Current from a foreign source, picked up by a pipe or tank and discharged where it does damage. DC stray current from another operator's groundbed, a DC transit system or welding returns enters a pipe in one place and leaves in another, and where it discharges back into the soil it corrodes metal fast. AC interference from parallel power lines creates shock hazards and AC corrosion. It is diagnosed by switching the suspected source and watching potentials, and cured with bonds, isolation, coating repair or mitigation grounding.
Potentials swing every time a train goes by, that's stray current interference from the transit system.
Also heard as
- stray current
- stray current corrosion
- DC interference
- AC interference
Related terms
Foreign line
Field term for another operator's pipeline or buried metal structure near or crossing your own.
Bond
Wire or cable connection that ties two metal structures together electrically, often to control CP current.
Decoupler
Solid-state device that blocks DC but passes AC and fault current, grounding a pipeline without losing CP.
Hot spot
Localized area of active corrosion on a pipeline, or the targeted anodes installed to protect just that spot.