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Cracking corrosion of low carbon steel in environment with a high concentration of co2 and h2s

The obtained results showed pitting and general corrosion at both temperatures of 24 oC and 82 oC. In case of stress corrosion cracking (SCC) testing at 82 °C, microscopy of the samples tested for 30 days developed pitting corrosion in the surface and cracking starting in the surface of the samples. The cracks, mostly found in the middle of the samples where the maximum bending occurred. General corrosion was also observed in the samples, with significant decrease in the dimensions of the samples after testing (due to general corrosion). However, in case of sulfide stress corrosion (SSC) and hydrogen induced cracking (HIC) tests at room temperature (24-25 oC), no cracking was observed on the sample. | Vietnam Journal of Science and Technology 55 (5B) (2017) 210-216 CRACKING CORROSION OF LOW CARBON STEEL IN ENVIRONMENT WITH A HIGH CONCENTRATION OF CO2 AND H2S Nguyen Thi Le Hien1, *, Le Thi Phuong Nhung1, Nguyen Dinh Dung1 Luis F. Garfias2, Tran Hung2 1 Vietnam Petroleum Institute, 167 Trung Kinh, Yen Hoa, Cau Giay, Ha Noi 2 Wood Group, 17900 Park Row, Houston TX 77084, USA * Email: hienntl@vpi.pvn.vn Received: 11 August 2017; Accepted for publication: 11 October 2017 ABSTRACT Cracking corrosion of API 5CT Grade L80 Type 1 low carbon steel has been studied in a in brine solutions with H2S 12.3 psia and CO2 9.4 psia. Testing was performed according to the methodology reference from the NACE TM0177, Bent-beam test method in solution B for stress corrosion cracking and sulfide stress corrosion cracking test and NACE TM0284, immersion test method in solution A for Hydrogen induced cracking test. The obtained results showed pitting and general corrosion at both temperatures of 24 oC and 82 oC. In case of stress corrosion cracking (SCC) testing at 82 °C, microscopy of the samples tested for 30 days developed pitting corrosion in the surface and cracking starting in the surface of the samples. The cracks, mostly found in the middle of the samples where the maximum bending occurred. General corrosion was also observed in the samples, with significant decrease in the dimensions of the samples after testing (due to general corrosion). However, in case of sulfide stress corrosion (SSC) and hydrogen induced cracking (HIC) tests at room temperature (24-25 oC), no cracking was observed on the sample. Keywords: stress cracking corrosion (SCC, SSC, HIC), CO2 and H2S corrosion, low carbon steel. 1. INTRODUCTION The presence of carbon dioxide (CO2), hydrogen sulfide (H2S) and free water can cause severe corrosion problems in oil and gas pipelines. Internal corrosion in wells and pipelines is influenced by temperature, CO2 and H2S content, water chemicals, flow velocity, oil or