Internal corrosion direct assessment technology and applications for pipelines
DONG Shaohua, WANG Dongying, DONG Guoliang, ZHANG Hewei
1 China University of Petroleum-Beijing ,Beijing 102200, China 2 Beijing Petroleum Pipeline Company Limited of Petro-China, Beijing 100101, China 3 Kunlun Energy Company Limited, Beijing 100101, China
ICDA(Internal Corrosion Direct Assessment) technology is used for evaluation of the integrity of pipeline systems which are transporting dry gas with exposure to moisture or free water (or other electrolyte) in short-term, especially for pipelines on which ILI (In Line Inspection) cannot be carried out. There are four steps: pre-assessment, indirect detection and direct detection and post assessment. Through ICDA, the potential of water accumulation and internal corrosion in pipelines can be evaluated to identify the most probable corrosion area. If no corrosion is found in this area, it is unlikely that water will accumulate at other downstream sites. In this thesis, the method and steps of ICDA are presented and it was carried out on the pipeline section between Shenmu to Fugu valve of the Shan-Jing natural gas pipeline in Shaanxi Province. The total length of the pipeline is 52.09?km. According to different natural gas transportation modes in winter and summer, the critical angle for water accumulation in the pipeline is 6.17° in January and 1.97° in July. The data of the elevation along the pipeline is analyzed, and the elevation angle profile is obtained. Through the excavation of the high risk area with bigger inclination (larger than critical angle), there is no significant wall thinning and the pipeline is in good condition. The internal condition of the pipeline can be further determined by ICDA, which is significant for assessment of the pipeline safety status where it is not possible to carry out the ILI and in unpiggable pipelines.
