摘要
随着我国城市建设的不断推进,对城市轨道交通和能源的需求越来越大,城市地铁系统与埋地油气管道平行或交叉的情况越来越多,由地铁等轨道交通引起的动态直流杂散电流引起的管道腐蚀问题也越来越受到关注。目前对于动态直流杂散电流干扰下的腐蚀机理尚不明确,以某遭受地铁杂散电流干扰的输气管道为研究对象,采用腐蚀试片法进行了地铁影响下管道受干扰参数的测试分析、地铁杂散电流对邻近油气管道的腐蚀影响及腐蚀风险评价方法研究。结果表明:动态直流干扰下,管道腐蚀特征为局部腐蚀,其腐蚀速率远远大于自腐蚀试片腐蚀速率,且均超过了标准要求(0.0254mm/a);若干扰段管道防腐层存在破损,破损点越多、破损面积越大,同等大小的干扰电流在此处造成的电流密度越小,其遭受的干扰腐蚀风险越低,但其他腐蚀风险更高。基于上述分析获得了动态直流干扰下管道腐蚀风险的评价准则,建立了基于断电电位偏移量和偏移时间比的管道腐蚀风险评价方法,可实现地铁干扰下管道腐蚀风险的非开挖间接评价。
With the advancement of the urban construction in our country and the increasing demand for urban rail transit and energy, the paralleling and crossing conditions of city subway system and buried oil and gas pipelines are more and more, and the pipeline corrosion problem caused by the dynamic DC stray current made by rail transit like subway gets more attention. The corrosion mechanism of dynamic DC stray current under interference is not yet clear. A gas pipeline suffering subway stray current interference is taken as the study object, and the corrosion block test method is used to carry out the parameter test analysis of pipeline under the influence of subway and the study on the influence of subway stray current on oil and gas pipelines nearby and corrosion risk assessment methods. The results show that under the subway dynamic DC interference, the corrosion characteristic of pipeline is local corrosion, whose corrosion rate is far higher than the coupon corrosion rate of self- corrosion, and they both exceed the standard requirements (0.0254 mm/a). If the anti- corrosion layer of the interfered pipeline is damaged, the more the damage points and the larger the damaged area, the smaller the density of the current caused by equal interference current, the lower the interference corrosion risk it will suffer, and the higher the other risks it will face. Based on the above analysis, the assessment criteria of pipeline corrosion risk under dynamic DC interference are obtained, and the pipeline corrosion risk assessment method based on the offset and offset time ratio of power- off potential is established, which could realize the trenchless indirect assessment of pipeline corrosion risk under subway interference.
作者
张文艳
傅江
王小平
ZHANG Wenyan;FU Jiang;WANG Xiaoping(Gas Management Department of PetroChina Southwest Oil & Gasfield Company;Exploration and Development Research Institute of PetroChina Southwest Oil & Gasfield Company)
出处
《油气田地面工程》
2019年第10期110-117,共8页
Oil-Gas Field Surface Engineering
关键词
油气管道
地铁杂散电流
腐蚀影响
风险评价
oil and gas pipeline
subway stray current
corrosion effect
risk assessment
