1. Stray currents corrosion of underground steel pipelines
Groza Stefana Madalina
ISBE, 2nd year

2. ELECTROMAGNETIC POLLUTION

5. Earth’s molten iron-nickel core
Charged gases of the ionosphere
Resonances
Biological time clocks

6. MAN ANIMAL PLANT
DISORIENTATION
DISCOMFORT
DEATH

7. ALL TYPES OF BACKGROUND RADIATION HAVE INCREASED SO DRASTICALLY AND SO QUICKLY IN THE LAST FIFTY YEARS THAT WE CAN NO LONGER HOPE TO COPE WITH THEM.

8. STRAY CURRENT CORROSION
ELECTROMAGNETIC FIELDS NATURAL PROCESSES
ELECTRIC AND MAGNETIC COMPONENTS
THERMAL SIDE EFFECT

9. THE CORROSION OF THE UNDERGROUND STEEL PIPELINES
TECHNOLOGICAL AND INDUSTRIAL DEVELOPMENT
PRODUCTION AND CONSUMPTION OF ELECTRICITY
ELECTROMAGNETIC POLLUTION
THE CORROSION OF THE UNDERGROUND STEEL PIPELINES

11. The first mobile laboratory specialized in investigating and determining the dispersion in DC currents
(Los Angeles, 1910)

12. Stray currents may originate from
cathodic protection system
electrical welding machines
grounded dc electric sources
street railway systems, etc

13. Stray current corrosion
DC traction system
Stray current corrosion
In this case rails act as primary current return path and the surrounding ground acts as a conductor that can carry stray currents. There is a fundamental tendency for the return current in the rails to flow from the train to the substation. Because the tack is not perfectly insulated from the ground, there is a tendency for the current to flow in the ground in the same direction. Here the stray current will be picked up by the pipeline near the train and discharge near the substation.

14. The corrosion resulting from stray currents (external sources) is similar to that from galvanic cells (which generate their own current) due to the fact that the corroding metal is again considered to be the anode from which current leaves to flow to the cathode.
Soil and water characteristics affect the corrosion rate in the same manner as with galvanic-type corrosion.
Despite the apparent similarity, stray current strengths may be much higher than those produced by galvanic cells and thus corrosion may be much more rapid. Moreover, seeking the path of least resistance, the stray current from a foreign installation may travel long distances along a pipeline causing severe corrosion where it leaves the line.

15. Accentuated degradation of the fastened elements in the Budapest’s subway
The corrosion of the gas pipes due to the stray DC currents which originate in Bucharest’s tram and subway
Damages of the pipeline in Cluj-Napoca

16. Stray current corrosion prevention
Eliminate or reduce stray current
Acting on the source instead on the consequences
Increasing the global circuit resistance

17. an external current that reduces or inverses the anodic current.
CATHODIC PROTECTION
sacrificial anodes
impressed current/voltage anodes
CURRENT DRAINAGERS
varying the boosting DC voltage
changing the resistance of the direct connection
bringing the galvanic potential of the metal to a level where the anodic reactions are impossible for the given circumstances
an external current that reduces or inverses the anodic current.
possible when the sources of the stray currents are accessible
the connection is made unidirectional, such that current can only flow from the buried structure to the negative pole of the DC source, thus rounding the electrolyte (the soil)

18. Bibliography