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内腐蚀的直接评估(Internal Corrosion Direct Assessment,ICDA)技术是用于评价通常输送干气、但可能短期接触湿气或游离水(或其他电解液)的输气管道完整性的系统方法,适用于不能开展内检测的管道。其包括4个步骤:预评价、间接检测、直接检测、后评价。ICDA评估管道水聚集和内腐蚀的可能性,从而找出首个最有可能的腐蚀区域位置,如果这个区域位置通过验证没有发现腐蚀,则其他下游部位出现水聚集或腐蚀的可能性很小。本文提出了ICDA的步骤和方法,对陕京天然气管道一线陕西段神森站至府谷压气站段进行了ICDA评估,评价管道全长52.09 km,按照冬夏季天然气输送量不同,计算得出了管道水积聚析出的临界角冬季1月份为6.17°,夏季7月份为为1.97°。分析沿线高程数据,得出全线高程倾角分布图,选择多个倾角(大于临界角)较大的高风险区域位置开挖,发现管道无明显壁厚减薄,管道状况良好。通过内腐蚀评估可进一步确定管道的内部状况,对于不能实施内检测的管道安全状况评估具有重要意义。
The Internal Corrosion Direct Assessment (ICDA) technique is a systematic method for evaluating the integrity of a gas pipeline that normally delivers dry gas but may come into contact with moisture or free water (or other electrolytes) for short periods of time and is suitable for Can not carry out the test pipeline. It includes four steps: pre-evaluation, indirect testing, direct testing, post-evaluation. The ICDA assesses the probability of water plumes and internal corrosion in the pipeline to find out the location of the first and most likely corroded area. If no corrosion is found through verification of location in this area, there is very little chance of water concentration or corrosion in other downstream areas. This paper presents the steps and methods of ICDA to evaluate the ICDA of Shen Shan Station to Fugu Compressor Station in the Shaanxi section of Shaanxi-Beijing natural gas pipeline. The total length of the pipeline is 52.09 km. According to the difference between natural gas delivery volume in winter and summer, The critical angle of water accumulation in pipeline is 6.17 ° in winter in January and 1.97 ° in summer. Analyze the elevation data along the line, and get the elevation profile of the whole line. Select the excavation of high-risk areas with multiple dip angles (greater than the critical angle), and find that there is no obvious wall thickness thinning and the pipeline is in good condition. The internal condition of the pipeline can be further confirmed by the internal corrosion assessment, which is of great significance for the assessment of the pipeline safety status which can not be implemented in the internal inspection.