Study on the Influence Law of Specimen State and Environmental Factors on Pipeline AC Interference Testing

LIANG Dong, HU Shaolei, ZHENG Yuheng, WANG Binbin, GAO Bowen, ZHU Langxian, YAN Maocheng

doi:10.16577/j.issn.1001-1560.2025.0016

Materials Protection >

2025 , Vol. 58 >Issue 1: 134 - 140

DOI: https://doi.org/10.16577/j.issn.1001-1560.2025.0016

Study on the Influence Law of Specimen State and Environmental Factors on Pipeline AC Interference Testing

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(1.State Grid Southwest Pipeline Co.， Ltd.， Chengdu 100100， China；2.National Metal Corrosion Control Engineering Technology Research Center， Institute of Metal Research，Chinese Academy of Sciences， Shenyang 110016， China)

YAN Maocheng (1976－)，Associate Professor，Research Focus:Corrosion and Control of Materials in the Oil/Gas Industry， Tel.: 18030680597， E-mail: yanmc＠imr.ac.cn

Received date: 2024-04-22

Revised date: 2024-07-05

Accepted date: 2024-07-07

Online published: 2025-02-28

Supported by

National Natural Science Foundation of China General Project Funding (52071320)

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Abstract

The pipeline stray current test is influenced by many factors， such as the coupon area， surface state and soil resistivity， which differ significantly from theoretical values， bringing uncertainty into the evaluation of interference and the formulation of mitigation measures.In this study， the influence law of factors such as specimen state， specimen area (simulating the damaged area of the anti-corrosion coating)， and local soil resistivity on AC voltage，AC current density and other AC interference parameters was investigated through on-site testing of typical interference pipelines and indoor simulation experiments.Results showed that the specimen area had a significant impact on AC current density.As the specimen area increased，the measured AC interference current density significantly decreased.The lower the environmental soil resistivity，the higher the measured AC current density.The surface state of the specimen had a significant effect on the AC current density test results.The AC current density measured by preembedded and precorroded specimens was significantly higher than that of new specimens.Under cathodic protection， local environmental alkalization occurred on the surface of preembedded or precorroded specimens， leading to an increase in pH value and a decrease in local soil resistivity， which resulted in a reduction in the diffusion resistance of the specimens， thereby significantly increasing the measured AC current density of the preembedded or precorroded specimens.

Key words： oil and gas pipelines; stray current; cathodic protection; test coupon method; anti-corrosion coating defect

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LIANG Dong, HU Shaolei, ZHENG Yuheng, WANG Binbin, GAO Bowen, ZHU Langxian, YAN Maocheng . Study on the Influence Law of Specimen State and Environmental Factors on Pipeline AC Interference Testing[J]. Materials Protection, 2025 , 58(1) : 134 -140 . DOI: 10.16577/j.issn.1001-1560.2025.0016

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