针对雅克拉气田天然气西气东输管道巡检开挖过程中发现的典型腐蚀案例,应用超声波测厚及管壁探针测深技术对开挖点腐蚀管道进行了检测,结合管道介质工况、周围土壤及地形条件,对腐蚀管道的外防腐蚀层情况、腐蚀产物、腐蚀特征、腐蚀因素及原因等进行了观察、测试及分析.结果表明,管道腐蚀原因为防腐蚀层及阴极保护失效状况下的含水土壤溶解氧腐蚀.结合管道设计、运行参数及检测数据,进行了管道安全性评价及剩余寿命预测.结果表明,该管道上游3.5 km以内管道处于非安全区,需及时开展腐蚀治理.针对管道腐蚀问题,提出了针对性治理措施.

Aimed at the corrosion of west to east gas transmission pipeline in Yakela gas field founded during excavation,ultrasonic thickness and wall probe sounding technology were used to detect the corrosion of excavated pipelines.Combined with the pipeline medium conditions,surrounding soil and terrain conditions,the corrosion of pipeline anti-corrosion layer,the corrosion products,the corrosion characteristics,the corrosion factors and mechanism were observed,tested and analyzed.The results showed that the cause of pipeline corrosion was dissolved oxygen corrosion in soil containing water under the failure condition of anti-corrosion layer and cathodic protection corrosion.Combined with the pipeline design,operation parameters and test data,the safety evaluation and prediction of residual life of the pipeline were conducted.The results showed that the pipeline upstream within 3.5 km was in a non secure area,needing corrosion control.Aimed at the corrosion problem,specific measures were put forward.