Investigation on corrosion rate and a novel corrosion criterion for gas pipelines affected by dynamic stray current

•Synchronized potential measurements to determine subway stray current influence zone.•Determination of novel criterion for stray current interference and corrosion probability.•Developing a procedure for field investigation of dynamic stray current interference.•Quantitative analysis of dynamic stray current corrosion rate based on current monitoring.

Influence zone of the dynamic stray current from subway was determined on parallel and crossed gas pipelines via synchronized potential measurements at different transverse distances from railway right of way. Results showed that the interference magnitudes decrease substantially with increasing the distance. Twenty-four hour monitoring of pipe to soil potential, lead to a new corrosion criterion for the affected pipelines depending on the type of coating used. A procedure based upon potential measurements has been developed for field investigations. Calculations of corrosion rate via Faraday law and weight loss measurements using corrosion coupons were also carried out.