Effects of Sediments on the Corrosion Behavior of 20# Carbon Steel Pipe
GAO Qiuying1, ZHANG Jiangjiang1, YANG Zuguo1, YANG Dongming1, LIU Jining1, ZANG Hanyu2, ZHU Yuanyuan1, ZHANG Tao2
1. Northwest Oilfield Company, China Petroleum & Chemical Corporation, Urumqi 830011, China;
2. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
Abstract:The main material of the crude oil gathering and transportation pipeline in Tahe oilfield is 20# steel. The pipeline surface corrosion is mainly the wall pitting corrosion, with deposits in the pitting region. In order to study the corrosion behavior of sediments on the ground crude metal pipeline, based on the analysis on the sediment types on the inner wall of the pipeline, the cover of 20# carbon steel specimen with or without sediments is hanged in the autoclave to simulate the scene corrosion experiment, using the weight loss method, the polarization curve test, the wire beam electrode test and the scanning electron microscopy. With 20# carbon steel corrosion sediments under the coverage of the test piece, the weightlessness velocity, the corrosion process, the corrosion potential distribution and the SEM characteristics are determined, with no sediment covering the 20# carbon steel specimen. It is shown that in the area of 20# carbon steel without sediment covered, the corrosion weight loss rate is smaller than that with sediments covered; both corrosion processes are governed by the diffusion control, the latter by promoting the anodic process and reducing the corrosion potential and the corrosion resistance; the distribution of the corrosion potential does not change with time, the general corrosion, the corrosion potential distribution varies with time, with prominent pitting characteristics.