埋地钢质管道腐蚀防护系统模糊评价

The Fuzzy Evaluation of Buried Steel Pipeline Corrosion Protection System

为保证埋地钢质金属管道的安全运行,掌握其腐蚀防护系统的安全现状,利用模糊综合评价法对影响埋地钢质管道腐蚀防护系统的各项指标建立模糊集,采用层次分析法确定其指标的权重大小,对埋地钢质管道的腐蚀防护系统进行分级评价,通过非开挖检测和开挖验证,依据检测结果对其腐蚀防护系统进行综合评价。以青海油田涩北气田某管道为例,通过对此管道外防腐层状况、阴极保护有效性、土壤腐蚀性、杂散电流干扰、排流保护效果5个方面的非开挖检测,根据检测结果对该埋地钢质管道的腐蚀防护系统进行综合评价,得出该管道的腐蚀防护系统等级为良。同时对该管道的防腐层外观、防腐层厚度、管道壁厚进行开挖验证,开挖5处探坑内的管道均未发现明显的外壁腐蚀,防腐层厚度基本符合要求,该管线的腐蚀程度为Ⅰ级,与模糊综合评价法的结果吻合。模糊综合评价方法简单易行、操作方便,其评价结果可以指导生产实践,具有一定的工程应用价值。

To ensure the safe operation of buried steel metal pipes and master the safety status of its corrosion protection system, a comprehensive evaluation of the corrosion protection system should be taken according to the test results of trenchless detection.The fuzzy comprehensive evaluation method is used to establish fuzzy sets of indexes for the corrosion protection system of buried steel pipes and the weight of its indicators could be determined by using the analytic hierarchy process.The corrosion protection system of buried steel pipes was graded and evaluated. Taking a pipeline in Sebei gas field of Qinghai Oilfield as an example, comprehensive evaluation is based on the test results of trenchless inspection which include 5 aspects（external corrosion protection, cathode protection effectiveness, soil corrosion, and impurity current interference）. It is concluded that the corrosion protection system of the pipe is good.At the same time,the appearance and the thickness of the coating,the wall thickness of the pipes are verified.Excavation of the five pits within the pipeline did not find significant external wall corrosion,the thickness of the coating is basically in line with the requirements,the corrosion degree of the pipeline is grade Ⅰ,which consistent with the results of fuzzy comprehensive evaluation method.The fuzzy comprehensive evaluation method is simple and easy to operate,and its evaluation result can guide the production practice and have certain engineering application value.