Corrosion resistant powder coated metal tube and process for making the same

This invention relates to a metal tube, and more particularly to a metal tube having a corrosion resistant powder coated outer surface. A corrosion resistant tube comprises a metal tube having an outer surface. A zinc layer is electrostatically bonded to the outer surface, wherein the zinc layer is selected from the group consisting of powdered zinc, powdered zinc nickel alloys, powdered zinc cobalt alloys, and powdered zinc aluminum alloys. One or more polymeric layers may be electrostatically bonded to the zinc layer, or to a surface treatment layer, wherein the polymeric layer(s) comprises powdered thermoplastic materials selected from the group consisting of powdered nylons, powdered fluoropolymers, powdered polyesters, and mixtures thereof. Optionally, the polymeric layer(s) may be electrostatically bonded directly to the outer surface. A process for producing corrosion resistant tubing may also contain the steps of electrostatically charging aerated particles of a powdered material in a fluidizing chamber and conveying grounded metal tubing through the charged particles, thereby uniformly coating the tubing outer surface, and heating the coated tubing.