Stray current interference is a phenomenon whereby a metallic structure picks up a DC current that is leaked by an external DC power system into the soil, and subsequently discharges that same current, causing corrosion. Stray current corrosion typically affects underground pipelines, storage tanks, sheet piles, etc.
In the case of railroads, the DC traction current travels from the substation to the train and back via the rail beams. When these are not sufficiently insulated, especially at road crossings, leak currents are injected into the soil and can be picked up by underground structures such as pipelines.
The challenges of stray current interference relate to the fact that these currents
- negatively affect the cathodic protection of the underground pipelines;
- cause accelerated corrosion at the discharge points;
- generally vary with time, and are therefore hard to survey and control.
Elsyca offers engineering services based on modelling technology for troubleshooting and mitigating stray current corrosion. The analysis substantiates any necessary investments and ultimately results in a better control of the integrity of the infrastructure, by:
- quantifying the corrosion, both for the underground structure as well as for the railroad;
- determining the mitigation measures;
- assessing corrosion risk by the study of "what-if-scenarios".
A conference paper by Elsyca and the Dutch gas operator Gasunie on their experimental approach to DC interference can be viewed here.