Flying pigs: the essential process that keeps the gas flowing

3 min

‘Pigging’ may not be a familiar term but it is a critical process for ensuring the safety and integrity of the pipelines that supply gas during these cold winter months.

We all rely on gas, especially during the cold season, in our homes and businesses but, given there are thousands of kilometres of gas pipelines throughout Australia, ensuring these pipes are in good working order is a priority for the industry. This is where pigging comes into play.

A pipeline inspection gauge, or a pig for short, is an essential safety and maintenance tool, utilised in the utility pipeline industries to identify potential corrosion, defects (such as cracks that could develop into leaks) or any blockages or obstacles that might obstruct the flow of gas. This plug like device helps to maintain the integrity of the pipeline, ensuring the safe and reliable supply of gas for consumers and businesses alike.

Pigging a pipeline starts with a pig trap – a Y shaped section in the pipeline that includes a launcher and a receiver. The launcher is the pig’s entry point into the pipeline, where it is pushed along by line pressure. The receiver acts as a point to remove the pig from the pipeline, as well as any debris that it has knocked loose.

There are different types of pigs utilised for a variety of purposes, a gauge or calliper pig for instance measures any narrowing of the pipeline which helps determine if a more advanced or expensive pig will be able to pass through. This is often followed by a cleaning pig which ensures that the pipeline is free of any debris or blockages. This literally clears the way for intelligent or smart pigs, which have magnetic sensors to measure the thickness of the pipeline wall, in their search for defects like corrosion.

Some of these smart pigs (which require certain velocities in the pipeline to successfully perform the tests and deliver reliable data) have GPS capabilities which helps maintenance teams save valuable time and money by isolating and zeroing in on a problem. The alternative would require a team having to work through hundreds or even thousands of kilometres of pipeline to locate an issue. Smart pigs are also instrumental in determining the remaining life of an asset.

Pigging is undertaken periodically (usually by the asset owner, such as APA Group) and it tends to happen every ten years or so. AEMO, in its role as the market operator, has to provide approval for any maintenance to ensure that all planned works do not impact the reliability of gas supply or systems security.

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