There are more than 33,000 km of high pressure steel pipelines stretching across Australia, of which 25,000 km are used for natural gas transmission.
This extensive long-distance network is used to transport high volumes of fluids, ranging from water to cities and farmers, oils to refineries, to gas to customers and industry. Large sections of the pipelines are buried underground, which makes it unobtrusive and quiet.
According to the article on APPEA, maintaining the integrity of the pipeline against occurrences such as corrosion and cracking is one of the key challenges with long-distance pipelines, especially given the decades of service expectancy from pipeline infrastructure. Timely intervention on even the slightest crack in the system is essential to avoid major pipeline failure with massive repercussions.
To detect pipeline anomalies, pipeline maintenance services use an important tool to verify integrity- it goes by the name “the intelligent pig.”
PIG stands for pipeline inspection gauge, or pipeline intervention gadget.
Intelligent pigs are basically robotic devices that are pumped through pipelines to make detailed measurements of the pipeline’s geometry, metal thickness, and cracks or corrosion in the pipe wall.
The PIG would travel hundreds of kilometres through pipeline networks, in a very hostile environment, while the pipeline is still operational. They face high pressures (up to 50 times that of a family car tire) and are often in petroleum fluids.
An intelligent pig is equipped with high tech instruments to take specific measurements such as: magnetic flux, which measures how easily induced magnetism flows through the metal; ultrasonics, such as that used to look at unborn babies, to measure wall thickness and cracks; and callipers that measure accurately the internal diameters of the pipe, and pick up pitting in the wall.
The PIG stores all these measurements in its built-in computer and the data is downloaded once it completes its journey. With this information, a picture of the health of the pipe is made and maintenance plans are updated to ensure the pipeline stays in the best physical condition.