| SUN Jian-bo,SU Xin,ZHANG Yong.Effect of H2S/CO2 Corrosion Scales on the Hydrogen Permeation Behavior of Low Chromium Steels[J],47(6):17-23 |
| Effect of H2S/CO2 Corrosion Scales on the Hydrogen Permeation Behavior of Low Chromium Steels |
| Received:February 13, 2018 Revised:June 20, 2018 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2018.06.003 |
| KeyWord:oil country tubular goods low-chromium steel H2S/CO2 corrosion corrosion product iron sulfides hydrogen permeation |
| Author | Institution |
| SUN Jian-bo |
China University of Petroleum East China, Qingdao , China |
| SU Xin |
China Petroleum Pipeline Research Institute, Langfang , China |
| ZHANG Yong |
China University of Petroleum East China, Qingdao , China |
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| Abstract: |
| To investigate the effect of corrosion product film containing chromium on the hydrogen permeation of Tubing Steels, corrosion tests of 80SS, P110-3Cr and P110-7Cr steels were carried out in high pressure and high temperature environment with the coexistence of CO2 and H2S. The hydrogen permeation current density of the specimen was measured by Devanathan-Sthachurski double-cell technique before and after corrosion. Scanning electron microscope/energy dispersive spectroscopy (SEM/ EDS), and x-ray diffraction (XRD) were used to analyzed the morphology and composition of the corrosion scales. The results show that, the corrosion products formed on the three materials are mainly composed of metastable mackinawite iron sulfides, and the typical CO2 corrosion product FeCO3 crystal is not found. There is an enrichment of chromium element in the corrosion products of P110-3Cr (7.4%) and P110-7Cr (13.75%) steels. The apparent diffusion coefficient of 80SS, P110-3Cr and P110-7Cr specimens decreases with the increase of chromium content in steels after corrosion at 120 ℃. The surface hydrogen concentration of 80SS, P110-3Cr and P110-7Cr specimens without corrosion films is 0.98×105 mol/cm3, 9.54×105 mol/cm3 and 9.3×105 mol/cm3 respectively. And the surface hydrogen concentration of the specimens with corrosion films is 0.93×105 mol/cm3, 5.17×105 mol/cm3 and 8.52×105 mol/cm3. The corrosion process of the three tubing steels is controlled by H2S under experimental conditions. The decrease of the effective hydrogen diffusivity is mainly related to the enrichment of chromium element in the corrosion products. Compared with the specimens without corrosion films, the surface hydrogen concentration of the specimens with corrosion films is reduced, and the corrosion product films have an obvious resistance to hydrogen permeation. |
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