我国渤海湾某油田开展了天然气利用项目, 天然气外输海管选用国产X65管线钢手工电弧焊接铺设完成。随着油田不断深入开发, 外输天然气中H2S含量持续增长, CO2含量高达10%左右, 使该海底管线面临着潜在的应力腐蚀开裂风险。参考NACE相关标准, 研究了不同工况条件下X65管线钢焊接接头在H2S/CO2环境中的抗硫化物应力腐蚀开裂(SSCC)性能。结果表明, 该X65管线钢焊接接头在H2S/CO2环境中抗SSCC性能优良, 但在低温偏酸性条件下表现出一定的SSCC敏感性。建议在管线的运维过程中采取措施控制外输温度并尽量降低酸性气体含量, 以防止SSCC发生。

An offshore nectural gas (NG) utilization project in Bohai Bay of China is carried out and API 5L X65 steel made in China is selected for the subsea NG transmission pipeline. Whereas, H2S content in NG is increasing along with the exploitation of the field, and CO2 content is up to 10%, so the subsea pipeline faces with stress corrosion cracking risks. Therefore, on stress corrosion cracking resistance of X65 pipeline steel welded joint in simulated H2S/CO2 environment was studied by referencing the test method of NACE TM0177-2005. Results show that the X65 pipeline steel welded joint has excellent performance of SSCC resistance in H2S/CO2 environment. However, a certain degree of SSCC sensitivity appeared at low temperature under acidic conditions. Some suggestions for controlling SSCC were presented in order to ensure the pipeline′s safety in running, includes controlling NG transmission temperature in a appropriate range and reducing acid gas content as far as possible.