Electrolysis & Stray Currents
CCE can assist with the protection of underground and underwater structures from the corrosive effects of stray electrical currents – often referred to as ‘electrolysis’. Electrolysis is the adverse effect of stray electrical DC currents on buried metallic structures.
Stray current corrosion is the damage that occurs when a direct current leaves a structure, such as a railway track and returns to the current source through another structure. Other less common sources include DC welders, DC motor drives and foreign CP systems. It differs from natural corrosion in that the damage is caused by an electric current from external sources leaving the grounded metal and is independent of the oxygen concentration of the environment.
An electrolysis mitigation system is designed to reduce the effects on metallic structures of the leakage of stray electrical currents. Where the source of the stray current is a rail system, the mitigation system comprises the feeder cables, the substation equipment and drainage bonds connected to the feeders – installed to minimise the effects of stray currents – and the electrolysis box and panel at the structure connection point.
Most of the DC current used to power our electrified Traction Systems (trains, trams and light rail transport systems) returns to the railway substations via the rail lines. However, some of this current leaks to ground (stray traction current) and in returning to the substations via this path can be picked up (and discharged) from metallic structures that may be buried nearby. This current leakage is undesired, leading to electrolysis type corrosion problems. This type of corrosion is significantly accelerated and may result in rapid failure of underground assets, such as pipelines, metallically sheathed cables, storage tanks, concrete reinforced structures and other buried assets.
In many States, when building or renovating in close proximity to an electrified traction system, as part of the development application (DA) approval process, the DA applicant may be required to engage an electrolysis expert to prepare an electrolysis report for the proposed development. This may be necessary when the proposed development is located in close proximity to a rail corridor. The purpose of this report is to identify the electrolysis (corrosion) risk to the proposed development from railway stray traction current or other DC sources that may exist in the area, and provide recommendations to control that risk.
Corrosion Control Engineering has been successfully completing electrolysis field testing and electrolysis reports for many years. We understand that DA applicants often need their electrolysis reports to be conducted quickly and efficiently. Our qualified team of technicians and engineers are well placed to provide a high level and timely service, from submission of a fee proposal to delivering a completed electrolysis report.
CCE’s electrolysis services include:
- Electrolysis Risk Assessment by Electrolysis Experts providing customers with Electrolysis Reports and recommendations.
- Field Testing – Electrolysis area tests to determine the extent of stray current issues within a traction substation area to ensure the effects of stray current corrosion have been minimised.
- Testing of stray current mitigation equipment.
- Investigate reported stray current corrosion issues to determine causes and provide mitigation measures.