In the oil and gas industry, it has been established that for pipelines fabricated with carbon steels, their limitation is related to H<sub>2</sub>S and CO<sub>2</sub> environments, which is 7 ...In the oil and gas industry, it has been established that for pipelines fabricated with carbon steels, their limitation is related to H<sub>2</sub>S and CO<sub>2</sub> environments, which is 7 to 10 psia of partial pressure of <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub>. Therefore, in carbon steel cracking is shown, after 7 or 10 psia of partial pressure of <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub>. The experimental work was performed under static conditions in autoclaves within a pH of 3 to 3.8;partial pressures of 16 - 96 psi for H<sub>2</sub>S and 15 - 53 psi for <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub>, in the temperature range of 25<span style="white-space:nowrap;">°</span>C - 150<span style="white-space:nowrap;">°</span>C. It was observed that the average yielding stress used in Sulfide Stress Cracking (SSC) tests decreases with temperature increment. Hydrogen Induced Cracking (HIC) evaluations showed that X52 steel, under conditions, was not susceptible to HIC. Results of SSC did not show indications of cracking after exposure to sour solutions, except for the specimen exposed to high H<sub>2</sub>S and <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub> content (96 psi of H<sub>2</sub>S and 53 psi of <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub> of the partial pressure) and high temperature (150<span style="white-space:nowrap;">°</span>C). Microcracks located between the upper and lower weld beads were also observed. However, the highest average corrosion rate was 0.27 mm/year (10.6 mpy), which occurred in samples exposed to 96 psi of H<sub>2</sub>S and 53 psi of <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub> at 150<span style="white-space:nowrap;">°</span>C. Likewise, the highest localized corrosion (severe pitting attack) was obtained at the same environment with a corrosion rate of 4.2 mm/year (167 mpy). The oil and gas industry could use carbon steels pipelines in partial pressure higher than 10 psia.展开更多
Hydrogen induced cracking（HIC） behaviors of a high strength pipeline steel with three different microstructures, granular bainite ＆ lath bainite（GB ＋ LB）, granular bainite ＆ acicular ferrite（GB ＋ AF）, and qu...Hydrogen induced cracking（HIC） behaviors of a high strength pipeline steel with three different microstructures, granular bainite ＆ lath bainite（GB ＋ LB）, granular bainite ＆ acicular ferrite（GB ＋ AF）, and quasi-polygonal ferrite（QF）, were studied by using corrosion experiment based on standard NACE TM0284. The HIC experiment was conducted in hydrogen sulfide（H_2S）-saturated solution. The experimental results show that the steel with GB ＋ AF and QF microstructure present excellent corrosion resistance to HIC, whereas the phases of bainite lath and martensite/austenite in LB ＋ GB microstructure are responsible for poor corrosion resistance. Compared with ferrite phase, the bainite microstructure exhibits higher strength and crack susceptibility of HIC. The AF ＋ GB microstructure is believed to have the best combination of mechanical properties and resistance to HIC among the designed steels.展开更多
文摘In the oil and gas industry, it has been established that for pipelines fabricated with carbon steels, their limitation is related to H<sub>2</sub>S and CO<sub>2</sub> environments, which is 7 to 10 psia of partial pressure of <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub>. Therefore, in carbon steel cracking is shown, after 7 or 10 psia of partial pressure of <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub>. The experimental work was performed under static conditions in autoclaves within a pH of 3 to 3.8;partial pressures of 16 - 96 psi for H<sub>2</sub>S and 15 - 53 psi for <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub>, in the temperature range of 25<span style="white-space:nowrap;">°</span>C - 150<span style="white-space:nowrap;">°</span>C. It was observed that the average yielding stress used in Sulfide Stress Cracking (SSC) tests decreases with temperature increment. Hydrogen Induced Cracking (HIC) evaluations showed that X52 steel, under conditions, was not susceptible to HIC. Results of SSC did not show indications of cracking after exposure to sour solutions, except for the specimen exposed to high H<sub>2</sub>S and <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub> content (96 psi of H<sub>2</sub>S and 53 psi of <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub> of the partial pressure) and high temperature (150<span style="white-space:nowrap;">°</span>C). Microcracks located between the upper and lower weld beads were also observed. However, the highest average corrosion rate was 0.27 mm/year (10.6 mpy), which occurred in samples exposed to 96 psi of H<sub>2</sub>S and 53 psi of <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub> at 150<span style="white-space:nowrap;">°</span>C. Likewise, the highest localized corrosion (severe pitting attack) was obtained at the same environment with a corrosion rate of 4.2 mm/year (167 mpy). The oil and gas industry could use carbon steels pipelines in partial pressure higher than 10 psia.
基金supported by the National High Technology Research and Development Program of China(Grant No.2015AA03A501)the National Natural Science Foundation of China(Grant No.51274063)
文摘Hydrogen induced cracking（HIC） behaviors of a high strength pipeline steel with three different microstructures, granular bainite ＆ lath bainite（GB ＋ LB）, granular bainite ＆ acicular ferrite（GB ＋ AF）, and quasi-polygonal ferrite（QF）, were studied by using corrosion experiment based on standard NACE TM0284. The HIC experiment was conducted in hydrogen sulfide（H_2S）-saturated solution. The experimental results show that the steel with GB ＋ AF and QF microstructure present excellent corrosion resistance to HIC, whereas the phases of bainite lath and martensite/austenite in LB ＋ GB microstructure are responsible for poor corrosion resistance. Compared with ferrite phase, the bainite microstructure exhibits higher strength and crack susceptibility of HIC. The AF ＋ GB microstructure is believed to have the best combination of mechanical properties and resistance to HIC among the designed steels.
