• EC • Season Cracking • Intergranular • SSC • LME • MIC • SCC • HB-HE-HIC • Fatigue • Erosion • Fretting • Stray Current  • Index

Different Types of Corrosion
- Recognition, Mechanisms & Prevention

Stray Current Corrosion

Recognition

What is stray current corrosion? Stray current corrosion or stray current electrolysis refers to corrosion resulting from stray current -current flowing through paths other than the intended circuit.

The process of stray current corrosion is electrolysis in nature. The extent of damage or loss of metal is directly proportional to the magnitude of stray current passing through the system. Underground pipelines and storage tanks without CP systems are particularly susceptible to stray current corrosion. Stray current corrosion tends to be localized, causing a concentration of pits that is not normally observed at locations where the stray current leaves metal structure.

Mechanisms

What causes Stray current corrosion? Stray current corrosion is different from natural corrosion because it is caused by an externally induced electrical current and is basically independent of such environmental factors as oxygen concentration or pH. Environmental factors may enhance other corrosion mechanisms involved in the total corrosion process, but the stray current corrosion portion of the mechanism is unaffected.

Stray current may originate from the following sources:

• (1) Electric railways 

• (2) Cathodic protection systems

• (3) Electrical welding machines

• (4) Grounded DC electric sources

Prevention

How to prevent stray current corrosion? Stray current corrosion can be prevented through:

• Identify the source of stray current

• Stop the leakage from the intended circuit by maintaining good electrical connections and insulation.

• Install impressed cathodic protection system to offset the effect of stray current.

For more details

More details on stray current corrosion are included in the following corrosion courses which you can take as in-house training courses, course-on-demand, online courses or distance learning courses:

Corrosion and Its Prevention (5-day module)
Corrosion, Metallurgy, Failure Analysis and Prevention (5 days)
Marine Corrosion, Causes and Prevention (2 days)
An Advanced Course in Cathodic Protection (5 days)
Cathodic Protection of Underground Pipelines (2 days)

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