which said conduit means is a central pipe extending axially down the metallic portion and into the interior of the threaded nipple.