Electroless Nickel Plating Applications to Enhance Corrosion Protection, Equipment Reliability and Cost Effectiveness in Centrifugal Compressors

Abstract

Abstract Coating technology is an efficient and cost-effective solution to protect equipment from aggressive environments. Corrosion and particles erosion are the most important material degradation phenomena in process centrifugal compressors leading to loss of performances, increase of vibrations and potentially safety concerns, especially for compressors operating with toxic gases. Among the today available coatings, Electroless Nickel High-Phosphorous plating (ENP) is one of the most robust and reliable solution. In this paper, the ENP corrosion resistance in continuous wet harsh environments was investigated through customized autoclave tests. The campaign assessed the corrosion resistance of both proprietary standard ENP (10-13%P) and proprietary modified-ENP, respectively with PTFE and SiC particles, ("doped-ENP"), in a single (SL) and double-layers (DL) fashion. All DL-ENP samples (standard and doped), showed an excellent corrosion resistance in harsh environment up to 10 bar H2S, 150 bar CO2 and 100000 ppm of chlorides. Among the SL samples, standard ENP showed the best results compared to the doped options. The samples characterization highlighted that the standard ENP is an effective barrier against the ingress of the corrosive gas mixture. On the other hand, the "doped" SL samples showed a reduced corrosion resistance. This reduction seems to be caused by the disruption of the ENP dense and amorphous film, resultant from the dopant particles inclusion. In this same study, the electroless in situ repair of locally damaged ENP was also investigated. As a result of the restoration process fine-tuning, a seamless ENP patch repair was obtained, thus ensuring the complete refurbishment of the original coating.