Cailiao Baohu (Sep 2023)

Testing Analysis of AC Corrosion Safety Boundary Based on X70 Steel Corrosion Coupons

  • WU Guangchun, CAO Guofei, CHEN Yuliang, ZHANG Mengmeng, WANG Xiuyun, DU Yanxia

DOI
https://doi.org/10.16577/j.issn.1001-1560.2023.0228
Journal volume & issue
Vol. 56, no. 9
pp. 169 – 176

Abstract

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In this paper， based on the on-site testing of cathodic protection corrosion coupons buried in 6 cities in China， combined with some indoor corrosion simulation test results， the safety boundary of cathodic protection for buried pipelines under AC interference was preliminarily established through the analysis of the correlation between cathodic protection and interference parameters of the test coupons and corrosion rates.Results showed that corrosion rate of the test coupons under AC interference decreased with the increase of the test coupons area.The AC corrosion safety boundary based on polarization potential was established: control the polarization potential to be in the range of－0.85～－1.20 V(vs CSE) and the AC current density to be less than 30.0 A/m2， or control the polarization potential to be in the range of－0.95～－1.10 V(vs CSE) and the AC current density to be less than 100.0 A/m2.The AC corrosion safety boundary based on DC current density was established: control the DC current density to be in the range of 0.15～20.00 A/m2 and the AC current density to be less than 30.0 A/m2， or control the DC current density to be in the range of 0.15～1.08 A/m2 and the AC current density to be less than 100.0 A/m2.The AC corrosion safety boundary based on pH was established: control the pH to be in the range of 10.0 ～14.0 and AC current density to be less than 30.0 A/m2 or control the pH to be in the range of 11.3～12.5 and AC current density to be less than 100.0 A/m2.

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