Corrosion behavior of aluminum alloy in sulfur-associated petrochemical equipment H2S environment

This experimental study focuses on the corrosion behavior of aluminum alloys in hydrogen sulfide (H2S) gas and liquid phases. The corrosion behaviors of 3A21, 6061, and 6063 aluminum alloys are investigated via scanning electron microscopy, energy dispersive spectroscopy, and thermogravimetry-differential scanning calorimetry. The results show that the corrosion rates of the three types of aluminum alloys increase with temperature, and the slope of the corrosion rate curve decreases gradually after reaching a certain temperature. At 75 °C, the corrosion rate reached 0.0675 mm/a, 0.0881 mm/a and 0.0613 mm/a in the gas phase, respectively. The corrosion products show white-yellow-gray irregular pits and a honeycomb-like morphology, and the main components are aluminum hydroxide, alumina, and aluminum sulfide. In particular, the 6061 aluminum alloy presents the most severe corrosion in H2S gas. Compared with the H2S gas phase, the corrosion rate in the liquid phase is higher. Additionally, the irregular pitting and honeycomb-like morphologies are more evident. Corrosion becomes more significant as temperature increases. Although the corrosion products in the two phases are composed of the same components, the content in the liquid phase is higher. The heat absorption and mass loss of the corrosion products present the same regularity. This indicates that the corrosion of the H2S liquid phase on the aluminum alloy is more significant than that of the H2S gas phase.