Application of HVOF thermal spraying to solve corrosion problems in the petroleum industry—an industrial note

Abstract

Commercially available thermal spray coatings have seen limited use in corrosion applications due to the presence of interconnecting porosity and oxide networks. Use of vacuum chambers or post-treatments can eliminate most defects, but these methods are costly and impractical on a large scale. The ability to produce such high-quality coatings by thermal spraying in atmosphere and without post-treatments would offer important advantages as a means of building and repairing process equipment. A modified HVOF process using unique inert gas shrouding has resulted in highly dense, low-oxide coatings of metallic alloys. These coatings were extensively evaluated for severe petroleum industry corrosion applications in laboratory and plant testing, with exposures as long as 5 years. Coatings of corrosion-resistant alloys, such as type 316L stainless steel and Hastelloy C-276, were shown to act as true corrosion barriers. They were protective to underlying base metals in severe environments and in most cases exhibited corrosion resistance comparable to the corresponding wrought alloy. The process was scaled up for on-site plant use and successfully applied to numerous corrosion problems in petroleum industry plant equipment. Significant technical and economic advantages can be realized by use of thermal spray coatings to solve plant equipment problems.