Research on Stray Current Corrosion Evaluation of BuriedMetallic Pipeline in an Urban Rail Transit System

摘要

In this paper, a research is made on the stray current corrosion evaluation of buried metallic pipeline inan urban rail transit system. The long-term accuracy of the polarization potential measurement is foundnot to be perfect for the stray current corrosion evaluation, which is caused by the life cycle, theworking condition and the IR drop error of the reference electrode. Furthermore, according to theFaraday laws of electrolysis, an optical fiber sensing method is proposed to measure the straycurrent, which can be applied to evaluate the stray current corrosion status directly. The maximum ofthe stray current is found to be 20 A. And the design principle and configuration of the optical fibersensing system are demonstrated. Moreover, the comparison is conducted between the polarizationpotential measurement results in 2004 and the results in 2010, which verifies the analysis results on theimperfect long-term accuracy. In addition, the transient response test and accuracy test of the opticalfiber sensing system are conducted, which indicates that its response time and relative error are lessthan 0.73 ms and 0.4%, respectively. Finally, the stray current corrosion status of the pipeline 60are evaluated based on the results of the direct measurement method, which indicates that the corrosionperforation will be caused in anode region if the corrosion time is greater than 2 months and 11 monthsat 20 A and 4 A, respectively.