dc stray current interference

DC current leaving a metal structure via an electrolyte such as the soil or seawater will result in metal loss.  The metal loss can be calculated using Faraday’s Law.

DC interference can originate from:

  • Adjacent cathodic protection systems
  • Railways
  • Metro systems
  • Tram systems
  • Industrial systems
    • Welding operations
    • Mining
  • High Voltage DC (HVDC) power transfer systems
  • Solar power farms
  • Wind turbines
  • Space weather (telluric current)

The increased use of electrified transit systems such as tramways and railways can cause catastrophic damage to buried structures such as pipelines and steel reinforcement because of stray currents.

Stray current corrosion can affect rail life, signalling systems, rebar corrosion and corrosion of buried utility structures. Suitable track design and corrosion prevention measures on the structures can prevent this.

 
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SITE SURVEYS

 

  • Structure and rail potentials
  • Surface potential gradients
  • Soil resistivity
  • Synchronised data logging
  • Synchronised rail current measurements
  • EMC and earthing investigations
  • Cathodic protection system effectiveness

MITIGATION MEASURES & INCREASED MONITORING

 

  • Diode Drainage Bonds
  • Cathodic Protection Systems
    • Potential Controlled Transformer-Rectifiers
  • Electrical Resistance (ER) Probes
    • Real Time Corrosion Rates
    • DC Current Densities
    • Cathodic Protection System Performance
  • Remote Monitoring Systems
  • Long Term Data Logging Solutions
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SPECIFICATION REVIEW, CONSULTANCY & STRATEGY DOCUMENTATION

Corroconsult can provide the necessary documentation and specifications to enable the stray current and corrosion control and the earthing and bonding systems to be installed, commissioned and operated in accordance with the required European and National standards.  The documents and the works can be coordinated between the various disciplines (e.g. signalling and civils) to ensure a consistent approach both from the technical and the materials point of view.

 

Where project designs already exist they can be reviewed by Corroconsult and, if necessary, amended to ensure compliance and consistency.  This shall include the stray current and earthing issues associated with existing civil engineering designs for infrastructure e.g bridges.

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