A.o. Smith Corporation

Edwin C Pow

James L Chevalier

James S Stubbe

A cathodically protected water heater which eliminates the need of a conventional anode rod. The water heater tank includes a cylindrical shell enclosed by upper and lower heads and a flue which is mounted within openings in the lower and upper heads. The outer surface of the flue as well as the upper surface of the lower head is coated with a metal anodic to steel, and the metal coating on the flue extends continuously from the lower head to a location above the upper head. The remainder of the inner surface of the heater is also coated with the anodic metal. The anodic metal is applied in a sufficient thickness at least at the junction of the lower end of the peripheral flange of the upper head and the shell to bridge and seal the crevice opening which typically exists between the free end of the upper head flange and the shell wall. The coating over the crevice hydraulically seals the exterior weld between the upper head and shell from water contained in the heater and provides a corrosion barrier and anodic surface to contained water. Where welds are provided through the metal coating at the upper head/flue and shell/lower head junctions, the metal coating flows about the welds to also hydraulically seal them off from contained water and provide a corrosion barrier and anodic surface to contained water.

Cathodically protected water heater

A cathodically protected water heater which eliminates the need of a conventional anode rod. The water heater tank includes a cylindrical shell enclosed by upper and lower heads, and a gas burner is located beneath the lower head. The waste products of combustion are discharged upwardly through the tank via a flue which is mounted within openings in the lower and upper heads. The outer surface of the flue as well as the upper surface of the lower head is coated with a metal anodic to steel, and the metal coating on the flue extends continuously from the lower head to a location about the upper head. The inner surface of the shell and the upper head are coated with a corrosion resistant coating, such as glass or metal anodic to steel as well, and the upper edge of the flange in the upper head bordering the opening is welded directly through the metal coating to the flue while the outer periphery of the lower head is welded to the lower edge of the shell. When a metal anodic to steel is coated onto the interior surface of the upper head and shell, it is applied in a sufficient thickness at least at the junction of the lower end of the peripheral flange of the upper head and the shell to bridge and seal the crevice opening which typically exists between the free end of the upper head flange and the shell wall. The metal coating over the upper head/shell crevice hydraulically seals the exterior weld between the upper head and shell from water contained in the heater and provides a corrosion barrier and anodic surface to contained water. Where welds are provided through the metal coating at the upper head/flue junction and shell/lower head junction, the metal coating flows about the weld and contacts the abutting corrosion resistant material to also hydraulically seal off those welds from contained water and provide a corrosion barrier and anodic surface to contained water. As the anodic metal coating is located centrally in the tank and extends the full height of the tank, more effective cathodic protection is achieved.

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Menomonee Falls, WI, United States of America

Edwin C Pow