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Corrosion behaviors of X70 steel under direct current interference

Jun Wang (College of Pipeline and Civil Engineering, China University of Petroleum (East China), Qingdao, China)
Zili Li (College of Pipeline and Civil Engineering, China University of Petroleum (East China), Qingdao, China)
Gan Cui (College of Pipeline and Civil Engineering, China University of Petroleum (East China), Qingdao, China)
JianGuo Liu (College of Pipeline and Civil Engineering, China University of Petroleum (East China), Qingdao, China)
Chuanping Kong (College of Pipeline and Civil Engineering, China University of Petroleum (East China), Qingdao, China)
Long Wang (College of Pipeline and Civil Engineering, China University of Petroleum (East China), Qingdao, China)
Ge Gao (College of Pipeline and Civil Engineering, China University of Petroleum (East China), Qingdao, China)
Jian Guo (College of Pipeline and Civil Engineering, China University of Petroleum (East China), Qingdao, China)

Anti-Corrosion Methods and Materials

ISSN: 0003-5599

Article publication date: 15 January 2019

Issue publication date: 25 April 2019

Abstract

Purpose

The purpose of this paper is to study the corrosion behaviors of X70 steel under direct current (DC) interference at 0-1,200 A/m2 in simulated soil solution.

Design/methodology/approach

The Tafel polarization curves of X70 steel under DC interference were tested using electrochemical method, the corrosion rate was calculated using weight-loss method and the change in steel surface was analyzed by optical microscopy.

Findings

The results showed that E-I polarization curves under 200-1,200 A/m2 interference were linear; with an increase in the DC density, the corrosion potential of X70 steel shifted positively, solution pH after the weight-loss tests increased and corrosion rate increased linearly. A mathematical relationship between polarization resistance Rp and current density was established. Corrosion morphology indicated that pitting corrosion and crevice corrosion occurred on the X70 steel under DC interference in simulated soil solution.

Originality/value

All tests were conducted at a relative higher DC density (200-1,200 A/m2). The linear fitting method is proposed to fit data of Tafel polarization curves under DC interference. This study provides guidelines for safe operation of X70 steel pipelines.

Keywords

Citation

Wang, J., Li, Z., Cui, G., Liu, J., Kong, C., Wang, L., Gao, G. and Guo, J. (2019), "Corrosion behaviors of X70 steel under direct current interference", Anti-Corrosion Methods and Materials, Vol. 66 No. 3, pp. 307-316. https://doi.org/10.1108/ACMM-08-2018-1992

Publisher

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Emerald Publishing Limited

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