Effect of H2S on Coatings

Abstract

ABSTRACT Coatings are developed to provide appropriate property response to severe environmental conditions; e. g. heat, stress at temperatures extremes and chemicals. The influence of hydrogen sulfide on coatings and their protective functions for metal products was investigated in this work. Six selected primer and one powder topcoat system were applied and exposed to five natural gas mixtures with hydrogen sulfide content of 5%, 10%, 15%, 20%, 25% and 30% to evaluate the chemical and thermal stability of these materials under the follow-operating parameters: –Temperature: 120 °C–Pressure: 15 MPa–Decompression velocity: 6 sec.–Duration of test: 48 h As a result of exposure to hydrogen sulfide, embrittlement and discoloration of the coating was observed. A series of pigments like TiO2 and Fe2O3 formed sulfates as attacked by hydrogen Sulfide. With an increase in hydrogen sulfide content in gas mixtures, the embrittlement of the coating became more important. Only one system (CEV-236, PR-8008) among the tested species was found to be chemically and thermally stable. It is imperative to incorporate hydrogen sulfide scavenging components in coatings to increase chemical stability in sour gas field operations.