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In this study, the corrosion behavior of X52 pipeline steel affected by H2O content in supercritical CO2 streams containing O2, H2S, SO2 and NO2 impurities was investigated by the weight loss test and surface characterization. The corrosion differences of the steel in impure supercritical CO2 streams containing different H2O contents were analyzed. The influence of the variation of H2O content on the corrosion mechanism of steel in the complex impurity-containing supercritical CO2 streams was discussed. The results show that the H2O content limit is 100 ppmv in supercritical CO2 streams containing 200 ppmv O2, 200 ppmv H2S, 200 ppmv SO2 and 200 ppmv NO2 at 10 MPa and 50 °C. The impurities and their interactions significantly promote the formation of corrosive aqueous phase, thereby exacerbating the corrosion of X52 steel. The corrosion process of X52 steel in the environment with a low H2O content is controlled by the products of impurity reactions, whereas the impurities and the products of impurity reactions jointly control the corrosion process of the steel in the environment with a high H2O content. [ABSTRACT FROM AUTHOR]

To analyze the stress distributions of electrofusion joints of polyethylene (PE) and its composite pipes, a finite element model of these joints subjected to internal pressure and axial force was established by means of the Abaqus finite element analysis software. The effects of pipe type and strength on the failure mode and burst pressure of electrofusion joints were investigated, and then short-term burst tests were conducted to verify the model. The results indicated that failure mode of electrofusion joint of PE pipe presented a ductile failure. The strength of reinforced thermoplastic pipe (RTP) influenced the failure mode and burst pressure of electrofusion joints. The failure mode transferred from pipe failure to electrofusion coupler failure with an increase of strength. The burst pressure increased with the strength of RTP at first and then tended to became stable. [ABSTRACT FROM AUTHOR]

Abstract: A Mo–Si–Al coating, which is mainly composed of Mo(Si,Al)2 and Mo5(Si,Al)3, was developed to protect a Nbss/Nb5Si3 in situ composite by air plasma spraying. After oxidation at 1250°C, the oxidation curve followed parabolic law and even after oxidation for 100h, the weight gain of Mo–Si–Al coating was 8.24mg/cm2. The surface of the oxidized samples became flatter and smoother as time increased due to the formation of SiO2 glass. Moreover, the microstructure of Mo–Si–Al coating changed and a layer structured interdiffusion zone was formed at the substrate-coating interface after oxidation. [Copyright &y& Elsevier]