Stray Current Interference Corrosion and Protection Technology in Long-Distance Natural Gas Pipelines

Abstract Long-distance natural gas pipelines are subjected to interference from multisource stray currents, resulting in corrosion rates far exceeding natural levels. Existing research often overlooks multisource coupling, and traditional cathodic protection systems are prone to instability under 0–50 Hz fluctuations with insufficient monitoring coverage. To address these issues, this study establishes a three-dimensional coupled finite element and boundary element joint model for pipelines, soil, and power sources. It quantitatively analyzes potential distribution under multisource stray currents with amplitudes of 0–10 A and frequencies of 0–50 Hz. An experimental platform with a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="1 ratio 20" display="inline" overflow="scroll"> <mml:mn>1</mml:mn> <mml:mo>∶</mml:mo> <mml:mn>20</mml:mn> </mml:math> scale ratio is constructed for protective technology research. The results show that composite protection reduces the standard deviation of potential fluctuations from 0.25 V (unprotected) to 0.05 V, achieving an 80.00% reduction. In a 48-h weight loss experiment, the average corrosion rate under composite protection is only <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="0.05 m m divided by normal a" display="inline" overflow="scroll"> <mml:mn>0.05</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>mm</mml:mi> <mml:mo stretchy="false">/</mml:mo> <mml:mi mathvariant="normal">a</mml:mi> </mml:math> . Electrochemical tests reveal increased polarization resistance, a 2.1-fold increase in Nyquist curve radius, an 89.67% transient suppression rate, and an overall protective efficiency of 87.52%. This study constructs a closed-loop verification framework combining modeling, experimentation, and protection under multisource stray current scenarios. Results show that the proposed composite protection technology can control pipeline potential fluctuations within <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="plus or minus 10 m upper V" display="inline" overflow="scroll"> <mml:mo form="prefix">±</mml:mo> <mml:mn>10</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>mV</mml:mi> </mml:math> and reduce the corrosion rate to below <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="0.05 m m divided by normal a" display="inline" overflow="scroll"> <mml:mn>0.05</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>mm</mml:mi> <mml:mo stretchy="false">/</mml:mo> <mml:mi mathvariant="normal">a</mml:mi> </mml:math> , demonstrating good potential stability and corrosion inhibition capabilities. This method has potential application value in the optimization and upgrading of in-service pipeline protection and provides certain engineering reference significance for improving the operational safety of the national energy pipeline network.