稠油热采注汽管线爆裂失效分析

Cracking analysis of steam pipeline for thermal recovery of viscous oil

对胜利油田发生的数起稠油热采注汽管线爆裂失效事故的原因进行了综合分析。分析表明，爆裂失效均由管线内壁的局部腐蚀引起，局部腐蚀是由出现在管线内壁的非金属夹杂、点坑、魏氏组织、带状组织等缺陷在较高的温度。压力和水汽二相流条件下，组织选择性应力腐蚀和氢腐蚀共同作用的结果。为防止类似事故的再次发生，提出了严格控制介质水的含氧量，避免原材料较严重组织缺陷，以及考虑采用15CrMo高温抗氢钢代替st45．8／Ⅲ钢等改进措施。

The causes of cracking of several steam pipeline for thermal recovery of viscous on in Shengli Oilfield are analyzedcomprehansively. The result of the analysis shows that the cracking is caused by local corrosion of the pipeline inwalls,and the corrosion is resulted form the combined action of the strueture-selective stress corrosion and hydrogen carrosionwith such defects as non-metallic impurity, pitting, Widmannstatten structure, banded structure on the inner surface ofthe pipeline at high temperature and pressure and under the condition of water-vapor two-phase flow. Some measures forpreventing the cracking are given, including controlling strictly the oxygen content in the medium of water, avoiding seri-ous structure defects of raw material, and adopting 15CrMo steel instead of St45.8/Ⅲ steel.