| ZHANG Jie,LI Lin-tao,HUANG Zhi-juan.Strain Corrosion Sensibility of Duplex Stainless Steel in Environment with Low H2S and High CO2 Pressure[J],45(7):96-101 |
| Strain Corrosion Sensibility of Duplex Stainless Steel in Environment with Low H2S and High CO2 Pressure |
| Received:March 03, 2016 Revised:July 20, 2016 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2016.07.017 |
| KeyWord:duplex stainless steel cracking sensibility pitting corrosion temperature low H2S partial pressure corrosion rate |
| Author | Institution |
| ZHANG Jie |
Research Institute of Petroleum Engineering, Sinopec Northwest Oilfield Company, Urumqi , China |
| LI Lin-tao |
Research Institute of Petroleum Engineering, Sinopec Northwest Oilfield Company, Urumqi , China |
| HUANG Zhi-juan |
Research Institute of Petroleum Engineering, Sinopec Northwest Oilfield Company, Urumqi , China |
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| Abstract: |
| Objective Aimed at the service restrictions of duplex stainless steel in standard IS15156, cracking sensibility of duplex stainless steel 2205 at different temperatures and diverse low H2S partial pressures was studied. Methods The experiments of weight loss and three point bending test were carried out in the simulated corrosion environment based on acid oilfield containing low H2S and high CO2 in West China. High temperature and pressure autoclave was used during the test. SEM combined with EDS was joined to analyze the surface morphologies and corrosion scales. Results The corrosion rates of duplex stainless steel 2205 were low in our experiments. All of the results were below 0.014 mm/a. The effect of H2S partial pressure was not evident. But pitting corrosion caused by oxide inclusions such as Al2O3 was discovered. Stress corrosion cracking happened to duplex stainless steel 2205 during the test at 100 ℃ under low H2S partial pressure. Meanwhile, selective corrosion occoured. Ferrite phase corroded prior to austenite phase. Pitting corrosion occurred at other test temperatures. And also, the cracking sensibility diminished to a certain extent with the elevation of H2S partial pressure. Conclusion Under low H2S partial pressure, the cracking type of duplex stainless steel 2205 was hydrogen embrittlement stress cracking according to the analysis on the pattern of fissure. The oxide inclusion induced pitting corrosion which led to the assembling of H. And then, hydrogen embrittlement happened. With the lifting of H2S partial pressure from 6 kPa to 165 kPa, the raising sensibility of local corrosion relieved the hydrogen embrittlement. The cracking susceptility reduced. Duplex stainless steel 2205 was not suitable for the mesotherm condition containing low H2S in wellhead. The service restrictions based on H2S partial pressure was not perfect. |
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