Cathodic protection counters corrosion of pipelines

SA Water’s extensive network of buried pipelines requires protection from a never-ending problem – corrosion, a.k.a. rust. The gradual destruction of pipes through corrosion is caused by the electrochemical reaction of the metal pipes with the surrounding soil and can be controlled through an ingenious technique called cathodic protection.

Cathodic protection helps maximise the life of these assets through the use of sacrificial anodes. These are magnesium or aluminium rods that channel the electrically induced corrosion away from the pipes and attract the destructive electrolytic action to themselves. For this reason, they rust more quickly than the pipeline they are protecting, before corroding completely before the metal pipe can react with the electrolytes. Quite a sacrifice indeed!

Sometimes the electric fields created by the anode can protect a pipeline several kilometers from the anode itself and so is an effective preventative measure across our networks.

Our team is charged with protecting SA Water’s pipeline system by monitoring the pipe-to-soil potential of the pipe. When a minimum reading is reached, the anode is tested and, if used up, it is replaced.

A new sacrificial anode site at Williamstown was successfully tested by Water Engineering Technologies’ South Para team to protect the 800 mild-steel concrete lined pipeline that runs through Fromm Square from corrosion. This preventative maintenance intervention will significantly extend the pipeline's expected life and reduce the risk of community disruption that would result having to replace it. Through the use of our capabilities we have helped SA Water realise significant savings for each anode install and replacement.