A new corrosion sensor that takes advantage of the features of pipeline coatings to perform electrochemical corrosion rate measurements offers exciting potential as an effective way to detect and prevent dangerous corrosion in underground pipelines.
High pressure underground pipelines are typically protected against corrosion by a combination of barrier coatings and cathodic protection systems. When their coatings become disbonded, pipelines become susceptible to corrosion, which can eventually lead to leaks or catastrophic failure. For example, undetected oil leaking from a corroded pipeline in Qingdao, China, in 2013 caused a major explosion and killed 55 people. A major gas explosion on Varanus Island in Western Australia in 2008 caused an energy crisis in the state. The explosion was also due to unidentified localised corrosion.
Maintaining the vast network of pipelines that carry oil and gas across Australia is a massive task that involves millions of dollars a year spent in regular assessment to detect corrosion issues and target sections that need to be replaced or repaired. Operating pipelines safely relies on inspection to detect and repair disbonded areas, but digging up pipelines is expensive, so pipeline managers use sophisticated indirect assessment techniques to locate and prioritise defective areas. Even so, the tools available do not always detect localised corrosion.
An effective and commonly used method to detect corrosion is smart pigging, where a non-destructive testing device known as a pig is inserted in the pipe and carried along by the fluid flow. However, this method is expensive and is usually only carried out at intervals of at least five years. Smart pigging is capable of locating pipeline defects through metal loss evaluation but usually only detects corrosion once the damage is greater than 30 per cent of the original pipe wall thickness.
A new corrosion sensor that enables continuous and real-time monitoring of the efficiency of cathodic protection and the initiation and spread of localised corrosion could complement smart pigging as an effective way to detect and prevent dangerous corrosion. This new sensor is being developed by a research team led by professors Mike Tan and Maria Forsyth at Deakin University’s Institute of Frontier Materials, supported by the Energy Pipelines Cooperative Research Centre. The sensor simulates the conditions occurring at typical corrosion defects and measures corrosion rates electrochemically. The sensor can check remotely every day and identify localised corrosion in its early stages. In the case of Qingdao, for example, the sensor would have shown the extent of the problem.
The advantages of sensors over other methods include their low operational costs, their flexibility for use with different pipeline designs and their high inspection frequency. Deakin University PhD student Facundo Varela is the driving force behind the development of this new sensor. He says that it is an exciting new technology that could help people to see an essentially invisible process that occurs underground and to inexpensively evaluate the associated risks in minutes. Testing in the laboratory has given good results and the probe will be tested on pipelines in the field this year.
For more information contact Professor Mike Tan at {encode=”mike.tan@deakin.edu.au” title=”mike.tan@deakin.edu.au”}
