An apparatus for processing a molten material comprising: a metallic vessel comprising a wall, the metallic vessel arranged to convey the molten material; and at least one flange attached to the metallic vessel and configured to deliver an electric current to the vessel wall, the at least one flange comprising: a first ring extending completely around the metallic vessel in a closed loop, the first ring comprising a first portion including a first thickness and a second portion including a second thickness different from the first thickness, wherein a radial line extending from and perpendicular to a centerline of the metallic vessel in a plane of the flange crosses a width of both the first portion and the second portion, the first portion extending around the metallic vessel by an angular extent greater than 180 degrees relative to a longitudinal axis of the metallic vessel, the second portion extending around the metallic vessel by an angular extent greater than 180 degrees relative to the longitudinal axis of the metallic vessel, and neither the first portion nor the second portion extends completely around the metallic vessel. an outermost ring, wherein a thickness of the outermost ring varies as a function of angular position about the metallic vessel; and an electrode attached to the outermost ring, and a portion of the outermost ring adjacent the electrode is thicker than a portion of the outermost ring opposite the electrode. a metallic vessel comprising a wall, the metallic vessel arranged to convey the molten material; and at least one flange attached to the metallic vessel and configured to deliver an electric current to the vessel wall, the at least one flange comprising: a first ring extending completely around the metallic vessel in a closed loop, the first ring comprising a first portion including a first thickness and a second portion including a second thickness different from the first thickness, wherein a radial line extending from and perpendicular to a centerline of the metallic vessel in a plane of the flange crosses a width of both the first portion and the second portion, the first portion extending around the metallic vessel by an angular extent greater than 180 degrees relative to a longitudinal axis of the metallic vessel, the second portion extending around the metallic vessel by an angular extent greater than 180 degrees relative to the longitudinal axis of the metallic vessel, and neither the first portion nor the second portion extends completely around the metallic vessel. an outermost ring, wherein a thickness of the outermost ring varies as a function of angular position about the metallic vessel; and an electrode attached to the outermost ring, and a portion of the outermost ring adjacent the electrode is thicker than a portion of the outermost ring opposite the electrode. a first ring extending completely around the metallic vessel in a closed loop, the first ring comprising a first portion including a first thickness and a second portion including a second thickness different from the first thickness, wherein a radial line extending from and perpendicular to a centerline of the metallic vessel in a plane of the flange crosses a width of both the first portion and the second portion, the first portion extending around the metallic vessel by an angular extent greater than 180 degrees relative to a longitudinal axis of the metallic vessel, the second portion extending around the metallic vessel by an angular extent greater than 180 degrees relative to the longitudinal axis of the metallic vessel, and neither the first portion nor the second portion extends completely around the metallic vessel. an outermost ring, wherein a thickness of the outermost ring varies as a function of angular position about the metallic vessel; and an electrode attached to the outermost ring, and a portion of the outermost ring adjacent the electrode is thicker than a portion of the outermost ring opposite the electrode.